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JoeTR6 (Forum Supporter)
JoeTR6 (Forum Supporter) Dork
7/27/20 11:34 a.m.

The same thing happened with my Fiesta ST.  The peg didn't completely break off so I was able to run a 10-32 bolt through it.  

dps214
dps214 HalfDork
8/10/20 1:25 p.m.

I talked my codriver into taking an event off from the GT3 so that I could justify buying a new set of tires for the Cayman since the rears seemed to have finally bit the dust at the last local event. Also an opportunity to see what the yoko A052s are all about and if it's something we're interested in trying out of the GT3 down the road. That event was the Peru CAM Challenge this past weekend.

So I mounted up the tires and installed rear tie down hooks so the car is a little bit less of a pain to strap down in the trailer. I'm not a huge fan onf any of the front tie down options, so we stuck with strapping through the wheels for now. Annoying, but much less so than having to strap all four wheels.

Put the car in the trailer and headed out friday morning to try to get a feel for the car on the practice course. Being a CAM event (basically a match tour format) the whole event was basically test and tune for us, but there were enough other AS cars in attendance that we wanted to have a decent setup on the car for the real event. Made a sway bar change and some tire pressure tweaks and then got the car all stickered up for saturday. Classy tape numbers because no part of this car is magnetic and large enough to hold magnetic numbers, and I keep putting off getting vinyl ones.

Saturday morning we had some teething issues with the tires, forgetting that these aren't rivals and need to be as cold as possible to be happy. Fixed that for the afternoon and the car felt a lot better and was about half a second faster. We ended up fourth and fifth overall of the 30-something non-CAM cars at the event. Sunday morning we went even more aggressive with tire cooling and I decided to try running with the shocks "off" to see what happened. Some combination of those two things and the slightly cooler weather resulted in a better feeling car and another couple tenths improvement in time, despite never really having a run without at least one noteworthy mistake. Usually at somewhere around 7-8 runs on the same course I start to get in my head and overthink things that I'd been doing well all weekend, and this was no exception. My fastest run of the weekend, not exactly sure where the cone was:

The course was...very CAM. It walked awkwardly in places but ended up being pretty fun and a nice departure from the typical generic Peru course. I wouldn't want every course to be this way, but getting to use basically all of the ~76mph second gear every now and then is fun, even if the couple of drag strips on the course put us at a pretty decent disadvantage to the other AS cars which were all corvettes and made it a little hard to judge just how competitive this car is. As for the tires, they're fine but not life changing. Working from cold is nice, but it's a huge pain to keep them cool enough to work past the first runs of the session.

Also did some pandemic autocross trailer camping in style at a local campground, since the event site doesn't allow anyone to stay overnight.

dps214
dps214 HalfDork
8/18/20 10:02 a.m.

Another weekend of local autocross. Saturday was.....wet, to say the least:

Sunday was dry and I liked the course better. I made a bar change from saturday as the A052s seem to be extra sensitive to chassis setup. Still probably too stiff and I never loved the way the car drove, but after three runs (which we all know is what really matters) I had top pax and top raw time even. Couldn't quite hold on to that as everyone else's tires came up to temp and mine overheated, ended up third on index and second on raw time.

 

dps214
dps214 HalfDork
9/9/20 9:28 a.m.

Almost forgot to post...finally completed the trifecta (street, autocross, track) last friday at Mid Ohio. Showed up early enough to get this photo with my friend's air cooled 911 at registration:

I went cautious and set the rear bar to full soft (basically equivalent to stock), that plus sport mode shocks resulted in the car generally having a touch of on throttle understeer and being mostly neutral on turn in, but the right (wrong?) inputs could also get the rear unsettled a bit. Probably not the fastest setup, but safe, still fun, and easy to push hard knowing that I didn't really need to leave space on corner exit to catch a slide. The car held up great, oil temps would start to climb after a few laps, but a half lap of cooldown was enough to bring them back to a comfortable place, and that usually coincided with the tires wanting a cooldown as well, so it really wasn't too big of a deal. Brakes were great, never had any heat or fade issues, though at some point in the day they seem to have left some deposits on the rotors.

