BMW Compact Build

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Do It Sidewayz

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DaveK

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Do It Sidewayz
If you are binding the springs look at these.

http://www.integrashocksandsprings.com/pages2010/springs2010.html

I got a set, and they are real nice, much lighter, and have more travel for the same length of spring...since i really doubt you can get more than a 14" spring back there.

Unfortunately it looks like they're only making 2 5/8" springs, so that's a no-go.

The other issue I'm running into is that most of the 'low coil count' springs are barrel type springs and I'm not sure I've got clearance for those when the car approaches full compression. Thinking I could probably do a 4" normal spring and a 12" barrel spring and not have tire clearance issues if I stick the 4" spring up at the top...but that's 4 springs I'd need to order.

Dave

Are you using a 2.5" ID spring? if so, big deal. A 3" i could understand.

I just had a big tele-conference and have some 200lb barrel thangs here and they measure about 94mm OD, barely one red c**t hair over the 21/2 thangs or maybe 1/16 of a mythological king's thumb a side.

We came to conclusion a) he has more room than he thought without banging springs into anything and b) there may be some just right on the edge of coil bind-a-tude-ation occuring so we'ze gonny try a 16" straight 2 1/2" first..
Even on suspesnion most problems are solved with the simplest answwers and this seems the simplest to try since the car really works so well except this little 90mph or 140 km/hr boing and sharp bump or little jumpy things.

It's just so easy to ramp up the complication...

---

John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.

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john vanlandingham
I just had a big tele-conference and have some 200lb barrel thangs here and they measure about 94mm OD, barely one red c**t hair over the 21/2 thangs or maybe 1/16 of a mythological king's thumb a side.

Sweet! For some reason I forgot to mention that at full compression I've got room for ~18" of spring. Of course to get the back end to sit low enough, I have to use helper/tender springs.

Have been digging to try and figure out what this bumpstop is that's on there. Its marked with "EKT 4". Searching for that yielded nothing, but some further searches for Bilstein HD bumpstop have pulled up pics of similar looking ones from Xterra and the Subie Legacy. Still no info on the effective rates, but these damn things are crazy stiff and just under 2" tall.

Its the one on the far right:
http://racecompengineering.com/images/bumpstopcompareSM.jpg

Dave

Buddy of mine just asked me a question about an Evo video I put together from a goof around day at CORE. Went back and watched it and realized that I've got footage of that same "straightaway" that's causing the bottom out issue on the BMW.

Skip to ~1:25 in to see the bump:

http://www.streetfire.net/video/ams-video-contest-submission-3_548437.htm

Then here's the BMW vid again:





Skip to 0:53 where the front rolls through the dip nicely and the rear gets bounced.

Obviously in-car vs. out-of-car video makes it apples & oranges, but thought it was interesting. FWIW, this was when the Evo was making right about 300whp at 22psi.

Dave



Edited 1 time(s). Last edit at 07/15/2011 06:41PM by DaveK.

It's really hard to tell anything concrete from the video, but my impression is there is not enough compression damping.

Went out to CORE yesterday for another testing session. Goal for the day was to determine if we could make the shocks work, or if I'd need to send them back out for a re-valve, and/or cut the towers out and make room for something longer.

On Saturday night I swaped back to the original JVAB shocks. These are ~8.5" travel Bilstein shocks with 260/90 valving. Instead of using the eyelet with the 1" spacer up at the top, I changed that out for the short spacer that came with Stig's Magnesium units. I figured that this would give me additional up travel because at rest I could now see an extra inch of piston. The downside of this change is that I've limited the amount of droop travel (18" vs 16.875".

First session - I installed the 2" soft bumpstop. First impression is that I love the damping on these shocks much more than the stiffer valving on Stigs shocks (350/110). Second impression when flying down the back straight is that I bottom out without really even attacking the course.

Second session - I added an Ohlins bumpstop to the mix. The squat under acceleration didn't seem to feel any different (good!), but running over the rougher stuff it was more resistant to bottoming out (also good), but when I tried to up the speeds a bit, I was still getting a pretty good bang over some of the bumpier parts with a some bounce back.

Third session - I removed the Ohlins bumpstop and replaced it with the ones the shocks came with. I've got no idea on specs for this bumpstop, but it's ~2" tall. So, with 4" of bumpstops on the car I headed back out. Once again I'd get good squat under acceleration, but I could really hammer on the car down the straights and it wasn't until committing 100% to some of the roughest spots that I felt a mild bottoming out. The great news is that even when it did bottom, I wasn't getting rocketed off into the weeds, it was controllable.

