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Hub shims

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prmac

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Hello again from the Great White North.
I have a 1976 MGB with wire wheels. I am changing my wheel bearings and am having to shim it up to adjust the play, however, looking at three different diagrams I am having a hard time deciphering exactly where they should go. I'm in rural Northen Ontario so a mechanic with proper tools is probably a hundred miles away if I was lucky.
Can someone walk me through the placement of these shims?
Thanks and I hope it's warmer where you are than here-6 degrees C- 42 Farenheit-Brrrr.
Thanks.
Paul
 
Goodgawd, man!! Get outta there!!!
 
Why, Doc?
 
Rural northern Ontario? He's got about three days of "summer" a year!

And they're <span style="font-style: italic">over</span> now. :jester:
 
Oh, I thought you were talking about the artice on my web site....
 
*swoon*

:smirk:
 
I read it awhile ago and did a re-read just now. I really need to check the front of my '63 to be safe and while I'm at it check the '74 again. I have a slight shimmy, left to right over bumps, on the '74 and I am not happy with it.
 
Guess old John Weimer & I have 'wrong' wheel bearings....to shim or not to shim, that is the qwuestion...MGB over engineered everything; John Twist is correct in utting them back in to continue to over engineering...as he said in his article "use them if you must, but you don't have to"....I rarely use them & haven't seen any problems.
 
John Twist never said they are there because of over-engineering. He maintains that they are necessary and he is correct (as noted in the video linked above). Yes, you can run without them and most likely have no problems. The spindles on an MGB are quite strong for the load they carry. Then again you can leave a lot of things off the car and in most cases be fine, but that doesn't mean it's the best way to go about it.

Hub shims serve many purposes, some of which are:

- Eliminate bearing end float, which extends the life of the bearings.
- Eliminate wheel wobble, which reduces vibration and increases steering response.
- Allows proper torque on the hub securing nut, versus finger tight without shims.
- Secures inner seal spacer, which prevents the spacer from spinning and wearing into the spindle, as well as allowing leaks.
- Places the entire hub assembly in compression, which in turn places the spindle under tension, and this substantially strengthens the unit as a whole.
- Prevents the inner bearing cage from spinning on the spindles, causing wear.

There is no way to reach the factory specified torque on the hub securing nut without the shims. In fact, if you put any tension at all on the nut without the correct number of shims in place, the bearings will be crushed. Finger tight is not how you want a fastener designed to hold the entire hub assembly in place!

The engineers at M.G. were very experienced and very clever people. They kept spacing shims in the hubs for the entire 18-year production run. Considering how cheap the penny pinchers of BMC and especially BL were, it says a lot that they continued to install these "extra" parts and pay for the labor to set them up when they could have saved so much money by eliminating them from the design.
 
Not gonna try to dissuade you, Steve...just know I've torqued the hub to the correct amount & nev er had bearing failure or any other type failure without the little shims in place.

But, I am going to disagree with some of your points:

"Eliminate wheel wobble, which reduces vibration and increases steering response"....properly trorqued with or without the shims, the shims play no part in that.

"Allows proper torque on the hub securing nut, versus finger tight without shims."...as I said, you can torque properly with or without shims.

"Secures inner seal spacer, which prevents the spacer from spinning and wearing into the spindle, as well as allowing leaks." Can't see how shims that are smaller in diameter than the greased surface will stop leakr...& have never ever seen a spacer wear into a spindle.

"Places the entire hub assembly in compression, which in turn places the spindle under tension, and this substantially strengthens the unit as a whole." Compression can be reached with or without the spacers; plus, they alone provide no strengthening...it is the correct torque that provides the oneness & strengthening.

But, I'm not going to change your mind & you're not going to change mine...if I have spacers available, I use them...if not, I don't worry about them.
 
Tony, with due respect you aren't quite grasping how this type of hub assembly works. Let me address you arguments...

<span style="font-style: italic">"...the shims play no part in that."</span>
- Sure they do. The shims are there partly to control end float. The more end float exists in the bearing assembly, the more the wheel can move not only laterally but in every axis. This can accentuate any wheel balance imperfection (especially oscillation) and increase vibration. The effect is minimal for sure, but I see no reason to leave "slop" in the wheel assembly unnecessarily.

<span style="font-style: italic">"you can torque properly with or without shims"</span>
- Absolutely not! If you run without shims and then torque the hub nut to 70 lbs/ft then you will have a seized bearing, and possibly a damaged (brinelled) race. The only way to avoid this is to increase the width of the spacer until the bearings are no longer being smashed into the races. This is precisely what the shims do.

