E30 Rally Car

Hmm.  This appears to be the cheap solution:

https://www.aircraftspruce.com/catalog/lgpages/brakevalve.php?clickkey=8314

This is a still-cheap solution but which allows you to release it by stomping on the brake pedal:

https://smile.amazon.com/Park-Lok-Universal-Hydraulic-Parking-Brake/dp/B01N9VOQTJ

All of the fancy one-way valves where you can you engage the brake then add pressure are $200 or more.  I'm leaning toward one of the above.

I don't have a brake proportioning valve.  Do I need one?  I'm also worried about the fact that so much of the rear bake line is braided stainless--this stuff flexes more than hard line.

Berck said:

Argh--It never occurred to me that reman calipers *weren't* painted.  I'll try to investigate.  But you're right, if they're not, painting them now would be probably be worth a $6 can of paint.

I definitely won't have trouble priming the fuel system:)  I'll have the start-bypass switch so it'll let me run both fuel pumps without oil pressure for starts, then I can flip the switch to make it so that a dead engine results in dead fuel pumps.  Which, when I think about it, is a sane idea even if the rules didn't require it.

I do, in fact, have a locking hydro parking brake, but I wanted to ask you guys about it.  I have this:

This works great as a parking brake.  It seems less than ideal for on-stage use, however, since you've got to push the button.  And the button is somewhat recessed, which seems very not-ideal.  I was considering a few options:

(1) Remove the ratchet mechanism and add a hydraulic parking brake.  In airplanes we use a one-way valve thing where when engaged, you put pressure in the system and it stays there until you disengage.  I'd assume there's a similar thing available for cars--I could certainly use the one I'm putting in my airplane but it's expensive, and also airplanes have totally separate left/right brakes, so it's actually two valves and I only need one.

(2) Remove the ratchet system and carry some sort of wedge to shove under the parking brake.

(3) Find some way to enable/disable the ratchet mechanism.

(4) Extend/replace the button so it's easier to push

(5) Leave it as-is. It's a rear-wheel drive car and I'm no Colin McRae; do I really need a handbrake?  As much as I enjoy unnecessary handbrake turns on the street in the snow, it's maybe just asking for trouble?  On the other hand, why did I buy a rally car if I can't do handbrake turns?  And if it's there, I'm likely to use it and then get it stuck like an idiot.

I can think of maybe 3-4 times ever where I thought to myself  "damn, I really wish I had a hydrobrake there" (at least half of those times at the STPR super-special hairpin that no longer exists). I'm sure the really good RWD guys use them for something productive, but I can't say I've ever thought I needed one expect maybe for doing some cool showboating for spectators or something ;) I'd probably forget to clutch in and snap a driveshaft u-joint or something, lol. 

Also, to extend the button simply push the handle further back. The handles tend to slide forward over time, but in the corect position the button should stick out plenty to use it if needed. 

If you disable its ability to lock when pulled, then it won't work as a parking brake. And trust me, you'll definitely need a parking brake (and it *may* be something checked at tech for certain rallies, if I recall correctly). That reminds me I need to tighten mine up since on really steep hills it doesn't hold very well, especially when the brakes are hot coming off a stage. 

Forget "need" or "make productive use of"... but would you have more *fun* with an operable hydrobrake?  With my driving skill, I *know* I'm not ever winning anything in an old 4-cylinder BMW, so it's all about how much fun I can have learning how to do this.

Yeah, I get that I still need a parking brake.  All my 5 options do that, just trying to figure out which one.  Good information about the button/handle slippage--makes sense.  I couldn't understand why BMW thought having a recessed button was a good plan.

I'm leaning toward the $20 valve from aircraft spruce.  I could just thread it into the back of that thing before I finish bleeding my brakes and be done with it.  Then I'd have the best of both worlds.

Berck said:

Forget "need" or "make productive use of"... but would you have more *fun* with an operable hydrobrake?  With my driving skill, I *know* I'm not ever winning anything in an old 4-cylinder BMW, so it's all about how much fun I can have learning how to do this.

