Interesting discovery while shimming king pins

[motoMark]

As I progress with the new king pin project on my 51 Cambridge, last night I discovered I need to buy more shims. While I was doing a dry fit to make sure everything was looking ok, I was surprised at the amount of clearance between the bearing and the knuckle. When I originally took everything apart, there was 1 shim (0.011") on both the driver's side and passenger side. Even with the 2 additional shims from the king pin service kit, it wasn't enough to take up the play.

 

So I measured the height of the new bearing and the old bearing to see if there was a difference. I was surprised to discover the new bearing was 0.025" shorter than the old bearing, meaning I need to add another 0.025" in shims to each side. Using my feeler gauges, my driver's side needs a total of 0.045" in shims and the passenger side needs 0.035".  I ordered a set of 10 (0.005") shims from Speedway Motors and that should get me where I need to be.

 

Has anyone ever run into this issue before? 

[kencombs]

New bearings are probably metric, vs original were inch sizing.   Really common to find replacements for older measurements are not available, just a close metric equivalent. 

 

 

[Dodgeb4ya]

Never have run into that....I'd get the right bearings.

[47 dodge 1.5 ton]

When I did my truck last year the new bearing was only .003 thicker than the original. Tells me they didn’t compress much over time.
 I would look your new bearings over well and try searching the thrust load as designed. I’m not sure if anything is/was published in a service manual but, possibly folks on here may know what the original requirement was.

 A lot of work to do twice if you have an issue. Don’t think I would be concerned so much about adding shims, just the load rating.

 Does the ID fit the shaft the same?  
  Wanted to add— you may want to pre pack the brg before installing, I didn’t because I wanted a tight shim fit. After assembly, I could not get grease to the brg and ended pulling the first side I did back apart. I was still able to get the same shim back in, just a little more difficult.

Edited March 30, 2023 by 47 dodge 1.5 ton

[motoMark]

10 hours ago, 47 dodge 1.5 ton said:

When I did my truck last year the new bearing was only .003 thicker than the original. Tells me they didn’t compress much over time.
 I would look your new bearings over well and try searching the thrust load as designed. I’m not sure if anything is/was published in a service manual but, possibly folks on here may know what the original requirement was.

 A lot of work to do twice if you have an issue. Don’t think I would be concerned so much about adding shims, just the load rating.

 Does the ID fit the shaft the same?  
  Wanted to add— you may want to pre pack the brg before installing, I didn’t because I wanted a tight shim fit. After assembly, I could not get grease to the brg and ended pulling the first side I did back apart. I was still able to get the same shim back in, just a little more difficult.

I'll take a look at the bearings to see if there are any markings on it that can lead me to a load rating. But if I don't find anything I'm just going to run them. Besides the height, the appear to be dimensionally the same as the old ones and fit the new king pins just fine. I don't have a problem shimming them for correct fit. Maybe I'm being too trusting, but since I bought the kit from Andy Bernbaum's, I'm inclined to think the bearings are appropriate for their intended application.

Thanks for the advice on pre-packing the bearings. Never thought about that.