GRINDING NOISE IN A SWB GQ

[baxy]

Hey Guys,
I have a tb42 swb with a 5 inch lift on 35's.
After fitting the lift I have a horrible grinding noise at about 70 km/h onwards. It is only there if I back off or drop it into nuetral.
I have replaced all bushes and universal joints???
Any ideas???

[Suspension Stuff]

Maybe your rear tail shaft uni joints are out of phase. Are they parallel to each other?
I assume you have adjusted and played around with your lower adjustable rear control arms rods.
If so maybe you need some gearbox spacers to reduce the angles.

Shane

[LIF71T]

You wil probably need a cardinal joint drive shaft to get rid of the problem
I,ve had the same thing with a 4" lift with the same symtems .Tried alot of things to stop it but it all went away with the drive shaft, problem is they are not cheap.

[Suspension Stuff]

If you have got is set up right and if you try the gear box spacers and you are still getting vibes you could try some spacers under your engine mounts( watch out for the shroud).
But I reckon you should sell your coils and go a bit smaller like to 3-4".

If you do try out double cardin joints. You can get one off a Hilux and get someone to modify your tail shaft. As already said not cheap.

You will than have to do some cutting and welding on your axle housing because with the cardinal joint it requires you to point the rear diff straight towards the gearbox which then makes your coils shape like a banana so you have to move the coil base plate and you also have to move your shock mounts or you will stuff the shocks. The double cardinal joints by design usually don't have the same range of movement therefore you reach their limits and have vibrations anyway. That is what I found personally. Others will know a lot more than me about this. Maybe there are different double cardin joints you can get.

I hope this helps
Shane

[MD4x4]

Mate,

Everyone has there own opinions on this and every SWB GQ will have different characteristics.

My 1st SWB had 15mm gearbox packers, upper adjustables and normal length lower trailing arms. 5" Lift no vibration. No Double Cardinal.

My current SWB has upper adjustables and 15mm extended lowers. No gearbox packers and 4" lift in the rear. I was running the upper adjustable trailing arms and tuned out the vibration. Last weekend I fitted the extended lowers and had heaps of vibration again. I adjusted the uppers 15mm longer and now the vibration is gone again.

Point is a 5 to 10mm adjustment on your trailing arms can make a heap of difference.

I do not believe you need a double cardinal tailshaft.

[baxy]

Thanks for all the input.
I should have mentioned I have fitted drop boxes which space the gearbox down and also have extended lower rear arms and 3rds upper adjustable arms.
Shouldn't the vibration or noise be there under normal acceleration and not only when backing off or rolling in neutral?

[viperguy]

the grinding aint from ur unis.. its from the spline. with the bigger lift ur shaft will be stretched longer thru the slip joint meaning les bearing between the two ends of the shaft. this introduces a wobble in the shaft. amplified by the age gq's are getting to these days.. temp fix, use a high quality high temp grease in the slip joint regularly, like once a month or even more. vibes are from unis outta sync or phase or whatever..

[MD4x4]

Thanks for all the input.
I should have mentioned I have fitted drop boxes which space the gearbox down and also have extended lower rear arms and 3rds upper adjustable arms.
Shouldn't the vibration or noise be there under normal acceleration and not only when backing off or rolling in neutral?

When you ajusted the upper arms did you shorten them or lengthen them?

Most people initially lengthen them to rotate the diff upwards thinking they need to straighten the uni in line with the shaft.

This is incorrect. The pinion mating face to the tailshaft needs to be parallel with the mating face on the tailshaft at the gearbox.

MD