Chris' Daily/Track Compromise GTI

My favorite part of this thread is seeing the lap times dropping with more laps and these upgrades

hybridmomentspass said:

My favorite part of this thread is seeing the lap times dropping with more laps and these upgrades

Thanks. It's been fun. I raced RC boats, planes and cars for over 20 years and the progression was similar in each hobby. Practice, find a limitation, upgrade, repeat...

I like this car, but I don't love it. I'm trying to draw a line in the sand and say that these are the last upgrades I'm going to do to it. There's a ton that could be done to the motor to make the car faster but that rabbit hole is really deep. IMHO this car isn't worth dropping that kind of cash into. I REALLY want a 981 Cayman S. It can do everything this car can and then some and not need a ton of upgrades to do it. 

I had the car aligned on Thursday. I asked for -2.8/-2.2 camber and zero toe F/R. He was only able to get -2.2 in the front with the camber plates and ball joints both maxed out. I wound up with-2.2 and zero toe F/R. We'll just have to live with it. 
 

I put 300 highway mikes on the car this weekend. These springs are definitely a better match for the Konis. The ride is ridiculously smooth UNTIL you hit a big transition. Then it sounds like it is hitting the bump stops HARD. I did some research and found out that the European GTIs are 15mm lower from the factory. VW makes a set of bump stops that are 15mm shorter. Seems like that would have been a great thing to buy before I had the springs installed. 

A little more research says that some spring manufacturers recommend trimming 1/2" off the to of the stock bump stops when installing lowering springs. That makes sense to me. I'm going to trim them when I prep the car for Sunday's track day. 
 

There's a rub on the front fender liners. It's only in one spot when I hit a hard bump. I'm going to use my heat gun to warm up the liners and stretch them up up a bit. There's plenty of room in the fender to do it. 

Sunday afternoon I took the Mrs. for a drive to go hiking about 30 miles away. To get there we have to drive over the mountains, through a small farm town with atrocious roads and then back into the mountains again. With the added weight of a passenger and the rough roads the front tires were rubbing quite a bit.

On Monday night I attempted to heat up the fender liners and stretch them out of the way. I found out that there's a foam pad between the top of the liner and the fender. It wouldn't allow me to push the liner up into the fender that much. I wound up pulling the liner down and trimming about 2 inches off the bottom edge of the pad. That helped but the liner or fender was still rubbing. I also noticed that the ball joints were NOT all the way out like I was told. I was able to move them out about 3/16"-1/4" (.4-.5 degrees) per side. I had to readjust the length of the tie rods, reset the toe and re-center the steering. It took about an hour with a pair of straight edges and tape measures to get it right. Once I got the alignment reset it drove great but it was still rubbing over bumps so I ordered a cheap fender roller off Amazon.

I rolled/pulled both front fenders yesterday and took it for a drive on the same mountain roads. The car feels really good now. It doesn't lean into turns. It just goes where you point it. I drove it hard over some dips and bumps and it didn't rub once. I could feel it hit the bump stops once in a while but it doesn't seem to bottom out nearly as often as it used to either.

My Nankang AR-1s are supposed to be delivered today. If they show up I'll be heading to Laguna Seca on Sunday to see if all of these changes actually make a difference.

My tires showed up Friday afternoon. Yeah!

On Sunday morning I headed to Laguna Seca. I set my pressures to 35 F/R cold for the first session. Afterward the tire pressures were around 46/43 hot. That's a lot more pressure gain than I'm used to, but there was a little over 100F temperature gain since it was in the low 40's for the first run. I dropped them to 42/38 hot and kept lowering them by 1-2 PSI after every session. I wound up at 38/38 at the end of the day.

Overall the car feels really good. The tires seemed to have more traction just about everywhere. I picked up a full second over my previous fast lap and had quite a few below my previous best lap.

The one thing I'd like to improve is entry to mid corner rotation. Before the last set of suspension changes it had a little off throttle oversteer. Now it's stuck everywhere. Looking at the  tire temperatures it looks like the rear tires could use a bit less camber. I'd like to add a bit of toe out in the rear too.

