Bump Steer And Roll Centre: Lowering Subframe?

[Mad Scientist 106]

I've recently been trying to get my head around suspension geometry, and have been looking at the various bump steer solutions, and roll centre kits. In combination with this, I've had some issues with my front arb hitting the exhaust manifold, which I plan to fix with longer drop links.

 

This is when it dawned on me. Wouldn't spacing the subframe mounts out, which would effectively lower the subframe the correct amount (same as the amount the cars lowered) fix all of these things?

 

Any thoughts?

[calvinhorse 870]

No that would make it worse.

 

You'd move the pivot point of the wishbone down when it needs to go up

Edited August 20, 2013 by calvinhorse

[Mad Scientist 106]

Ahhhhh. Yes, that makes sense now!

[Mad Scientist 106]

That could be, thinking about it, the stupidest idea I've ever had.

 

Actually no, that involved an electric fence and a call of nature.

[Cameron 16]

No. 1 or No. 2?

[Mad Scientist 106]

Number 1, which nearly caused a number 2.

[Batfink 201]

lol. If you think about it as you lower the car the hubs in relation to the steering arm go up so you would have to raise everything else to match. Problem is the driveshafts and other components in the enginebay will simply get in the way.

Kev

[Rich_p 23]

Digging this up as I've been thinking about this the last couple of days.

 

Bump steer kits are/were available from bridgecraft. As far as I can see the just space the track rod arm down but the angle of the wishbone or tca remains the same.

 

Spacing the wishbone down too has to be the way to go?

 

I'm assuming this would have to be acheived with rosejointed bottom arms with a long pin/bolt with on going into the hub. The bolt/pin would have a spacer on it which should be the same size as the spacer on the track rod arm so both come down the same amount thus keeping the geo in line?

[welshpug 1,646]

Its not as simple as just keeping both the same distance, but its a starting point.

 

this is a prototype bridgecraft lower balljoint extender.

 

 

 

 

the other way around it which citroen sport peugeot sport and satchell engineering have done is use a 307 or 405/6 hub carrier that has a screw in lower balljoint, and replacing this with a screw in pin and move the pivot point down to the wishbone.

 

[Batfink 201]

You sadly cannot run anything smaller than a 15" wheel though.

[Rich_p 23]

I wonder if they'll ever start selling them?

 

I was toying with the idea of trying to run smaller wheels but can cope with 15's if that's the only way

[allanallen 528 2 Cars]

As welshpug says the 405/406 solution is the better way by far but requires custom longer wishbones and driveshafts, not to mention different brakes etc. Our extenders are proving a nightmare due to the ever varying lengths of aftermarket driveshafts!! the angled position of the BBJ hole on the hub makes it difficult.

We do a kit for Clios, both bump and rollcentre and it's much nicer/easier due to the hub design. Plus they have a replaceable BBj so we also supply a rose jointed item which bolts straight on. Peugeots are a pain in the frecking arse!

[Rich_p 23]

It's a shame you can't convert clio hubs for use on peugeots!

[Rich_p 23]

With the extenders, do they pivot inside the hub and the original balljoint is fixed into the extender?

 

If so it it possible to do the opposite and have the extender fixed in the hub and then the original balljoint pivots in the extender? (if the extender is machined to accept that movement?

 

Or would doing that way create additional forces which could cause it all to fail?

[allanallen 528 2 Cars]

No idea what you mean rich. The extender is fixed rigidly to the hub, the wishbone clamps into the extender exactly like it would in the hub. The only pivot is at the ball joint as standard.

 

Clios use bolt on dampers so it'd be an even bigger job than fitting 405/406 hubs unfortunately.

Edited October 11, 2013 by allanallen

[welshpug 1,646]

307's use a two bolt damper, satchell engineering use them on their 106/Saxo kit with their own damper leg and an inverted 205/309/306 bilstein insert.

[allanallen 528 2 Cars]

Colins 106 set up up looks very nice. Tis much nicer with a bolt on damper, not only for the adjustability. Just a shame about the expense of having to change all the major front end components to do it.

[welshpug 1,646]

Yeah, shame to fit one bit without the rest doesnt cost that much really

[Rich_p 23]

No idea what you mean rich. The extender is fixed rigidly to the hub, the wishbone clamps into the extender exactly like it would in the hub. The only pivot is at the ball joint as standard.

 

Clios use bolt on dampers so it'd be an even bigger job than fitting 405/406 hubs unfortunately.

 

I was having a brain fade day and posting on here while also working! For some reason I thought the pin from the bottom arm was rounded so also pivoted inside the hub. My head is now back to normal!

 

I'd still like a pair of extenders though!

[Rich_p 23]

I've been thinking about hubs etc again today and remembered this thread and as Welshpug had mentioned the C2R2 set up I thought I'd post this as it shows the set up

 

http://www.citroenpartsdirect.com/C2R2max-catalogue/E14.pdf