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Re: Rear axle preload

This all begs the question of the effect of significant clearance in the carrier axle bushes. Would make things difficult for the seals but any other effects?

When tinkering with a.c races in particular considerable care is necessary not to get some excessive preload during assembly. It is fatally easy to press dents into the tracks.

The carrier ball bearings depart from the usual convention for races adjacent, and have the thin edge of outer rings facing each other. Someone is sure to have assembled these the wrong way around at some time!

I have expensively replaced these bearings in the past but, correctly adjusted, do they ever fail? One does most of the work so can reverse.

As a matter of interest, how is carrier run out usually assessed prior assembly? Just sitting the carrier in bearings is not very representative. Ideally could hold gently loaded between chuck and a housing held in a tailstock mount, but some work involved.

Location: Auckland, NZ

Re: Rear axle preload

Hi Simon,I had a similar problem to this a few years ago when doing up a replacement axle for my Ruby. Tried all sorts, in the end I found that one of the axle tubes was bent. Not so as to be immediately visible but when bolted together it made things really stiff to turn. Just a thought and something to consider?

Regards Ian.

Ps you could only tell when the two halves were bolted together and looking along the full length from above.

Location: Worksop Notts

Re: Rear axle preload

I didnt think you could fit an early differential housing in a late axle.

Re: Rear axle preload

I've been out doing more measuring and playing.

The bearings all seem to be the same size. I measured the new ones against the old ones and they are all identical.

One thing I did notice was one adjuster was bottoming out on the spring clip and washer holding in the oil seal. When I assembled them I noticed the seal is a little thicker than the cup so a real bugger to get in. One of the washers was bent up and this was preventing the adjuster screwing fully out (away from the carrier). For now I have removed both seals and will replace them with the kind that go into the housing itself and do away with the cup/washer/spring clip.

That helped. But it still binds up. I also looked at my original axle and removed the adjusters from it. These are in much better shape (my others had been turned by a cold chisel it seems). There is a small (a few thou) difference in adjuster widths too. I made sure all threads were clean and things move freely.

It still binds up! But it is now closer. I also found with things bolted tight it only binds in some positions. The torque tube isn't attached so I can turn the crown wheel by hand and I find there are some positions where the adjuster is free and others were it binds. With no pinion involved I don't see how the crown wheel can be affecting things so could the carrier be bent? I checked the housing itself and I don't think that is bent.

I also remeasured the crown wheel run out and that is now out of spec reading about 5-6 thou. It's all a bit hard to measure as I don't really have anywhere stable/rigid enough to do it. Just touching things makes a thou or more difference.

I couldn't measure the widths of the carriers. I don't have a suitable way of doing it and the original carrier is so bent and rusty I can't get it back together easily.

Find a new carrier to try I guess?

Location: Auckland

Re: Rear axle preload

Austin in the shed
I didnt think you could fit an early differential housing in a late axle.

Ah, it's not the early (23-28) carrier. It's the later sort but with the smaller diameter half shaft bushes. I had them reamed to fit the later shafts.

Location: Auckland

Re: Rear axle preload

Simon,

If the assembly binds up in different rotational positions it would seem that something in the carrier is definitely out of line.

The assembly should spin freely and the crown wheel should run true with the adjusters tightened enough to give a pre load to the AC bearings.

Replacing the seals with lip type in the axle housings should help.

If you have another carrier this should confirm the problem (hopefully the replacement isn't bent)

Tony.

Location: Melbourne, Australia

Re: Rear axle preload

If you take the half shafts out and re assemble the diff carrier back in the axle and it still binds up it only leaves the carrier to be bent.
If you have a friend with a lathe put the diff carrier,bolted together,between centres,spinning it by hand will show if it is bent.
You say the crown wheel runs out of true,if the carrier is bent it will run out.

Re: Rear axle preload

Austin in the shed
If you take the half shafts out and re assemble the diff carrier back in the axle and it still binds up it only leaves the carrier to be bent.
If you have a friend with a lathe put the diff carrier,bolted together,between centres,spinning it by hand will show if it is bent.
You say the crown wheel runs out of true,if the carrier is bent it will run out.

I did just try bolting it together with just the carrier in place with no half shafts or crown wheel and that's fine. Plenty of slack between the adjusters. The carrier does seem to be true but I haven't tried it in the lathe yet. Edit: actually I just did while waiting for the kettle to boil. The carrier runs true.

I think the issue might be that the crown wheel is a very tight fit on the carrier and the bolts very tight in the holes. When it was bolted up the two halves of the carrier weren't coming fully together. I have carefully filed the carrier to remove all bumps and so on so now the crown wheel does fit on it more easily. You have to drop it on totally square though or it binds. The issue I have no is even though the crown wheel goes on and sits flush the holes don't line up enough to get the bolts through. In one position of the three they do but in the other two they don't. I ran a 3/8th drill through them so the holes are clean. They just aren't quite in the right place. I didn't want to go making them bigger though! Seems all this stuff should be tight but still able to be assembled by hand.

