Worn rear wheel bearing or something else?

[Adde]

Hi

Some updates regarding my progress the last week (1, 2), and some further questions regarding shimming the drive shaft into the gearbox (3).

Sorry for the very long mail, but I have so many question marks.

Since last time, I have:
1) checked the bearings in the rear hub and the seems to be in good condition. Now reassembled with an looctite equivalent on the bearing and splines.

2) Changed the universal joint as there was a very small clearance/movement axial in it. I must say that the UJ was not that easy to remove, it took me quite some time.

3) I have now assembled the drive shaft again, and can now conclude that there is an axial movement (end float) in the shaft connected to the gearbox, as some of you already suspected earlier in this thread (BDA, and buzzer).  As I understand it this is not unusual, and something that can be fixed through shims, correct? I have tried to search for guidance in earlier threads and found some useful info, but I still need some more guidance.

Is it correct that I can fix this through shims and that it can be done without disassemble the gearbox except from the diff nut (fig 1)?

What is the the correct procedure for shimming the drive gearbox?
1) Remove the drive shaft.
2) Remove the diff nut (where to get the tool, can it be homemade or handled in any other way?)
3) Add shim(s) outside the spacer (can I get universal shims with ID 25mm OD 35mm, as last post in http://www.lotuseuropa.org/LotusForum/index.php?topic=618.0)
4) Reassemble everything
5) See if the axial movement is gone, if not start over from (1) and add another shims.

Is this the correct way, or should it be done different?
Can I decide what's decent number (total thickness) of shims without reassemble everything in between?
How tight should it be, as tight as I can get it?
Isn't the contact face between the gears in the diff extremely important for the wear (i.e. needs accurate measurements), or can it be handled in this rather basic method?

What will/can happen if I don't fix this at once?

Some figures borrowed from "http://www.lotus-europa.com/manuals/misc/transmission/diff_nuts.html"

Best regards
Adrian Dahlquist

[BDA]

Having done u-joints and reassembled the upright including using hardened spacers and torquing the axle nut and locking it, other than the differential bearings, the only other place to look is shimming the u-joint yoke on the tranny. I THINK this is the most likely problem you're experiencing. It is certainly the easiest to address so I think you should fix this and if it doesn't fix it, go to the tranny. The shims are available on your side of the pond from Richard at Banks, SJ Sports Cars, and other vintage Lotus outlets. The idea is to stuff enough shims between the yoke and tranny so there is no slop after you install the roll pin. You don't have to take the differential nuts off (rdent.com has a tool for the diff nuts if you end up needing one). You should get more than you think you'll need.

In steps:
1. take the drive shaft off from the output shaft of the tranny (it sounds like yours is already off the car).
2. put a couple of shims over the output shaft, put the u-joint yoke back on the output shaft and sight through the roll pin hole to see if the hole in the output shaft lines up with the hole in the yoke.
3. add or take away shims till the holes line up. (I might add an extra thin shim here.)[/size][/font]
4. install the roll pin. If the thin shim made it so the pin won't go into the output shaft, take it out and try again. It should fit now.
5. test for play. adjust if necessary.

If that doesn't fix your problem, you may have a problem with your bearings which might imply a problem with the crown & pinion back lash. If that's the problem, things get a little more complicated. Hopefully the shims fix it.

[4129R]

Get the tool to undo the castellated ring nut from Banks.

Don't try and undo it with a hammer and chisel or you will break it, and replacements are made from unobtainium.

Or if you are passing by in Norfolk you can borrow my tool.

Alex in Norfolk.

[jbcollier]

Ok, where EXACTLY do you have axial play?

Does the half-shaft move in and out?

With the half-shaft removed, does the splined output shaft move in and out?  If so, how much?

[Grumblebuns]

If the half shaft is locked to the differential output half with the roll pin, won't the remaining sources of axial movement be the U-joint at the inboard side or the output shaft at the differential or possibly a worn roll pin hole or broken roll pin?

According the Renault manual (I'm using the NG manual for reference), the differential adjusting nuts are turned in until all end play is removed and the differential still turns freely. If there is output shaft end play could the differential adjustment nut been previously misadjusted.

Before doing anything else have a second person move the wheel back and forth while you pinpoint where the movement is.

[jbcollier]

If the output shafts have axial play, then the diff gear shim/spider gears have worn.  This usually results from insufficient shims between the half-shaft and the seal run.  You have to strip the transaxle to repair.  Very minor amounts of output shaft axial movement is ok.

The large side nuts hold the seals but their primary function is adjust the diff's crown gear position and bearing preload.  This CANNOT be adjusted in situ.  You have to remove the transaxle and bell housing to set it up properly.

