Mounting the engine without subframe spacers, and without tilt.

[BruceBe]

As has been said but completely overlooked, there is no need to mess with anything during the swap. It fits perfectly fine without any modifications to the subframe/steering/suspension/etc..

Yep, we simply modified the pan to get the engine as low and level as possible. I've documented the process elsewhere on the forum. In our view, this approach met more of the success criteria for our project than spacers. Since it's a race car, we had no desire to alter the suspension geometry in any manner (beyond what we have already done to achieve acceptable handling response over the last 8+ years).

Keep in mind, that the lower control arm mounts to *both* the body and the subframe. Spacing the subframe alters the angle of the LCA, which can have an impact on any anti-dive built in to the chassis (it will increase anti-dive, in this case). It will have a 2nd-order effect on caster as well. With a lowered car, it will also further place the LCA in unfavorable, non-linear areas of the camber curve.

How much of this is relevant AT ALL to a street car is a matter of opinion, but none of it is directionally correct. However, if modifying the oil-pan is outside the scope of a particular project, it's probably not the end of the world.

-Bruce

[The Dark Side of Will]

I'm with you Dark side (how ironic), there are many ways to skin a cat, and as far as I am concerned there is the right way and the 'it works' way of doing things. Very German like of you.

Call me crazy, but if we are messing with suspension geometry to accommodate the m60/2, what is the point in choosing an e30 as a base over another car? For me the reason I want to do it in an e30 is to have an e30 feeling factory-esque car, with ~280-300hp, and a V8 sound (which i have grown to love with my x5 4.4). If we start messing with geometry even a bit, as far as I am concerned it is not the same car.

Thanks!
Spirited discussions lead to the best learning. It always hurts when our deeply held beliefs are challenged, but the learning process.
No hard feelings should result because we all end up better for it afterward!

As has been said but completely overlooked, there is no need to mess with anything during the swap. It fits perfectly fine without any modifications to the subframe/steering/suspension/etc..

I think this whole thread was started to discuss a way of installing the V8 with zero angle across the guibo. Apparently, with the V8 "dropped in", there's an angle across the guibo that's greater than stock.

My take on it is that you need to know three things:
1. You need to what you have now. (IE, what your design parameter is in the initial configuration and where it is relative to optimal.)
2. You need to know what you're going to change (How much and in which direction you need to change your design parameter, which parts you'll change to get there and what side effects those modifications will have.
3. You need to know what you end up with. (What your design parameter is after the modification, what it is relative to expectation, and whether it's better or worse than it was)

For the driveline angle topic, item three has been partially adressed. (This Post)
None of the above have been addressed on the bump steer topic.

What I've described above is the basics of the process of deliberate engineering development. In this case, it's of a vehicle from a normal street car into a hot lapping demon. :twisted: :borg:

If you're just after "the stance" or "the sound" or want to cruise around and only make a few shakedown trips down the 1320, then disregard everything I've posted in this thread. :p

[E30SPDFRK]

I'm with you Dark side (how ironic), there are many ways to skin a cat, and as far as I am concerned there is the right way and the 'it works' way of doing things. Very German like of you.

Call me crazy, but if we are messing with suspension geometry to accommodate the m60/2, what is the point in choosing an e30 as a base over another car? For me the reason I want to do it in an e30 is to have an e30 feeling factory-esque car, with ~280-300hp, and a V8 sound (which i have grown to love with my x5 4.4). If we start messing with geometry even a bit, as far as I am concerned it is not the same car.

As has been said but completely overlooked, there is no need to mess with anything during the swap. It fits perfectly fine without any modifications to the subframe/steering/suspension/etc..

[noid]

I'm with you Dark side (how ironic), there are many ways to skin a cat, and as far as I am concerned there is the right way and the 'it works' way of doing things. Very German like of you.

Call me crazy, but if we are messing with suspension geometry to accommodate the m60/2, what is the point in choosing an e30 as a base over another car? For me the reason I want to do it in an e30 is to have an e30 feeling factory-esque car, with ~280-300hp, and a V8 sound (which i have grown to love with my x5 4.4). If we start messing with geometry even a bit, as far as I am concerned it is not the same car.

[The Dark Side of Will]

I challenge you to replace the E30 rear suspension with something lighter... ;)

And if you think E30's have a snap oversteer problem, go drive a Pontiac Fiero to 10/10ths! :woowoo:

[dirty30]

Anyone looking to perfect the suspension geometry of an E30 is wasting thier time when there is that snap oversteering, non-adjustable, unsprung heavy trailing arm mess out back! Save the serious track nerd geometry stuff for the E36 guys!








Semi j/k fellas.

[The Dark Side of Will]

Driving is not measurement.

For example, if the car feels nervous braking for a bumpy corner, is it bumpsteer or toe?

When I buy a body for my project, it will be an iX.
If I find I have the desire to change the stock bump steer curve, I will take a measurement. I'll probably snag the setup pictured above to adjust the factory curve.

Right now I'm still making sure I can package everything in the engine bay, get the gear ratios I want, etc.

[E30SPDFRK]

Why don't you do some yourself then and stop arguing with people that have first hand experience?

[The Dark Side of Will]

We can go back and forth about what's significant and what's not all day, but in the end ONLY the measurements matter.

Apparently no one has ever done any...

[Jonsku]

However, moving the rack up or down relative to the crossmember, even as little as 2 mm WILL change the bumpsteer curve of the suspension. If you change the shape of the curve without knowing what your before and after curves look like, you're just shooting in the dark. You might as well try to fix a no-start condition by replacing random lightbulbs.

If you're concerned with such small change, be my guest. However, it would be very beneficial to the people to understand that such a change does NOT have ~any effect on the drivability of the car.

Btw, some E36 / Z3 steering racks are already lower in mounting point height than the E30 units and thus need couple 2mm spacers in order to mount properly. I've NEVER heard any complaints / comments related to bad bump-steer behaviour due to the spacers (which can of course be used in two ways - up or down).

Two V8 projects here have used E36 rack with spacers on the top-side, thus lowering the rack. Neither of them used subframe spacers, and worked very well.

[bmwmech1]

I've said my peace...:)

Garey

[The Dark Side of Will]

What about spacing both the subframe and the control arm bushing mounts the same amount? That would change caster to a degree too, but if the level change of the bushing center and the subframe are the same this should not be an issue right?

Not significant.
What matters is the axis from the center of the inner ball joint to the center of the outer ball joint.

[The Dark Side of Will]

This page has the brutally simple diagrams that I hope will explain the topic of bumpsteer:

http://www.quadratec.com/jeep_knowle...article-68.htm

Here's a simple DIY setup for measuring bumpsteer:

http://www.roclife.org/forums/showth...r-measurements

No more excuses.

[tttoon]

What about spacing both the subframe and the control arm bushing mounts the same amount? That would change caster to a degree too, but if the level change of the bushing center and the subframe are the same this should not be an issue right?

[The Dark Side of Will]

I agree with what you're saying Garey, but you're also forgetting that the top of the strut stays with the body. So in reality, it is the same as a 20mm drop as far as the subframe is concerned. The vehicle and bottom of the struts will stay the same height while the subframe drops down.

And when people talk of bumpsteer on here, I believe they're speaking of the extra force you get acting on the tie rod after it passes horizontal rather than changing its plane relative to the control arm.

He's not forgetting that at all.
Spacing the subframe down is very very similar to lowering the car by the same amount. The only difference is that the length of the strut doesn't change with subframe spacers.

There is only one definition of bumpsteer:

"The change in toe a wheel demonstrates as its suspension traverses its travel."

There is no other definition of bumpsteer.