Changes for next time:

I'm going to shoot for 38/37psi hot (down 1 in the rear). 

Reduce rear camber .5 degrees. Add a little toe out (~.1 degree per side).

Any input would be appreciated.

There was a guy in a new GT3 RS in my run group. In the third session he was killing me on the straights but I would catch him in every corner. He finally let me by and then followed me for the rest of the session. After that session he pulled up to me in the pits and asked if it was OK for him to follow me since I seemed to know the lines pretty well. He wound up following me out for the last three sessions and I was still holding or gaining ground on him every session. That was truly the highlight of my driving career. LOL!

Sooooo, three weeks in with the lowering springs and I'm sick of bottoming out the suspension. I really like how these springs ride UNTIL they bottom out though. I came up with a game plan to raise the car back up 1/2". I have Ground Control camber plates in the front. They have an aluminum cup for the spring to ride on an axial ball bearing. A guy with a lathe could just make a copy of that cup that is 1/2" taller, right? I pulled the right hand spindle and strut assembly off the car and took some measurements. A couple hours later...

While I was in there I noticed that the bump stops look like they are tearing at the base. Well, the cup in the GC camber plate is the right depth but it's ID is .350" narrower than the one on the stock strut mounts. There's no way that the stock bump stop would ever fit. I made an aluminum ring to fill in the cup and glued it in place with Locktite 609. That will give the stops double the surface to sit on. Adding the 1/2" lower mounting position to the 1/2" lower springs means I need to cut and inch off the stock bump stops to get them to engage at the same point as they did on the stock setup.

For the rear there are 7.5mm thicker spring perches available from the Audi TT (Part #8J0512149KT). The springs are mounted ~60% of the way out on the arm so that should translate to a 1/2" lift in the rear.

I buy coilovers for the opposite reason most people do.  I use them to NOT lower the car!  I think my Golf R is lowered maybe 3/8" and my 996 is lowered 3/4". 

I want to retain as much bump travel as I can, which is something most lowering springs don't do...

docwyte said:

I buy coilovers for the opposite reason most people do.  I use them to NOT lower the car!  I think my Golf R is lowered maybe 3/8" and my 996 is lowered 3/4". 

I want to retain as much bump travel as I can, which is something most lowering springs don't do...

If I were to do it all over again I'd probably go with coilvers. I wouldn't have dropped it more than 1/2" either. These springs were supposed to drop the car 15mm. In hindsight I think that was against the Euro GTI not the US version so it turned out to be more like 30mm. They do have full bump travel. They will certainly have full bump travel after I preload them 1/2".

I've had the car back together for about a month and it's been a little better since I raised it up 1/2". The VWR springs are a better match for the Koni Yellow shocks and the car drives great on relatively smooth roads. Unfortunately there are a few things stacking up against them:

1. We live in farm country and a lot of the roads are in pretty bad shape.
2. My current alignment has moved the tires closer to the lip of the fenders so they are more prone to rubbing now.
3. The VWR springs are stiffer but have a lot less travel than the stock springs so they are more prone to bottoming out hard.

I want to keep the firmer ride I gained with the VWR springs on smooth roads and the extra 1"-1.25" of bump travel I lost to them back for the rougher roads.

I started looking into different lowering springs (stiffer but not as low) and the Ground Control coilover conversion kit. I decided that the coilover conversion would be a safer bet because I could control the spring rates and ride height independently. I found this thread by bostonaudi on the mk5 forum: https://www.golfmkv.com/forums/index.php?threads/spring-rate-testing-orgy.165926/ His findings line up with my thought on spring rates. Basically 300lb/in is about as stiff as you can run before the car starts to get harsh over bumps and potholes. Using 8" long springs allows the car to have plenty of bump travel before the suspension bottoms out.

Last week I ordered the Ground Control coilover conversion kit with 8" long 290lb/in springs F/R. The springs should be about 50% stiffer than stock and about 27% stiffer than the VWR springs. At the same time they'll have about about 2" of bump travel available. I'll start with the ride height at 1/2" below stock and see how it goes.

I sold my GTI this afternoon. It was a great car and part of me will miss it but it was time to move on.

DO WHAT?