So Bill If you have a spun front bearing with consequent damage to the pinion is there any way to correct that damage and restore the interference fit? Will knurling the shaft do it, or are we to welding or chroming?
Hello Terry,
I have the bearing journal of the shaft built up using the electroless nickel plating process.
http://www.electromold.com.au/products/nicocover
The plating material can be heat treated at a very low heat, way under that which will affect the HT of the shaft or cause distortion.
Regards,
Bill
That is an interesting product, just how is it deposited onto the parent meaterial?
Youtube is our leel frenā¦
Iāve had similar shafts chrome plated and then ground down to the right size. Very expensive and I donāt know if they do it any more. I take it you donāt grind it to a specific size if you use the nickel?
Damn thats what I normally do 
So its cooked 
Hello Terry,
Electroless Nickel plating can be deposited extraordinarily uniformly. When a journal is being reclaimed, its highly likely that the surface is not so uniform either in finish, roundness, taper, or any combination of these defects. Accordingly, I cylindrically grind the journal to eliminate these defects, then have it Electroless Nickel plated with no post plating operation. Whatever is the finish of the substrate, thatās the finish on the Nickel on completion.
Regards,
Bill
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Hello Robin,
The cooking parts is not a necessity of Electroless Nickel plating if plating only for appearance, or rust prevention. To get a hard surface, the plated part has to be heat treated within, if memory serves me well, four hours of the completion of plating. That post plating heat cycle in the video is more likely to be to counter hydrogen embrittlement. This would only be required for high tensile steel parts.
Electroless Nickel is a superior alternative to Zinc Plating of E Type Front Suspension parts. Zinc plating is a sacrificial protection of the underlying ferrous metal and will eventually disappear whether the car is taken out or not; hence the reason Zinc Plating loses its initial look and dulls off. Not so with Electroless Nickel plating.
Regards,
Bill
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Well - thanks everyone for your good advice. Sorry not to have joined in much but I have been away working.
Looks like a rebuild is the best way forward - dammit. Not very convenient at the moment as the car has to be back together for transporting in a weeks time - a little restoration work is being carried out.
I may try the pinion torque method first and see how it all sounds.
Best regards to you all and thank you - very interesting.
Ian
I just had a fiddle with my flange nutā¦
My 2$:
Just tighten the nut to 80 - 100 lb.ft and see, you have nothing to loose.
The manual states that if you exceed 140 lb.ft of torque you should change the spacer, and thatās because above 140 lb.ft you start to crush the spacer.
If you have the output shafts not connected to the diff you could try and measure the pinion drag with a scale while tightening the nut. I think that if your final measurement is about 5 lb.in more than your initial measurement you are in the safe side.
Hi Bill I remain somewhat curious about the interference fit on the front pinion bearing. This is a video of Paul Cangalosi rebuilding the same type of differential I did - that is one with the collapsible sleeve on the pinion. If you look at the 15 minute mark he discusses the collapsible sleeve, but you will also see that the bearing is clearly not an interference fit. Mine was the same. This is what was confusing me.
Hello Terry,
The following picture is of a Pinion Shaft from a 3.31:1 Gear set removed from an S3 E Type Differential to be replaced with a 2.88:1 Ration. The bore of the bearing (a brand new bearing - never having been pressed onto a shaft) measures 30.162mm. The diameter of the journal where the bearing is to be located measures 30.17. For a journal of that diameter and hardness, its reasonable interference. You will note that the allowance for fit of the bearing and shaft is able to support the weights, in the sum of 6.5kg (and could support a whole lot more); far more force than the effort shown in the video and shows that it is not a running fit.
The video showed that the fit of the inner bearing was interference with the shaft and despite this class of fit, the following picture, a closer view of the journal for the Inner Bearing, shows clear indications of the bearing having spun on the shaft.
Under normal circumstances, the outer bearing is less likely to spin on the shaft, for even in the absence of any interference fit with the shaft, the inner race of the Outer Bearing is clamped between the end face of the Companion Flange and the Collapsible Spacer (Solid Spacer and Shims if used). However, if there is any diminishing of resistance by the Collapsible Spacer, for whatever reason, the actual clamping force on the Inner Race will decrease, but the pre-load on the bearings will increase. This is the perfect condition to promote spinning of the bearing on the shaft. Accordingly, I would prefer a combination of slight interference fit of the bearing and good clamping force being applied to the bearingās inner race.
Regards,
Bill
Always a useful reference: I still have my NRC book.
https://www.fictiv.com/hwg/sites/default/files/inline-images/dowel.jpg
