BMW Compact Rally Car Build

[DaveKern]

Clutch and UUC lightweight flywheel bolted up to the engine.



Engine and tranmission now bolted up as well...but that makes for a boring picture.

More tomorrow.

Dave

[wolferj-RIP]

Agreed, the spiffy blue flywheel makes a better picture!

BTW, did you find the specs you needed on the rear diff and axels?

[DaveKern]

Originally Posted by wolferj

Agreed, the spiffy blue flywheel makes a better picture!

Yep, and there's something else in that shot too.

Originally Posted by wolferj

BTW, did you find the specs you needed on the rear diff and axels?

Nope, didn't get any specifics on the axle length. I did get confirmation that the mid sized diff is 3/4" wider than the small diff. If cars with the small & medium both use the same rear trailing arms, then the other axles have to be a touch narrower.

That was great news, as it means that my Supra diff is narrow enough that I should be able to fit 10mm wide adapter rings onto the diff.

Dave

[wolferj-RIP]

Originally Posted by DaveKern

Yep, and there's something else in that shot too.



Nope, didn't get any specifics on the axle length. I did get confirmation that the mid sized diff is 3/4" wider than the small diff. If cars with the small & medium both use the same rear trailing arms, then the other axles have to be a touch narrower.

That was great news, as it means that my Supra diff is narrow enough that I should be able to fit 10mm wide adapter rings onto the diff.

Dave

Yeah, nice clutch, too... I will see if I can squeeze myself under the ti tommorow to measure the shaft length difference. I still have the original ones in the garage for comparison. (IIRC, Jesse did a post regarding the difference on the shaft lengths with pics and measurements, but I can't track it down...)

[cooljess76]

I did take a photo, but it came out messed up. Somehow the vantage point made the small case diff look like the same size as the medium case. Somewhere along the line the pic got deleted or lost. I think I accidentally deleted it from photobucket and it killed the link. Now that my diff is installed with the halfshafts, I don't have a way to measure total length because the halfshafts are in the hubs and not perfectly extended.

I'm getting ready to mount my UUC flywheel and M5 clutch too. BTW, got anymore pics of that purdy stainless header?

[DaveKern]

Originally Posted by cooljess76

I'm getting ready to mount my UUC flywheel and M5 clutch too. BTW, got anymore pics of that purdy stainless header?

Not yet, will probably wait till they're mounted up on the motor - but I'll be modifying the flanges so it may be a week or so. Based on how much of a PITA headers appear to be to install, I'd like to try to bolt them to the motor and then install the whole assembly.

Does anybody know if that's doable, or will the motor with headers installed be a nightmare to fit into the engine bay/trans tunnel? FWIW, I have no front assembly on the car so I think I'll be able to just slide it in.

Dave

[spidertri]

I just got my E30 axles yesterday, they are 325i ABS axles and measure 22 3/4". I measured from the top of the CV end plate not from the bump out in the middle. I figured the bump would be in the output flange cup.

[DaveKern]

Spent another day in the garage.

Bolted up the tail lights and mounted the hatch - ughhhh, that thing is heavy and bolting it back to the chassis is a real PITA - next time fiberglass, lexan & 4 hood pins.

Spent some time under the car as well, and got the rear subframe and trailing arms bolted on.



Also spent some time yesterday doing a quick pare down on the wiring harness. I know there's a ton more I could take out, but since I'm new to BMWs, I don't want to cut too much. If anyone's a wiring guru, I'd love to know what stuff could be cut out and what has to stay. Here's what it looked like at quitting time:



Dave

[cooljess76]

When I removed the chassis wiring harness off of my M3 donor, I was shocked at how much it weighed. If I had to guess, I'd say it was 25-30lbs with the fuse block attached

[J!m]

Dave:

I have wiring diagrams available if you want/need them....

Also, with the nose off the car, I would still suggest removing the right hand engine mount from the engine. This gives a bit more room to work around the steering wheel shaft, which is aluminum and easily bent.

[DaveKern]

Originally Posted by J!m

I have wiring diagrams available if you want/need them....

I've got a Bently manual that I've been referring to quite a bit, but can't say I've looked to see how good/bad the wiring diagrams are. Of course, the manual may be different than the TI by a little bit too.

Since I'm still not sure how wild & crazy the build will eventually be, I'm a bit hesitant to really strip down the harness - i.e. if I go with lexan windows, I can remove the entire door harnesses, but for this winter, I'm leaving the glass, so all that crap stays.

I did have questions on a few bits of the wiring harness though:

ABS ECU - if I'm disabling ABS, can I trace & remove every wire that comes out of or goes into the ABS computer?

Security system - can I pull all the wires, or is this something that may need to be kept in one piece because of anti-theft crap?

Door/Trunk ajar sensors - any need to keep these?

Power locks - any need to keep these?

Airbag system - I think I already yanked the brain out and chased wires as far as they go on the interior side of the harness. Hopefully that's ok.

Wiring that connected under the driver seat (and maybe passenger seat too?) - I'm guessing this might be related to the airbag system?