 

mr2s2000elise
mr2s2000elise SuperDork
9/9/20 9:30 a.m.

Nice to see the a052! I am running same one my Mr2 and elise . Real step up from my a048s

dps214
dps214 HalfDork
11/11/20 11:06 a.m.

Well, I've been slacking as usual, time for some updates. It's been almost exactly a year of ownership, and while that year didn't go anywhere near the way I (or anyone) expected, I have no regrets and the car has been pretty much flawless. Despite working from home more than half of that time, I managed to put something like 5k miles on it, which I think is more than I've put on my DD in that same period. And I probably ended up doing more motorsport events with it than I would have in a normal year because of the way everything worked out. 

This weekend was the last event of the season, and so it's time to really turn my attention to winter projects. There's some boring maintenance and reliability upgrades on the horizon, but that's not the interesting part. There's a decent chance that the 981S is going to be classed for STU (autocross) next season, and I want to turn my attention slightly towards more track stuff and maybe some SCCA TT events. This season pretty much concluded that I'm only ever going to autocross this locally (and it looks like our local season may be sparse to non-existent next year) so I don't really care too much about autocross competitiveness but would love to get more tire on the car and hopefully a setup that wears the tires a bit less aggressively...and is faster, of course. Luckily what I was looking at as a half-baked STU build more or less lines up with SCCA TT "sport" class rules. So that's the route I'm going.

My main goal was to make it through a year without buying any new tires....so here's the second set of new tires I've bought this year:

Okay, it's technically two pairs of rears, because I got a deal I couldn't pass up but could only buy complete sets of a single size. I've been intrigued by the goodyear supercar 3s for a while, and they were extra cheap and one of the few tires that has a 295 width size (the limit for mid engine STU cars assuming those rules go through) so it was any easy choice. While nominally 295s, they're dimensionally nearly identical to the RE71R/rivalS 305s. TT allows up to 315s, and while those tires might fit under the rear fenders, the wheels needed to get the most out of them don't really, so this should be a good compromise that will work, look decent, and not rip the fenders off. Fronts will be 275s. I'd actually prefer 265s, but goodyear made some ...interesting choices for sizes of these tires and the only 265s are super giant diameter which won't work. Mounted them on some Tire Rack clearance special wheels that are a bit better match to the fronts than the porsche replica wheels I used to test fit a while ago, and here's what we've got (front tires are used stand in RE71Rs):

Only a little silly looking with the staggered diameters (18" front, 19" rear) and different wheel designs. They both fill out the fenders much better than the tiny, narrow AS wheels/tires did, so that's nice.

The other big thing is swaybars. The TT rules are kind of weird on this, there's some aftermarket options that I probably could have gotten approved, but most of them are pretty expensive or not quite the adjustment range I want. The rules do allow OE bars from other trim levels of the same car though. I already have a GT4 rear bar, and I happened across a lightly used GT4 front bar for pretty cheap on ebay. So that was another easy choice. Unfortunately the GT4 bar is a slightly different shape and mounts to the knuckle differently, and neither the GT4 endlinks or my stock endlinks will work. So I need to either make or buy something for that, but the aftermarket bars have the same issue so I would have had to deal with that either way. Much like the rear bar, this has the ability to be set to nearly as soft as stock, which is a nice option to have for something that's still primarily a street car. But bar, endlinks, and mounts, all for cheaper than just the bar new:

I had originally intended to upgrade to GT3 control arms as well, to get more camber in the front end, but I think I'm going to hold off on that for now. For one thing, they're not TT legal, so I'd have to swap back to stock for TT events which is a pain. Also, I really don't expect much of a handling improvement from it, mainly better tire wear. There's two issues with this though. One, the current setup seems to wear the street tires pretty much perfectly, which means adding camber would help track tire wear, but probably hurt street tire wear. Two, the control arms are expensive. Like 2-3 pairs of front tires worth, so even if they double the life of the front tires, it's going to be a while before it's actually a net cost savings. So I'm going to leave it alone and see what happens, the extra front roll stiffness and better sized wheels/tires should make for better wear anyway.

dps214
dps214 HalfDork
11/13/20 11:17 a.m.

