cerby front suspension 1997 car

[zak carr]

my front shocks are shot to bits and i want to replace them with AVO units. problem is the front springs are coil bound. any body else had this problem. it seems to aggravate the bump steer as there is so little travel. can i fit new springs with wider spaced coil but higher poundage rate. some body please help

[jody]

www.joospeed.net

Speak to Joolz, he is the man in the know.



Jo

[joospeed]

avos work surprisingly well on cerbies, they suit heavier cars well. going up on the front spring rate is a very good move also.

[Beej]

Zak, what bump steer? As an onetime Marcos owner this is a problem with which I am intimate! but I have not subjectively detected any bump steer at all on my 4.5. Is there a difference in the suspension set up between 97 and 99?

[joospeed]

there is a bump steer issue on the cerbie, but coil bound springs make it better not worse .. bump steer is the change in toe as the suspension goes through it's travel - it's not "hitting a bump and the car going off line" .. that's just "hitting a bump and the etc etc". you can limit bump steer by fitting stiffer springs to limit the wheel travel (a coil bound spring or a spring sagged to run on the bump stops is just a very stiff spring then..), but it's a bodge and the real cure is addressing the suspension / steering pick up points. the cerbie gains toe out as the wheel goes to bump, but it's not much (about 10 mins for each 2 inches of travel) .. but it is responsible for killing inner tyre edges if not corrected at every service as the front springs sag - adding negative camber and toe out is the culprit for all those damaged tyres. I think the toe out on bump might be deliberate .. I used the same technique on the front of the 3000M to cure some understeer problems on the brakes .. it makes the front end more "darty" as the suspension compresses so you can turn in on the brakes .. of course then tvr spoil it by making the cerbie rear end too wayward to exploit that fully. stiff front springs work well on cerbie though cos it brings in a bit of understeer which makes the car more stable, and you have to apply power to neutralise the handling rather than backing off the throttle every time the back end steps out .. not a quick way around a track. it also helps traction at the rear by reducing the inner tyre unloading.

[Imelda]

quote:
As an onetime Marcos owner

Beej what Marcos did you have?

[Beej]

10 mins in each 2 inches explains why I hadn't really noticed it. I take your point about it being possibly deliberate, toe out under bump would make the car more stable under straight line braking and less crisp on turn in - classic safety measures.

Imelda, I had a very quick 3.5 Mantula Coupe, metallic BRG, tan leather indoors, bump steer was actually visible, let alone measurable in minutes! It was so bad it would literally leap between lanes on the motorway if you hit a decent hump in the surface at anything over the legal limit. I got fed up of changing my trousers. Cured it by fabricating new steering arm pick ups and a front anti-roll bar.

Some years ago I was tempted by a Mantis - not the loony supercharged version but pretty damned quick all the same. I could not detect any bump steer, so I figured Chris Marsh had changed the "Marcos do not bump steer" policy that his father subscribed to.

[Imelda]

Aye, no bump steer in mine I don't think, though I'm not sure I'd recognise it if there was (bit of a mechanical numptie you see). It seems to track pretty straight apart from the odd bit of tram-lining so I assume Marcos fixed it for the Mantis.

[Beej]

oo er so you've got a Mantis AND a Cerbera. Well thats just showing off. Love the mantis, such a great shape and really quick too. Better handling than the Cerby but, if you will pardon me saying so, even more of a kit. Main reason I didn't buy it was they hadn't changed the doors so they must still leak - even worse than a TVR!

I wish I could claim 2 supercars in the family.. closest I can get is a knackered old Lotus and a hideous orange MG. I dare not mention the other cars (German, you see).

[Imelda]

No no. Sorry, I think I must have mis-led you. That's what comes of doing this and trying to work at the same time. Must get a job like Carzee's, then I can concentrate full time on PistonHeads .

I don't have a Cerby as well as a Mantis, though I certainly would if finances allowed. And Mrs Imelda wants a Griffith. And I want a Wedge, preferably a 450SEAC. Ooh and I need an Integrale . And a Stratos would be nice too.

Gimmee gimmee gimmee....