Yeah, I get that I still need a parking brake.  All my 5 options do that, just trying to figure out which one.  Good information about the button/handle slippage--makes sense.  I couldn't understand why BMW thought having a recessed button was a good plan.

I'm leaning toward the $20 valve from aircraft spruce.  I could just thread it into the back of that thing before I finish bleeding my brakes and be done with it.  Then I'd have the best of both worlds.

ah ok, I think I misread what your plan was there!

pull the handle off and put some adhesive in there before putting it back on, that should do. I'm paying attention since I've been thinking about a hydrobrake just for the cool factor myself (and lacking anything much else affordable to do to my car lol). 

Also, if it were me I'd replace a bunch of that flex line with hardline, just because it tucks away nicer IMO. Not sure it matters much funcationally though. Side note: i still have the stock proportioning valve, but if I ever go hydrobrake I'll definitely add an adjustable valve for the rear so I can tweak things.  So in your place I would definitely do that. 

Do you know offhand the easiest way to remove the stock proportioning valve so I can replace it with a manual one?  Might as well have it in the cockpit so I don't have to get out to dial it in.

Agreed that the flex line looks sloppy, but then again my hard lines are not guaranteed to look any better!

And now I'm down a terrible rat hole.  Aircraft happily use aluminum brake lines with aluminum AN fittings for brakes.  I have a nice AN flaring tool I'm reasonably adept using on aluminum tubing (and also stainless tubing that I used for the fire supression system in the Vee), so I was thinking any brake lines I needed to do I'd just do more of that.  But the internet seems to think that AN fittings and aluminum lines for brakes is a terrible idea?  Can I do nicop and and aluminum AN fittings?  Or do I have to buy some expensive double-flare tool because that's what cars use?

Aluminum 3030-0 3/16" tubing (what I put in my airplane) is rated for a working pressure of 880psi ("2x safety factor!").  Apparently automotive brake pressures might be closer to 2,000psi in a panic stop according to random internets.  Aluminum 5052 tubing is rated... higher, but I can't figure out how much higher.  If I just look at 3030 alloy vs 5052, it looks like 5052 is ~75% stronger, but that all depends on the heat treatment and wall thickness and... I'm not a mechanical engineer.  I'm guessing 5052 is probably good enough for rally car brake lines, but I'm also guessing nickle copper with aluminum AN fittings is also fine.

Even F1 never used aluminum lines or fittings: steel or titanium.  Aluminum is weak and easy to gall or crack.

NiCopp with steel AN or JIC fittings and you can still use your AN flare tool.

obsolete said:

NiCopp with steel AN or JIC fittings and you can still use your AN flare tool.

Perfect, thanks.  I was bothered by the likelihood of steel corroding in the presence of brake fluid.  It seems like cars with steel brake lines rust out no matter what.  And while aircraft spruce doesn't sell AN818/9-3 fittings in stainless steel (only 1/4" or larger, for some reason), they are available elsewhere.  I'll do that and stop overthinking things.

Brake lines rust from the outside in, not the inside out.  That's why they usually fail under retainers or at the tube nuts: corrosion is highest there.

Minor progress.  Driver's seat re-installed in a more favorable location with some actual grade 8 bolts instead of rusty bolts that were in there.

Much cleaner in there now.  I'd ideally like more leg room, but any further back and I'd have trouble getting the shifter in 1/3/5.  A little higher would give me more leg room, but make me even more likely to whack my helmet on the cage.  So this will probably do.

Painted the trunk rust with rust bullet and top-coated with some rustoleum.  Not perfect, but this is Colorado so it's good enough for now.

Tried to figure out what transmission I have.

Googling those numbers shows that it's a ZF transmission that ws used on...  I don't know?  There are conflicting answers.  It seems to be geared rather low for this car (but that could be the rear end, who knows).  Probably about right for rally use anyway.  I mostly wanted to figure out if I should put ATF in it or not, and I at least found that answer:

Is there a preferred ATF oil for these manual transmissions?  Looks like some BMW people recommend Redline D4, so I'll probably use that unless you guys have other ideas.

