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post #1 of 22 (permalink) Old 05-08-2019, 12:36 PM Thread Starter
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Gearbox assembly question

Hello,

When re-assembling the gearbox shafts, do the internal splines need any particular lubrication?
My question is related to whether these are lubricated by the gearbox oil in normal use or if there needs to be some moly grease in there beforehand? I don't see a lot of oil ingress paths.



The same question goes for the inside surface of some of the inner races of the gear bearings, the face which sees the shaft might not see much oil as it doesn't move around the shaft.

Thanks.
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post #2 of 22 (permalink) Old 05-09-2019, 07:01 AM
Richard Jemison
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Splines

Lube is un-necessary as the splines lock the tripods that the slider rings sit on.

Lube the surfaces that move on other parts like bearings, gear bushings etc.

Richard Jemison
RJR Racing

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post #3 of 22 (permalink) Old 05-09-2019, 10:28 AM Thread Starter
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Thanks, I understand what you're saying, there's no axial or rotational movement between the tripods and the shaft.

There is however a slight amount of play as this is not a press fit, won't that cause any wear if not lubricated?

Cheers
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post #4 of 22 (permalink) Old 05-23-2019, 01:43 PM Thread Starter
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Richard, thanks again. You were absolutely correct. There is indeed no need for lubricating those. In fact upon more careful inspection I found there are always ways for oil to make its way in there.

Both shafts are now assembled and I have done both nuts up to the right torque but I'm not fully happy with it, I've got two questions:

1 - I have measured the flange to pinion distance before and after, I did not change or touch the main bearings at all and still it's now 0.076mm longer, this is above the stated 0.03mm tolerance. Is this something I should be worried about? Should I now check the pinion to diff teeth attack pattern?

Edit: The measurement was not done via indicator as per the manual, it was measured in a CMM.



2- The main shaft has got some play that I don't remember it having before. I've double checked the torque figures, it doesn't rock back and forth at all but it rocks up and down quite a bit. Is this normal? It could be given it is supported at both ends by needle bearings but this feels excessive to me...
Videos here:
https://photos.google.com/share/AF1Q...J1endVVEdsLTBB

https://photos.google.com/share/AF1Q...J1endVVEdsLTBB

Thanks
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post #5 of 22 (permalink) Old 05-23-2019, 02:08 PM
Richard Jemison
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assembly

Yes the additional length will result in noise and rapid wear. Allowance is only .001" or .03 mm.
The shafts are supported on both ends and in 3 places on the main/pinion shaft. The center bearings allow a little movement on their own.

If you have used a non original bearing, tripod, shim, spacer, gear sleeve or gear that will likely be the reason.

Richard Jemison
RJR Racing

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post #6 of 22 (permalink) Old 05-24-2019, 12:30 AM Thread Starter
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No, all of those parts came out and went back in in the same order, I only replaced synchro rings and selector rings which are obviously not part of that equation.

The only thing that could have changed is one of the gear bearing inner races being assembled the other way around compared to how it was. I didn't pay too much attention to those.
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post #7 of 22 (permalink) Old 06-04-2019, 02:44 AM Thread Starter
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An update on this now that I have tried a few things and repeated the measurement a few times

227.755mm <- Original measurement before disassembly

227.832 <- After replacing syncro and selector rings

227.833 <- After confirming nut torques. Pinion shaft nut did need a little more torque but that didn't make a difference.

227.837 <- Disassembled the whole stack again, confirmed position and orientation of every tripod, spacer, sleeve and shim, one sleeve potentially the other way around. Unfortunately it made no difference.

So after all this I know:
- The measurement is very repeatable and accurate.
- Something is wrong with the stack or the initial measurement came out wrong.

At this point I think I will have to confirm the ring gear attack pattern... I really wanted to avoid this. Any other options left?

Thanks.
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post #8 of 22 (permalink) Old 06-04-2019, 05:42 AM
Richard Jemison
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Assembly

you should pattern the Ring & Pinion to insure correct engagement. Not so hard to do as the Transaxle should be assembled and torqued together properly. The ring geag can be removed from the right side to see results.

Pics & instructions of such can be found at Richmond Gear on the I-net.

Richard Jemison
RJR Racing

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Last edited by Alfar7; 06-04-2019 at 05:46 AM.
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post #9 of 22 (permalink) Old 06-09-2019, 10:57 AM Thread Starter
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Drive


Coast


Pinion


This seems to confirm the pinion length is excessive, do you agree?

Cheers,
Pedro
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post #10 of 22 (permalink) Old 06-10-2019, 07:13 AM
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Mesh

I agree. But I hope you didn`t do anything to alter lash. (carrier bearings)

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RJR Racing

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post #11 of 22 (permalink) Old 06-10-2019, 09:41 AM Thread Starter
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No, I didn't, and the backlash pattern looks good to me in fact.

Although let's be fair here I'm still at a loss as to why the pinion length would have changed.

I will measure the shim ring between the flange and 4th and either fabricate a new one or grind this one down...
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post #12 of 22 (permalink) Old 06-10-2019, 10:24 AM
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Flanges

DON~T do anything to the bearing flanges, reduce the shim collection behind the bearing.

Richard Jemison
RJR Racing

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post #13 of 22 (permalink) Old 06-11-2019, 02:14 AM Thread Starter
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No, I'm certainly not going to touch the bearing races. There is a shim ring but certainly not a "collection", there's only one thick shim.
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post #14 of 22 (permalink) Old 06-16-2019, 12:01 PM Thread Starter
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Ok so I've been shaving a few hundreds of mm from the shim ring. The target was to remove 0.082mm, I did it in three steps, first removed 0.03 then 0.06 and finally 0.09mm and patterned the ring gear each time to have a feel for how sensitive it is.

I don't have pictures of the first step, but the following is the -0.06 step:

Followed by the -0.09mm step:

power

coast


I can see it sits much better, not sure if I should remove a little more. What's your opinion?

I am still chasing the reasons as to why the assembly had grown in length but I don't think I will ever know.
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post #15 of 22 (permalink) Old 06-16-2019, 04:20 PM
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My apologies for coming late to this thread -- and late to the world of Alfa Romeos! My experience has been 23 years of service to another European marque's transmissions. My thoughts, please take with as many grains of salt as you wish.

Unfortunately the method of bluing will not give you meaningful results. The problem is that taking a pattern as you've done does not simulate how things will actually load up and center under engine load: with the engine pushing one way, the road forces and drive train friction pushing the other. These forces moves the contact center on the pinion and ring gear teeth. When properly measured by the factory (well, the ones I am familiar with) to minimize mechanical noise, the pinion depth is done in a rig that creates load.

Normally my experience has been that, barring particular circumstances, you do not need to measure and adjust pinion depth. The particular circumstances that would make it desirable to measure depth include changing the ring-and-pinion set, machining to the case, or of course some previous service that made a mistake in shimming (and that happens...).

Kudos to you for measuring with a CMM! I hope this is helpful and good luck with the project. It seems (from my brief acquaintance) that getting quiet running of Alfa pinions is a persistent problem.
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