863 Parking Brake Disc/Snap Ring Question

[cdawg]

Just joined and this is my first post. Looks like a great site with lots of experienced users. I'm in the process of repairing a broken parking brake (traction lock) mechanism on my 863 F series. I've opened the chain case, cleaned out all the contaminated fluid, and retrieved the numerous "broken" parts. Here's my question: the snap rings which the brake discs are bolted to are set into a small groove that is cut around the end of each drive gear. Several of the small sections of the end of the drive gear that serve to hold the snap ring in place are broken off. While the snap ring still appears to have enough of the drive gear "ends" that are not damaged or broken off, I need to know how important it is to have a completely undamaged drive gear for the snap ring to be seated. In other words, will putting the snap ring back on a somewhat damaged drive gear be a recipe for premature/future failure? I'm unsure of how much stress or side-to-side movement the brake discs experience, but suspect there is at least some. Any experiences or alternate fixes for this problem would be greatly appreciated. If the drive gears have to be replaced, the drive motors and motor carriers have to be removed and disassembled, and I'm not really wanting to dive-in that deep.

 

[Tazza]

I'd like to think as long as the snap ring still sits on there it will be ok. It is really only there to stop the disc falling off the shaft. With that said, there has to have been side load to damage the seating groove that you have now.
I'd like to say that it will run fine as it is. Not a lot you can do about the damage, i'd let it run and see how it holds up.

 

[cdawg]

I'd like to think as long as the snap ring still sits on there it will be ok. It is really only there to stop the disc falling off the shaft. With that said, there has to have been side load to damage the seating groove that you have now.
I'd like to say that it will run fine as it is. Not a lot you can do about the damage, i'd let it run and see how it holds up.

Thanks, Tazza. One of the steel guide blocks for the traction lock / parking brake mechanism that bolts to the underside of the chain case cover came loose and fell into the brake disc, causing the damage. You mentioned the snap ring is there only to stop the disc from falling off the shaft. I guess my concern is that the disc is actually bolted to the snap ring, and was thinking that if the snap ring didn't stay locked in its groove, then "all hell would break loose." It looks like there are enough undamaged areas on the end of the shaft to hold the snap ring in place. I think I will follow your suggestion and give it a try. Thanks for the reply. If anyone stumbles on this post that has experienced a similar situation, I'd love to hear from you...

 

[Tazza]

Thanks, Tazza. One of the steel guide blocks for the traction lock / parking brake mechanism that bolts to the underside of the chain case cover came loose and fell into the brake disc, causing the damage. You mentioned the snap ring is there only to stop the disc from falling off the shaft. I guess my concern is that the disc is actually bolted to the snap ring, and was thinking that if the snap ring didn't stay locked in its groove, then "all hell would break loose." It looks like there are enough undamaged areas on the end of the shaft to hold the snap ring in place. I think I will follow your suggestion and give it a try. Thanks for the reply. If anyone stumbles on this post that has experienced a similar situation, I'd love to hear from you...

On the ones i have worked on, not an 863, the snap ring just stops the disc sliding off, it floats around the shaft quite a lot, more so than i'd really like, but it does the job.
I can see that guide falling off causing some damage!