[Grumblebuns]

I should have mentioned that the manual requires the differential adjustments have to be done with the transaxle removed and cases split. It's not a job to be done lightly as pulling the transaxle is a pain in the ass. You really need to identify the source of the movement first, you don't want to get into the transaxle unless you narrow it down as the source.

I'm doing the differential bearing preload and backlash adjustments for the first time with a 336 transaxle in my Manual transaxle/driveline class. Really looking forward to learning about this as I have another spare 336 disassembled on my work bench as a practice run.

[Adde]

Thanks for all the replays, really appreciate.
I need to digest the information and think through this some more before deciding what to do next as I haven't been able to determine if the movement is the UJ sliding on the "tranny" axle or if its the tranny axle itself. I was just in my garage making an attempt, but was not able to remove the UJ from the tranny axle (due to the loctitet I added earlier this week). Which I, however, think indicates that the movement is in the tranny axle, as I otherwise likely would be able to remove the UJ.

I have also been thinking about whether this minor movement will be any problem in reality, or not. My thinking is that this movement will only be present when the car is standing on the jack, and unload the suspension, hence removes the compression force on the driveshaft. But, when the car is standing on the ground, will the suspension be compressed and and the driveshaft pushed against the tranny, as it also acts as the upper linkarm,

It is hard to tell how big the axial movement is. I captured a video with my cellphone when the car is on the jack, see https://youtu.be/Jm_Uz5Prbaw.

[EuropaTC]

It is hard to tell how big the axial movement is. I captured a video with my cellphone when the car is on the jack, see https://youtu.be/Jm_Uz5Prbaw.

If I'm viewing that correctly, my initial impression is that you have far too much movement there. My car is rock solid at that point, not even a "feel" of movement, whereas that looks like it's physically moving. 1mm ?

Assuming the roll pin isn't broken (it doesn't look like it)  then there's either something adrift with the bearing/diff settings or a lot of shims missing.  I can't tell you what I have in the way of shims on mine but I'd guess it's no more than 2 or 3 shims at between 0.005" to 0.010" thick.

I really wouldn't drive the car in that condition. at the very least I'd remove the roll pin and insert shims to take up the play.

Brian

[BDA]

That movement is unacceptable and since you have a roll pin installed, and assuming it's not broken, it is because of slop inside the tranny. You're going to have to take the tranny out to take care of it. I'm no expert, but I would say that at a minimum, the bearing pre-load (and thus the crown/pinion back lash needs to be adjusted), but I think more likely you have issues with the bearings themselves and they will need to be replaced. Those bearings not only take the loads from the crown gear but also the upper lateral suspension loads.

I wonder if you've misunderstood about the loctite? It should be used on the splines of the stub axle where it mates to the hub (which holds the brake drum and wheel studs). There is none needed on the output shaft ("tranny axle") to u-joint yoke joint nor is any desired for the reason you found - it makes taking the half shaft off the output shaft a lot more difficult and it doesn't add anything. It will require heat to break it loose.

[jbcollier]

OK, too much play and insufficient shimming.  Do not drive it.

Busy right now but will post a detailed explanation later.

[BDA]

I really wouldn't drive the car in that condition. at the very least I'd remove the roll pin and insert shims to take up the play.

OK, too much play and insufficient shimming.

When I had my tranny out, I didn't check for lateral movement in my output shafts (just the crown/pinion back lash and bearing pre-load) so I don't have direct experience with this. And since I have a twin link rear suspension, I don't have to concern myself with shimming the u-joint yoke in the first place. I always thought that the shims were there to keep the roll pin from taking the suspension loads. So maybe my understanding of this is flawed.

I look forward to your comments, John.

[4129R]

and I thought if the shims between the drive shaft and the gearbox were insufficient, the roll pin would just break.


I think it may be a problem with the shimming of the diff, but will let others with better knowledge of pre-loads, diffs, planet gears, and the mystery of the correct differential building explain. 

[Adde]

It seems as I have a bigger problem then I was hoping for. Lets see if anyone has some good advise how to solve it.

[Adde]

Hi

I want to start by apologizing for possibly using the wrong terminology or misunderstanding it all.
But, what are you opinion about this:
I'm thinking that maybe the issue is a too big backlash in the "spider" gear connected on the tranny axle where I see the movement. (That would then also explain the rotational movement (Backlash) that I mentioned in my first post).

If so, can it be worthwhile to try to tighten this by first tighten the diff nut until the axial and rotational movement is gone and then just lose the nut slightly to get some backlash in the gear?