Fireblade Vibration

[GasMan]

Just had a fantastic drive from Liverpool to Bounemouth. But I am puzzeled by a Vibration? Can anyone shed light on this. My Car is a disc braked Live axle Fireblade, with a full race cage (with the Curvey Loops) and carbon aeroscreen. Also 13" MB mag wheels with ACB10's. The vibration comes in at around 80MPH then lessens again as I go faster. It feels like a drumming. And I get the impression it is road surface dependant. Its definitely not from the front wheels as steering is perfect with no steering wheel shake. As my journey progressed I thought it was getting less? But it was still there. I also wondered if it could be due to turbulance from the Cage at that certain speed? Any Ideas?

Matthew

[7Nut]

Check all of your prop bolts, right through from the diff to the engine.

 

[GasMan]

All prop bolts checked prior to my trip. No problems there.

Matthew

[STEVE GILBERT]

Bent Half shafts?

 

Jack the back up and see how much runout there is on the wheels.

 

When I had an Ital axle in mine with the Alloy hubs/disc brakes, the runout on mine by the time you put the wheels on was awful.

 

When I scrapped the Ital in favour of the English Axle I had the 1/2 shafts trued on a big lathe so they were absolutely spot on. The wheels now spin with no runout.

 

Other things could be sloppy wheel bearings, bent wheels, loose reverse box, knackered hardy spicer joints, flat spots on tyres etc etc etc

 

HTH

 

Steve

 

See My Caterham Fireblade Here.

[STEVE GILBERT]

Oh and another thing,

 

Check the rear hub nuts are done up. Back the two grubscrews right off first though and then do them up again after otherwise you force the bearings down the shafts and bust any tack welds off that may be on there.

 

I have seen the 1/2 shafts shatter around the keyway allowing the shafts to spin in the hubs, normally indicated by a bunch of swarfe in the 'bowl' of the hub, around the nut.

 

Steve

 

See My Caterham Fireblade Here.

[millsn]

Car ever been on 4 wheel alignment? Mine's doing this since I removed the old washers aligning the 'A' frame.

[GasMan]

Thanks for the suggestions. I did think about flat spots as I've had a couple of spins when doing trackdays, and there did appear to be improvement towards the end of my 270 mile trip possibly suggesting diminution of the flat spot with miles?

I'll ask Ruff Seven who looks after my car if he thinks run out could be the problem or A frame alignment. Its definitely not bent wheels or bearings and not the reverser box.

Matthew