Knuckle Shims:Still have questions...

[JLH911]

I've done a search and read up on this subject, but I still have doubts/questions.


When I took apart my knuckles, I had two shims on the top (thin and thicker) and then only one on the bottom.

I assumed this was correct, but after reading the forums, I noticed some say it should be the other way around.

I do not have the SST to do this properly. I know the new kits come with new shims, but how do we know if we should use them and in what combination. I heard all the shims in the new kit are of the same thickness.

I'm not replacing the birfs or knuckle housings.

If I put it back the way it was, how do I know that isn't what caused the axle seals to leak?

Does checking the preload with the fish scale assure that it's correct?

Thanks.


Btw, sorry about all the questions, but I want to make sure I get this right and btw, I'll be using the Marlin seals.

 

[Joshua993]

I may not be able to answer your question exactly, but I can weigh in. When I rebuilt my knuckles, I put mine on exactly as they came off, and it was 1 thick, 1 thin on top, and one on the bottom that was slightly thicker than the thin one on top. Using the fish scale, I was able to verify that everything was the way it should be after reassembly and proper torquing. I didn't have the SST for the job either. I do not believe that shim arrangement will contribute to axle seal wear, so much as it will knuckle bearing wear. So, my advice would be to put it back the way it came apart - it should be correct.

 

[Dynosoar]

Put the old ones back on the same way they came off. Dont use the new ones.


Dynosoar

 

[Rigger]

Put the old ones back on the same way they came off. Dont use the new ones.

X2. It worked for me.

 

[tonyota]

I always put the old ones back in also. I use the fish scale just for grins & giggles...It always comes out within spec. Shims won't cause axle seals to wear out, in my experience. Don't over think it, it just makes it harder.

 

[Mr. Toad]

. . . I didn't have the SST for the job either. I do not believe that shim arrangement will contribute to axle seal wear, so much as it will knuckle bearing wear. So, my advice would be to put it back the way it came apart - it should be correct.

The advice is right: if you're using the same knuckle and axle housing, re-use the shims as you found them.

I also agree that improper pre-load can cause premature knuckle bearing wear. However, using the wrong shims will cause the seal to leak because the axle-shaft will not be centered in the seal. It may not leak right away, but the seal will leak if you use the wrong shims. (FWIW, the Marlin axle seals are advertised to be much more forgiving of eccentric axle shafts -- I'm testing some now)

 

[tonyota]

The advice is right: if you're using the same knuckle and axle housing, re-use the shims as you found them.

I also agree that improper pre-load can cause premature knuckle bearing wear. However, using the wrong shims will cause the seal to leak because the axle-shaft will not be centered in the seal. It may not leak right away, but the seal will leak if you use the wrong shims. (FWIW, the Marlin axle seals are advertised to be much more forgiving of eccentric axle shafts -- I'm testing some now)

HMMMMMM. Makes sense when you put it that way, just never seen it for myself. I also have Marlins axle seals in my wheelin rig now (goin on 2 years & no problems)

 

[coolotisdog]

I just did my knuckles, and I did not use the stock shims only because the bearings that came with the kit I ordered were not the same as stock knuckle bearings. I used the shims that came with the wheel and knuckle bearing kit. I can't really say if it makes much difference right now, maybe in a couple months I can have more feedback. That was just my logic anyway.

 

[MANUCHAO]

I did just what Dynosar stated... BUT the shims on your knuckles looked shot for what I remember....
Other than Coolotisdog has any body else used the new shims that come with the new kit and what have the results been ???

I would imagine if you measure the thickness of both shims (old) with a vernier caliper and use that as a guide for the new ones you should be ok...
Im glad my shims were in really good shape when I pull them apart so that made the decision pretty easy...

Hope other chime in this subject....

 

[JLH911]

Yeah, they do look shot, but I think that's just caked on grease. I'm going to try cleaning them up when I get the chance. Only smooth metal should show after I get done. We'll see.

If they are shot, I guess I'll order some exact ones like the old ones, that is if Cdan carries them.

I did just what Dynosar stated... BUT the shims on your knuckles looked shot for what I remember....
Other than Coolotisdog has any body else used the new shims that come with the new kit and what have the results been ???

I would imagine if you measure the thickness of both shims (old) with a vernier caliper and use that as a guide for the new ones you should be ok...
Im glad my shims were in really good shape when I pull them apart so that made the decision pretty easy...

