Pre war differential casings

[Tony Fearn]

- Jaw reversal - I want to check what you mean by this, Tony? From what I remember putting Polly’s diff back together, the 4 bolts have only 2 positions that work. Ie the flange can only go on in 2 positions 180 Deg apart.

Hi Bruce.
Have a look at the photo I put up regarding the two types of jaw couplings. The one on the right seems from your photo to be similar, but perhaps is reversed.
My photo shows the usual orientation.
Nevertheless, it probably doesn't matter in your case as you have UJs. I was only commenting.

For KC:- Bruce mentioned post 6005, how do you bring just this post up (if at all possible) within the pre-war section?
Tony

[Keith Clements]

Tony,
You gave us the link to topic 6005
viewtopic.php?t=6005
not post 6005 in your previous post in this topic..
but to answer your question just put a p instead of a t in the URL.

[James Baxter]

I dont think it matters which end of the prop has the splines. They take up the change in length and transmit drive in just the same way which ever way round they are mounted.
Yes there are 4 holes and 2 ways to mount the ends, cant go wrong. But if you disassemble the spline part, make sure you rebuild back into the same tooth slot. That is to say, make sure both UJs are in line. Otherwise you no longer have a carden shaft. They usually make a clonking noise when phased badly, but i am not sure of the effect if just one tooth out. Most people know this i am just covering all bases.
We also wedged the rear axle to have the same angle from prop to pinion, as the angle from prop to gearbox. (wedges like those providing caster on the front axle) This ensured the prop acts perfectly as a carden shaft and the speed errors of a UJ cancel each other out. Servere suspension deflection spoils it, but at least we have it right most of the time.
We made the adaptor plates to accept the UJ prop in aluminium, much lightened with shape, and holes drilled. Then painted them black so no-one will ever know. Except.....oops.

[Brucegirvan]

Thank, James. Never stop pointing out the obvious. I was aware of the ‘in’ and ‘out’ of plane parallelism for the UJs, it seems +/-3 to 5 Deg is acceptable. When we replaced ED’s rear springs we didn’t need any wedges. 8 have assumed that remains true over time…perhaps not? Of course measuring in itself is an error strewn unless you have a laser alignment system. And it is very important that the UJs are able to move in unison so I’d always advise that their main joints are in phase and not out of phase, which includes not being at 90 Deg. For future readers, here is a good pictorial explanation of angle of alignment. Most of these types of image show the input and output UJ bearings in phase - ie with 0 Deg offset on the ‘knuckles’ for any US reader.
https://www.pirate4x4.com/forum/attach ... gnment.gif

Well done on your hi carbon, iron-doped aluminium adaptor plates . I suspect you have the necessary kit to machine etc….whereas I have a local garage that won’t let 3rd parties use their machines and are OK with steel but not good at all with Al...there’s an expensive story there (for them and me). I should have gone to our local model engineering club instead; one for the next phase in improvements.

Tony’s diff casings has arrived and look good. I have yet to dismount ED’s back axle so will report when I can. If anyone can point to a good set of instructions on disassembly/reassembly I’d be grateful. Our search of these forums has unearthed a few hints, and we managed PO’s OK, but I am sure there is wisdom out there and I’m grateful for any.

[Keith Clements]

Is it good practice to have a Hardy Spicer Universal Joint at one end and a Layrub (or similar rubber joint) at the other?

[Brucegirvan]

Keith - any preference for which end?

[Keith Clements]

My gut feel and engineering sixth sense tells me that joints cannot be mixed because a Hardy Spicer needs the opposite end to be rotating in the same phase. I would need to look at all the rotational vectors and mass movements to get to a scientific proof.
There is a similar issue with Layrubs where the location and orientation of the bolts, nuts and washers makes a difference to the rotational balance, particularly as the coupling is not always straight so that out of balance forces act around the centre of coupling. It is like having a bent road wheel!

[James Baxter]

I agree I wouldnt mix them.
The hardy spicer acts like a carden shaft. What one end does badly, the other does in opposite to make it OK again. So ideally work as a pair.
Of course a CV joint is what we all really need.....

[Brucegirvan]

It has taken some time to get back under Eddie…so here’s the updated from today, which was just to remove the back axle from the car for disassembly.

Condition of all main parts was very good and my hopes were ‘up’ when there appeared only minor surface marks on the pinion. They were even higher as the crown got rotated….until the attached photo showed a quite catastrophic tooth failure.
Tomorrow is the day to disassemble, and it will be interesting to see if the tooth part/s are still somewhere (they should be) and if the additional missing rivet on the crow wheel is the culprit.

