Upgrades have spoiled my ride - what's wrong?

[sparkythecat]

I replaced the lower front wishbones on my 98 Chimaera 400 a few weeks ago together with uprated bushes and new lower ball joints. At the same time I fitted the Steve Heath ARB droplinks. I also fitted an exchange set of reconditioned standard wheels as the lacquer had lifted on two of mine. This gave me the opportunity to fit a set of new SO2 PPs I'd managed to track down.

The car was only driven about 30 miles before it went to a TVR indie for service with a request that the steering geometry be checked and adjusted.
In the past two weeks I've driven the car about 2500miles around northern France. I'm not really happy with it. Although the tyres, now nicely broken in, are much more grippy than the well worn S03s they replaced, the steering isn't quite right and the problem seems to be getting progressiely worse. On anything other than glass smooth surfaces the slightest bump in the road surface seems to make the steering wheel twitch from left to right in my grip.

Any help in diagnosing this problem would be appreciated

[Hut49]

Probably worth checking that the drop-links are installed with correct alignment - i.e. not pre-loaded at rest. If they are not aligned correctly then movement will be against an in-effect rigid joint rather than movement through the joint as intended. Just a thought...

[spend]

I seem to recall a similar thread a while ago when owner had fitted TRE's back upside down.... Did you load the wheels before torquing up the suspension bolts?

Dave

[sparkythecat]

I'm happy that the drop links were installed correctly, Spent ages chopping and changing the washers to get them right.
Don' think the TRE's have been off. I haven't looked yet, but presumed the track adjustment would have been made by freeing off the lock nut then turning the rod with grips rather than splitting the joint and rotating the TRE. I'll jack it up and take a look

[Cider Andy]

It's a simple reply and I'm sure you've checked already, but what pressures are the new tyres at? It sounds like you've covered everything else that's been changed.

[shpub]

To be honest I can't see the droplinks causing knockback through the steering. This is normally caused by steering geometry problems or tyre pressures way too high. Most tyre fitters seem to put 30+ lb in the tyres but then forget to let them down to their correct pressure.

If you have adjustable shocks, also worth chceking that they haven't been set too hard.

[JonathanT]

sparkythecat said:

This gave me the opportunity to fit a set of new SO2 PPs I'd managed to track down.

Not sure if it's related, but I understood that there are *no* new SO2 PPs anywhere in the world. Apparently new SO2s are not Pole Positions and are intended for something like Porsches. The sidewall stiffness is different as is the tyre compound.....

[sparkythecat]

JonathanT said:

sparkythecat said:

This gave me the opportunity to fit a set of new SO2 PPs I'd managed to track down.

Not sure if it's related, but I understood that there are *no* new SO2 PPs anywhere in the world. Apparently new SO2s are not Pole Positions and are intended for something like Porsches. The sidewall stiffness is different as is the tyre compound.....

The tyres I fitted are new 'old stock' tyres. They are a few years old, but have been stored properly in their original wrappers. They are definitely the
proper S02PPs for the car.

[GreenV8S]

Check the tyre pressures.

[sparkythecat]

Tyre pressures now checked and there is 22psi in both front tyres.

Just to try and explain a bit better. Imagine driving your car along a road and there is a joining line or expansion gap in the surface. Driving across it you would normally just hear the pit-pat from the tyres as both sets of wheels passed over it and you may just feel a slight tremor through the wheel.
As it is, in the same driving circumstances, my car feels as though one of the wheels has dropped in a pothole and the wheel jerks markedly in my grip.

This wasn't the case when the indie originally set the camber and toe so I'm wondering if somethings loosened?.

I'll heave my bulbous frame under the beast at the weekend and report back in due course.

[TVRBubblecar]

Just a thought - are the new wheels ok ? - not slightly buckled / out of balance ?

Chris

[trackcar]

Seems you're gradually eliminating most of the common causes one by one so time to get a bit more adventurous .. if it's a shimmy in the steering that can happen if you have tired/ineffective dampers .. teh damper can't resist the movemnt of the wheel's vertical movement as strongly as previously so the travel increases, this sets up a gyroscopic loading at right angles to the direction of travel of the wheel, in our case it means the wheel tries to turn sidewyas as it's pushed vertically upwards .. upshot is that if you have a weak damper on the front of the car this can lead to the steering wheel shaking over bumps in-extremis

[That Daddy]

Excessive toe/out on the front wheels can feel like this at times,it can certainly make the steering wheel jump around and the car generally feel awful over anything but a perfectly smooth surface,but it would have to be out by a mileother than that everything the other guys have already suggested,good luck.