Location: Auckland

Re: Rear axle preload

OK, more playing. I just don't get it at all. I tried my bad axle casings and the same thing happens. I tried measuring the carrier in the lathe more accurately. My poor little lathe is too small I think. I removed the bearings and gripped it in the 3 jaw with a centre on the other end but it's not rigid enough. I measure 15 thou of wobble on the other end like that. Even set up in the 4 jaw chuck with half a thou run out there I was getting 20 thou on the other end. Every time I set it up I got a different reading so I don't know if my carrier is bent or I just don't know how to set up a lathe!

Either way I don't see how that would cause the bearings to jamb on the adjusters? The adjusters push on the outer ring of the bearings and that can't be moving in and out in the housing enough to jamb them up surely? There is a lot of room there for them to move.

Been looking at this too much. Need a break from old car bits for a while.

Oh, one silly question. Which side of the carrier should the crown wheel go on anyway? The two halves of the carrier aren't identical. I put it on the side that looked to be machined (it has a thicker base) but maybe I have it wrong? It is certainly a lot looser on the other side!

Location: Auckland

Re: Rear axle preload

OK, replying a lot to my own post here I know but I cracked it. I gave up, went for a fast drive in the MG, bought some wine, came home, cooked dinner, had a glass and watched MacGyver. One of these things did the trick as I had a sudden idea. I tried the axle with the carrier and crown wheel but not half shafts. That was fine and everything is very free. So I took a close look at the shafts. One of them is bent. I guess the bent shaft was rotating and rubbing the inside of the adjuster in some positions locking it up.

Since I had the carrier stuck in the housing I also remeasured the crown wheel run-out. It's held very firmly in the big half of the D. I got a run-out of two thou so that looks good.

Location: Auckland

Re: Rear axle preload

Simon,

That is very good - I was coming to think it could be a bent axle

Next I hope that the CW&P work nicely together

Tony

Location: Melbourne, Australia

Re: Rear axle preload

Still didn't fix it. Even with a different shaft. I think maybe now the bushes are out of alignment maybe? I did have them reamed but maybe they aren't concentric.

Location: Auckland

Re: Rear axle preload

Being an odd size 57/64"it is unlikely that you will have a piece of rod to check alignment.
The Companion (page 167) suggests spinning the carrier on a half shaft to see if it is over 3 thou out of truth (either side in turn) this should indicate if the two bushes are aligned sufficiently.

Tony.

Location: Melbourne, Australia

Re: Rear axle preload

Hold a half shaft in the vice with half of the carrier on,hold it up close to the carrier so can't run along the shaft and spin by hand.If its badly out you should see it.
Ideally if you could rig up a dial clock to check it.
Or hold it in the lathe chuck if the 1/2 shaft will go down the spindle.

Re: Rear axle preload

You say you have a 8:41 tooth CWP. Do you mean 8:42 tooth which is the more common 5.25:1 ratio?

Whatever, is the 8 tooth pinion correct for the crown wheel you are using. Austin made three 8 tooth pinions, that for the 5.25:1 ratio, the 5.625:1 ratio and the 5.125:1 ratio. If you aren't using the correct pinion, it will mesh fine with the crown wheel right up until the point you give the diff casing the final tighten at which point it will lock solid.

Steve

Location: Nr. Selby, North Yorkshire

Re: Rear axle preload

Steve Jones
You say you have a 8:41 tooth CWP. Do you mean 8:42 tooth which is the more common 5.25:1 ratio?

Whatever, is the 8 tooth pinion correct for the crown wheel you are using. Austin made three 8 tooth pinions, that for the 5.25:1 ratio, the 5.625:1 ratio and the 5.125:1 ratio. If you aren't using the correct pinion, it will mesh fine with the crown wheel right up until the point you give the diff casing the final tighten at which point it will lock solid.

Steve

Hi Steve, it's definitely 8:41. Apparently (according to the green book) that's a late 37 Ruby one.

I finally worked out the problem was the bushes I had reamed out. They were off centre. I measured 30 thou wobble on a half shaft where it came out of the carrier. More than enough to bind the shaft on the adjuster.

For now I hand filed them out to be free and have given up trying to set up the diff. I will get new bushes an try again then but for now I have assembled things as best I can to get the car on all four wheels so I can continue working on it. I don't have an engine yet so the car isn't powered. I just need to be able to set it up and roll it about!

Location: Auckland

Re: Rear axle preload

Simon,

I suspect to ream the carrier axle bushes you require a reamer and guide vaguely like the recently discussed kingpin reamer to carry out the job with the two halves assembled.

Tony.

Location: Melbourne, Australia

Re: Rear axle preload

If you have a reasonably accurate 3 jaw chuck on your lathe,make a plug gauge.890 dia as your halfshaft first,check carrier face run out in lathe.
Bore out bush (Each half). with boring tool.

Re: Rear axle preload

For now I have everything assembled so the chassis is rolling and I can work on the body. No engine yet so nothing is powered. I'll order new bushes and go from there I think!

Location: Auckland