So, focusing more on track stuff means more travel, which means having the ability to make long drives without ruining the good tires, which means...tire trailer time. Which means adding a hitch to the cayman. There's an off the shelf option, but it's expensive. I was nearly prepared to just spend the money, but the more I looked at it, the more I realized I wasn't a fan of the design, specifically the way it mounts to the bumper beam. That plus the cost was enough motivation to try to make one myself. (Note, I understand why the off the shelf option is made the way it is, and it seems to work...it's just not for me). The only place to mount to is the rear bumper beam. On previous generation cars this was a pretty substantial single piece aluminum extrusion, which is pretty easy to just bolt straight to without too much forethought. The newer cars, though, are a thin wall, multi-section welded construction, which makes things a bit more complicated. I bought a spare bumper beam so that I didn't have to tear apart the car just to measure up and design the thing, and could keep the stock one intact. I made up a 3D model of it and got to designing:

What's not visible from that shot is that there's a middle "wall" between the inner and outer shells of the main beam. My plan was something that mounts to the rear wall of the beam and sandwiches it for maximum strength and stiffness (because 2.5mm thick aluminum). I wanted to keep it as small as possible to keep the hole in the outer skins as small as possible to keep as much strength as possible. This is what I came up with, it uses a 1 1/4 receiver because it's tiny and cheap and plenty strong for what I'm doing with it.

The only slight problem is the safety chain placement. Since this whole thing is physically within the bumper cover, anything mounted to the hitch itself will be really cumbersome to connect to and the chains will probably be dragging on the bumper cover which isn't great. For now I've got it as a piece that welds to the actual ball mount, but that might change still. And here's the complete system, with backing plate and some extra reinforcement plates to help distribute the load wiile keeping the main piece as small as possible. All three pieces that go inside the bumper will have nuts welded to them, the two side plates will slip in before the main hitch.

That might be hard to picture, here's the best shot I could come up with of the whole assembly:

As I said, the bumper beam itself is pretty thin wall aluminum, so I wanted some kind of confirmation that it would hold up, and wanted to evaluate some of my design choices, so I tossed it into FEA. It showed a substantial improvement from the extra width of the mount plate, and that radiusing the corners of the hole(s) in the bumper made a big difference in the stress concentration in those areas. It does a pretty decent job of distributing stress through the whole beam, and the couple of concentrations at the corners of the hitch plate are pretty much unavoidable.

Unfortunately I can't find properties for this specific material, but most other aluminum extrusion materials I could find were well over 100MPa yield strength, most in the 200 range. On top of that, not really being sure of the loads involved, I ran the analysis with a 500lb vertical load (50lbs tongue weight x 10G) and a 500lb horizontal load (1G braking). In reality the trailer is going to weigh around 400lbs with 30-40lbs tongue weight (more on the actual trailer taler) and I have to imagine 10G is a bit extreme, probably more like 3-5. So there should be a pretty decent safety margin there which makes me feel confident.

So I got to cutting on the beam itself to verify measurements and make sure there weren't any surprises inside. Cutting through the middle layer was interesting. Luckily I remembered that my tire rubber scraper is actually an oscillating multi-tool, and with a different blade is capable of cutting metal. That was the only thing I could come up with that could cut inside the hole like that. It made soe truly terrible noises but worked pretty well. The corner radiusing didn't go quite as well as I had hoped, but it should be good enough.

And that's where I'm at now. I need to do some final measuring/test fitting and then order up some laser cut parts for the hitch and get a friend to weld them together. There's a heat shield that bolts to the back of the bumper that will need some massaging to fit everything, but that should be pretty easy.

rothwem
rothwem Reader
11/13/20 11:35 a.m.

