FJ40 Tech help?

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Spud

Spud

Joined
Mar 8, 2007
Threads
116
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1,339
Location
In a van, down by the river
Hi guys, I have been away a while, was hoping someone could help me with what I assume is a simple question.

77 FJ40. Front end on jack stands and when I grab one of the wheels there is play if I wiggle it from top and bottom. There is no play side to side. Correct me if I am wrong but the no-play side to side would mean my wheel bearing was adjusted OK. I confirmed this by pulling the hub and adjusting the bearing, all was good. There is play when I grab the top and bottom, feels like a bit of a loose knock. I think this has to do with the small shims on top and bottom of the Knuckle, can someone let me know if I am onto a clue here?

It is only on Pass. side. and I am investigating a Death Wobble issue. So far I brought my toe-in from approx. 1/4inch down to about 1/8th. and I cleaned all the mud from my rims cause' I thought for a while it was just due to a balance issue.

Only get the wobble at about 30/40mph and all is OK if the road has zero bumps/cracks, when I hit a bump it goes bonkers. If I tap the brakes or give it more gas I can usually get it to relax a bit.

Thanks for any input. :cheers:
 
fairly new...
 
if you lift that side keep the tire on ....try moving the tire at the top or bottom to find movenment?
 
Yes, uh, that is what I tried to express in the OP.

I did a bit of further research on Mud and believe I am looking at Worn Steering Knuckle Bearing or perhaps I can adjust the preload on the biatch to get the slop out.

:cheers:
 
oops yes i do read that you already wrote that...sorry about that.

I would say yes the knuckle would be the big issue...you are correct there were shims that would take up the slop....but...

is the axle new to you? or did this just become a problem?
 
The problem may have been there a little and got worse recently. Previously I have had the rig going 65-70 and it was OK, (ok a bit scary) but no shimmy. This was a year or two ago after working out all the Caster correction and lots of linkage parts new etc.

Just recently it is doing this wobble only at 35-40 on pavement, again it happens when I hit even just a small bump that is on pavement and then it just starts wobbling like it it really out of balance.

So I jacked the front and see one side has a bit of play. Planning to try and get the play out via adjustment and or shim additions...Yes, I know you have to keep the top and bottom shim packs even to keep the birf alligned in the Knuckle. Actually I am not a total Newb I have rebuilt a couple front birf axles previously. I just never recall having to mess with the knuckle bearing before. So that is why I posed the question here figuring some of you locals would have an input comment etc. I think it should work out with the adjustment.

Thanks
 
yeah i think it should probably work out with adjustment...the knuckle should be a repack and put back...never had an issue with it being that far off...and never had to change the shims ...but...it could have just gradually got worse or possibly the bearing is bad?...not that i've ever seen one bad...

i would be supprised to see a wupped bearing

I know that you are FAR from a newbie :)

I hope it works out...if its not that ...then...i am at a loss

would be interested to see the process again...as its been quite some time that last time i did one...newbie or not....the older you get the harder it is to remember....even yesterday LOL
 
Excellent, I read that over and some great tips to work it out. Thanks Rick, appreciate you taking the time.
I need to go back and check the wheel bearing again. Maybe it was not quite torqued enough.

If'in it aint that, I'll follow your advice and move on to the next connection.

:cheers:
 
Splangy said:
Invest in a knuckle rebuild kit ($100), some moly and wheel bearing greases, some rubber gloves, and a big bag of rags. Access to a Haynes or FSM would be recommended as well! ;)
Click to expand...

I was trying to avoid all that as it may not be necessary. The axle was rebuilt prior to me getting it and not quite time yet to tear into it. Another year or so I'll give it a tear down. Just needing to work out this play.
 
So, here is what I found out and how we fixed the problem.

Again, if your following along, I mentioned there was play if I wiggle the wheel by grabbing at 12 and 6 position. I have the truck jacked up and I use a 6x6 that is a bit wider than the perches on my springs, along with a couple small blocks this puts the front end off the ground and enough room to move the steering and wheels in a full pivot from side to side.

Once up, I can feel the wheel bearing and it is good. The play is easy to feel by putting your right hand on the hub and left at the top of the wheel, leaning over the wheel I can lift or wiggle the hub and feel a little bit of play, much like a worn or loose wheel bearing but different. This play was only on passenger side, driver side is snug.

I pulled apart the upper and lower blocks containing the knuckle shim packs and bearings. Lo and behold, the shim pack did not match top and bottom. Actually the top had two shims, a very thin and one about twice as thick. The bottom only had a thicker one. So, knowing these are subposed to be evenly shimmed to maintain the right seal/wiper stance, and knowing I am dealing with a bit of the old "looseness", I removed the ever so thin shim from top and bolted it all back up nicey nice. I applied a generous multi-squirt session with the old grease gun and got it lubed up once again.

I loaded up the dogs and went for a ride, first on the road about 5miles and hitting 40-45 mostly it did really well without any death wobble issue. I brought it up to almost 60 on a straight and it felt just as good. So then I hit a bit of trail and wheeled it some.

I am happy as it looks like this issue is licked.
Keep going...
 
From my 60 days those shims are done to center the assembly using a special tool, so they might not be even to be right. That looseness could be from your trunion bearings and by removing a shim you compensated for it.

You might consider a knuckle rebuild at some point when you have time.
 
Don't lose that shim you pulled... you should put it back in when you put in new bearings. As Rick said the shims are used to center the knuckle on the axle and set the bearing preload. As your bearing wore out the preload dropped out of spec causing the play. I can't say for sure but what you did could lead to some leaking of the innner axle seal. Unless you have the knuckle tool to measure exactly what shims are needed it is best to rebuild as it was. Lots of threads on this out there...

Eric
 
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