Pinion shaft diameter

[Roger]

Could someone confirm the Pinion shaft diameter on my 1933 RP is it going to be 1” or 1 1/8”?
I would like to purchase the shaft before stripping so need to know the size in advance.
It  is 6 July 1933 5.25 Diff by the numbers on it, not sure what the 7829 number is though.
       

Thanks in advance.

Roger

[Chris KC]

Roger,

In my understanding 1933 *should* be a 1" dia shaft.
From some time in 1934 the shaft, which was still 1" for most of its length, acquired a 1.125" thicker section adjacent to the pinion.

This presumes of course that no-one has mucked about with the innards radically.

If it has gone bang you'd be well advised to check the condition (esp. run-out) of the diff carrier before installing a new CWP.
If not, and it's not making a dreadful noise, I'd take a peep inside before buying new parts; sometimes original parts are in surprisingly good condition and still have much service left in them.

[Roger]

Roger,

In my understanding 1933 *should* be a 1" dia shaft.
From some time in 1934 the shaft, which was still 1" for most of its length, acquired a 1.125" thicker section adjacent to the pinion.

This presumes of course that no-one has mucked about with the innards radically.

If it has gone bang you'd be well advised to check the condition (esp. run-out) of the diff carrier before installing a new CWP.
If not, and it's not making a dreadful noise, I'd take a peep inside before buying new parts; sometimes original parts are in surprisingly good condition and still have much service left in them.

Chris,
Thanks for your reply, I have just finished renovating my car and driven it about 50 miles there is is a very loud noise from the rear axle on drive which goes when I take my foot off accelerator.
As I did not strip the Diff originally I thought it would be best to do a proper job now I know the rest of the car is sorted. 
Are the shafts interchangeable?

Roger

[Chris KC]

I take it there's oil in it?

What you say doesn't sound great, though a bit of noise is to be expected even on a good 'un.

Good idea to take a look anyway, a blown CWP is a bit of a disaster at the roadside, one of those things you can't just get out and fix.

I believe the 1" shaft can be fitted in a later casing 'simply' by adding a sleeve; and likewise a later pinion shaft can be made to fit an earlier casing by turning off the 1 1/8" section. Precision machining work is called for though, you're much better off with the right bits.

I'm sure Robert Leigh had a good used 5.25 CWP for sale on here recently, as far as I know he still has it. Sorry I can't immediately recall whether it was 1" or 1.125".

[Bob Culver]

Crownwheel teeth can be viewed through the filler hole. 
The larger shaft and roller bearing can be used but some simple peg arrangement is necessary to prevent the outer bearing ring migrating. Adjustment is easier as the pinion withdraws simply, whereas the ball race has to be eased out of the housing to view the meshing if the view thru the plug hole is inadequate. For normal use, with the higher rating of genuine modern bearings, the original ball OK.
if the old cwp is not damaged or worn very deep, wear steps should be very carefully removed with a Dremel or suchlike before attempting adjustment. 
Adjustment of worn can be tricky as the ratio operates in two hunting sets.

[Stuart Giles]

I believe the 1" shaft can be fitted in a later casing 'simply' by adding a sleeve; and likewise a later pinion shaft can be made to fit an earlier casing by turning off the 1 1/8" section.

You could get the later pinion ground down to 1"; it's too hard near the actual pinion gear to turn it. But the 1 1/8" pinion can be fitted in the earlier casing simply by using the spacers for the 1 1/8" pinion along with the later roller bearing. Not sure it's actually necessary to drill through the casing and put that peg in to stop the roller bearing's outer moving. But on the couple of occasions I've done this mod, I drilled and tapped the casing, screwed in a bolt with some loctite from the inside and cut off the "spare" length of bolt shank and head.

With Roger's nasty noise being on drive only, it is possible that the problem is with either the pair of thrust bearings or the retaining nut having come loose, although the graunching noises are usually on the overun when that's the problem.

[Roger]

I take it there's oil in it?

What you say doesn't sound great, though a bit of noise is to be expected even on a good 'un.

Good idea to take a look anyway, a blown CWP is a bit of a disaster at the roadside, one of those things you can't just get out and fix.

I believe the 1" shaft can be fitted in a later casing 'simply' by adding a sleeve; and likewise a later pinion shaft can be made to fit an earlier casing by turning off the 1 1/8" section. Precision machining work is called for though, you're much better off with the right bits.

I'm sure Robert Leigh had a good used 5.25 CWP for sale on here recently, as far as I know he still has it. Sorry I can't immediately recall whether it was 1" or 1.125".

Chris, I have drained the oil out and let it settle in a shallow dish I then decanted it into a container.
The remains left had very fine brass particles in it, but not a great amount.

Roger

[Roger]

     I have now dismantled the back axle and found that the run out on the crown wheel was in excess of 0.020”.
 Also the six bolts of the carrier were very difficult to remove because of the misalignment of the two halves of the carrier.
I have now found a replacement carrier which gives about 0.005” run out.
I am now assembling this, here is a photo of the result so far, could I have some views of where to go next. Do I need to move the pinion in more or does this look acceptable?
There is a distinct line where the blue lines up with the lower edge of the previous wear marks on the teeth.
This is my first attempt at rebuilding a diff so any help would be appreciated.


Roger

[Bob Culver]

I presume you have access to or someone will supply standard guidelines to patterns and adj. Both sides of teeth have to be considered.
Where bedded in can spend a lot of time chasing a pattern which may not be achievable. Keep notes and return to the best. The two mesh combination of the 8:42 teeth can also be puzzling.
If the run out is not evident from pattern, presumably little worn. 
If there is a wear step on the pinion can get very heavy line contact at the very outer (heel) edge of cw which hides main mesh and promotes chipping.
I appreciate it done for photo but usual to check finally assembled with casing halves fully tightened. Then involves repeat withdrawal of the pinion or working thru plug hole.  Considerable care necessary not to overload pinch the side bearings at any stage.
Judging by how quickly many change axle shafts etc, where any gasket change alters meshing,  many diffs must run with less than optimum or with altered previous adjustment.

It is years since I did but from books, viewing cw, toe contact, CW too close; low contact, pinion too far in. Backlash must be maintained.
Drive side ideally somewaht to the toe, tending like 4th tooth from bottom in photo, but also further up the tooth flank. Other side of teeth ideally central.

[Robert Leigh]

I take it there's oil in it?

What you say doesn't sound great, though a bit of noise is to be expected even on a good 'un.

Good idea to take a look anyway, a blown CWP is a bit of a disaster at the roadside, one of those things you can't just get out and fix.

I believe the 1" shaft can be fitted in a later casing 'simply' by adding a sleeve; and likewise a later pinion shaft can be made to fit an earlier casing by turning off the 1 1/8" section. Precision machining work is called for though, you're much better off with the right bits.

I'm sure Robert Leigh had a good used 5.25 CWP for sale on here recently, as far as I know he still has it. Sorry I can't immediately recall whether it was 1" or 1.125".

'My' CWP has a 1" shaft and I still have it for sale. I put 'my' because it's not mine; I am hoping to sell it for a friend in France, but it is here near Cambridge.
Robert Leigh