Suspension confusion

[Stavro55]

Im after a bit of advice regarding rear suspension setup on my MR2 sw20. I bought it not so long ago and haven't driven it much, been doing a few jobs. The car is on BC coilovers. The previous owner used it for trackdays and there a few prints from where its been aligned and corner weighted . The is barely a finger between the tyre and arch. When i jack it up the wheel barely moves and theres very little vertical movement when i put my weight on the rear arches. I jacked the car up by the subframe so both wheels were in the air, still no wheel movement only when i removed a droplink did the wheel drop. This all seems a bit strange to me but im no car suspension expert. To me it doesn't seem like the car has much chance of keeping the tyre on the road. Maybe its setup more for smooth tracks than roads. Anybody with good knowledge of these things can advise me? My instinct is to go about resetting ride height and travel, but im a little reluctant due to the fact this has been done professionally previously. The rear is on 17s btw.

[GreenV8S]

Unless it's being driven on a billiard table, it should have suspension movement. It doesn't sound as if it has any movement at all. That may be because the wrong dampers are fitted and they have been bottomed out to get the desired ride height. Just because the corner weights and geometry have been adjusted professionally doesn't mean the suspension has the correct components and is working correctly.

[take-good-care-of-the-forest-dewey]

This video should be complusory viewing for idiots (not you OP) who think stiff coil-overs are the answer to fast...

https://youtu.be/m9kQrbPEXKU

OP your instincts are correct... also BC don't have the greatest of reps. They not inherently bad, just very very cheap.

[Stavro55]

Thanks for your replys guys. I agree with what both of you are saying. The dampers aren't bottomed out though as the wheel drops when the droplinks to the sway bar is removed.

[LimSlip]

The standard rear spring rate is around 3.7kg/mm and those BC coilovers likely have 8kg/mm springs, way too stiff for road use IMO.

[Stavro55]

What mskes you say that? I would have though if the spring rate was too high the shocks would be at full extension not the other way round?

[LimSlip]

Stavro55 said:

What mskes you say that? I would have though if the spring rate was too high the shocks would be at full extension not the other way round?

Stavro55 said:

When i jack it up the wheel barely moves and theres very little vertical movement when i put my weight on the rear arches

This suggests very high spring rate, or excessive preload. Do the coilovers have a "helper spring", a short spring made from flat section steel that sit one end of the main spring? These have a low spring rate and are only used to keep the main spring seated and compress flat with weight on the car, but will still allow the damper to extend with weight off the wheels.

[Stavro55]

No, no helper spring. But also I mentioned that when the swaybar droplinks are removed the shock then fully extends.

[Stavro55]

I really appreciate the help btw. 😊

[LimSlip]

Can you see what's preventing the anti-roll bar from lowering any further, e.g. is it fouling on part of the suspension or rear subframe? Is the anti-roll bar an aftermarket part? Could be that the drop links are not correct for the coil overs.

[mat205125]

Stavro55 said:

No, no helper spring. But also I mentioned that when the swaybar droplinks are removed the shock then fully extends.

Does the ARB sway bar move when the drop links are disconnected?

[GreenV8S]

Are you jacking up both sides, or one side only?

[LimSlip]

GreenV8S said:

Are you jacking up both sides, or one side only?

Stavro55 said:

I jacked the car up by the subframe so both wheels were in the air,

Must be the anti-roll bar or drop links fouling on something I'd have thought?

[ATM]

Stavro55 said:

I jacked the car up by the subframe so both wheels were in the air, still no wheel movement only when i removed a droplink did the wheel drop.

Seems simple to me that either the anti roll bar is jammed or something else is preventing the wheel movement. There are no other variables. Unless perhaps the anti roll bar has a factory added bottom or limit or stop to prevent droop.

[GreenV8S]

LimSlip said:

GreenV8S said:

Are you jacking up both sides, or one side only?

Stavro55 said:

I jacked the car up by the subframe so both wheels were in the air,

Must be the anti-roll bar or drop links fouling on something I'd have thought?

I agree.