DonDP

The vibration is through the chassis, but can obviously be felt through the gear lever too. I have checked all engine mounts and and gearbox mounts. Clearance between the gearbox and chassis is very tight, roughly 0.5mm at its closest (lower left longitudinal). I removed the rivets under the gearbox mount (for the floor) as these seemed unnecessary considering the mount bolts over them. This has given a marginal improvement in clearance. Still need to test.

So I made some noise this morning.... first of all I noticed that the crank shaft pulley is not quite straight - not sure if this is normal? I took a slow motion video here: Once it was nice and warm I revved the engine right up to 7k-ish in the garage. There is more vibration coming from the front of the engine than the back (relative ro car). Again not sure if the amount is normal or not since all the belts and ancillaries are at the front?

I haven’t done in the garage as yet, mainly due to noise and neighbours... might have to annoy them today... I have removed the exposed belt and checked all pulleys, alternator by hand and all seem smooth.

310r limit is 7500rpm. My rev counter does over read slightly so vibration is probably within the last 800-1000 rpm

Hello, I have a vibration at high RPM over 7k which is definitely engine related. You can’t really notice it until flat out in 4th gear. I assume it’s because it spends more time getting to the shift point that makes it more noticeable. It is however, always there, you can simulate in 3rd holding it at high rpm and equally there is some vibration in neutral both with clutch engaged and when released. I am trying to work out if this is just a trait of sigma engine, possibly the 310 with the different cams? Does anyone else have this? Is this a case of TADTS?

Hi All, Most likely the last update to this thread... Had a great day at Bedford with no vibrations!!! I cannot say what resolved it for sure but after replacing the prop shaft, both rear wheel bearings, discs and pads I am a happy 7 owner. Thanks again for all the help and suggestions. Now I can get on with the wide track converson :-)

Ian, which half hood do you use? I use a Caterham one with mine for an FIA bar, but the fit could be better.

Update and GOOD news !!!! It would seem (from the limited testing I have done) that the issue is resolved! So it was either the rear brake discs or the rear wheel bearing on the offside. I am going to change the nearside rear wheel bearing as a precaution and book another track day to fully test. Thanks everyone for all the support and suggestions. Weather permitting my next track outing will be the 13th May at Bedford. Will keep you posted.

Hi All, A quick update... New discs and pads are on, although the runout still exists which is good and bad. Good, that this is likely the source of the problem, and bad that I can now only see this being the wheel bearing, the stub axle of the drive shaft or the hub flange itself. Popping a new wheel bearing in this weekend as its the cheapest option, but I do not have high hopes that it will resolve it. More likely to be one of the other two, or both of them! Has anyone every warped a hub flange or bent the stub axle on the drive shaft!? I guess anything is possible....

Thanks @Jim123, will only use the lathe to see if the disc has run out and just replace it if it does. @Tom_Arundel that is certainly a possibility, will see if I can get a measurement with the dial gauge there before stripping it down.

@elie boone, great idea, need to find a local with a lathe! The run out is on the hub and the disc. Highest and lowest spots are in identical locations which is why I am not sure its an issue with how they are mounted together, but will definitely check that.

@Jim123 The reason behind the rebuilds is that its an ex grad car, the previous owner bought it and then sent it to PT Sports Cars to get it to 310R spec. PT reportedly take the engine out for this work, so whilst engine was out it was a good opportunity to refresh the box. This also included the Titan diff upgrade which is why that is low on my list too. I took it upon myself to change the prop as I thought this might be the issue, unfortunately not... Thinking about it more. Before I order any parts, I am going to swap the disc/hub flange assemblies from left to right and see if this also moves the runout I am observing. Can start to rule parts out then.

Thanks guys, I took a few videos of the caliper movement. You can see it quite well in , particularly if you look at the caliper slide pin boots.I haven’t felt it under braking but my thought are that this may be either because the entire axle path is off axis or as it is a single pot floating caliper on the rear the sliders may be masking it. Perhaps I should measure the wheel runout? I would say the vibration is a 5 out of 10. The vibration does not cause the vehicle to be unsafe at high speed, It just buzzes through you to a point you feel your head vibrating! there is no vibration at the steering wheel. Gearbox was rebuilt 1500 miles ago by road and race which is why I am hoping this is elsewhere on the car but good idea to see if the gear lever is vibrating on my next test run.

@Tom_Arundel & @ScottR400D you are correct, my mistake, one too many zeros. Readings are 0.3mm (rotor) and 0.18mm (hub flange). Significant enough to visibly move the caliper at idle in 4th gear. This would be amplified significantly at the radius the tyre meets the road. It is 10x more runout that the other side. Something is definitely wrong. @Jim123 not sure, its difficult to work out where straight is! Might as well do new disk and wheel bearings and see what the measurement is. Worse case it will need need a drive shaft, hub flange and bearing carrier too...

@ SM25T The hub flange and disk are both distorted (high and low) at the same points so I can’t see this being something between them. I take that to be that they are either both distorted, the disc is causing all the distortion, the wheel bearing/bearing assembly or driveshaft. @Jim123 not sure about which line compared to the car... however the the runout runs across whole rotor, hard to tell where the ‘straight’ part is...