E30 Roll Centers

[BraveUlysses]

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

[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.

[nando]

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

[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]

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

[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.

[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'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.

[BlackbirdM3]

Thanks for the info everyone.

Blackbird, I was planning on adding a couple more spacers under my camber plates as well, as I think they may be binding on the top spring perch.

What size wheels are you running with your 13mm roll center spacers?

Sadly, 16s. The car is far faster everywhere with 15s. You can only add to the top of the camber plates. The strut extension is the limiting factor, In order to add the spacers on top of the camber plates, you need to remove the original mounting bolts (the 3 that go through the body that hold everything on the car) and replace them with longer ones that allow you to put a donut shaped spacer on top of the whole mess.) I can take pics of what I did if you want. I also have the same issue with the spring hats contacting the underside of the camber plates. (I'm going to buy some Vorshlag plates that use the stock hats mounted to the plates. They are expensive, but they look like the best design for stock style springs.)

Will

[Digitalwave]

Thanks for the info everyone.

Blackbird, I was planning on adding a couple more spacers under my camber plates as well, as I think they may be binding on the top spring perch.

What size wheels are you running with your 13mm roll center spacers?

[BlackbirdM3]

You can get spring spacers for the rear from Ireland. Add those with the subframe risers, and thick spring pads, you can get pretty close to where you need to be. On my M3, I have 13mm front spacers, and then I added spacers to the tops of the camber adjusters (because the total length of the Strut assembly is what dictates the roll center) I have GC camber/caster plates that were too low of a stack height, so I had some spacers made up that brought the stack height up to just a little more than the stock non adjustable strut mounts should be. With the Turner J stock springs, the setup is very hard to beat, no body roll, car is firm, but not harsh. Totally neutral handling.

Will

[autox320]

few pics I can find on this computer from last winter working on it

note I changed to hex head bolts on the inner lower 2 which allowed clearance at full droop







changed the two inner socket screws to hex after this photo

[autox320]

RC spacing front and rear is worth the effort. Bought mine from Lee. Using 17x8 apex wheels E30M3. Spacer thickness is 26mm - offset is 16mm. Not many have the offset ones that add front trackwidth. I bought the last offset set from Lee if you want a set can also order them through Millway in Sweden they carry them.

Most I've seen run the 13mm spacers and no offset. Can also make a diy bumpsteer gauge setup and see how far off for bump under compression or droop. Any amount raising the RC in the front helps with a lowered E30 though.

If choose the offset spacers they do have an advantage IMO. You will need to dent tune your fender wells and lips. Possibly break out the grinder etc. I'm having to relocate the tie down points on the front frame rails. I ran a new set of NT01's and the inside just can barely scrub the tie down when the tire gets hot and expands. But they are worth every penny in the handling dept. I"m currently on HR race also, but looking to move to a coil over in a year or so.

I forgot to mention that if use the offset ones they fit easier since more clearance to the wheel barrel. But you'll want rack limiters and a hammer for the other areas inside the wheel well :)

[bataangpinoy]

Totally worth using the rear subframe risers, even in a street car.

[M-technik-3]

I bought my sppl centers from Lee, years ago. He might still have some