Thread: 4.7 Diff Ratio & Set up ?

G'Day All,
On my 300 TDI Disco I have recently been given a set of 4.7 ratio CW&P sets and put 35" tyres on it, now this car is not locked or used for much off road work (I have another for that) And I know that those ratios are weaker but in this car It is just more about drive ability and the 3.5 Ratio even with 265/75R16's on sucked the power big time.

Now to the problem:
A mate of mine set the diffs up with the 4.7's, but as soon as they were fitted I got diff noise?? So I pulled the rear out which seemed to be the noisiest and re-checked the pinion Height and the teeth meshing pattern with machinist blue, re-set it up and hey-presto NOISE STILL THERE !!

So before pulling them out and going through this in out process with no result for numerous times I want to see what I can find out !!

NOTE: When fitting the rear set we obviously had to remove the rubber doughnut style tail shaft and we fitted the yolk that was on the original diff with the 4.7's and a range rover tail shaft !! We also noted when doing this that the original yolk on the doughnut style off the 3.5 Ratio pinion had a flange / spacer built onto the end of the yolk and in the 4.7 Pinion there was a separate spacer fitted just in the nose cone ? so we re-used this spacer in my original housing which allowed it to set up good !

Another Note : Now after this I have had a look at the original housing that the 4.7's came out of and they have a bearing in the nose cone ?? with bolts that you can remove to take out the bearing ???

NOTE 3 : I also found that when the 4.7 CW&P set was put in in my housing, due to the smallness of the pinion the bearing caps were out of whack, as in when you pull them into the crown wheel one cap was in past the locking pin and the other was hanging out, I found that the solution to this was a 5mm spacer for the crown wheel that is available through ARB for fitting their lockers with different ratios !, Which I did.

NOW TO THE QUESTION :
A : Am I wasting my time ? Can this be done ?
B : I thought about using the other housings but it seems the carrier bearings are different which leads be to believe that my center with fine spline gears would not fit anyway ? That's if these CW&P sets need to be in the housing with the bearings ?
C : Or could it be that the CW&P sets are just worn and noisy ?
D : Any other suggestions ?

This has become more trouble than its worth now and think I may give up and go back to old gear sets or buy some 4.11's But I do like the ratio if it can be worked out.

Thanks for any suggestions
Cheers

Thanks mate, we did check the back lash and it was fine, I did not remove the pinion bearing, was told it was in good condition, but that brings up another possible problem ? are the pinion bearings the same ?

Originally Posted by Blknight.aus

it sounds like you may not have the setup on the pinion bearing correct.

If you can do a perfect setup and it blues out correctly, you fit it and drive it then when you re do the blueing its off then its the pinion bearings not set up properly and the pinion is shifting under load.

it will also pay to check the back lash on the CWP if its a second hand diff set (and assuming that the pinion mounting is ok and theres no bearing carrier distortion) dont go for a tight setup run it nearer to the outside limit for the backlash tolerance.