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BMW E36 Compact Budget Build

Posted by Nate.Vincent 
mhooper
Michael Hooper
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Re: BMW E36 Compact Budget Build
June 17, 2016 05:37PM
Quote
NoCoast

What's travel on your Bilstein shock in rear? We were looking at using 10" travel in rear with turrets. Reason I ask is it seems that the tower height is a little shorter than I recall our measurements putting it, but it's also been a few months since I looked at it. Basically make sure you are into the bump stops before the arms run out of room and start beating themselves up/bending and adding camber.

Speaking of, are you planning a stock location spring or coilover? I found a set of e30 convertible springs and planning to start with those with a shock to try to reduce the bending load there. We've discussed a hydraulic bump stop sitting inside the spring instead of on the shock too in order to keep that load in the strong part of the arm and reduce the aforementioned bending. Kern's Compact is getting some nice rear camber now after a few hill climb events.


Interesting... I too bend trailing arms on my e30 with no big incidents to speak of... Analyzing them it is very difficult to determine exactly how they are bending... I also considered hydraulic bumpstop in factory spring location... Hmmm. I've bent them with cool overs and with convertible springs so not sure the coil over is the culprit...
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NoCoast
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Re: BMW E36 Compact Budget Build
June 18, 2016 12:12PM
STA setups just are going to bend. Reinforced mounts and proper damper setup. The lever action on the mounts is greater with a coilover than a spring mounted bump stop so might reduce.it but probably plating the beam is advisable.



Grant Hughes
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john vanlandingham
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Re: BMW E36 Compact Budget Build
June 18, 2016 01:40PM
Quote
NoCoast
STA setups just are going to bend. Reinforced mounts and proper damper setup. The lever action on the mounts is greater with a coilover than a spring mounted bump stop so might reduce.it but probably plating the beam is advisable.

Expand on this. That's an "assertion". How was this thought thru? Show homework.



John Vanlandingham
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NoCoast
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Re: BMW E36 Compact Budget Build
June 19, 2016 05:11PM
Just think of it from solid state with bump stop fully compressed.
Now think 100 lbs of force into tire levers off the bump stop and pulls, pushes, twists on the sta to beam mounts.
As the.bump stop is moved closer.to the wheel the force gets greater on the mounts.



Grant Hughes
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mhooper
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Re: BMW E36 Compact Budget Build
June 19, 2016 06:10PM
Plated/ boxed them before snow drift and stpr... Nothing bent there but pretty mellow stages.
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Nate.Vincent
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Re: BMW E36 Compact Budget Build
June 19, 2016 09:14PM
I was planning on copying what Prodrive did on their e30s. Coilover mount in double shear too.



This weekend I helped a friend and crewed for the FCPeuro e30 at the AER race in Palmer Mass. One of our drivers got pinched and we had contact on both rear wheel. chewed up one of the tires on one side and on the other it contacted the wheel (and some other stuff). It knocked the trailing arm out and we finished the last three hours of the race with toe out in the rear. It seems these arms are certainly the weak spot.
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john vanlandingham
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Re: BMW E36 Compact Budget Build
June 19, 2016 09:24PM
Quote
NoCoast
Just think of it from solid state with bump stop fully compressed.
Now think 100 lbs of force into tire levers off the bump stop and pulls, pushes, twists on the sta to beam mounts.
As the.bump stop is moved closer.to the wheel the force gets greater on the mounts.

smoking smiley It may be legal in Colorado but you should still watch what you do when smokin that stuff...

It may be fun but it seems to cloud reasoning...
The arms are weak..In normal trailing use they do not need to be strong as all impacts just bat the arm away (up)..
No so when force comes from side.



John Vanlandingham
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NoCoast
Grant Hughes
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Re: BMW E36 Compact Budget Build
June 20, 2016 10:11AM
I found side forces bent one way, jumps and compression bent the other.
Its not reasoning, its Archimedes. :-)
I'm cool with arms bending. Easy enough to change overnight and in service. Beams I want stronger.



Grant Hughes
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Nate.Vincent
Nate Vincent
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Re: BMW E36 Compact Budget Build
June 20, 2016 01:33PM
Quote
mhooper
Plated/ boxed them before snow drift and stpr... Nothing bent there but pretty mellow stages.

Pics would be great if you have any.
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mhooper
Michael Hooper
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Re: BMW E36 Compact Budget Build
July 01, 2016 05:42AM
http://www.eeuroparts.com/blog/5665/rcr-sets-the-bimmer-up-for-rally-americas-snodrift-this-weekend/

If you scroll down in that article I have a pic of the trailing arm...

I can send u a bunch more if u email me at hooprally at g mail..

Little hard to tell in that pic but there is a 1.25 tube between the trailing arms then 16 ga sheet stitched in top and bottom... The support to the shock mnt is more to help with lateral loads.... I have yet to see a dual shear modification I like... (Soneone please post something nice to show me how!). The issue I have with what I've seen (flat bar coming off t arm to catch outside of shock) is it looks like a big lever to oil can the trailing arm on a big hit...

I will prob go that route of dual sheer eventually but want to really think it through first.
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