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Rear wheel bearing preload


240ZMan

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I'm installing a rear wheel bearing on my '73 240 and have it all back together. I made sure both the outer bearing is all the way down on the axle stub, and the inner bearing is all the way in against the lip inside the hub. When I apply 150 lb-ft of torque to the lock nut (the max my torque wrench can measure) the effort to turn the flange at the wheel bolt is so high I can barely move it with one hand. If I back the lock nut off so it's almost loose it moves with no significant resistance.

I made sure to put the spacer/sleeve on between the bearings.

The Haynes manual says to start with 180 lbft and go up from there. I'm not even close.

Any suggestions?

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Within a week or two, I'll be doing this same job (putting back together after painting this weekend). So I've been thinking about it. The inner wheel bearing is easy to tell if it is seated or not, since you install it before you put the axle in. You can look at it from the wheel side, and see if it is up against the inner flange. No worries.

But I have been wondering about the outer bearing. Even if it is seated perfectly on the shaft, you then have to force the outer edge of the race into the interference fit inside the hub. And there isn't any way to see if it is completely seated. I really don't think that the torque on the shaft nut will pull it into place - like the other bearing races, I'd bet it has to be "pounded" into place with an appropriate drift or bearing installer. Or in this case, I guess you'd have to pound on the outside of the axle plate to seat that outer bearing.

If the outer bearing isn't seated completely into the hub, as you tighten the nut, the inner bearing race (of the outer bearing) would be pulled inward toward the distance piece (it won't be against the distance piece, since we're assuming it isn't completely seated in the hub), and would then bind the outer bearings. That's what I expect is happening to you (just an educated guess). So, how did you install the outer bearing/axle into the hub? Were you depending on the shaft nut to pull the outer bearing into place? I don't know that that won't work, but I doubt it.

Any more experienced opinions?

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Mark, you're thinking along the same lines as I am. After sleeping on it I'm sure the issue has to be that one of the bearings isn't seated properly. I made sure by looking through the hub that the inner was all the way seated. As you point out, there isn't any way to confirm the outer is seated. However, the whole axle stub assy slid in easier than I thought it would. To get it in the last bit I used a mallet on the wheel flange and heard the sound change when I thought the outer bearing had been seated. I hit it a few more times for "good measure".

At this point I guess I'll have to pull it out and try again tonight. Perhaps it just needs a few tries?

Still looking to hear from others who have done this job before.

Thanks.

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Found the problem: although I had driven the seal about 2 mm beyond the edge of the hub, I guess the inner flange was rubbing on it a little when I fully torqued it down. I pulled everything out, drove the seal further in, and all is well.

It had been a week since I pulled the old one out and I didn't remember how far in it had been. And the FSB and Haynes manuals don't say how far to drive it in either. Now I know :)

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Found the problem: although I had driven the seal about 2 mm beyond the edge of the hub, I guess the inner flange was rubbing on it a little when I fully torqued it down. I pulled everything out, drove the seal further in, and all is well.

It had been a week since I pulled the old one out and I didn't remember how far in it had been. And the FSB and Haynes manuals don't say how far to drive it in either. Now I know :)

Cool. Now I know what to look for when I put mine back together! Painting starts tonight!

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Good luck Mark, I will say that of the many projects/fixes/rebuilds I've done on my Z so far, this was by far the least-fun. I don't like pounding on hard-to-get parts that are supposed to operate precisely, and can cause really bad things to happen if they fail.

With luck I won't be doing this one again.

Daniel

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Good luck Mark, I will say that of the many projects/fixes/rebuilds I've done on my Z so far, this was by far the least-fun. I don't like pounding on hard-to-get parts that are supposed to operate precisely, and can cause really bad things to happen if they fail.

With luck I won't be doing this one again.

Daniel

Thanks Daniel. This rebuild on my 280Z is kind of a "practice" for what I hope will be an even better rebuild on my 240Z later. Already did a couple things on the 280 that I will remember NOT to do on the 240! :eek: Hopefully the synthetic grease, all new Nissan parts, etc will make this the last time on this car at least for me!

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Thanks Daniel. This rebuild on my 280Z is kind of a "practice" for what I hope will be an even better rebuild on my 240Z later. Already did a couple things on the 280 that I will remember NOT to do on the 240! :eek: Hopefully the synthetic grease, all new Nissan parts, etc will make this the last time on this car at least for me!

This situation reminds me of my rear suspension rebuild. I put the new seals and bearings in and torqued the nuts. One of them turned freely and the other was bound up. I thought about it and then checked the workbench... Bingo! There was the inner spacer still on the bench. Ouch! I took it apart and re-installed the spacer and guess what, no more friction. I guess you just cannot put these things together w/o double checking EVERYTHING! Funny things happen when you get tired. (Glad I checked the freeplay!) :finger:

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Another question on the rebuild. Can someone post a picture of the "B" mark on the hub that correspondes to the "B" mark on the spacer? Any help would be great.

Thanks,

Skip

I hadn't posted this before because Bambikiller has a similar pic in another thread, but I suppose it can't hurt to have it in two places. This is from a '78 280Z, but it looks pretty much like the one Bambi posted off a 240Z.

post-4028-14150795427066_thumb.jpg

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Marks pic of his clean hub shows it very well.

Yeah, the marks are fairly shallow in depth, so it doesn't take much paint, rust, dirt, or whatever to obscure the mark. I had to spray my spare hub with penetrating oil and apply a brush to remove debris in order to find the mark on mine.

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  • 2 weeks later...

and what is the significance of this B mark? I haven't seen it referenced in my Clymer manual, and haven't really looked at the haynes yet, but I too am in the disassembly stage right now, and trying to save any future headaches.

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and what is the significance of this B mark? I haven't seen it referenced in my Clymer manual, and haven't really looked at the haynes yet, but I too am in the disassembly stage right now, and trying to save any future headaches.

The letter marking (A, B, C) on the outside of the hub needs to match the letter marking on the "distance piece" that goes inside the hub between the inner and outer wheel bearings. There are other threads that have more detail on this:

http://www.classiczcars.com/forums/showthread.php?t=14450&highlight=distance+piece

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I decided to take my rear assembly to a shop to pull the stub axles and bearings so I wouldn't mess them up without a press to and slide hammer to disassemble them. The bozo at the shop stripped the stub axles, where that crimped nut is. I don't know how, but he stripped about 1/2" of thread on one and 3/4" on the other.

Good thing I have another set on the car right now. Like they always say, if you want it done right, do it yourself. I am so po'd right now, plus they still charged me $40!!!!

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I decided to replace the rear wheel bearings on my 78 280 in an attempt to solve a grinding noise - bingo, one of the bearings nearly locks up when I test it. I'm fairly certain that rust flakes caused the bearings to go bad as the cavity between the inner and outer bearings had a small pile of rust in it. So: how should I prevent rust from forming in there again before I reassemble everything? I have some POR but I can't find anything about high temp situations. I'm also thinking of just filling up the entire cavity with grease to match the new grease in the bearings. Any thoughts? Also, any thoughts about using the electrolitic rust removal process to clean up some of the pieces (axle stub, intermediate piece btwn half-shaft and stub nut)?

Cheers!

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