Sapphire box clunk, help plz
I have had to change the viscous coupling on my sapphire 4x4 as it had basically burnt out, I don't know how long its being like that as I have only had the car 3 months and it only showed up when having a dyno run at MSD.
When the gearbox was out it was taken to a gearbox specialist to check it out and fit the viscous, they came back that the box was ok no problems
( there wasn't any that I knew about but just wanted it checking as it was out) now the box is back in with the new viscous fitted there is a really bad clunking noise coming from the back end of the box which was not there before when the old coupling was in so only running on 2wd, any ideas what it may be?

 

Chain is fucked and hitting the casing as its stretched and is no providing drive as opposed to being free running

 

had the box back out and checked the drive chain and its ok no stretch or anything.
what the f**k is wrong? plz guys help me

 

I have used GEARS lots of times for cossie transmission stuff, I find their knowledge excellent and they are always very helpful over the phone, maybe give them a call to see what they say.

TBH what Dojj said sounds correct, but it would have to be totally fubar to hit the casing which I find a bit unlikely. When you say the chain was checked, did you check it or the gearbox place?

Also two other q's, how do you know the noise is coming from the back of the box specifically, and what power is the car running?

p.s boxes are cheap as chips if you look about, if you're convinced there's an issue i'd just get another one.

 

The gearbox is out again at the gearbox place and they say the chain is good and definitely no play to give it slap against casing.
The car was up on the ramp with the wheels running and when the power went on there was deffo a banging/ clunking towards the rear of the box I think it was around were the vc is. Car has near standard power 240bhp.
Its got to be something to do with the 4x4 system as when the vc was burntout and only running 2wd it was fine with no noise.

 

Well I'd deffo be checking the diffs, shafts and props next. Not sure what else there is to look at?

 

Just checked the props and they seem ok, the front diff has a bit of play about half inch of move till the wheels move you can also feel a bit of a click when moving it.

 

Front prop joint?

 

Is the ratio between frt and rear 50-50 as when we had it up on the ramp and running the frt wheels looked to be slower than the rears.

 

The only sure way to church is on a 4wd rolling road
But the passenger wheel should turn faster than the drivers front for some reason
Running it on a ramp doesn't put any load on the system so it shouldn't be trusted as an example if it being sorties it not

 

Well box went back in after the gearbox people had another look at it and declared it fit, frt diff covers removed and checked all ok, took it out for a spin and the box was as quite as a mouse, nothing, no clunks or anything !