Sooooo, gents. Who at know of someone with a 1930-34 crown-pinion diff set, and or complete rear axle?

Also, can anyone recommend crown and pinion makers? I would be shocked if anyone thought this can be salvaged? Can anyone advise otherwise? I’d hazard not many miles of running before a bigger failure occurred.

Yours Bruce (hoping for a less ‘stressful’ 2023 )

[Chris Spencer]

Bruce - I'm assuming that JCS doesn't have anything suitable ? I do have to clear a vintage parts hoard but I don't know what is amongst it and secondly its currently interstate (has been for several months) so until the solicitor comes back to me I cant do anything - If I hear of anything in the interim I'll advise accordingly - I currently have a trip North scheduled in the early part of the new year if that helps on the logistical front

I have a very good & talented contact who runs engineering business in Sussex - He holds a laser welding facility of which he puts to good use and I have seen some remarkable repairs undertaken with this kit - normally by machining out the defective tooth to a rebate in the crown wheel then laser welding a new machined tooth to the rebate - I can always forward a few images and ask if you wish - Chris

[Tony Fearn]

Hello Bruce.
In the March of 1979 (over 43 years ago!) I paid one of my occasional visits to Roy Braddock of Jowett fame when he lived at North Rode in Cheshire. Every time I visited him, I returned home with what Roy deemed was a little something that I might just need some day.
Reading your post below I remembered that on a shelf I had such a thing, and I doubt it will ever be needed.
It's a new old stock differential crown-wheel and pinion, with rivets.
Something in the back of my mind, and I didn't make a note of it at the time, seems to remember that they could possibly be for a Bradford, but I was assured by Roy that they could be used in a pre-war rear axle if necessary.
I don't think they are actually paired because the pinion has 9-50 stamped on it, whereas the crown-wheel has, amongst other stamps, 4-54 on it.

Pinion stamps ... 2114x1 ... 9-50 ... VBW ... 17 1/2 degrees and NOGH

Crown-wheel stamps ... 2103x4 ... 4-54 ... VBW ... 17 1/2 degrees ... and NOGH. It has 43 teeth and is 7 1/4" O.D. and 4 7/16"I.D.

There rivets to fit.

Let me know if of interest.
All the best for the New Year,
Tony.

P.S. There are still the two used crown-wheels shown in my October post if you don't have any other luck.

[Brucegirvan]

Chris - I’d be interested to know if your engineering maestro could.
I’d also be interested in understanding what is in the vintage parts hoard.
I’ll give you a call over the next few days as I still have that lining for you!

Tony - I have got to:
The crown-wheel numbers: 43 teeth, 17.5Deg, N.C.C.H, 2103x4, 8-36
The pinion is still in the housing, so I can’t get to its numbers until Fri/Sat., though it does have 8 teeth!
Apologies, as I had not assumed your Oct gears were available! It sounds like you may have something suitable. Shall I just move next door?
Is there a reference to show what the 2103X4 and 8-36 mean?

In one of the images you can spot the failed rivet. Interestingly the tail is very much still in place. Some of the rivets have nicely rounded heads and some are far from ‘nice’, so I wonder if the crown has been replaced at some point, off some of the rivets were.

[Tony Fearn]

Is there a reference to show what the 2103X4 and 8-36 mean?

Hi Bruce.
As far as I'm aware, the 2103x4 is the sort of reference number printed in a Jowett Company Spares booklet,
and the 8-36 means whatever it's stamped on was made in August 1936. (viz con-rod stampings etc.)
Tony.

[Brucegirvan]

Is there a reference to show what the 2103X4 and 8-36 mean?

Hi Bruce.
As far as I'm aware, the 2103x4 is the sort of reference number printed in a Jowett Company Spares booklet,
and the 8-36 means whatever it's stamped on was made in August 1936. (viz con-rod stampings etc.)
Tony.

Tony - well I finally got to the pinion and the results are:
17.5Deg, 8-36, VBW and 2114x1

So other than the X-XX references they look OK. I’ll call you later.

Kind regards

[Brucegirvan]

An update - “yes” things are slower than I would like however we are moving but perhaps not quite in the right direction. After having drilled out the rivets and removed the crown with the damaged teeth I noted that there is a crack in the cage, which has clearly taken some beating in the past. Is it possible/wise to weld up the cage? Also, from the heat marks the rivets would appear to have been hot formed…is that the preferred way or has anyone tried cold forming?