Final drive end play

Talk about the E-Type Series 3
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panamacarrera
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#1 Final drive end play

Post by panamacarrera » Thu Mar 11, 2021 3:42 pm

I've taken the final drive out of my S3 to replace the oil seal, it has been leaking oil for some time now.

The unit isn't noisy, so I had no intention to do anything more but on checking for play in the drive pinion shaft I've found no obvious end float but there is an appreciable clunk when I apply lateral movement.

Is this something alarming that needs immediate rectification, or something that I can live with till next winter when I have more time?

Cheers

Nigel
'71 S3 OTS

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44DHR
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#2 Re: Final drive end play

Post by 44DHR » Thu Mar 11, 2021 11:25 pm

Hi Nigel,
Just trying to understand your issue and where you are applying the “lateral” movement.
The oil seal you have replaced is on the Drive Pinion, so presumably you removed the drive flange to do this.
After you fitted the new oil seal, how much torque did you apply to the Pinion nut or did you just tighten it back to a reference mark on the nut showing the previous setting ?
If you overtightened the nut, potentially the crush spacer between the Pinion bearings could have collapsed which would affect the backlash on the Crownwheel giving too much play ?
Regards,
Dave
Dave Rose
1967 Series 1 4.2 FHC

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#3 Re: Final drive end play

Post by mgcjag » Fri Mar 12, 2021 9:04 am

The depth of the pinion is set by shims......tightening the nut in the input shaft pulls the bearings together to set the bearing preload this is the amount of force required to turn the input shaft.....can you explain exactly how you replace the seal........usually on older bearings the preaload will have deminished making the input shaft easier to turn....if all the oil is removed this will make it even easier so you will/could feel a (clonk) in the backlash zone of the pinion and Crown. .....Steve
Steve
69 S2 2+2 (just sold) ..Realm C type replica, 1960 xk150fhc

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#4 Re: Final drive end play

Post by 44DHR » Fri Mar 12, 2021 10:00 am

Steve,
I understand the Pinion setting is set by shims to match the figure etched on it, but it was the bearing preload I was concerned about if the collapsible spacer had been over torqued after fitting the new oil seal.
I’m still trying to understand Nigel’s “lateral” movement, if he could advise us ?
Regards,
Dave
Dave Rose
1967 Series 1 4.2 FHC

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#5 Re: Final drive end play

Post by panamacarrera » Fri Mar 12, 2021 10:14 am

Hi Gents
Thanks for your replies.
I haven't replaced the oil seal yet, the diff is out of the cage which is at the powder coaters and I will replace the oil seal once the IRS is back together again and I can lock the thing with the handbrake (Ed China - Wheeler Dealers).
If I pull the flange along the length of the car, in and out of the diff, there is hardly any movement at all and no 'clunk'.
But if I move the flange left to right, across the line of the car, or up and down, there is fractional movement which produces a 'clunk' in the diff.
Does that give you guys a better idea of the issue?
Cheers
Nigel
'71 S3 OTS

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#6 Re: Final drive end play

Post by mgcjag » Fri Mar 12, 2021 10:27 am

Hi Nigel...in my opinion you need it rebuilt......there should be no movement in/out...up/down...left/right. .....you should only be able to turn the input. .....Steve
Steve
69 S2 2+2 (just sold) ..Realm C type replica, 1960 xk150fhc

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#7 Re: Final drive end play

Post by 44DHR » Fri Mar 12, 2021 3:30 pm

Nigel,
I’m with Steve on this.
There should definitely be no movement “in and out” due the preload on the Pinion bearings, but if the differential is empty of oil, you can get a very minor movement and noise when the Pinion flange is spun back and forth, due to the lack of oil on the mating Crownwheel.
So, if there is movement “in and out” on the Pinion flange, definitely check that out. The easiest thing to check for “clunks” while you have the differential out is to take off the rear cover and inspect the Crownwheel for the correct backlash to the Pinion. The amount of backlash allowed is etched onto the circumference of the Crownwheel. You just need a Dial indicator to do this.
It just makes sense while the Diff is out to open it and check the general condition of the differential. If it is a Powerlok LSD, if the two end Belleville spring plates are broken or cracked, the clutch plates will not be fully “locked” as the preload on the clutch packs are reduced. In this instance the “clunk” could be the internal Pinion mate cross shafts knocking as they move up the locking ramps in the casing. You should be able to check this by seeing the effectiveness of the differential being locked when trying to turn both output shafts against each other.
Trust this makes sense,
Regards,
Dave
Dave Rose
1967 Series 1 4.2 FHC

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#8 Re: Final drive end play

Post by panamacarrera » Mon Mar 22, 2021 2:39 pm

Thanks all, and thanks to Steve for the nudge (In another post) to update this post.

I went back to the diff again and had a check for play and had a go at measuring free play with a dial indicator.

Based on the results and Dave's comments re-clunk, and the fact that the diff wasn't noisy before taking it out of the car - I've decided to put it back into the car as-is and see how we get on. I'm hoping to get some real use out of the car this summer - and I still have to take the engine out to check an oil leak from the rear of the engine.

Thanks for the feedback guys.

Cheers!

Nigel

:drinkingcheers:
'71 S3 OTS

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