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Old 05-26-2019, 06:00 PM   #1
Res731
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Default Measuring carrier bearing preload

I've been trying to measure the carrier preload using a variety of gaskets. It's not that easy determining the reading but with 3x10 gaskets I get around 10-12 in lbs. When i use 2x10 + 1x6 it reads around 20-22 but as I'm turning it seems the carrier grabs and the it jumps to 30+ is it better to be on the low side or get to the 20. Also could there be a reason for the drag or is that most likely technique? I made a tool based on the posting by H L Chavin made from PVC.

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Old 05-26-2019, 07:12 PM   #2
Synchro909
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Default Re: Measuring carrier bearing preload

I've just encountered the same thing. I opted for a lower setting and all seems to be well, not that I've done many miles since. I figured that there are plenty of cars running about with bearings that are too loose but none with bearings too tight. Besides, I have had to replace the pinion bearing in other club member's cars after someone set it too high.
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Old 05-26-2019, 07:49 PM   #3
Terry, NJ
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Default Re: Measuring carrier bearing preload

I did a rear last year and was advised to err on the side of loose/lower resistance. Much less chance of burning the bearings. I bought my gaskets separately and got a bigger selection. Rear ends are something I don't want to do twice! Buy your self an IR temp gun. It's the best thing for testing for heat. With an ambient temperature today of high 80s and a long uphill climb, I registered 110 F. Yes I still check now and then! I hope you went to at least a 3.54 ratio!
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Old 05-27-2019, 08:16 AM   #4
redmodelt
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Default Re: Measuring carrier bearing preload

I use what Tom Endy said; 18 INCH POUNDS with used bearings and 20 INCH POUNDS with new. Did you lube the bearings? If the bearing(s) are grabbing, could be false reading on your torque wrench or something is out of alignment. I trust you are not trying to use a clicker or 200/600 INCH POUND wrench. Can't do it with the first and almost impossible with the 200 or 600 INCH POUND wrenches.
Mine is a little lower then this one;
https://www.homedepot.com/p/Presa-1-...B&gclsrc=aw.ds
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Old 05-27-2019, 10:40 AM   #5
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Default Re: Measuring carrier bearing preload

There is a on-line tool company that caters to the bicycle trade, They sell a flexable beam torque wrench for reasonable $. Once you use it you'll have the FEEL. Likely only use it as a reminder years later.
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Old 05-27-2019, 11:39 AM   #6
Res731
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Default Re: Measuring carrier bearing preload

I'm using a beam style inch lbs torque wrench. For lubes I used some diff oil, I assume that's good enough.
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Old 06-01-2019, 06:28 PM   #7
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Default Re: Measuring carrier bearing preload

Success. I had made setup bearings to try to determine how many shins I would need. Didn't end up being a good solution as the number of shims I needed with new bearings vs the setup bearings was vastly different.

I got about 15 inch lbs torque while keeping .032 in paper gaskets.
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Old 06-05-2019, 09:33 PM   #8
Paul Bjarnason
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Default Re: Measuring carrier bearing preload

I agree with going to the low side of the pre-load setting. When I first set up my pinion pre-load I used 20 lbs like the manual says. But, it was too tight, as the bearing seemed to grab. I backed it off to 12 lbs and all is well -- well, until I start driving it! LOL Seriously, I think the greater danger to insufficient pre-load is in the carrier bearings, which I did set at the 20 lb pre-load and it seemed to take it OK.
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Old 06-05-2019, 11:53 PM   #9
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Default Re: Measuring carrier bearing preload

Are inch pound wrenches reliable these days? One friend was a rad lad engineer and tested all their torque wrenches. He found most quite accurate except for the inch pound ones. They were very inaccurate, according to him. I haven't tested mine. When I did my rear I was shown to put it together, stand the banjo up on an overdrive shaft tightened into my vice and get a grip in the side of the banjo and pull as a quick jerk. If correctly set it would rotate one complete rotation before stopping. It did and I put it in the car. Has worked fine for several years now. (That was per the late Alex Jenke, during a seminar he and Bob Grady did in Sacramento, many years back.)
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Old 06-06-2019, 09:15 AM   #10
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Default Re: Measuring carrier bearing preload

I use an older dial type Snap On torque wrench. I have it calibration checked once a year and it has stayed accurate since it was new in the early 80s. It measures torque equally well both ways.

The key thing with tapered rollers is to first eliminate all shake or play in the set. After that a person has to deal with the rolling torque and break away torque. Most of the ones I set up in the helicopter transmissions are around 11 in/lbs for rolling torque but they are a pretty big set of bearings. For an old banjo, you would be safe at anywhere from 10 to 20 in/lbs. They want the rolling torque higher on new bearings so that they will wear longer without becoming loose but there are limitations to the effectiveness of too much or too little. Too little and the set will loosen up more quickly in service. Too tight will cause overheating and possible damage to the rollers. If you set them at 15 in/lbs with not too high a break away torque, they should do just fine. After all, it's doubtful that most enthusiasts will ever reach the 100K after overhaul mileage mark on their pride and joy.

Surface hardening in the tapered rollers only penetrates so deep so a worn set of bearings will already be getting closer to the depth of hardness limits. This is why the used bearings have to be set up with less rolling torque. There life limitations are an unknown factor though even on a good looking set so keep that in mind when choosing to reuse old tapered roller sets.

Last edited by rotorwrench; 06-06-2019 at 09:21 AM.
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Old 06-06-2019, 10:12 AM   #11
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Default Re: Measuring carrier bearing preload

Quote:
Originally Posted by Res731 View Post
Success. I had made setup bearings to try to determine how many shins I would need. Didn't end up being a good solution as the number of shims I needed with new bearings vs the setup bearings was vastly different.

I got about 15 inch lbs torque while keeping .032 in paper gaskets.
This EXACTLY the reason for setting pre-load. To compensate for manufacturing inadequacies of bearing production.

Timken is good - probably the best - but not perfect. No human produced product ever is. Pre-loading gets past the humanity and brings it to the essence of what one is trying to achieve.

And why I doubted an earlier statement about bearing "replacements."

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Old 06-06-2019, 12:54 PM   #12
rotorwrench
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Default Re: Measuring carrier bearing preload

Timken tapered roller bearings were a design that could be used in a lot of applications and were very reliable as long as the design didn't overload the bearing sets. The old Hughes helicopters used them in there early design transmissions which are basically just 90 degree gear boxes for main and tail rotors. They had the limitations calculated to the T on the amount of torque load they could take and how long they would last in service with high torque loading.

The bearings are more precision than a lot of folks give them credit for. Even front wheel bearings are set up with a preload but not as much as a rear axle carrier has. It's just the way they are designed. If they weren't precision, they wouldn't turn with any amount of preload. Ford should have used metal shims for set up but the technology of the day gave way to paper. If you set them up on a fixture that holds the axle housing assembly vertically, you can assemble the axle & carrier assembly into the housing and install the remaining axle bell then measure the gap on the parting flange to find out where the shim thickness would be with no preload and then deduct shim thickness from there to get the preload. After a person has set a few of these up, you can get a good idea about where to start with shim gaskets and how much they compress during torque up.

New tapered bearing sets may not be as good as the old ones from Ford. Ford Timken sets usually had the Ford script on them. Now days it may even be that Timken bearings aren't the quality they used to be. We have to use something though so Timken it will be until proven to be unreliable.
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