I am unclear on part of the shimming process. If you don't know off the top of your head, what I am looking at can be found in the FSM pg FA-24 at the bottom where the shim formulas are shown in two boxes. The top box: LOWER SHIM THICKNESS E E=D-3MM is self explanatory, it is the lower formula that I am unsure of. It reads: UPPER SHIM THICKNESS F F=C-E. Specifically I do not understand what "total shim adjusting thickness C" is or how to get it. Hopefully one of you will be able to help, I'm starting the rebuild tommorrow. Thanks in advance for any time and thought put into this question.
Clarification of knuckle shims please
- Thread starter Ryan S.
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I always just reuse the shims when doing a knuckle rebuild. Just make sure you keep them together and put them in the same place and you should be fine.
- Thread starter
- #3
Man Jerk said:
I wish that I was comfortable doing that, it would save me money and worry. The thing is that if I just put the shims back, I am assuming that they were correct in the first place. I don't know if they have ever been redone, but I do know that the PO always took it to a different (cheapest) mech. for repairs and many of the repairs were done incorrectly and band-aided to get by. I bought the centering tool so that I could know that this time there would be no question as to whether or not it was done right. The other thing is that I'm a newbie mechanic and don't understand some things completely, but this board is helping immensely. Thanks for your input, and sorry to make a short story long.
I would put back in the shims in the same spots and then after you get the bolts tight on top and bottom you use a fish scale to check the preload.Then you will know if it is good or not. Been awhile since I have done it but there are some writeup on here.
Here is one.
https://forum.ih8mud.com/showthread.php?t=14336
Morgan's writeup helped me.
http://www.birfield.com/~morgan/tech/axle/index.html
Here is one.
https://forum.ih8mud.com/showthread.php?t=14336
Morgan's writeup helped me.
http://www.birfield.com/~morgan/tech/axle/index.html
Ryan, since you have the manual, I won't have to post pics so you can follow this as I call out "figure #'s" i.e. "6-33" ...all right?
OK, so you have your "E" measurement, good. This gives you your lower shim thickness. E = D minus 3mm.
Now let's get your upper shim thickness "F". For that, first you need your "C" measurement. As follows:
C = A minus B
For "A" See "6-34". A = the distance between the the two adapters (top and bottom), see the illustration of the caliper with reference to the adapters.
For "B" See "6'35". B = the outside dimension of the knuckle housing as measured with the same caliper, and parallel to trunion openings.
The difference in measuremen A minus B is your C.
Now take your measurment for C and subtract it from E (which you have) and you now have "F". F = C minus E.
"F" is your upper shim thickness.
.
OK, so you have your "E" measurement, good. This gives you your lower shim thickness. E = D minus 3mm.
Now let's get your upper shim thickness "F". For that, first you need your "C" measurement. As follows:
C = A minus B
For "A" See "6-34". A = the distance between the the two adapters (top and bottom), see the illustration of the caliper with reference to the adapters.
For "B" See "6'35". B = the outside dimension of the knuckle housing as measured with the same caliper, and parallel to trunion openings.
The difference in measuremen A minus B is your C.
Now take your measurment for C and subtract it from E (which you have) and you now have "F". F = C minus E.
"F" is your upper shim thickness.
.
With these results, you then mix and match the thicknesses, however many you need (the lower box with shim sizes) to equal the measurements you obtained for the upper and lower.
E = x number and variety of shims equal to your "E" measurment.
F = y number and variety of shims equal to your "F" measurment.
.
E = x number and variety of shims equal to your "E" measurment.
F = y number and variety of shims equal to your "F" measurment.
.
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- Thread starter
- #7
JWEST, thanks for the info. It's exactly what I needed. Now that I see where it came from, I should've been able to figure it out.
Ryan, you will still need to check with a fish scale as it's hard to measure 1/10mm with a caliper by eye! I found that I needed to add a bit to get the preload right.
- Thread starter
- #9
cruiser_guy said:
I'll be sure to scale everything that the FSM says to, I just have to go get a scale tonight. BTW, I checked out your frame replacement pics today. Nice!
Yes. Good luck and take your measurments and preloads carefully.
We're all pretty much in agreement that if you replaced your shims exactly as before, you should be ok. But, I know you want to get it right, and I think you bought the tool since you weren't certain if it was done correctly before?
Anyway, keep the shims in order as you do the job and use them as a gauge to compare your calculations. It should be in the ballpark.
.
We're all pretty much in agreement that if you replaced your shims exactly as before, you should be ok. But, I know you want to get it right, and I think you bought the tool since you weren't certain if it was done correctly before?
Anyway, keep the shims in order as you do the job and use them as a gauge to compare your calculations. It should be in the ballpark.
.
Your formula was correct. I used to bolt up the swivel hubs with new bearings and no shims. Then measure the longitudal movement with a dial indicator. This was a very long drawn out process and it was also years and many swivel hub rebuilds ago. I find the easiest way is to put 3mm in the top. start with around 2 mm in the bottom. bolt up the locators and turn the knuckle. Simple formula, The knuckle must turn freely from lock to lock with a simple push and must not have any lateral movement. The knuckle bearings simply carry the weight. they need NO preload or they can seize. They will operate for many years with slightly too much clearance, so if you have to, er on the loose side rather than tight. This comes from 14 years of experience as a mechanic and countless swivel hub rebuilds. For a first timer i recommend doing it the right way until you're comfortable. Cheers. Dan
- Thread starter
- #12
Faaaaaaaaaawwwwwwwwkkkkkk! Read my new thread
Been a while since I read the FSM, so please bear with.
So after you install the shims, wouldn't you be able to use the measuring tool to verify proper alignment? Couldn't you go through the procedure again, only this time the pointer would scribe the same (center) line on the shaft from both the axle housing & the outer knuckle?
So after you install the shims, wouldn't you be able to use the measuring tool to verify proper alignment? Couldn't you go through the procedure again, only this time the pointer would scribe the same (center) line on the shaft from both the axle housing & the outer knuckle?
Tinker said:
In theory it should, but in practise I don't believe the pointer will scribe the exact line on both.
When determining the shim thicknesses, Toyota has worked out a 3mm substraction (E = D minus 3mm) in the bottom thickness and shifted that to the top as the "final" running tolerance. Same "total shim thickness" but a difference in distribution from top and bottom. Perhaps due to greater weight being placed on the top bearing and subsequently "settling in".
In re-measuring for verification (shims added), you might then see this 3mm differential as the difference in the two scribed lines, one for the housing and the other on the knuckle.
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