<span style="font-style: italic">"Can't see how shims that are smaller in diameter than the greased surface will stop leak"</span>
- I didn't mean that the shims themselves make a seal. I was referring to the seal spacer (for the inner grease seal), which if left by itself will rotate with the hub and wear into the base of the spindle. The farther it wears, the sharper the groove becomes, which greatly increases the risk of cracking. It can also result in an increased spacer to spindle tolerance would increase chances of leaks. Fortunately, as noted, MGB spindles are quite strong even when damaged.

<span style="font-style: italic">"Compression can be reached with or without the spacers"</span>
- No, it cannot! If the spacing shims are left out then the best you can do is create tension on the spindle. But... if the spindle is under tension without spacing shims in place in the outer assembly then you are putting pressure on the bearings instead of on the spacer and surrounding components. It is physically impossible to place the outer assembly in compression without enough bearing spacing.

The bottom line is that you cannot achieve correct end float without the proper amount of spacing between the wheel bearings. The large spacer is intentionally narrower than needed to allow for adjustment in the way of shims, which sets the bearing end float within a given torque range.

<span style="font-style: italic">...just know I've torqued the hub to the correct amount & nev er had bearing failure or any other type failure without the little shims in place.</span>
I believe you, but that isn't an argument to not use shims. I've never seen a lot of things but that doesn't mean they won't happen tomorrow! What I <span style="font-style: italic">have</span> seen is multiple instances of the type of damage I explained above on MGBs that did not have their bearing end float adjusted properly.

Sorry for the long post, and no ill will intended or anything. I only mean to present the facts. I simply become concerned when I see people being advised to leave parts out of safety-critical components. I still agree that these spindles are very strong and are unlikely to fail, but I also see no reason to take any chances when the parts in question cost $1.00 per wheel and take 10 minutes each to install.
 
Steve...no disrespect intended - but neither of us is gonna budge on this issue so to me let's just call it a dead horse....

However, I've been driving MG's since I was 16 (I'm 63 now) & have probably owned close to 100 MG's over the years & have been building them since I was a teen....& the first thing I do to an MG is go through all the systems before putting one on the road....sometimes I use shims, most times I don't because they're not there....plus, I've disassembled probably another 100 or so cars.....& I've never, ever had a problem with one of my cars nor have I ever seen evidence of problems with all the cars I've parted out...so, thanks for the long diatribe...maybe it'll help somebody else make up their mind about how their cars go together.
 
All I can say is that I've researched this thoroughly. Everything I posted above can be verified by numerous automotive experts and engineers. I'd rather leave personal opinion for non safety-critical issues. I can also link to several discussions on the use of shims on other discussion forums for anyone interested. Photos of the issues I mentioned above can be found in said discussion threads.

And yes, I've been driving MGs since I was 16 also! Still have that first one. :wink:
 
I declare a truce. You both have made some good points - and I've been driving British cars since before I was born - mom thought I was kicking, but I was actually shifting! LOL! (Ok, not really).

My 2 cents, for what it is worth is this: speaking only for myself, if I have a choice of doing something (especially dealing with safety) by the book or doing it some other way, I'll <span style="text-decoration: underline">probably</span> choose the by-the-book method just to be on the safe side. While experience is certainly a valid teacher, doing something by the factory procedure, unless it has been proven absolutely wrong or dangerous, is usually a reasonable approach to take in my humble (but admittedly non-expert) opinion.
 
Hey Guys,
Thanks for the help. Sometimes I do think about getting out of here, but soon the land will be afire with red and orange of Autumn leaves and I love it all again here in the great White North.
Still having problems, I torqued one side with the shims and one without (for no other reason than lack of enough shims). The without keeps loosening and the with shims, well the castle nut stripped so it's going to take a week for the dog sled to get parts here. The side with the shims coned them so I will have to check the end of the spacer to make sure it isn't damaged. Too bad I was planning on going down to Watkins Glen to see the B's, midgets, etc. and other Brits in action.
Looking at the video, makes me almost wish I didn't have wire wheels as the nutting up is a bit harder, especially since one hub doesn't have the drill hole for the cotter pin.
I'll keep watching for any new advice an am putting up a new Thread about my Wedge Master Cylendar Reservoir.
Again, Thanks for the help and be nice.
Paul
 
prmac said:
especially since one hub doesn't have the drill hole for the cotter pin.
Click to expand...

Are ya sure it isn't cleverly disguised as grease with a rust patina? I've seen 'em plugged like that and WELL camouflaged. Dig around there. I've never seen a wire hub without that access.
 
On a wire wheel car i normally whack my thin wall 1 5/16 socket and extension right over the cotter pin and remove the nut. Then take a small drift and remove the remaining part of the pin. You really have to look for the cotter when you do it that way. Maybe its still in there? Bob
 
OOPs correction! The 1 5/16 thin wall is for the rear ww hubs on a later style diff. I do the fronts as discribed above only with a smaller socket! Bob
 
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