I see you did that FEA there, but why not use the studs that the OEM bumper beam mounts to and fab up a steel bumper beam out of steel box tubing with a hitch welded to it?  Then you won't have to worry about bolting to that flimsy aluminum structure.  

dps214
dps214 HalfDork
11/13/20 12:32 p.m.

Way more effort, complexity, and weight than I'm interested in. And who knows if this will see long term use (hence everything being as reversible as possible). There's plenty of people using the even crappier of the shelf setup, so I'm really not concerned. I did find one guy that did some reinforcing of the stock beam, but he was hauling a bike rack and some other heavier stuff.

nocones
nocones UltraDork
11/13/20 12:41 p.m.

Watch out for the strength at the bumper beam mounts to fatigue resistance.  

I had a 350Z that someone did exactly what you are planning.  The beam was fine and had no issues with the load.  The unibody where the beam mounted failed at the stud mounts due to fatigue from the trailer tongue load lever arm.  

Looking at pictures online it appears that the Cayman bumper mount is a bit more structure then the Nissan used but it was the same basic, bend the ends of the unibody "frame rails" out and spot weld a thicker plate on with studs attached.   The fatigue occurred along the inside of that plate shown below.  

Depending on how smooth/consistent the ID of the longitudinal chassis is you may be able to make an insert that reinforces the plate/chassis joint.  Or you may never have an issue because the Porsche might be made better, but Just wanted to let you know about an issue I encountered.  

dps214
dps214 HalfDork
11/13/20 2:47 p.m.

And the trailer itself. I'm cheap and I'm honestly not sure how much use it will see, so I wanted to keep this as cheap and simple as possible without being sketchy. I actually spent a while looking around at used stuff, especially small jet ski trailers that could be converted. One of the limitations is that the only place I really have to store it is upright in the corner of my garage, so the total length needs to be 8' or less. I couldn't find anything quite small enough, but eventually found a very lightly used harbor freight trailer, already assembled with a plywood bed and some tie down eye bolts, for marginally less than the new price of just the trailer. I decided that was as good as I was realistically going to get and had the benefit of being new, not 5-30 years old. Of course it would need some reconfiguring still, but that was going to be the case no matter what.

Overall the thing was pretty well assembled, but it appeared to be wired by someone who had once seen someone do some wiring, a long time ago, maybe in a youtube video. Grounding appeared to be optional. The side lights weren't grounded at all, and the main harness was only grounded through the trailer hitch. I was planning of doing a much better job of it anyway, in hopes of doing it right once and never having to think about it ever again. I reused the stock wires but connected everything with heat shrink crimp connectors which, despite getting about the cheapest ones I could find on amazon, seemed to be actually pretty decent quality. Most of the wiring I wrapped in nice mesh split loom, the main run down the tongue got a fiberglass sleeve for some heat insulation from the cayman's center exit exhaust that's just below tongue height.

The wheel bearings were surprisingly well packed, but I went through it all to make sure the bearings were set correctly and pumped a bit of extra grease in for good measure. One of the "issues" with these trailers is that they're sprung super stiff, especially since this one will never see more than about a quarter of its rated capacity. So since I was in the "take it all apart" mood, I pulled off the springs and removed the extra leaves and did my best to unbind the front bushings. The result is...still way too stiff (internet calculator says ~300lb/in each, total sprung weight is probably not much over 300lb), but at least now it has some amount of noticeable suspension travel. Before and after:

Then reassembled everything:

As for what's going on the trailer, I'm taking a different approach to most. The typical layout is tires front or back, and a toolbox of some sort on the other end. Since this thing needs to be stored upright I don't want to have anything too bulky permanently attached to the trailer, and I really don't carry too much in the way of tools (and porsche did a good job of putting a decent amount of storage space in the car...just none of it quite the size of a tire) so I really don't have much use for a toolbox. To make the most use of space and end up with somewhat decent weight distribution, the tires are going in two stacks, front to back. That more or less leaves room to stuff a bike on as well, which I could see wanting to do at some point.

