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08-02-2021, 04:02 PM | #1 |
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Pinion Bearing Preload
I plan on putting in a Mitchell Overdrive unit in my 30 Coupe. I'm on a waiting list to get the unit, so in the meantime I'm stocking up on tools to do the job by myself. Just got a pinion gear puller and installer from Synder's, and when I looked at the instructions I was surprised to see that the puller was also manufactured by Michell Manufacturing. Instructions for the use of the puller said to remove the two large pinion bearing nuts after carefully dimple punching the inner nut to mark its location relative to the keyed slot. Then take off the nuts to install a backing plate. This would destroy the preload for the bearing. Other instructions I have seen regarding the driveline say to remove the pion gear and bearing nuts as a unit so as NOT to destroy the preload. Question is, can the preload be accurately reset by the punched dot method or is it better to remove the unit as an assembly without affecting the preload. Since preload can also be reset using a torque wrench, is it really that sensitive? What's best, keep original preload, use the punch point technique, or use a torque wrench. I'm just a shade tree.
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08-02-2021, 04:24 PM | #2 |
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Re: Pinion Bearing Preload
The center punch idea would not be repeatable. You are right taking the nuts loose and destroys the preload. You could estimate the prelode
. A tool is available from mitchel to remove as a unit. Then you keep your prelode. They might rent it orsell it John
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08-02-2021, 04:53 PM | #3 |
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Re: Pinion Bearing Preload
Bearings should not be preloaded at room temperature because they need some play for thermal expansion, just like a wheel bearing.
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08-02-2021, 06:09 PM | #4 |
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Re: Pinion Bearing Preload
One method is to check the preload with an inch pound wrench on the end of the dr. shaft before removing the nuts. Then reset with the same wrench as recommended in publications to 20 inch pounds or hopefully the same value as before removal. There is an article on the Santa Anita A's website for od's.
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08-02-2021, 06:18 PM | #5 |
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Re: Pinion Bearing Preload
Can we assume that you are talking about removing the pinion assembly from the banjo and not removing the pinion from the drive shaft?
If so instead of removing the preload nuts I used a 1 1/8"split collar clamped to the drive shaft with the Mitchell Puller you have. Steve shipped me the puller with the O/D unit. https://www.mcmaster.com/catalog/127/1344 Last edited by Y-Blockhead; 08-02-2021 at 06:24 PM. |
08-02-2021, 07:20 PM | #6 |
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Re: Pinion Bearing Preload
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08-02-2021, 07:49 PM | #7 |
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Re: Pinion Bearing Preload
Watch this carefully and then be sure to follow Mitchell’s instructions carefully.
https://m.youtube.com/watch?v=fKRHYlwR7eU |
08-03-2021, 12:52 AM | #8 |
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Re: Pinion Bearing Preload
You really cant use a torque wrench to check pre load, you need a continuous read type, like an inch pound beam torque wrench. Without going back to my notes, I beleave it is 18 inch pounds.
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08-03-2021, 10:19 AM | #9 |
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Re: Pinion Bearing Preload
GPierce: Thanks for the video. Very good.
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08-03-2021, 10:32 AM | #10 |
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Re: Pinion Bearing Preload
My 1935 Motors Manual says you should feel a light drag on used bearings and a heavy drag on new bearings. I would not remove the nuts, but if no drag is felt, I would tighten them just enough to get a slight drag. Keep in mind the outer nut will change the drag when it is tightened. these rear ends do not require a rocket scientist to work on them.
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08-03-2021, 11:19 PM | #11 | |
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Re: Pinion Bearing Preload
Quote:
Last edited by marc silva; 08-03-2021 at 11:26 PM. |
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08-04-2021, 10:29 AM | #12 |
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Re: Pinion Bearing Preload
Marc, ya done good!
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08-06-2021, 10:05 AM | #13 |
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Re: Pinion Bearing Preload
You could send your puller back. The Mitchell comes with one. I would also just do it according to the instructions how ever on reassembly I would just reset the preload. It's not that hard and only adds a little time to the project.
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08-06-2021, 10:12 AM | #14 | |
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Re: Pinion Bearing Preload
Quote:
As has been said and repeated; It's not rocket science. |
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08-06-2021, 10:15 AM | #15 |
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Re: Pinion Bearing Preload
This is incorrect. These are not wheel bearings. They need to hold the gears perfectly with no play. Keep in mind that thermal expansion also cause the housing and shaft to grow and lenghten.
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08-06-2021, 06:16 PM | #16 |
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Re: Pinion Bearing Preload
One thing that is not mentioned is what was the preload before disassembly? I have seen some that had almost zero preload.
The 20 inch pounds recommended is for new bearings, that will wear in. I shoot for about 5 inch pounds with used bearings, as they are worn in to each other. This is easily checked with a beam style torque wrench, but the shaft needs to be vertical to be accurate. Contrary to posts above, the puller does not come with the OD Unit.
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08-06-2021, 07:16 PM | #17 |
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Re: Pinion Bearing Preload
There is an excellent article about rebuilding a rear axle in the Jan-Feb 1995 Restorer magazine "Model A Ford Rear Axle Adjustment", starting on Page 10. I highly recommend reading this article. I used this method on my car and it worked well.
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08-06-2021, 07:44 PM | #18 | |
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Re: Pinion Bearing Preload
Quote:
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08-06-2021, 09:05 PM | #19 |
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Re: Pinion Bearing Preload
go to santaanitaas.org it has the best pictures and instructions on the scroll down to preload on the pinion. Bearings are precision don't take a chance with someone telling you to just guess at it these old cars were built to higher standards than most think thats why so many are still running on the roads. the old punch mark is a hit and most times mis as you are setting by sight not torque. going to the trouble you are it just takes a little more time to do it right. as for taking it out as a unit I can't see it being done as the pnion has to have one timken bearing install and slide from inside housing and the the outboard bearing is put on and it can't go through to the inside of the housing. thats when you torque them together.
So don't try it or you will bust the ring out of the housing that holds all together. Just my two cents for what it's worth it I've seen and heard so much mis information on this I had to reply Jim IHS
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