playing at kingpinbearing

maeserik · Post by **maeserik** » Wed Nov 29, 2006 5:45 am

Last weekend i found after a checkup there is a little playing at the kingpinbearing on the left knuckle.( not much, but while wobling with the wheel i could feel it, front wheel off the ground) First i thought it were the wheelbearings, but they seemed OK. Are the kingpinbearings adjustable or do i have to replace both bearings up and under ? The axles were rebuild in the past and last year during the restoration, opened, cleaned and filled with new lubricant. Everything move smooth so far. Does anybody hav a detailed pic of these bearings, most of the pics on the web are mb knuckles, not exactly the same.

It is not a big problem, but maybe easy to fix.

thanks

TomM · Post by **TomM** » Wed Nov 29, 2006 4:48 pm

Hello Maeserik,
I just looked through your pictures. Nice work on the rebuild!

I recently replaced my kingpin bearings and bearing cups during the front axle rebuild. The play in the kingpins is adjusted with shims during installation. If there is play in yours it would be proper to dis-assemble the hub and check the bearings rather than try to adjust bad bearings. I found that my cups had been heavily damaged. Replacement is relatively easy and requires about 2 hours per side working liesurely. You do not need to dis-assemble the brakes other than to disconnect the hose and remove the backing plate with wheel cylinder and shoes intact.

The hub assembly is slightly different from the MB in that the M38 does not have shims on the bottom kingpin. Also, the arm assembly is cast into the hub on an M38 where it is separate on an MB.

When re-assembling the kingpins and hub, the procedure calls for you to adjust the number (thickness) of shims under the top pin assembly. This procedure is the "play" adjustment. To adjust this properly you must remove the seal on the back of the hub as well as the tie rod end. Per the manual, a scale should be used to pull the hub (where the tie rod end had been connected) so that resistance is 6-9 pounds (about 2.75-4 kg). I used an inexpensive fish scale to make the adjustment. Add or remove shims to get the proper tension being sure to torque the bolts properly between tries.

There may be others who have replaced kingpin bearings and cups without dis-assembling the tierod end and seal. The manual does not show a method for this however.

The MB procedure is similar in that they apply a scale and adjust the shims to get the proper tension (although it may be a different tension from the M38). The MB manual has an excellent picture of the procedure using the scale.

Hopefully this helps.

Tom

maeserik · Post by **maeserik** » Thu Nov 30, 2006 12:40 am

thanks, i shall buy new cups and bearings and possible replace them,

i shall take a closer look to see if there are shims between the parts, maybe there is much to paint on it now

TomM · Post by **TomM** » Thu Nov 30, 2006 8:41 am

The shims on the top are hard to see under grease and paint. Additional shim sets are available from suppliers. They will be handy to have.

Regards,

Tom

maeserik · Post by **maeserik** » Tue Dec 05, 2006 12:22 am

Problem solved, after a closer look with two persons, we adjusted the wheel bearings a little bit ( 1/6 turn tighter) wheel turns free and without playing now.

Thanks for the good advice !