A trip to lowes and digging through my scrap metal bin and some cutting and drilling later, and I had a pair of poles, quick release mounts, and some reenforcement plates for the underside of the plywood.

I measured out the spacing, leaving room to be able to fit the larger diameter stock wheels and tires just in case, marked it out, and drilled. I taped a fender washed to the underside of the mount to center it on the mark, then marked out the hole locations from the mount itself.

And, fully assembled, then with tires attached:

In the earlier photos there's an extra pair of holes towards the rear, that's for a spare tire to eventually mount to the underside. Which is also why the bolts on the rear pole mount are upside down, so that they're not skewering the tire. (I drew it all out in cad and there was no way to avoid either the spare overlapping the pole mount or the car tires overlapping the spare mount) Remove a bit of the flange from the rear crossmember and a tire fits perfectly between that and the middle rail, and is hung from the platform by a big U bolt. This all needs a bit of refinement still (...and an actual spare), but I'm not super concerned about having it right away since everything is brand new and the first few trips will probably be short.

There's a few finishing touches, but it's pretty much done at this point. Other than actually building and installing the hitch on the car, the last unknown is the car side wiring. I'm not super excited about splicing into the car's harness, but there doesn't really seem to be an alternative.

docwyte
docwyte UberDork
11/13/20 4:05 p.m.

I have a Wilwood hidden hitch for my 996.  I grabbed it used off Rennlist, but I would've been happy to spend the money for one new.  Not worth it to have damage done to the car from a design that ends up not working out, would rather go tried and true.

Also don't think you'd be adding a lot of weight to do what rothwem is suggesting.  You'll add more weight by running a full tank of gas.

dps214
dps214 HalfDork
11/13/20 5:05 p.m.

Fair, but what I'm getting at is there's at least one at least slightly worse design out there being sold that, to my knowledge, nobody has had any issues with, even hauling more weight than I will be.

dps214
dps214 HalfDork
12/9/20 3:36 p.m.

Okay, more progress. Decided I had fiddled with everything enough and it was time to stop messing with it and just order parts. Decided to splurge on getting the parts laser cut rather than trying to hack it together myself. Cut the receiver tube to size and relocated the pin hole, and here's what we've got:

One of the benefits of getting the pieces laser cut is it's partially self jigging. Should make welding that much easier. All the holes are going to get nuts welded to them for ease of assembly. I was even considerate enough to my friend that's going to do the welding to put the nuts through a vinegar bath to remove the zinc coating.

Before and after:

I used the backing plate as a drill template for the bumper beam. Something I didn't think about was that apparently 7/16" OD drill bushings don't exist, so I cobbled one together from a nylon bushing and a piece of aluminum tube, which all worked really well. I then used just the aluminum tube as a bushing for an intermediate hole size.

And then I test fitted the heat shield and reshaped it until it fit nicely...well as nicely as it's going to. The stud in the bottom center in the photo above is one of the heat shield's mount points, so it needed to be reshaped to account for the extra thickness, and to clear the bolt heads.

Then it was time to weld the main piece together. This...got interesting. About half way through the wire feed on my friend's mig welder ate itself, so we gave up for the night. Between a combination of my own impatience to get this done and not wanting to make my friend feel pressured into hurrying to fix or replace his welder, we decided the next morning to break out his old stick welder and finish it that way. Some new welding rods and a few practice welds later, and he got this thing stuck together. It's not quite as pretty as I would have hoped, but it's plenty strong and once it's painted and stuffed inside the bumper you won't really be able to see it anyway.

Fresh from welding:

After some cleanup:

And the side plates - one mig, one stick for comparison:

Currently waiting for paint to arrive, once it's painted it's pretty much ready to be installed.

dps214
dps214 HalfDork
12/9/20 4:12 p.m.