So, all in all, a great day at the track. Due to muddy conditions the past few weeks the track was probably the roughest I've ever seen it, and there were still some big mud holes to avoid, rendering timing a useless endeavor. Also tweaked the seat forward a little for the wife and she went out and cut a few laps too. She was keeping it in 3rd & 4th, but jeez...she knows where the go-pedal is!!

Next up I've got some modified front knuckles on the way and hopefully I'll be able to solve that 1/2" toe out on both sides issue. I may also play around with ride heights a bit more, and hoping to drop a 200# 16" spring back there to see how that feels, and will likely repeat the bumpstop experiment. I think we were making the swaps in ~10 minutes.

Dave

Slight confusion here, the bump stops that you ended up using are 4" tall, or 2 2" stacked? and all the others were 2" tall?

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phlat65
Slight confusion here, the bump stops that you ended up using are 4" tall, or 2 2" stacked? and all the others were 2" tall?

A) JVAB = ~2" static
COT58-25 = 2.283" static (0.710 @ 1000 lbs, 0.636" @ 2000 lbs)
C) 00563-04 = 1.107" static (0.388 @ 1000 lbs, 0.331" @2000 lbs)

First session = B
Second session = B & C
Third session = A & B

I'm thinking about trying out a COT75-40 bumpstop in place of the JVAB supplied one, as I think that will come in a little softer than the one I've got, and then I'll have a known rate as well. Also, picking up some high travel 185# springs on the way home from work tonight.

Dave



Edited 1 time(s). Last edit at 07/25/2011 05:37PM by DaveK.

Thanks for clearing that up. Keep us posted, as this setup may just end up in my car. I would like to have more acceleration compression, and I am at the lowest limit of ride height, and I would love to drop the car 1-1.5"

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DaveK
I'm thinking about trying out a COT75-40 bumpstop in place of the JVAB supplied one, as I think that will come in a little softer than the one I've got, and then I'll have a known rate as well. Also, picking up some high travel 185# springs on the way home from work tonight.

The Hypercoil 185# high travel springs were waaaay too wide looking to even consider fitting to the car. They'd fit in the shock tower, but I'd run into clearance issues on the tires in a big way. I'm already having to run 20mm spacers, and with the 195/70 BFGs I'm outta room on the fender side too....Compact Cup widebody could be a good fix:



Anybody want to sponsor it?

I picked up a set of 14" 200# springs and they've got 3 less coils and a lot more void space than the 175# springs I've been using so coil bind is no longer a possibility. Will get those mounted up and head back to CORE this weekend for another round of testing. May stick some tie rod spacers in there too to get a few more degrees of angle out of those front tires.

Dave



Edited 1 time(s). Last edit at 07/26/2011 05:07PM by DaveK.

Check your email. Sent you a place I found just off Arapahoe Road that could possibly help diagnose without having to tow 120 miles round trip. It's a short road but has only one way in and out and has lots of compressions and one smallish jump thing. Down along a creek in a culvert so quite well hidden as well.

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NoCoast
Check your email. Sent you a place I found just off Arapahoe Road that could possibly help diagnose without having to tow 120 miles round trip. It's a short road but has only one way in and out and has lots of compressions and one smallish jump thing. Down along a creek in a culvert so quite well hidden as well.

Got it - I still need to get the check engine light to dissappear so I can run the car through emissions.
I actually don't mind the tow out to CORE if I'm going to get more than a couple hours of run time in. Just knowing we've usually got the run of the place and don't have to worry about cops or pissing off the neighbors is pretty nice...and the $250 season pass means heading out there costs me nothing other than diesel.

There's a rally-x out there on Saturday too. Now that Mark has a job, you guys should bring out a rally car or run the starlet.

Dave

Yeah. CORE will always be better. But this is probably 3-4 miles from any house. Closest thing is the WalMart 2-3 blocks away. The road is in the bottom of a culvert along a creek bed and would be good for testing what you are trying to test I think. Go check it out in the A6 some night.

I'm busy doing nothing this weekend. I'm not working come Monday though. Subaru engine swap, which I should be able to do on Monday, then it's all about the Merkur!!!

Steve's planning to get his new Toyota Corolla running though. RWD fun this winter!

Another trip to CORE this weekend - have to say, damn we're lucky to have a place like this to really shake down a car hard.

Unloaded the car and set to work swapping in some new parts. We figured that there would be a bunch more swapping going on, as we had new springs and new bumpstops so all sorts of combinations would be possible.

First up:

-JVAB Bilsteins 260/90 valving with short eyelets
-Hypercoil 200# 14" springs (helper springs removed) tightened just enough not to rattle at full droop
-1" spring spacer (due to running out of threads on shock body)
-COT 75mm soft bumpstops
-14.5" fender/wheel center ride height (~0.75" taller than last time out)

Took a 75% lap and things seemed good. Took the next lap about the same but aimed for the spots that had given me trouble in the past. No issues. Then banged out a succession of 90%+ laps and hit the rough spots every which way possible, and no bottoming out!

