OK so I've started rebuilding the English Axle...sort of. Help please!

[Julian Thompson]

Didn't get very far

 

Managed to undo the main nut using large pieces of scaffolding pole to create enough leverage - quite a task!

 

Except the main diff casing won't pull away from the axle with all the nuts undone and the main drive input flange taken off...

 

...how do I split the casing? Must the half shafts come out first? If so, how?

 

OR,

 

...must I space the axle casing away from the nose and then "apply force" to the drive shaft prop input 😬

 

Any help greatly appreciated....

[allen]

Halfshafts have to come out first - hope you've got a slide hammer, this attaches to the flange where the wheel bolts on and a metal 'lump' is slid violently allong the shaft away from the hub, the jolt as it reaches the end of travel 'hammers' the bearings and halfshafts out.

 

Make sure you have the vehicle in a position where you have room in the garage to withdraw the halfshafts - been there with car on axle stands and couldn't clear one of the half shafts cos of the garage wall 🙆🏻

 

allen

[philwaters]

I made a make-shift slide hammer to do this on mine - here

 

Phil Waters

[j passfield]

If the axle is off the car you won't have a chance in hell of pulling the half shafts, UNLESS you can secure it solidly. Try to hold one half of the axle in a decent ( read bloody big engineers' ) vice otherwise all the impetus from the slide hammer will just try and drag the axle across the floor. If of course the axle is still on the car just make sure it is sitting securely on axle stands, you will be surprised at how much effort is needed on the slide hammer to get the shafts out. Good luck !

[Julian Thompson]

Ah

 

Right - OK - Yes,

 

Axle is off the car, and I do have a good slide hammer, so I guess I need to secure the axle to a soild thing and have a hammer at it.

 

So - are we saying that the half shafts are not secured in to the diff by anything other than an interference slide fit

 

Scary?

[j passfield]

You need to remove the brake drums and then the back plate assemblies, secured by four bolts or nuts and bolts around the flange of the axle tube. Try and borrow an old Escort workshop manual, that will give you all the detail.

[Manxseven]

Julian,

If it all goes pear shaped you know where to come 😬 😬

 

 

Caterham Fireblade here

[Dave Wilson]

You need to remove the brake drums, then there are 4 retaining bolts that are accessed through a hole in the end of the brake drum drive flange. These secure a steel plate which houses the seal and must be removed before the half shaft can be withdrawn, from memory they are 5/16" UNF. Once these are removed, attach slide hammer to drive flange and hammer away. Bearings are about 3/4" wide, so once the shaft come out this far it can be pulled out by hand. Good luck..

[Manxseven]

I think Julian has discs on his axle?

 

Caterham Fireblade here

[Julian Thompson]

OK - Yes I gettit!!

 

As Simon says I'm on discs but I understand- the 4 retaining bolts on the disc caliper adaptor plate need to be removed then I can slide hammer it and then withdraw the halfshafts then withdraw the main diff nose...

 

...will give it a whirl tomorrow

 

Ta fellas don't know what I'd do without you 🥰

[Jorgen]

Hi Julian

 

I have a Cortina Haynes book that descibes the axle work. The axle is the Atlas type. I am not sure how different it is from the English one. If you think it will be usefull I will be happy to send you a copy of the pages.

 

Cheers

Jorgen

[Julian Thompson]

Thanks Jorgen - appreciated - yes please. sales@thompsonsltd.co.uk

 

Actually with the right info (thanks chaps!) it was dead easy to remove the half shafts and strip the diff..

 

..now just got to rebuild it all into the new casing!

[Julian Thompson]

WARNING

 

🙅🏻‍♂️ BORNG TECHNICAL POST AHEAD 🙅🏻‍♂️

 

OK - So the axle is now fully in bits and I managed to get the bearing off the input shaft next to the pinion - 😳 - tricky little hours entertainment that 😬

 

Anyway, that's done now and I have been thinking about this solid alloy spacer I have been told to replace the crush tube with.

 

I also spoke to Phil at R&RT - (what a fabulous bloke - hell of a nice chap ) who also could not understand how you could say what the "finished" length of the crush spacer would be in order to machine it BEFORE you press the pinion shaft in to the bearings and assemble the whole thing...

