kccampro

Take a look at this, these control arms came of a 928 that was raced in PCA events. It looks like someone when through the trouble of adding an extra bolt through the control arm on both sides. My guess is that this would reduce the 'passive rear-wheel steering' of the 928 (to quote Jeremy Clarkson). Thoughts?

76FJ55

Yes the addition of that bolt it to lock the bushing in a fixed position elimination the

Weissach steering effect.

Hilton

Interesting.. first pic I've seen of it done. Its been discussed plenty over the years, and is something Marc Thomas used to advocate apparently, but that others felt wasn't necessary. John Veninger had his done too IIRC.

https://rennlist.com/forums/928-foru...h-pinning.html

https://rennlist.com/forums/928-foru...rear-axle.html

BC

There is a reason no one ever posted a picture if it when mark t at devek was charging hundreds for the job. Its a BOLT though the lower pivot area.

Ispeed

Pinning the weissach link would let you set toe accurately and probably get a lot more miles out of a set of rear tires. 20 year old rubber bushings combined with sticky 295 size tires (when it was designed for old 225 rubber) would mean a lot of movement and consequently a lot more tire wear.

Can it be rebuilt with a heavier duty rubber bushing? That may be a good idea for anyone using wide rear tires.

kccampro

Thanks guys... that would explain it. With the axle 'pinned' as has been done on my control arms, has anyone gone a step further and welded the flat vertical section of the control arm to make it more of an I-beam? I'm speaking about the part of the control arm that tow truck operators are forever latching too to pull the car from behind and bending the control arm... With the bushing pinned is there any benifit to welding that section solid?

atb

At one point Mark Anderson was running modded lower control arms that didn't have the flexible blade. It had been replaced I believe with tube steel.

Gregg K

I was wondering why this website didn't have monoballs for the 928. I haven't looked closely at the system. But it seems like it's a replacement for the stock bushing. GT3 guys were talking about it.

http://www.elephantracing.com/suspen...dmonoballs.htm

mark kibort

Ive had no issues, no tire wear, with the unpinned weisach, running as it came from the factory. no tire wear and I would BET that my car handles better than any that has it pinned. I run 335rear tires, so there goes that theory.

If you understand how the weisach works, you can see that it actually can help in handling. certainly, it doesnt hurt any . my car handles the power perfectly and is extremely tame at the limit.

kccampro

So no purpose in welding up my control arms prior to powder coating? They're out of the car so now would be the time to do it. Any negitive impact of welding them solid?

mark kibort

In my opinion and experience, you WANT the Weisach left alone
https://rennlist.com/forums/928-foru...u-do-it-3.html

to be fast on the track, you use the weisach to create stability under braking. (it toes in under trail braking helping with the effect of oversteer during turn in)
AND, then it helps with corner exit, as the toe out effect alows for better rotation of the car with application of power, NO matter what the power and no matter what the tire size. ( i have 400hp, and 335s in the rear on slicks)

So, you wonder why the track videos of the guys that pin their cars are so loose??? maybe this is the problem. maybe the Pinning made sense on paper, but it doesnt seem to make sense for the track.

Speedtoys

...gotta be the Amsoil.

Speedtoys

I gotta wonder...does the roll center of the larger tire create new problems as well that are separate from what the suspension is doing?

entropy_engineering

I think it makes a difference (especially in lower gears) if you have an lsd or not, and which one. Is it an early early 8 clutch, an early 4 clutch, or the later electronic unit. In a low gear the tight clutch type will try to make the car rotate (potentially a lot) on exit with judicious throttle, so the situation can compound quickly adding the effect of the rear suspension. I understand (at least the early cars) have the diff. designed to tighten the clutches more based on torque which explains why it's so easy to tighten it up the most in first gear with the transmission multiplying accordingly. I've been surprised by the times I've left an intersection to turn left a little quickly on wet roads and had the back try to step out, especially after putting 295's on the back. Edit: By surprised the back stepped out I mean worse than a comparable car or what the conditions would suggest, not that I can ever be a jackass driver...