Check those Diff Mounting Bolts

[PeteGriff]

Hi all, have just come in from checking the Griff over ready for the journey to the Growl on Friday. I mainly wanted to find the source of a slight clonking noise developed recently which exhibited itself when pulling away or if changing gear sharply! I found the culprit, one of my front diff flange mounting bolts was loose and another not as tight as it should be!! When I refitted the refurbed diff in November last year all the bolts were torqued up and the locking nuts on tight. Anyway went over all of them and now they are nice and tight again with the locking nuts really tight. It just goes to show that with all that torque through the drivetrain, it pays to regularly check fixings. I took the opportunity whilst up on stands to check over other mountings bolts and fixings. So, am now ready to get down to the Growl. All the best, Pete

[TVR Beaver]

was checking mine tonight... and looking for play in the top one... I found it moves about 1 to 2mm when you jack on the diff... mind you, I was close to lifting the rear end so I guess its okay.. its a rubber mount so will move a bit....
when they have gone how much do they move?.. any idea

[PeteGriff]

TVR Beaver said:

was checking mine tonight... and looking for play in the top one... I found it moves about 1 to 2mm when you jack on the diff... mind you, I was close to lifting the rear end so I guess its okay.. its a rubber mount so will move a bit....
when they have gone how much do they move?.. any idea

Hi there TVR Beaver, firstly I hope you do not mind me saying but do not jack up on the diff! It will put unnecessary strain on the mountings and bushes. With regard to your question, the bushes are pretty firm, but would flex under the weight of he car when jacking. If you have any knocking or clonking under load or 'take off' it would be wise to first check your mountings are firmly bolted. The 1 - 2 mm you state above seems OK to me, especially as the weight of the car was almost on them. They do need to be flexible enough to absorb loads, but firm enough to not flex about too much when accelerating and changing gear. All the best, Pete

[TVR Beaver]

No.. I'm not jacking it up on the diff,... It was up in the air on axle stands (jacked up on the frame tubes)...
I was then jacking the diff to see if it would move... and from rest It moved about 2mm when the axle stands made the noise you recognise as being off-loaded...
.
That said, the diff is cast iron and the back end of the car can't be more than 400 KG???.... Whats the load from 300 BHP through the diff... I'm sure it would work out more, after all, it has to accelerate 1000 KG car (It could be worked out)... TBH I think jacking on the diff would be fine... but I agree... who wants a cracked diff casting!.