Loose spider gear shafts/axles in LSD

[Sander]

I am in process with a rebuild of my 1965 FHC differential including new clutch plates in the Thornton LSD. I got the clutch kit from Moss in France. Moss supplied me a box with an original Spicer/Dana 44 clutch kits.

After assemble the diff carrier with the new clutch plates the shafts/axles for the spider gears are loose in the carrier housing. I am not sure if they were loose before changing the clutch plates (didn't check). The spider gear wheels are not loose. It is only the axles/shafts for the gear which are loose. Correct me if I am wrong, but theoretically the shafts/axles can be loose if there is even pressure from both sides of the clutch pack. They are not fixed in the housing and only "sit" in a triangular milling. Or have I totally misunderstood the matter and perhaps the Dana 44 clutch kit from Spicer/Dana is not fitting?

When i turn the carrier by hand in the diff housing i can hear the shafts/axles rattle. I am afraid this will be a problem when driving the car.

Can anybody help me clarify if loose shafts/axles is a problem.

Jesper

[mgcjag]

Hi Jasper.....yes they should be able to move...its how the lsd operates.....however its not something that i have actually looked for and never noticed them loose.......details of operation in the service manual......obviously dosnt say loose but how they slide/move.....Steve

[Sander]

Thank you Steve.

I have also found some old school documentation from Spicer/Dana and they call the axles "Semi floating". After reading how the Thornton power lock actually works I now understand that the axles must be able to slide inwards along the vee shaped rampes in the diff cage. The sliding occur when torque reach a certain amount and each set of clutch plates are therefore squeezed further together, increasing the locking effect. Actually very smart. If the axles wasn't "loose" this mechanism could not work.

So my conclusion is that I don't have to worry about it. I will happy proceed with the ring and pinion setup on my new 3.07 gears.

Jesper

[44DHR]

Hi Jesper,
Steve is correct that the Pinion mate cross shafts should be able to move in operation, but they should not be loose enough to rattle excessively around when stationary. The Jaguar E Type Service Manual states “clearance in the differential case permits slight peripheral movement at the ends of the shafts.” Suitably ambiguous, but once everyone is coated in oil on assembly, any movement should be minimal. The Service manual also states “Due to the lateral movement of the pinion shafts in the differential case, a little more backlash may be apparent in a limited slip rear axle”. Your photo shows the components very clean and oil free, so once they are suitably lubricated, this should stop the present noises you are experiencing.

When you fitted the clutch packs each side, there should have been 2 friction discs with internal teeth which fit onto the bevel side gear splines, plus 3 friction plates with external “ears” which go into the differential case. The outermost “eared” friction plate is dished as it is a Belleville spring which when the two sides of the casing are bolted together provides a certain preload onto the side gear rings.
When the Powr-Lok Limited Slip Differential operates, the angled ends of cross shafts move up corresponding ramps in the differential case to force the cross shafts out, moving the bevel side gears out and locking the friction discs to the friction plates - making the whole of that side of the differential locked.
Just checking that when you assembled the clutch pack, were all 5 disc and plates fitted and was the outer plate the curved Belleville spring ? If the Belleville spring is cracked, it will not function correctly.

Also however the differential is rebuilt, the friction plates need to be perfect clean and given a coating of suitable LSD as new plates will “chatter” until suitably bedded in and oil soaked. This is what I use :-





A common practise is to drive a newly rebuilt LSD differential to an open area and drive a series of figure 8s to get the clutch plates operating and reduce potential chatter.

Trust this helps,
Regards,
Dave

[Sander]

Hi Dave,

Thank you for your detailed reply.

I am more relaxed now and don't actually think theres is a problem with “loose” axles in my unit. You are right about that my axles are clean and oil free and the rattle (or more precise clicking sound) i hear is probably because of the lack of oil.

Although I am convinced that there actually is no problem I yesterday evening took the unit apart again just to double check if the plates was fitted correct and to compare the Spicer/Dana clutch kit from Moss in details with my old ones. All plates was fitted correct. Thickens, diameter ect. are exactly the same as my old ones. Only difference is that the new Belleville spring plates is a little more (0,5-1 mm) curved than the old. This is probably because the old one is worn.

Now that i have separated the unit it again I can at the same time use the Redline additiv/oil you recommend to coat the plates. I used some ATF first time I assembled the unit but I found the Redline additive in my local parts shop.