suspension advice

[captain chaos]

My brother and I are new to Seven's and as he does not have net access at the moment I am after some advice for him. His de-dion x-flow has a tendancy to feel as though it is wandering on the road and the whole feeling is one of lacking control. He is intending to upgrade his shocks but we are seeking advice as to which bushes should be a priority(A frame?)and if any other advice can be offered.

many thanks

Gary

[StewartG]

You make it sound like an escaped sheep with diorhea!

[I.Mupferit]

The A frame bushes should definitely be checked, especially the centre one as it doesn't really last very long, but is easy to replace. What tyres has it got, some have a tendency to cause tram-lining and a feeling that the car is driving you.

 

[Graham Perry]

I would firstly check the A frame bushes at both ends as well as the radius arm bushes that go onto the Di-dion tube. The instability is almost certainly caused by some movement in the rear axle. I good way to check that if there is movement is to get one of you to stand by the rear wheel while the other sharply lifts the clutch pedal to pull away. You should be able to see if there is excessive fore/aft movement in the axle . THe tolerances on the di-dion tube are very close and on my car when a bush has gone you can usually see where one component has rubbed against another due to a failed bush.

 

You mention you are new to sevening so I assume you may have a car that you didn't build from new. If the previous owner eas a speed freak he may have added a little toe in to the rear suspension geometry which is a favorite trick either by machining the aluminium ears on which the hub is mounted or by placing thin washers between the ears and the di-dion tube. However I can speak from personal experience that if too much has been applied the car becomes terrifying to drive an wanders all over the place. Just take a couple of bits of batten and lay them against the outer faces of the tyres as a reference point and measure across the width of the front of the back tyres and then across the rear of the tyres. The dimension should be the same indicating that the rear tyres are running parallel with each other. Any difference of more than a couple of millimeters would indicate too much toe in or toe out and might be the cause of the problem. It might be worth doing the same for the front tyres as well, where the difference again should only be small.

[Simos]

 

Just to echo Brent's point about tyres, if you're fitted with Avon ACB10's (or other crossply) then the tramlining and instability on rough surfaces is incredible. I moved from michelin radials to acb10's and like you, thought the car was broken.

Forget "lightly caressing the steering wheel while listening to the feed back from the car..." more a case of grabbing the bugger as hard as you can while it shrieks at you through a mega-phone... very F1 :-)

 

I've subsequently changed to yoko a032's on my old rims which don't tramline anywhere near as much and I swear give me as much grip once they've warmed up a bit. They certainly wear out nearly as quick ! I use the acb10's for trackdays now and will probably try some slicks when they're gone.

 

Cheers, Simon.

[captain chaos]

Thanks for all the advice

Regards

Gary