Gotta install knuckle shims

[laguna80]

Been a long time y'all. So I need to put in knuckle shims since I have a pretty bad vibration with the disc brake swap. Do I have to dissemble the knuckle down to the birfields or can I just remove the tires to access the steering arms, then pop those off, install shims and put it back together? Is there anything under heavy tension there that wouldn't allow that?

 

[Pighead]

. So I need to put in knuckle shims since I have a pretty bad vibration with the disc brake swap.

Slow down, take a deep breath and start the story at the beginning.
( If you need to re-shim your knuckles you need to recenter the knuckle which means you need the re-centering tool...do you have a recentering tool?)
Could be a lot of other things. Tell us a story.

 

[laguna80]

Slow down, take a deep breath and start the story at the beginning.
( If you need to re-shim your knuckles you need to recenter the knuckle which means you need the re-centering tool...do you have a recentering tool?)
Could be a lot of other things. Tell us a story.

Sorry tried to keep it short cause I'm on my phone. Anyway, did a disc brake swap a while ago on my 74 piggie (yes I surprisingly still have it). Installed the parts but knew nothing about the shims. I had to move the truck when I moved and I noticed the vibration around 30-35 mph. Haven't driven it around btw. I have the shims now after doing more research and I wanted to install them and then do the whole fish scale thing to get it tightened up. Can't remember what that measurement is called. Before I tried to take off the arms, I wanted to see if I need to dismantle to hubs down to the birfields etc. I followed the disc brake swap guide in the 40's section when I did the swap and the parts are off of an early 80's mini truck.

 

[3_puppies]

Been a long time y'all. So I need to put in knuckle shims since I have a pretty bad vibration with the disc brake swap. Do I have to dissemble the knuckle down to the birfields or can I just remove the tires to access the steering arms, then pop those off, install shims and put it back together? Is there anything under heavy tension there that wouldn't allow that?

Slow down, take a deep breath and start the story at the beginning.
( If you need to re-shim your knuckles you need to recenter the knuckle which means you need the re-centering tool...do you have a recentering tool?)
Could be a lot of other things. Tell us a story.

X2 on what pighead said
knuckle shims will not cause a vibration. the shims are used to center the knuckle on the axle to keep the inner axle seal from wearing and leaking.
vibration could be a wheel balance, or leaf spring bushings or others

 

[laguna80]

X2 on what pighead said
knuckle shims will not cause a vibration. the shims are used to center the knuckle on the axle to keep the inner axle seal from wearing and leaking.
vibration could be a wheel balance, or leaf spring bushings or others

Knuckle bearing preload is the phrase I was looking for earlier. As far as the shims go, I have the nuts torqued down, but the steering arms still have a bit of a gap between the base plate and the knuckle. I'll investigate the vibration more, however I still need to get those shims installed since I never did it the first time around. I suppose I should take everything apart and inspect the seals since I've driven it that way a little bit. Suspension wise, everything "should" be fine since I haven't touched anything in that arena since I've owned the pig. I just know it drove fine before the brake swap and vibrated afterward. Thanks for letting me know, I'll get a full investigation tomorrow.

 

[Pighead]

but the steering arms still have a bit of a gap between the base plate and the knuckle.

Yes, you really should fix that. Vibration could be due to not tightening down the wheel bearings enough too...or they backed ff.

 

[nuclearlemon]

by tightening everything down with no shims, you may have forced the trunnion bearings onto the arms/caps and it may not be so easy to take it all apart again. you may end up tearing the bearings apart.

 

[PabloCruise]

X2 on what pighead said
knuckle shims will not cause a vibration. the shims are used to center the knuckle on the axle to keep the inner axle seal from wearing and leaking.
vibration could be a wheel balance, or leaf spring bushings or others

My understanding is that the shims on top set the vertical alignment, so the axle is centered in the seal, and the bottom shims set the pre-load for the knuckle. Or vice-versa, top to bottom.
But you need that knuckle pre-load.
You also need proper pre-load on the wheel bearings.

 

[snailwagon]

And depending on the parts available, you may not be able to get any toe-in, just toe-out. MiniTruck arms will make you want some shorter rods or ones with more adjustment.

 

[RHINO]

i was going to concur about the shims not doing anything for a vibe,, but if you have a gap then anything could be possible right now. you dont have to take anything off but caps to replace shims, but if your going to set bearing preload everything needs to be taken down to the bare knuckle to get the right scale measure, even the birf and felt.

 

[laguna80]

Felt like I should finish this thread. Turns out, I'm a bit of an idiot as the reason was that there was a gap there was because there were already shims. Anyway, I never found out and the truck is retired to the farm now.