E30 Roll Centers

[Digitalwave]

I'm using Ireland Engineering camber plates and the studs are very long, even with a strut bar attached. I should be able to space the camber plate down away from the strut tower. I am also going to add a couple of shims back between the spring top hat and the camber plate itself, which should prevent the binding. They came with 3 shims per side and I think I only ran 1 or 2. The Voshlag plates are very nice.

[Wh33lhop]

I like my raised subframe but combining it with camber and toe adjusters makes it a bitch to adjust them. There's no clearance once you raise it up. I wound up going back to a stock subframe with riser bushings (albeit for other reasons--my adjusters kept slipping) and it's serving me well.

Also bear in mind this will raise your ride height by a good half inch as well, since your Attachment points are moving up 12mm but your springs stay where they are.

[Digitalwave]

I ordered the subframe risers and I am not planning on the trailing arm adjusters.

I don't believe that they change your ride height by an equal amount to what they raise the subframe, since the spring is down the arm and the spring rate does not change, so the ride height doesn't change too much. In any case, if it does change I was running 3 spring pads in the rear so I'd be able to remove some of them to compensate.

[nando]

I like my raised subframe but combining it with camber and toe adjusters makes it a bitch to adjust them. There's no clearance once you raise it up. I wound up going back to a stock subframe with riser bushings (albeit for other reasons--my adjusters kept slipping) and it's serving me well.

Also bear in mind this will raise your ride height by a good half inch as well, since your Attachment points are moving up 12mm but your springs stay where they are.

what? no it doesn't. it doesn't affect ride height at all - it just moves the subframe up in relation to the body, reducing the amount of negative camber (just like if you had raised the car up 12mm with taller springs).

The ride height stays exactly the same because that's controlled by the length and stiffness of your springs, not the position of the subframe. Come on meow. :p

[lambo]

what? no it doesn't. it doesn't affect ride height at all - it just moves the subframe up in relation to the body, reducing the amount of negative camber (just like if you had raised the car up 12mm with taller springs).

The ride height stays exactly the same because that's controlled by the length and stiffness of your springs, not the position of the subframe. Come on meow. :p

The center of the hub is behind the spring so it would change it a bit. Not one-to-one, though.

[nando]

the amount it would change would probably be difficult to measure.

[Wh33lhop]

Think of the trailing arm as a lever with the fulcrum around the spring, which you've noted won't change position. You're moving one end of the lever up 12mm. Since the motion ratio is about 2/3, it would seem the ride height rises closer to 1/4". Either way I definitely noticed it when installing my risers.

[BraveUlysses]

Are the riser subframe bushings worth it on a car that's on coils but not slammed?

[autox320]

Gustave made great contributions to many subjects long ago. Here is an archive of his page. You can ignore the kmac eccentric bushings :) that's just shows how long ago this was written. Everyone by now knows the trouble with eccentric kmac bushes and how bad they were in the day. Not the same as eccentric adjusters most use today. Plenty of other very good info to reference and what the dtm guys were accomplishing with this chassis. Plenty of S14 specific parts for those interested.

http://web.archive.org/web/20080221023740/http://e30m3performance.com/tech_articles/susp-tech/index.htm

[nando]

Think of the trailing arm as a lever with the fulcrum around the spring, which you've noted won't change position. You're moving one end of the lever up 12mm. Since the motion ratio is about 2/3, it would seem the ride height rises closer to 1/4". Either way I definitely noticed it when installing my risers.

the 2/3 motion ratio is the distance from the wheel to the spring in the transverse direction, it's not really the same thing. if you think of the trailing arm like a teeter totter, with the spring being the fulcrum, the distance from the subframe to the spring in the parallel direction is a lot further than the distance from the spring to the wheel (probably more like 1/4 than the 2/3 motion ratio). Sure, it moves, but it's a very small amount.

[nando]

Gustave made great contributions to many subjects long ago. Here is an archive of his page. You can ignore the kmac eccentric bushings :) that's just shows how long ago this was written. Everyone by now knows the trouble with eccentric kmac bushes and how bad they were in the day. Not the same as eccentric adjusters most use today. Plenty of other very good info to reference and what the dtm guys were accomplishing with this chassis. Plenty of S14 specific parts for those interested.

http://web.archive.org/web/200802210...tech/index.htm

yes, I loved that site! Too bad the original was taken down, good thing for the internet archive. Should make a PDF of all his tech articles as they are still really helpful.

[aventari]

I get this "Page cannot be displayed due to robots.txt."

does it work for anyone else?

[kronus]

they've disallowed the Internet Archive from showing that domain, it won't work for anyone

[agent]

I was able to access it so I did a quick and dirty print of the pages to PDF.

[M-technik-3]

It still works for me, odd.