Originally Posted by J!m

Also, with the nose off the car, I would still suggest removing the right hand engine mount from the engine. This gives a bit more room to work around the steering wheel shaft, which is aluminum and easily bent.

Thanks for the tip! Is it possible to install the steering shaft after the motor is in to avoid the chance of bending it, or is space too cramped after the motor goes back in?

Dave

[J!m]

Originally Posted by DaveKern

I've got a Bently manual that I've been referring to quite a bit, but can't say I've looked to see how good/bad the wiring diagrams are.

It sucks. Besides the fact the ti is different from the rest of the E36's (and the roadster is also different, but that's another story...)

Originally Posted by DaveKern

Since I'm still not sure how wild & crazy the build will eventually be, I'm a bit hesitant to really strip down the harness - i.e. if I go with lexan windows, I can remove the entire door harnesses, but for this winter, I'm leaving the glass, so all that crap stays.

Seems reasonable...

Originally Posted by DaveKern

I did have questions on a few bits of the wiring harness though:

ABS ECU - if I'm disabling ABS, can I trace & remove every wire that comes out of or goes into the ABS computer?

Sure. Bear in mind you will get errors from the DME but I don't believe this will put you into 'limp mode'. It's a 95 right?

Originally Posted by DaveKern

Security system - can I pull all the wires, or is this something that may need to be kept in one piece because of anti-theft crap?

Depends on EWS-1 or EWS-2. 1 is easy; 2 is a bit more complicated, but eliminating it deletes a couple relays as well.

Originally Posted by DaveKern

Door/Trunk ajar sensors - any need to keep these?

I am reasonably certain you can jump these out- test first, if it is not a problem, you can eliminate the wire and jump it close to the module.

Originally Posted by DaveKern

Power locks - any need to keep these?

No; however make sure you can reach the mechanical actuators to open them mechanically- as a race car, aren't you required to disable door locks all together anyway?

Originally Posted by DaveKern

Airbag system - I think I already yanked the brain out and chased wires as far as they go on the interior side of the harness. Hopefully that's ok.

Should be fine. May possibly go to limp mode (crash control module); however if you deleted the CCM, you should be OK. I never deleted it that far, so I would think that if you delete the air bags the CCM should be deleted as well. I'm just unsure if that will cause complications with the DME looking for the air bags and CCM and going into limp mode too...

Originally Posted by DaveKern

Wiring that connected under the driver seat (and maybe passenger seat too?) - I'm guessing this might be related to the airbag system?

Driver side is the seat belt tensioner; passenger seat is that plus the occupancy sensor. If the air bags are gone, this should not matter.

Originally Posted by DaveKern

Is it possible to install the steering shaft after the motor is in to avoid the chance of bending it, or is space too cramped after the motor goes back in?

Dave

It's a bit cramped on the driver's side. To be clear, I meant car's right (passenger side) mount. Removing it allows room for the install. However, it appears you have Euro-style headers, which are quite a bit longer, so this trick may not work as well for you. I'd also leave the header nuts at the head quite loose to get a bit more 'wiggle room' with the long headers.

[DaveKern]

Originally Posted by J!m

Sure. Bear in mind you will get errors from the DME but I don't believe this will put you into 'limp mode'. It's a 95 right?

Depends on EWS-1 or EWS-2. 1 is easy; 2 is a bit more complicated, but eliminating it deletes a couple relays as well.

The car is a 1995, and October build IIRC. The motor is also a 1995 with the 413 DME I think and I got the complete engine harness with the motor.

Dave

[J!m]

Problems SHOULD be minor; you may want to contact Bluebimma as he has probably cut up more harnesses to the point you want to go to than I have.

My focus is on street cars and most people WANT the featurs to work...

[DaveKern]

Fuel System Questions:

Since I don't like doing things two or three times, I'd like to try and get the fuel system setup right the first time.

Currently I've got the stock 318ti fuel tank & pumps. In a rally car you re-route the fuel lines inside the car to prevent a rock from rupturing a line. I have to use stainless braided line with proper bulkhead fittings.

For this coming season, the car will be basically a stock S50 motor with header back exhaust, intake, lightweight FW and a chip. I'm assuming a stockish sized fuel system will be up to the task. Looking forward a year I plan to bump the power a bit (or sooner if a sponsor steps up with some cams, forced induction goodies, Euro motor). I don't expect to ever need more than 350whp, but for arguments sake, lets assume that at some point I may want to run 400whp.

What size fuel lines will I need to run to support those fuel levels on the S50 motor? Can I get away with AN-4 lines, or would I need to step up to AN-6? Is the stock fuel pump good enough, or do I need to look at higher capacity drop-in units?

On my E85 powered Mitsu Evo I use AN-6 feed and AN-4 return with two high-output Walbro 255 pumps in-line. That's enough fuel to support ~620awhp. Since the AWD Evo suffers from greater drivetrain losses than the RWD bmw, I'm guessing that the AN-4 will be sufficient.

Thanks!

Dave