I had been expecting to have to add another bumpstop, but I think the combination of a slightly higher ride height (i.e. more up travel available), slightly stiffer spring, and the longer more progressive bumpstop made it work.

On the whoops on the back straight, it flies pretty good. Only real issue I'm still seeing is that on the step-up style jump car likes to nose down on the landings, so much so that I've now got paint scrapes on the front of the front bumper. The good thing is that when the back sits back down, it just squats and goes, no crazy rebounds to deal with. I'm guessing the off kilter flying has something to do with that 6-cyl up front and no downforce on the back. That Compact Cup kit is looking better & better.

Going back to CORE being such an awesome place to shake a car...we did managed to find another weak link which cut our day short by about 30 minutes. I was cranking around the track and all of a sudden the throttle cable stuck. I fiddled with my feet through the pedals to see if something had gotten hung up. Nothing looked out of the ordinary so I killed the engine. Hopped out of the car and popped the hood. At first glance things looked ok, but I couldn't move the throttle linkage towards closing it at all. Looked closer and I could see something was up with one of the couplers on the intake, it was kinked. Weird!

Upon further inspection, the motor mount arm had completely removed itself from the motor mount and the mount was sitting ~1" too far forward. So, I look at the motor mount expecting to see that the nyloc nut and washer were missing....nope, they were still there, but had loosened almost all the way off. Turns out the engine had been moving around and it wallowed out a hole big enough in the motor mount arm so it was able to just slip off!

Also managed to find the limits of the stock cooling system. With the ability to rail on the car flat out, and with temps in the upper 90s, I was finally seeing the radiator temps moving past the half way point. Time to ditch the $100 Checker radiator for something with a bit more cooling capacity.

Dave



Edited 2 time(s). Last edit at 08/01/2011 12:01PM by DaveK.

Looks like I might've dropped a valve in the motor over the weekend. Here's answers to some questions from a thread in the general forum...figured it'd make more sense to have here.

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wvonkessler
Sounds like the dreaded E36 "money shift".

Nope, don't think so. I put a DSSR shift rod on there and have a DTM style shifter that's solid mounted to the trans tunnel, so its pretty rock solid.

The motor let go while wailing away in 3rd or 4th gear with wheel spin, i.e. it was riding the rev-limiter.

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wvonkessler
Time for the LS1/T56 combo?

Nope, don't want a combo that I can't use at MaxAttack events. Besides, if given the choice to go outside of the manufacturer, I'd have gone with a 4g63 since I have lots of spares from the Evo.

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modernbeat
Yep Dave, we are on our THIRD S54 engine in an autocross car. High RPMs took out the oil pumps in the first two even though we took the precaution of welding the nut to the gear face.

I don't think the oil pump failed in this instance...or are dropped valves a symptom of not enough oil in the head? I did recently have a new pump & baffle installed in the motor with the oil pump nut fix.

Dave

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DaveK
Looks like I might've dropped a valve in the motor over the weekend. Here's answers to some questions from a thread in the general forum...figured it'd make more sense to have here.

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wvonkessler
Sounds like the dreaded E36 "money shift".

Nope, don't think so. I put a DSSR shift rod on there and have a DTM style shifter that's solid mounted to the trans tunnel, so its pretty rock solid.

The motor let go while wailing away in 3rd or 4th gear with wheel spin, i.e. it was riding the rev-limiter.

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wvonkessler
Time for the LS1/T56 combo?

Nope, don't want a combo that I can't use at MaxAttack events. Besides, if given the choice to go outside of the manufacturer, I'd have gone with a 4g63 since I have lots of spares from the Evo.

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modernbeat
Yep Dave, we are on our THIRD S54 engine in an autocross car. High RPMs took out the oil pumps in the first two even though we took the precaution of welding the nut to the gear face.

I don't think the oil pump failed in this instance...or are dropped valves a symptom of not enough oil in the head? I did recently have a new pump & baffle installed in the motor with the oil pump nut fix.

Dave

Dave, my machine shop guys are always gritting their teeth when I have Euro shit with the Krautski 3 groove keepers. Very weak design they say.
The keepers --locks or split collets whadderever the fawk ya call them, bottom against eachother and the valve is allowed to roptate and move..
Bad... Well good in theory. German like theories.

We've kissed the flat side of the lockes agianst a good machinst griding wheel---not the pile of crap in some auto place where the boys been sharpening their chisels, but a good one.
Kissed the locks and checked they DON'T BOTTOM and that they grip the valve tightly...

Take a coupla second per lock.....

---

John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.