Meanwhile...time to destroy, er...disassemble the rear of the car some. Because porsche, removing the bumper cover requires removing the tail lights first. Step one: apply masking tape to areas you don't want to rip the paint off of.

Step two: remove the screw holding each tail light in then pry them out of their retaining clips.

Step three: raise spoiler, remove spoiler, lower to get the arms out of the way. Apply even more masking tape basically everywhere.

Step four: remove all the screws holding the bumper on. Then play several rounds of "which screw did I miss?" until the bumper actually frees itself from the car.

Thanks to the aftermarket backup camera that doesn't have a disconnect in the wire, just a ton of extra wire length, that's as far off as the bumper cover comes. But that's plenty of space for what I need to do in there. I swapped bumper beams and briefly reassembled and test fitted everything to make sure my measurements and spacing were right before welding anything. Then moved on to my least favorite part of this whole project: the wiring.

Step one: test wiring and make sure there's nothing weird about the way the led taillights work that interferes with the signal converter. Make several unsuccessful attempts because curt uses the world's dumbest wire color coding scheme on their universal trailer wiring harnesses. Red isn't power; black isn't ground but, somehow, power; brown (which the germans use for ground) also isn't ground. (I made that mistake at least twice throughout this project...it's just so easy to see the two same color wires and want to connect them). Eventually figure it out and get it all working.

This was one of the sketchier things I've done with wires but it worked.

Step two: rip apart the interior to figure out how to wire and install the stuff and how to tap into the taillight harnesses. The service manual documentation on interior removal is...not great which added an extra level of difficulty.

Step three: while you're in there, clean up previous wiring hackery. The bundle of electrical tape is some kind of diy mini-breadboard that's presumably a power converter of some sort for the backup camera. When I got in there it was insulated by plastic wrap and duct tape and just floating around loose under the carpet.

Step four: plan out wiring. Luckily porsche is nice enough to provide a fuse/relay block tucked in the right rear corner, so I can easily get power with a fuse tap.

Some deciphering of wiring diagrams reveals that the fuse on the far left is for...something related to the lighting system and is only powered with the key on, which should work.

Step five (not pictured): partially reassemble the carpets to figure out what free space there is to stick the tail light signal converter and how to run the wiring. There's a pretty convenient place inside the left quarter panel where there's a gap between the metal and the carpet, close to the tail light harness and the spot where I'm planning to run the wiring through to the bumper.

Step six: contemplate everything that's led to this moment and if any of it was a good idea as you cut the driver's side tail light harness in half. Then splice in the trailer harness wiring, definitely not confusing brown for ground again and having to cut that out and redo it. This is where it stands now, as finished as it can be without attaching anything to the car side wiring. You can also see the fuse tap wired in and the two wires that have to run to the other side of the trunk (power and right turn signal) are loomed together.

docwyte
docwyte UberDork
12/10/20 8:49 a.m.

I've decided to install my Wilwood hitch and one of things I'm not excited about is tapping the tail light wiring harness for the trailer lights.  I may use those crappy vampire taps so I don't have to cut wires but those aren't awesome either.

Oh yeah, on German cars brown is almost always ground, like 99.99% of the time.

dps214
dps214 HalfDork
12/29/20 12:49 p.m.

Okay, more progress and more being behind on updates.

When you live alone and are barely an adult you can do things like use a coat rack as a parts hanger while painting:

And the finished product:

Gave it a couple of days to fully dry, then assembled

Reinstalled the bumper beam to the car and it all seems to pass the "jump on it a bunch" test, which by my math should be at least as much force as it'll ever see in use, so I'm pretty confident in it. That means it's time to stop procrastinating and finish up the wiring. Here's most of the wiring splices, and the placement of the control box with the wiring loomed and run nicely:

At the top of that photo is the trailer wiring itself running out of the pass through hole for the bolt that holds the tail light in. That hole is plugged by a rubber cap that will be modified into a grommet of sorts. On the outside, here's the wire run through a gap between two pieces of chassis structure and down into the bumper area. I had to cut and re-splice the harness to be able to run it, but with the placement of everything, the stock length of the harness ended up being exactly right.