 

So - I've been thinking and want to ask your opinion on this idea

 

What about if I make up 2 dummy solid bearings the same width as a pair of the proper races and machine them slightly small o/d and over large i/d so that the whole thing can be trial assembled to do the measuring etc...

 

Is this silly or would it work?

[Julian Thompson]

....No - it's silly Julian (talking to myself a bit with this but at some point someone else with no experience will be daft enough to try and rebuild his own axle!)

 

So basically that would not work because you'd have no way of setting the bearing preload.

 

Instead I think the plan is this:

 

1) Clean up the pinion shaft. I have racked my brains and cannot think of any good reason why the bearings need to be so tight on the shaft Methinks the old bearings perhaps got a "touch warm" 😬 at some point?

 

2) Cook the new casing in the oven when Andrea is out 😬 and press the new bearings carefully home...

 

3) I need to machine up a simple tube to clamp in the diff clamps and then I can (hopefully now easily) slide the pinion shaft into the bearings WITHOUT the crush spacer OR a pinion shim... I reckon then to tighten the main nut to achieve a nice bearing preload (whatever that feels like - I guess smooth but play free? )

 

4) Now I intend to mic off the gap between the tube and the end of the pinion. This, if my crazy plan works, SHOULD ( 😬) be a figure from which I can deduce the thickness of the shim:

 

I reckon I need : 83.54mm (spec for start of pinion to centre of crownwheel) - thickness of pinion - RADIUS of my tube tool = SHIM THICKNESS ( 😬)

 

5) Machine up a shim to size determined in 4)

 

But... now I feel a bit stuck, because I'm back to Phil's conundrum - how to guage the size of the new crush tube..

 

Perhaps get a new CRUSH tube, assemble the whole thing on the NEW shim, MARK the main nut when the bearing preload is good, THEN strip it down, measure the crush tube and make a new one exactly the same - then reassemble, torquing the main nut exactly as before...

 

Flippin 'eck - might leave it at that for now and see what happens with that lot.

 

If you've been following that comments welcome BEFORE I cock it up tomorrow (Monday!) night

[Jorgen]

I will bring the book to work tomorrow for scanning. The copy should be with you in a couple of days.

 

Good luck with the axle work.

 

Cheers

Jorgen

[Julian Thompson]

That's really kind of you Jorgen.

 

Will put the rebuild on hold until I get it I think... *thumbup*

[Sheds Moderator]

Brave move Julian. 😬 . Your logic re the crush spacer seems reasonable, fit it to correct gear meshing then remove it, measure it and make a solid one. It sounds like a rave all told but every credit for having a go.

[Julian Thompson]

Cheers BOSS - Except the only thing is that the crush spacer will likely expand again slightly when I remove it...

 

...I guess I could add a couple of thou to compensate for that but it does not feel very "exact" an idea!

 

I have now managed to machine the input shaft so I have a smooth fit on the bearings so trial assembly should now be simple® 😬

 

 

[Bricol]

errrrrrr the bearings are a tight fit on the shaft deliberately - stresses and locates the inner race to design specs - I'd be a little wary of them now. You'd be quite surprised how easy it is to make a race skid on a shaft without the right fit.

 

And I may have missed the answer to this bit, so forgive me if I have - but why not simply fit and forget the crush spacer as per original?

 

Bri

[Julian Thompson]

Hi Bri

 

They are now a smooth push fit so no probs - they can't rotate once assembly has taken place because the spacer tube locks them to the pinion shaft, IYSWIM

 

If they were not slightly "cleaned up" you could never set the bearing preload because you would have to press the pinion shaft into the bearings and then to remove them and fit the shim would mean destroying the new bearings !

 

That crush spacer question is an interesting one though - basically the people who make the alloy diff nose maintain that if you do not use a solid one you can suffer "pinion creep" on higher powered applications. With the solid spacer it is obviously not possible for the tube to deform and so the set preload on the bearings remains constant.

