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zambon
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Pinion Depth

Post by zambon »

I am trying to rebuild a Platinum transaxle right now. On disassembly, I discovered that the pinion shim was badly worn. I found some shims from the Nissan parts bin that are close to the correct size. The shaft of the pinion is 1.1735in on the spot that the shim rests. The original shim has an ID of 1.1840in. My new Nissan shim has an ID of 1.1915in.
Does anyone think my Nissan shim is too sloppy on the ID? I sort of think that it isnt so important, since the load is on the face of the shim.

Anyway, I have had the Nissan shim surface ground to a thickness of .081in. I arrived at this number by measuring the original shim and finding it to be .070in. I thought I would start on the large side, since I could always have more material removed.

The photos show the pattern on my ring after installation of the ground Nissan shim. I am not experienced with setting these up, but it looks to me like the pinion needs to go deeper into the ring, meaning that my .081in shim is too thin.
Please let me know what you think. Sorry for giving measurements in inches, I am dealing with American machinists and inches are what they prefer to talk about
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Re: Pinion Depth

Post by Mats »

I agree.

I also strongly suggest that you get shims that are ready made and not ground. If you grind the surface the hardening is lost and it will wear fast.

Get a set of shims so you can try different heights, but you are VERY close to the correct height so no huge steps needed. You do however need to torque everything down or you will get a different result in the end when everything has settled.
Also, when you move the pinion further towards the centre of the diff you will also move the pattern on the coast side...
To get everything "perfect" you need to set the backlash (crown gear height) too, BUT you should of course focus on the drive side.
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Re: Pinion Depth

Post by zambon »

Mats,
Thanks for the suggestions. I had the hardness of the original shim tested and it seemed to be made of the same material as the nissan shims I found. What I had not considered was the possibility that the original shim's wear had compromised its hardness. I suppose I should go back to trying to find some of the original shims. Not an easy task, unfortunately. At least the grinding of the Nissan shim has helped me get closer to the specification I will need.

As far as backlash goes, I didnt even realize that it could be adjusted in our transaxles. Is it done by machining a shim to go between the ring and the differential?

Thanks for the help,
James
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Re: Pinion Depth

Post by Mats »

Surely there are other shims available from somewhere? Original ones are probably very difficult to find but similar sizes must be present in almost all gearboxes?

The crown wheel height is changed by shimming the bearings for the diff... And you must change both otherwise you change the preload on the taper roller bearings (TRBs) and you don't want that.

Yes, it sucks! :)
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Re: Pinion Depth

Post by zambon »

Surely they are available somewhere...
I know of one well known racer who has told me he would sell me a single pinion shim for 80usd if he had one the right size.. He seemed reluctant to even let a single shim out of his collection go. It seemed a little expensive to me. It would be ok if I could get the correct shim first try though.
I would like to find a source that would sell me a collection of shims in different thicknesses. Our transaxles are built by ZF, right? Do you know any other cars from those days that used potentially similar ZF transmissions and differentials?

I didnt know that our differential bearings had shims. I was under the impression that they were in a fixed position and I thought backlash was not adjustable. Not exactly happy to learn that there is another layer to this setup. It seems like this transaxle might be more of a long term project than I had hoped. Time to test my other Platinum box and see if it has a better looking ring and pinion setup..
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Re: Pinion Depth

Post by Mats »

No-one builds hypoid gears or TRBs without shims, cylinrical gears and ball bearings can do without shims but that is modern FWD country... :?
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Re: Pinion Depth

Post by zambon »

I checked the pattern on my spare Platinum ring and pinion...

It looks to me like this pinion is set a little too deep. I am disappointed because I had hoped that it would look better. Both of my Platinum transaxles came out of working cars that I drove. I noticed nothing amiss with either of them (aside from worn out synchros). Is it common to find these things set poorly? It might explain why some people consider the ring and pinion to be a weakness in these cars.

Im working, once again, on sourcing some shims. If anyone knows a source that will sell to individuals (not manufacturing companies), please let me know.
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Re: Pinion Depth

Post by Mats »

That's the coast side. What does the drive side look like?
And by the way, the pattern looks spot on to me. :)
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Re: Pinion Depth

Post by zambon »

Top photo shows the drive side. It looks to me like the contact is a little close to the toe, though I could be wrong as i am not experienced. If it is too close to the toe, does that mean I should adjust backlash and/or move the pinion away from the center of the diff? (Not that I have any such capabilities without the correct shims).

Mats,
If you think that I am wrong and the drive side looks acceptable to you, please let me know. I would love to forget about all of this and just run it.
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Re: Pinion Depth

Post by Mats »

Top photo did't show yesterday actually... The forum seems a bit slow lately.

I agree, too close to the toe, I was looking at the coast side.
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Re: Pinion Depth

Post by zambon »

I read in an automotive technician text book that the pattern shifts when it is taken under load. When i marked my gears, I spun the pinion by hand without putting any load on it. I had been under the impression that adding a load would only make the pattern easier to read.
Based on the illustrations in the text book, I am thinking I might be able to run the spare transaxle. I think if I had applied resistance, the pattern on the drive side would shift away from the toe, toward the middle of the ring.

What do you think?
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Re: Pinion Depth

Post by Mats »

Yes, that's why I said the pattern on the coast side looked great (if it had been om the drive side).
We agree that the toe is the inner diameter, right? :)
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Re: Pinion Depth

Post by zambon »

Yes, we agree about the toe being the inner diameter.

Im planning to take the new synchros off of the other gear set and install them in the transaxle from the second set of photos. That will be the transaxle that goes back into my car. I will continue to fix the one with the worn shim at a later date. Hopefully i wont break the one I install and the spare wont be needed. My car has been out of service for several years at this point and I need to put it back together and enjoy owning it again.

Thanks for the backup Mats, I am sure I am going to be asking you for a lot more of it as I work on other areas this spring.
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Re: Pinion Depth

Post by Mats »

I'll be here...

I'm sure I won't be alone and we can all pitch in. :)
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Re: Pinion Depth

Post by gtv-racer »

I'm also correcting pignon depth. I have the same marks as this one shown earlyer in this thread. Only a little more to the teeth foot
Image

So pignon has to move to the engine. +/- 0.15mm .What bothers me is that if wear is the case it shoud move towards the crownwheel. This is the oposite direction...

Then i ask myself is this the way to go? engineers blue....? It was fine with current hp level :|
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