Lowering a 928
#16
Rennlist Member
Join Date: Oct 2005
Location: Gatineau, Québec, Canada
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Post #7 for pics of the measuring points.
https://rennlist.com/forums/928-foru...questions.html
https://rennlist.com/forums/928-foru...questions.html
Last edited by Bertrand Daoust; 04-24-2014 at 08:27 PM.
#18
Three Wheelin'
Lowering an inch is common, and our bump-steer study showed that changes to the bump-steer and alignment were negligible at that height. At an inch, the suspension is still within its normal arc range.
Race tracks are fairly smooth - and you can count on them to not have potholes. Ride height is higher on street cars because of potholes and curbs (that race tracks do not have). Rumble strips are different - not the same as curbs.
Beyond an inch - yes, you should install a bump-steer kit to straighten your tie rod ends again, and check the alignment of the car.
And in all lowering cases, a set of Protection Plates is wise to prevent panning on driveway approaches. The first things to hit the pavement on a 928 are the air conditioner and the alternator. In lesser cases it just costs you an alternator. In the worst cases I've seen it snap the cast air conditioner mounts off the block, spelling end-of-life for the motor.
For more information on these suggestions, you may follow these links:
Protection plates: http://www.928motorsports.com/parts/chinplate.php
Bump-steer kits: http://www.928motorsports.com/parts/bump_steer_kit.php
Race tracks are fairly smooth - and you can count on them to not have potholes. Ride height is higher on street cars because of potholes and curbs (that race tracks do not have). Rumble strips are different - not the same as curbs.
Beyond an inch - yes, you should install a bump-steer kit to straighten your tie rod ends again, and check the alignment of the car.
And in all lowering cases, a set of Protection Plates is wise to prevent panning on driveway approaches. The first things to hit the pavement on a 928 are the air conditioner and the alternator. In lesser cases it just costs you an alternator. In the worst cases I've seen it snap the cast air conditioner mounts off the block, spelling end-of-life for the motor.
For more information on these suggestions, you may follow these links:
Protection plates: http://www.928motorsports.com/parts/chinplate.php
Bump-steer kits: http://www.928motorsports.com/parts/bump_steer_kit.php
#19
Developer
The aluminum protection plates are consumable - that is - every time they scrape the cement at the end of your driveway they wear off a little. They are supposed to - this way they are not striking sparks and starting fires. The ones on my '91 are about 8 years old and have rubbed enough times that I think they may be due for replacement. They are down about 1/2" from where they used to be.
Back in my day they used to call these "over-riders" and they were fitted to just about everything so you would go up and over the cement stop at the end of the parking space instead of bending a steering arm on it. They were common on a lot of cars.
The 928 has a brace with a tie-down hole in it (used to tie your 928 down as it was shipped on a boat). They are in the front, one on each side that braces from the frame to the bottom of the forward lower link bushings. They don't really protect the alternator or the AC compressor well, and they do not protect your S or S4 chin spoilers at all.
When the protection plates are fitted, they are barely visible. But they sure do a good job. I don't want to hijack the thread either, but here are just a couple pics. More info about these available at this link:
http://www.928motorsports.com/parts/chinplate.php
Back in my day they used to call these "over-riders" and they were fitted to just about everything so you would go up and over the cement stop at the end of the parking space instead of bending a steering arm on it. They were common on a lot of cars.
The 928 has a brace with a tie-down hole in it (used to tie your 928 down as it was shipped on a boat). They are in the front, one on each side that braces from the frame to the bottom of the forward lower link bushings. They don't really protect the alternator or the AC compressor well, and they do not protect your S or S4 chin spoilers at all.
When the protection plates are fitted, they are barely visible. But they sure do a good job. I don't want to hijack the thread either, but here are just a couple pics. More info about these available at this link:
http://www.928motorsports.com/parts/chinplate.php
#21
Rennlist Member
Off course the heights quoted assume stock wheel diameters.
It appears to me that the stock ride height in front puts the lower a arm parallel to the road surface.
It appears to me that the stock ride height in front puts the lower a arm parallel to the road surface.
#22
Rennlist Member
I have no adverse effects at 110mm front and 135mm rear. bump steer is an issue, of course, but less of a problem, if you are driving hard, due to the fact that the drooping wheel doesn't have much weight on it . however, around a very long 8-10second high speed high g turn, you can scrub off the inside edge, but this situation is very rare, unless you are lapping at willow springs.