34 replies to this topic

[dattoman]

Lash not set right

Case hardening wearing off gears

[rodomo]

How did you tighten up the pinion nut?

[Uncle Chop Chop]

Wrong oil?

[S pack]

Under what conditions is the whine most noticeable, under acceleration or deceleration or when the car just seems to be floating along? 

[S pack]

acceleration - not necessarily hard acceleration either, but it goes quiet when you lift on the pedal, but noise come back if you put light pressure on the accelerator to maintain speed.

It's not a bearing noise then. Your crown wheel and pinion mesh needs to be adjusted.

[Heath]

If it's noisy on power and the hardening has worn off the driving surface of the teeth then I'd probably consider that gearset pretty useless now. A hot six at full throttle for extended periods of time, probably not just a case of adjusting it out.

 

The most logical scenario is that the gear wipe/backlash adjustment is wrong and that has fucked the teeth. It sounds like you haven't even pulled the pinion out so simply adjusting the lateral position of the carrier assembly (and crownwheel) should have been a very simple exercise. 

 

What did you set the backlash at/how did you measure it?

 

The other thing is... how much oil did you put in it? A car that you're thrashing around a race track will go into corners and throw all the oil down the axle tube (leaving the diff-centre dry if there's an inadequate quantity of it), and that's when you get on the throttle too hence the on-power gear-whine.

[Bernie]

Some questions that may help us understand your method of install :What is your ratio ?Did you put the gears  back in the same mesh from where it came ?Did you measure the backlash before you pulled it apart?If so how much was it ?Seems to me you may have set the preload on the hemisphere bearings incorrectly .When you have given it a flogging you have lost some pre load and hence your back lash has changed causing it to whine on drive .

 

Bernie

[Heath]

As I said, it was reassembled back to the exact same setting it was before- no measurements necessary.

 

Maybe my last post came across wrongly, but I and everyone else in this thread is only sharing their advice in the hope that it will assist you. That came across pretty bluntly IMO. I'm not sure how experienced you are with differentials so the more elaboration you share on the process, the better for us. 

 

As in, the screw adjusters just went in the same amount of turns to the same spot as before?

[S pack]

Q's, Q's, Q's.

When you say you replaced the bearings - which bearings exactly? Axle bearings or the bearings on the LSD centre?

You say after putting the diff back together the pinion oil seal started leaking - had you fixed that leak before you took the car to Wakefield?

Tightened the LSD - what did you do to it?

[Heath]

Putting some shims into the LSD assembly shouldn't change any geometry. As long as your bolts can over-ride the preload of the shimmed up springs (the standard ones normally snap when you tighten up the LSDs), the two hemispheres should close up tight

 

I'm wondering if the replacement bearings didn't have quite the same dimensions. Bearings are bloody precise things, no question, but I'm not sure how accurate that lateral tolerance would be on the ground taper - it may not take a lot to really stuff up your wipe pattern. Your move in marking the screw adjusters and counting the turns should normally work fine if no parts change... hate to sound patronising but that kinda thing needs to be checked at the end :(

[S pack]

I'm wondering if the replacement bearings didn't have quite the same dimensions. Bearings are bloody precise things, no question, but I'm not sure how accurate that lateral tolerance would be on the ground taper - it may not take a lot to really stuff up your wipe pattern. Your move in marking the screw adjusters and counting the turns should normally work fine if no parts change...

^^^ +1. 

[Bernie]

Only real way to set up carrier bearings is to have the pinion out and use a spring scale to measure the drag .Tried to cut corners but have always had to set pre load on the carrier and the pinion and then install both and set backlash .It is a pain in the rear but the best way .Ratio is non hunting so teeth wear pattern will be even over all the gear set .Really need to measure the back lash ,have a look at the wear pattern and then pull the centre apart .Sounds like you may have to rip it out and change the pinion seal as well as set it up again .I am sure the people on here can help you through it .It isn't hard .

 

Bernie

[Uncle Chop Chop]

If it breaks and you can fix it yourself, then have another go.

[warrenm]

Shouldn't be any grease in the diff, it's all lubed with oil. The pinion has a "crush" tube between the 2 bearings which can crush down further on hard launchs, but a banjo doesn't normally handle, but still a possability on a circuit being on & off the throttle. If this has happened you should have some play in the pinion as the bearings wont have enough pre-load, time to give it a birthday.

[Bernie]

If you get underneath your car ,try and lift the pinion and tail shaft yoke assy up and down .If you get any movement at all  then you have lost preload .Should also feel a slight vibration on coast if that is the case .

 

Bernie

[Bernie]

Time to pull it out ,get some bearing blue or red lead paint and check the wear pattern on your gears before you take it apart .Check the back lash and right down the back lash .Take some of the back lash out and recheck the contact area .You should see the contact surfaces and the lash marks from the original settings as this diff would have done a few miles I would suspect .Once you have the correct pinion to wheel contact recheck your back lash and then the pre load on the side bearings .I usually move the crown wheel away from the pinion to set it up .You will only get a small amount of travel to get some feel of the drag.It is a feel thing .Hard to describe but you need some drag on the bearings .Some people say pull them up till you get no float of the bearings and then tighten it up 3 holes .Seems as though you are going to set up the pinion again I suggest you set the crown wheel bearings first then remove the crown wheel .Set your pinion up and install the new seal .Then install the crown wheel and set your back lash and then look at your contact  on the gears ,I have had as little as 3 thou on a small holden diff and had no problems. Your pinion may have either a solid spacer or a collapsible sleeve .I personally like the spacer as you can tighten the pinion nut up tighter with out pre loading your bearings .Takes longer but less hassles if everything is a bit loose with age .Use some loctite on the splines and nut if you are using the collapsible spacer .Check the contact area by using the crown wheel to turn the pinion not the other way .

Good luck

Bernie