Tried to sort out the brake proportioning valve situation, but I'm pretty confused.  The internet seems to think that there should be a proportioning valve under the hood next to the master cylinder.  I don't have that--Master cylinder directly connects both the front and the rear brakes.  No evidence of a proportioning valve anywhere.  Is it built in the master cylinder?

I'm thinking that unless the brake bias is too rearward, installing another proportioning valve isn't going to help me much.  Given that I've only very briefly driven the car and only at about 50mph with a stuck rear brake, I have no idea what it needs.  I was hoping to put it all back together and bleed the brakes once.  But now I'm wondering if I need to assess brake bias before installing a proportioning valve?  Which would mean bleeding them twice.  Whiny, I know, but the wife complains about brake bleeding so I try to do it as little as possible.

Interesting.... those numbers show it's a ZF 420 from an e39 5-series with the M60 V8 engine. I can't say I've ever heard of one of those in an e30 - the usual swap for a ZF would be the one from the M50/M52 e36 3-series. Not sure how they differ, but apparently they both bolt up to the M42 just fine, which is pretty interesting. 

If it's the same gearing as the e36 ZF transmission, that's ideal for rally and what most people *want* though ZFs are fairly uncommon compared to the other e36 transmission (G250). IIRC all the gears are shorter so really good for keeping it in a good power band all the time. Don't recall offhand what rear end people use with those, but I want to say 3.73 is common. So if you have the 4.10 rear in that car (which usually goes with the M42) you'd definitely have some short gearing. 

The OEM proportioning valve on mine is down below the booster and off to the side. You can see it dead center in this pic with the blue tape around it:

Now, my car is an early non-ABS car and yours was originally an ABS car, so no idea where the valve is on yours stock, but since the PO did ABS delete he may have eliminated it or moved it. I'd just follow the rear brake line all the way from the master to the rear of the car and see if you find it. Maybe it was eliminated entirely?

also, didn't notice this initially, but is that a steel oil pan? To my knowlege the M42 never came with a steel pan, so that may be one of the run that some German company made a while back for rally guys in the RG318is Cup. Or something custom-made. Either way, if that's a steel pan, that's great to have. If that's a dent....well, the OEM pan would have just cracked and broken (ask me how I know). 

I used to delete the stock proportioning valve, on the theory that the prop valve was intended to prevent rear brake lockup while under heavy braking on paved roads where you could build some ear-folding negative Gs.  The less traction you have, the less load shift forward you have, so the more work the rear brakes can do.

It might seem backwards that less grip means more rear brake bias, but I come from a mountain biking background where the rear brake is completely useless because it is super easy to use the front brake hard enough that the rear tire hovers off the ground, even if you stretch back far enough that your chest is on the saddle.  Rear brake is only useful at all when it is so slippery that you can't do that.

My oil pan is definitely steel!  That's definitely a dent.  Some surface rust, and a magnet sticks to it.  No idea that was a rare thing, awesome!  There's no markings on it, but the bung for the drain plug sure doesn't look like a factory weld:

Thanks for looking up the transmission for me.  I guess if it came out of a V8 car, it should be plenty beefy for the mighty M42.  It was described by the seller as a "close ratio 5 speed", and that seems accurate.  Measured the rear end gearing--without getting out a degree wheel it seems like ~3.9ish.  Not quite 4, but more than 3.7.  Given that the diff is welded, it's obviously been taken apart and anything could be in there.

I finished most of the wiring nonsense.  Oil pressure gauge works (warning light isn't there yet), fuel pump pressure switch works.  Master switch does kill the engine with obvious ill-effects.  Labeled some switches:

I still need to do something about the reverse lights to make it ARA legal, since "All reversing lights may only switch on by engaging reverse gear."  A quick look around the transmission did not reveal the reverse light switch location.  I suspect fixing this is going to be fun and is probably related to why the builder gave up and stuck a switch on the dash.

Of course, the new gauges don't dim because the BMW illumination circuit dims the ground side, not the +12V side, and the gauges except the the +12V to be dimmed.  Whatever--I'm guessing I won't notice.

