Rear bogie bushings

  • For registered users, a Google custom search option has been added that will search across several dedicated GMC Motorhome sites including this forum, GMCMI.com, and bdub.net. To use it, either click the "G" icon at the bottom of the search dialog or select the "Google search" tab in the search results. This new feature is also useful when your search includes words that are shorter than the 4 letter minimum supported by the forum's built-in search engine.

1976GMC

Active member
Dec 16, 2017
246
30
28
Washington State
I'm working on refreshing all brake hardware on our MH this summer. While I was doing that, I've decided that I will definitely be replacing the bushings on the rear bogie pins in the near future. I recall some discussions on the forum as to which modern bushings fit the bogie pins on the GMCs. I will be looking up that information. The parts diagram shows that there are two sets of seals (outer and inner) on the bogie pins. Anyone knows the part numbers / sizes for those o-rings/seals? Also, does anyone have a good write-up (perhaps with photos) on how to remove the rear suspension and to get to the the rear bogie bushings? It looks like you have to take off the entrie control arm assemby off as a unit and work on it off the coach. Is this accurate? How do you get to the frame bolts on the passenger side? I have a 2.5 exhaust pipe running just about in the "C" channel of the frame on that side. Do I need to disassemble exhaust system in order to unbolt the central support bracket? As far as part numbers, I don't know if it makes a difference - I have the bogie pins with dual grease zerks on them. Does this require any additinal or different parts for this job?
I would love to hear back from anyone who has dealt with this. Thank you in advance.
 
It sounds like all your assumptions are correct. Driver's side is easier; passenger side is made difficult by the exhaust. I've worked around it before, but it sure is easier with the exhaust out of the way. It allows the use of an impact, which is great when you're working solo.

For seals, many vendors supply o-rings. I did the extra legwork to identify x-rings that fit instead. This is closer to the factory implementation. Info should be contained in my Palm Beach build thread.

IIRC, the COTS bushings you can use are for a detroit engine. Of course, it's only useful if your pins are perfect still, which isn't always the case. How much slop do you have? Early detection is probably the key.
 
It sounds like all your assumptions are correct. Driver's side is easier; passenger side is made difficult by the exhaust. I've worked around it before, but it sure is easier with the exhaust out of the way. It allows the use of an impact, which is great when you're working solo.

For seals, many vendors supply o-rings. I did the extra legwork to identify x-rings that fit instead. This is closer to the factory implementation. Info should be contained in my Palm Beach build thread.

IIRC, the COTS bushings you can use are for a detroit engine. Of course, it's only useful if your pins are perfect still, which isn't always the case. How much slop do you have? Early detection is probably the key.
Two stroke (8v92) rod bushings IIRC, and they will need to be reamed after install.
 
  • Like
Reactions: tmsnyder
I had to do a rebuild on my bogies. Its quite the chore but when you are done you are good-to-go and confident

I had a machine shop remove and press the new bushings in

 
Last edited:
This is great info. Thank you all. Having pulled all brakes off the rear wheels I'm getting much better aquainted with all the parts back there. It will help when I get to tackle rear bogie bushings.
I will measure the control arm slop and let you know. It feels that one is a little worse than others
 
Really the most critical part is the TOP HAT that sets the play in the arms. This typically freezes up and no adjustment can be made then until it is free'd up

I think every coach would benefit from a bogie set dis-assembly, cleaning and freeing up of parts and re-assembly
 
I wonder how much grease actually stays between the bushing and the pin in the contact area. The bogie movement is typically quite small (about +/- 2.5 degrees) and the pressure of coach weight and airspring forces is only along a thin line. This farmboy mechanic's mind's eye can see the grease being forced out with no way of the rotation pulling any replacement grease back in leading to wear.

If they gave a way to spin the pins half a turn that would provide a way to pull fresh grease into the contact area. It might have been a good place to have a liquid oil as lube rather than grease.

I had mine pins done shortly after purchasing the coach. With 40,000 miles and lots of grease pumped in them, I have one that is worn again.

Just my take on it.
 
You could machine an opposing slot in the pin head and somehow rotate the pin in-situ.
DSC03113.JPG

or drill access holes in the frame
Drill the rear of the pin to the grease channel
tap for a zerk
Grease from rear of bogie thru access hole in frame
Seems like a great way to flow grease thru the bushing channel

I have a set of pins to experiment on, maybe I will inquire at the machine shop
 
Last edited:
Really the most critical part is the TOP HAT that sets the play in the arms. This typically freezes up and no adjustment can be made then until it is free'd up

I think every coach would benefit from a bogie set dis-assembly, cleaning and freeing up of parts and re-assembly
Forgive my ignorance, but what is the TOP HAT you're referring to?
 
The top hats are part # 12
DSC00544.JPGtop hat.jpg

DSC02931.JPG
DSC02932.JPG
DSC02933.JPG

They should float free, and they do, for months, but then kinda of harden into place
Then the play cant be adjusted out
 
Last edited:
  • Like
Reactions: 1976GMC