Knuckle preload (1 Viewer)

[woytovich]

So I'm swapping FJ62 knuckles onto my FJ40. I used the proper FST to measure the necessary shims... I checked my measurements and math 3 times - but I could still be wrong.

I am using all new bearings/races, shims, cone washers and nuts - all from Toyota.

Now that I have assembled the knuckle onto the housing and tightened the nuts to the high end of the recommended torque range (that's the kinda guy I am) I am getting basically zero preload... There is no resistance when I turn the knuckle side to side. BUT there is also no play, wiggle, movement of any kind that I can detect in the bearings.

If I used too much shim the preload would be too low... right? But at some point I should get play in the bearings... right?

I am going to check the math again but in the mean time any ideas/thoughts?

mark

 

[woytovich]

Should I remove the thinnest shim from top & bottom to see if I get the right preload?... or at least SOME preload?

 

[woytovich]

Math is right... I'm going to look at the shims I installed... maybe I rounded up...?

 

[Tokamak]

From what I have been reading and studing on the subject you should only adjust the shims on the top for preload. The bottom shims were determined by the centering tool to center the axle.

Lower shim = "E" = "D" - 3mm. It's figure 5-19 in my service manual.

Total shim is "C" = "A"-"B". Upper shim is is total shim "C" minus Lower shim "E".

If the preload is too low remove shims from the top. If too high add shims to the top. Tapered roller bearings take quite a bit of pressure to cause drag after all the slack is gone.

 

[woytovich]

Ok... so I pulled it apart, removed 2 of the thinnest shims from the top and re torqued... preload is now square in the middle of the correct range.

I hate this... this is what I refer to as "voodoo" when doing cruiser work (or any car work for that matter). The method for these fine measurements is not so straightforward... it is something that comes with experience. I suspect if 10 relatively inexperienced people use the FST to measure for the shims they will come up with 5 or 6 different solutions...

Well, I have Marlin double seals in the axles so I hope that the knuckle is aligned properly ENOUGH to not cause leaking problems...

Thanks,
mark

 

[Tokamak]

Good to hear it worked out for you.

I'm getting ready to do the knuckle preload and centering right now. Made my own tool posted as (home built centering tool). I just put in my bearing races and realized that I don't have a spring gauge. I'll try and find one tomorrow.

I bought the Marlin Heavy seals also. Cheap insurance cause I don't want to go in here again for a while.

Which knuckle bearings are you using, the TR0305A or the 3030D. Just curious.

 

[woytovich]

Ordered them from Toyota... Toyota part# 90366-17001-77 which is TR0305A

 

[67azcruizr]

Mark, as you probably already know, the bottom shims ONLY center the knuckle in the housing.

You top shims set your preload

I've set up 5 front ends and I'm only maybe 50% correct on the preload the first time around(seems to be the general census)..................I've learned not to load up the knuckle with grease before recording a correct preload

 

[woytovich]

Mark, as you probably already know, the bottom shims ONLY center the knuckle in the housing.

You top shims set your preload

I've set up 5 front ends and I'm only maybe 50% correct on the preload the first time around(seems to be the general census)..................I've learned not to load up the knuckle with grease before recording a correct preload

Thanks Sean... I do know that now - it would be nice if the FSM put in in such clear terms as you have. The first knuckles I did were on my 60 about 10 years ago and I just reused the shims. In swapping in different knuckles I needed to do the whole thing. It did occur to me at some point that it might be a good idea to hold off on the grease until I was more confident of the install...

 

[subzali]

Mark, as you probably already know, the bottom shims ONLY center the knuckle in the housing.

You top shims set your preload

I've set up 5 front ends and I'm only maybe 50% correct on the preload the first time around(seems to be the general census)..................I've learned not to load up the knuckle with grease before recording a correct preload

I've always thought that the combination of top and bottom shims both centers the knuckle on the housing and sets the preload - guess I'll have to go look at the FSM again...

I always thought that if your preload was out of spec you had to try to add or remove shims from both top and bottom as evenly as you can to keep the knuckle centered

 

[handcannon]

67azcruiser is correct. Bottom shims center the knuckle to the housing while top shims set preload.

Don

 

[greenbeast]

I literally just ran into same issue. Used FST from another mud member, checked my math multiple times and my preload just over 3 pounds. Guess tomorrow I will pull a shim off the top and see what happens!