There's no evidence of a brake proportioning valve where yours is.  If there was one there before, there's not now.  And I traced all the brake lines and didn't find one hiding somewhere else. So, I guess it's running without one.  Perhaps on gravel (as Pete mentioned), this is actually close to correct.  I can plumb in a cockpit-adjustable one for $45 and it's no big loss if I never use it.

Need to decide the order of things: hydro handbrake, parking brake valve and brake prop valve.  They're all going to be right there on the center console, do you suppose it matters what order I plumb them together?

Reverse light sensor should be way up high on the transmission, sometimes hard to see from below. RealOEM diagram shows it as #9 on that transmisison, though hard to tell exactly where that is (I think that's showing it see-through to the passenger side?)

A lot of rally guys put a dash switch to "cheat" in tech since the reverse switches on transmissions tend to get their wiring ripped out on stage. Other thing I've seen done is to actually mount up a momentary switch (like a horn button-type thing) so when the shifter goes into reverse the shifter stalk hits the button and activates the light. 

Yeah, that transmission should hold up fine lol. Hell, I use the G240 (original M42 transimission) behind an M50 6-cylinder and it's held up fine....

You may have a 3.91 diff. Not all that common, they mostly came on early M10 318s (like mine) but if it's a welded unit I think they could also be had on the 325IX and maybe others. That's interesting it has a welded diff and not an LSD.

My aftermarket tach doesn't dim and it's REALLY bright at night. I actually put some 30% window tint over it to tone it down a bit lol. 

No idea if the plumbing order matters. If Nonack is reading this thread, he'd know. 

Hmm.  This thread makes me think the transmission is a ZF310? https://www.bimmerforums.com/forum/showthread.php?1588633-Can-anyone-tell-me-what-Gearbox-it-is!  

I too was a bit curious about the welded diff.  It seems like a lot of time and expense went into prepping this car and a welded diff strikes me as the cheap way out.  Do some rally drivers prefer welded diffs on gravel?  I'm guessing that on gravel it's great, but it's every bit as terrible as I'd expect on pavement.  It feels nice on the dirt roads on my neighborhood at pretty low speeds, though.  I'm certainly willing to give it a shot--welded sounds a heck of a lot better than open.  I'm anxious to get it back on the ground and give it a test on the forest roads near my house...

I ran one for a while, it felt just like a tight clutch diff on pavement, except it would break axles if you backed up while turning.

In reply to Berck :

Our Merkur rally car had a welded diff that I eventually swapped for a mk3 Supra clutch LSD- mid corner behavior was similar but you definitely had to commit to get it to turn in nicely with the welded one.  It was way better than the open diff (which the car also had briefly) and mostly just annoying compared to the clutch LSD, there probably wasn't much of a performance difference.

In reply to ¯\_(ツ)_/¯ :

Thanks--makes sense.  Josh suggested you'd have thoughts about the correct plumbing order for hydro-hand-brake, proportioning valve, and parking valve? (I figured you tuned out as soon as you saw it was a BMW...)  Seems like the parking valve can go anywhere, but I'm not sure if the hand brake should go before or after the proportioning valve or if it matters?

I've never used a parking valve, always leaving the mechanical handbrake as backup, but I'd go master cylinder->proportioning valve->hydro brake->shutoff valve->to rear brakes if I were doing that.  Theory being that you want the proportioning valve first since you don't need the handbrake to push fluid through it when used, and you want the shutoff to have as few leak or expansion points as possible afterwards so that it's useful as a parking brake.

Thanks!  The cable handbrake was converted into a hydro brake with the cable cut and parking brake mechanism removed from one axle by the time I got the car... Putting all that back seems like a mess compared to the $20 shutoff valve.

Yep, totally understand why it's the simplest choice here, just wanted to point out that I haven't used one myself.

Berck said:

Hmm.  This thread makes me think the transmission is a ZF310? https://www.bimmerforums.com/forum/showthread.php?1588633-Can-anyone-tell-me-what-Gearbox-it-is!  

I think I got things mixed up. If that's a ZF it's a 310 (5-speed) and if it's a Getrag (6-speed) it's a G420. Both were used on the e39 - the five for the 6-cyl cars and the six-speed for the 8-cyl cars. So if you have 5 speeds, it's likely a ZF 310.