Hope other chime in this subject....

 

[JLH911]

I always put the old ones back in also. I use the fish scale just for grins & giggles...It always comes out within spec. Shims won't cause axle seals to wear out, in my experience. Don't over think it, it just makes it harder.

From what I read, the shims do affect how the axle fits within the seal. In other words, they are supposed center it(when done correctly) so that there isn't to much pressure in any one spot.

Who knows...


Edit: DOH! just saw Mr. Toads response about how the shims do affect centering of the axle.

 

[esh]

If you are really worried, go buy the tool and take the time to put together a knuckle to spec.

I put priority on proper pre-load. It can affect road behavior (safety). On the other hand, I have seen knuckles with many 10s of thousands of miles on them that had obviously been leaking for a long time- I have owned some and wheeled them (not gently) before I knew better. This is a regular pattern in new owners from my experience and it usually results in appreciation when pointed out.

 

[Joshua993]

However, using the wrong shims will cause the seal to leak because the axle-shaft will not be centered in the seal. It may not leak right away, but the seal will leak if you use the wrong shims.

I can see that I reckon. I wonder how far off on the shims you would have to be for it to happen... This is it - that point in time my physics and math teachers told me about, when it would all come in handy...

 

[3pits]

so how do you increase the preload?

 

[Cruiserdrew]

so how do you increase the preload?

You take out shim thickness.


I finally broke down and got an OEM knucle tool. It makes all the difference. You really can center the axle in the housing and get the preload right in one move. I got the preload right on the first try and could not believe it. It really works.

There are old rules of thumb that I have used before with success. Like One thick and one thin shim top and bottom will get you close most of the time. If preload is low, take out the thin on top and recheck.

I would try and center the axle first, then worry about the preload. Toyota got smart with the later Curisers-on the 80 series it runs no shims on the bottom, so you don't need an SST and you just add or subtract the top shims to get the preload you want. It's a much easier design to work with.

 

[ntsqd]

Prior to seeing what the SST looked like I had thought to build a tool that looks like the attached pic. Set the pre-load & measure the total shim stack height. Then while keeping that constant adjust the shims until the pin pilots in the seal bore and the disc pilots in the spindle register.

 

[3pits]

I am in the middle of a rebuild and my preload is at 6.25, I have one shim on the bottom that is 1mm, and of the two on top, one on top that is 1mm and one is .3mm I feel my preload is too low, I dont have the SST. I dont think I am the first one in this knuckle, so the PO may have put in the wrong shims.

From the thread link for the sst above there is a link to a pdf, in that document is says there are only 2 shims for this, a .5 and a .2. The kit I got from CO has 4 .5s 2 .2s and 1 .4,,,, ya think I should put the .5 and .2 in the top and the .4 in the bottom,, I probably have a .4 somewhere in my pile,,,but I have read pinhead says it should be about 1mm on the bottom,,,, which is what was there

so I would be going from 1.3 on top to .7 ish...

and I have searched my arse off and over read this stuff until I am crosseyed, I am shooting for somewhere between 6 and 12# of preload?? on an 88 62

 

[esh]

and I have searched my arse off and over read this stuff until I am crosseyed, I am shooting for somewhere between 6 and 12# of preload?? on an 88 62

Just like you found, there are more than two shim thicknesses. The cool sets have it marked.

Unless you have a tool to measure, I would follow the "leave what was in the bottom" (if it's in good shape) theory. Adjust the top to preload specs. If you are running Marlin inner seals you have that much more buffer for lack of having a centering tool. It is an excellent product.

Technically 6.25 is within Toyota's spec. From what it sounds like, replacing the .3 with the .2 will do ya.

 

[3pits]

i went with 1 mm on bottom and the .5 and .2 on top, got 12.5 or so in preload, so I put the .5 and .3 in and got about 10-11# of preload,,

 

[Moby]

I finally broke down and got an OEM knucle tool. It makes all the difference. You really can center the axle in the housing and get the preload right in one move. I got the preload right on the first try and could not believe it. It really works.

+1

Re-using the old shims usually works but it assumes that the previous shims were correct. Using the fish scale is an easy way to determine this. However if they weren't correct the SST is the way to go. My knuckle shims were not correct when I rebuilt my axle (no shims on top was a good indication). Now they are perfect, right in the middle of the spec.