 

Phil at R&RT liked the idea of the solid tube in theory but as I said we could not decide how we would be able to get the length exactly right without continual trial, machine and rebuild. The method I described earlier might solve this as long as the expansion of the crush washer is "measurable" somehow for when you strip back down and measure the new length.

 

Phil also said he'd not really seen any evidence that the crush washer was a bad thing but it is difficult to fly in the face of someone like the manufacturer of the casing when they are advising you to do a significant change like that.

 

Bit of a conundrum really.

[Sheds Moderator]

Julian, if you are using a crush washer then I would doubt that it will significantly expand on removal. Any piece of metal when loaded will deform first in an elastic fashion, ie its length will be recovered at 100% once the load is removed in the same way that a spring works. Subsequent deformation will be plastic, meaning that it will not spring back. I would suggest that the elastic deformation on a crush washer will be close to zero compared to the plastic movement and therefore will be lost in the overall scheme of things. In any case you will get some (minimal) elastic deformation of the solid spacer. If you are extremely lucky the solid spacer will deform elastically by the same amount as the crush washer. (Sign here for a book on hopeless optimism 😬)

 

On these grounds I would machine up the solid spacer to the same size as the crushed washer. You can always check the meshing afterwards.

[Julian Thompson]

OK - good plan BOSS - thanks for the explanation - I understand what you are saying and it makes sense to me as a non expert on metals etc.. additionally, if I do that and the preload doesn't feel OK when I assemble it I can just take it to bits again and whip off a couple of thou off the end of the tube.

 

Thanks - that is what I am going to do, then wait for Jorgen's manual and have a careful read.

 

Interestingly the use of a solid spacer does indeed seem to be "de-rigeur" in Escort rally circles - I even found one actually on the shelf and in stock at a rally place. It was only £20 so that is on its way for tomorrow - saves machining one up!

 

[Jorgen]

Julian

 

Did the mail arrive in you inbox. It was quite large, so could have been rejected by your server?

 

Cheers

Jorgen

[Julian Thompson]

It arrived perfectly Jorgen - thanks.

 

So, todays faffing?

 

Well I cooked the diff in the oven and tried to press in the bearings that I had kept in the freezer overnight.

 

Got the first bearing tapped in no problem in the nose of the diff but the back bearing is surrounded by much, much more metal and our Rayburn clearly didn't have the waft to overcome the heat sink effect... ☹️

 

So - I popped to a chum with a flippin' great furnace and gave it 300 degrees C 😬

 

...at which point Mr bearing decided to be good and drop straight in aided with a little help from a big press which was also handy. Not such an easy start, then.

 

The sideways bearings on the diff output shafts also were a bit tight, and required the use of a pretty hefty puller that I found kicking around at work. The new bearings pressed on the shafts again with a drift and a big vice, no problem.

 

So, so far, if you're going to have a go at this you DO appear to need a furnace and a press, a puller and a big vice...other than that, not too hard so far...

 

I now assembled the pinon shaft and bearings and pinched it up so that there is a bit of resistance to overcome before a smooth spin, and then fastened the diff in to the carriers for a trial run.

 

A quick pinion measurement shows that the original spacer is OK (as in the new casing is identical to the old one in terms of size) so I pressed on to horizontally position the diff crown wheel and measure the backlash (play) in the crownwheel/pinion assembly.

 

I furtled out a dial guage and it was very easy to use the winding collars on the axle to centre the crownwheel to give 0.006 inch of backlash on the guage...

 

...BUT

 

(and now I'm stuck again 😬)

 

Is this measurement taken from the extreme OUTER edge of the crownwheel OR the inner edge? (Or the middle )??

 

AND...

 

How do I set the preload on the crownwheel bearings???

 

So far I think there would be 2 ways - 1 way would be to measure the increase in distance between the bearing carriers under load or 2 to dissasemble, and reassemble with NO pinion, set the preload and MARK the position before reassembling... Sounds fraught. Prefer way 1? Sounds like a tiny measurement

 

Ideas?

[Julian Thompson]

Looks like option 1 is correct - excellent google help on this here (even seems to cover the position of the backlash measurement...

 

here

 

Now just need a spread guage (which I don't have ) - guess I could use a dial guage bolted to one lug on a really decent bit of bar?