I had some adhesive base zip ties laying around, which seemed like about the only way to secure the wiring to the bumper. The last one is left loose so that the end can be pulled out for use and "retracted" into the bumper when not in use. I added some edge guard to the top lip of the bumper to hopefully not rub through the loom.

"Out":

And "in":

Reassemble the rear of the car and the trunk interior, and it's pretty much done.

This was a preliminary test, I never took a photo of the final product and ended up deciding to use a different ball mount, but this is basically what it looks like:

The last few details were a license plate mount and something to attach the safety chains to. I don't love the chain mount but it's the best I could come up with and realistically should be plenty strong.

Found a day of decent weather and went for a quick test drive with the trailer. As you can kind of see in the photo above the wiring connector is hanging a little and was getting a bit warm from exhaust, so I wrapped the trailer side connector in some adhesive backed insulation I had. Everything else seemed to work just fine. So I think that's this whole project done. It ended up being more effort than I had hoped, but I like the way it all turned out. My only real regret is that I forgot to take note of how much the parts weighed before installation. I haven't kept great track of costs, but I'm pretty sure the whole thing including the trailer came out to not much more than just the off the shelf hitch would have been, and that would have required just as much installation and wiring time and effort.

docwyte
docwyte PowerDork
12/29/20 3:44 p.m.

I like that wire loom covering, where'd ya get it?  Makes things looks really clean.

dps214
dps214 HalfDork
12/29/20 4:08 p.m.

https://www.amazon.com/gp/product/B07J6GFRF5/ref=ppx_yo_dt_b_asin_title_o08_s00?ie=UTF8&psc=1 You can get it any number of places, this was the cheapest I found. The stuff is really nice - flexible, easy to work with and looks nice. 25' ended up being exactly enough for the trailer and car wiring, I think I have maybe a foot left over. Though I did misjudge the sizing a bit, if I had it to do over again I'd probably use 3/8" rather than 1/4". Everything fit but just barely and I had to stagger all the splices because more than one connector in the same place was too big for the loom.

docwyte
docwyte PowerDork
12/29/20 8:05 p.m.

Thanks!

mechanicalmeanderings
mechanicalmeanderings New Reader
12/30/20 1:55 p.m.

One thing that might help a little bit with the wiring is to run the wires through a wire lock pin (if you look up wire lock pin you’ll see what I mean). The pin goes in to lock the hitch closed on the ball.

 This keeps the wiring out of the way, close to the pivot, and out of the heat.

I do this on all the trailers I pull.

dps214
dps214 HalfDork
12/30/20 6:33 p.m.

Yeah I intended to do that (if you look closely you can see the lock pin in the last photo above) but between the wiring having to duck under the license and how close the whole thing is to the bumper it seems like it could end up binding up the connector in a left turn and just generally didn't have as much freedom as I liked, so I decided against it.

dps214
dps214 HalfDork
1/18/21 10:53 a.m.

Okay, time to get the car ready for the season. First the easy upgrade - I finally caved and got some nice reusable vinyl numbers. Of course right after I got these I learned that class letters aren't actually required for SCCA TT so I could have saved a few bucks but oh well, they were pretty cheap and I needed the S anyway.

The other two projects are some ignition coil heat shields from the 911 version of the engine, and a GT4 front sway bar to match the rear.

Heat shields come in four pieces, an upper and lower for each bank of cylinders.

The lowers are known to be basically impossible to install with the exhaust manifolds on. I got some super short bolts and was hoping that would do the trick, but there just isn't enough clearance between the valve cover and manifold. So only the upper two went on, but those are the ones that actually directly cover the coils so I'm not exactly sure what the lower shields really do anyway. I should have done more research first, the GT4 parts diagrams only show the upper shields so that should have been a clue to not even bother trying the lowers. Installing the upper shields wasn't all that difficult, but they're tucked up in there enough that it's hard to get a clear photo of, I think you can pretty much see what's going on here.

Then it was time for the front swaybar. This is one of those things that the engineers clearly didn't intend to ever be touched after initial install so it's a pain and nothing really goes smoothly. Step one is to get the car up as high as possible.

It's hard to get clear photos working under the car, but basically the bar mounts to the top side of the front subframe, so the process is to unbolt everything that attaches to the subframe, then lower the front end of the subframe enough to slip the bar out. The biggest issue I ran into is that for some reason the arms of the bar are basically U-shaped so the only way to snake it out from between the control arm and tie rod was to unbolt the lower control arms and then yank them out of the way. Of course the GT4 bar seemed to have been designed by an adult and the arms are basically just straight so it slips right into place fairly easily.

The front subframe also cradles the fuel tank, so that needs to be supported first:

The unbolt...everything, including the 10(!) M12 bolts that attach the subframe to the chassis, leave the rear bolts loosely installed, and start lowering. The bolts are officially single use, but they're giant fully threaded M12s, so there's no way they're actually TTY bolts and I know at least one person that's reused them and didn't die. I did replace the two in the front corners just to be safe because they get more torque than the others and also are the attachment point for the lateral link of the suspension, so those bolts failing would be a bad time.

Here's the comparison between stock (top) and GT4 (bottom). The GT4 bar is definitely thicker and has more reasonably shaped arm ends.

Now, because of the difference in end design and the GT4 having different knuckles, neither set of OE endlinks work with this setup. All of the aftermarket options are "racing" rod end style links, which I've had some mediocre experiences with in the past, and are kind of overkill since this is still primarily a street car and I'd like to keep the NVH as good as possible. But since I have a spare pair of GT4 links now, I'm probably going to take a shot at DIYing my own shortened and correctly angled links. To make sure I can get the geometry correct (and to help with aligning the car once this is all done) I built a pair of wheel stands so I can be under the car with it sitting at normal ride height. Now that I know these work, I'll build another two to use when doing the alignment.

dps214
dps214 HalfDork
3/1/21 1:58 p.m.

Finally a bit more progress. Started down the road of making my own eld links then decided that was a bad idea and to just buy some nice adjustable links. Then had to deal with waiting for parts, being sent wildly wrong parts, then having to wait again for the right parts from a different supplier. Ended up with tarett end links, swapped out the lower joint bolts for longer versions to reuse the stock nuts, mostly to minimize the number of tools required to make changes.

Their solution for weatherproofing the joints is these odd little boots that slip over the rod ends.

I'm an idiot and didn't read the directions very well and ruined one of the boots trying to install it, so now I get to wait again for a replacement before I can finish installing, but here's one of them installed. With the spacers on these the link angle is much better than the modified stock links would have been which is nice. Less nice, the larger diameter rods have some tight clearances with the abs wire bracket, a little bend out of the way makes it a lot better though.

dps214
dps214 HalfDork
3/8/21 11:14 a.m.

Finally got in the replacement rod end boot and was able to finish up installing everything. I think I put around 100 miles on the car over the weekend and so far everything feels fine. Front end is at least a little bit more responsive with no noises or noteworthy NVH increase from the end links. I put the bar on the default middle setting to start. After driving it I'm pretty sure it's going to end up full stiff but I want a baseline for comparison. Aligned it on sunday, I did a pretty good job of getting the subframe aligned right but missed on the steering rack - alignment was dead on to what it was but with the wheel off by like 10*. With the wheel cribbings the alignment went much smoother than having to raise, lower, and realign the car after every change.

And the results. Didn't actually change much, just re-centered the steering wheel and evened out the rear toe a little bit. Byproduct of that change was a little bit of a decrease in overall rear toe, which I think will be okay.

And the last piece of the puzzle arrived, the front tires. Should be able to mount them this weekend and then the car will be ready for a test and tune at the end of the month assuming weather cooperates.

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