OC-15 brake bands

[modifier]

Hoping for better results from this post than the last one with zero answers out of 114 views. lol

I'm completely rebuilding or replacing all the serviceable parts of the brake system on my 604. All slave and master cylinders will be renewed and I'll also have to disassemble and rebuild the dual hydrovac system if I find it needs it. I'd like to have the brake bands relined while I'm at all the rest so there is no chance of scoring the machined surfaces if the linings wear thin. The OC-15 is pretty different from the more common smaller rear ends, as I understand it, but there must be some similarities. I've taken the cover off and looked inside, and it certainly isn't obvious how to get the old ones off to inspect and rebuild if needed. It doesn't look like there is any room to work without removing a lot of other major parts. I find it hard to believe the rear diff as to come out to service the brakes.

601s have the same rear end, so maybe someone here can share some instructions on what it takes to do this. Hoping.

Here are a few picks of it in the shop and up on jack stands. Since those were taken the tracks are off and the wheels and sprockets were removed.

 

[Snowy Rivers]

Even the OC12 has to come out of many chassis to be able to service the bands easily.

Drop the tracks and a few bolts and a big floor jack.....that bad boy will come out.

Once the top is off the bands will be quite easy to get at.

I personally have not worked on a 15.....but the 12 brake bands can be removed pretty easy.

Unhook the internal linkage (Taking care not to drop any washers or cotter pins or other small parts) then the bands can be rolled out of the case.

The bands can be relined.

I had my OC12 bands relined by a specialty friction shop up in Portland.....
I drilled the heads off the brass rivets and removed the old lining and then cleaned the bands up well before taking them to the shop.
No sense in paying them to do what I can do.........

We discussed the usage and we picked the type of band material to use (Take a piece of the old stuff with you)


Good luck

 

[zspryte]

Another place that does very good work on Thiokols & OC rear ends is https://spryteimp.com/ (Snowcat Pat). They rebuilt my brake slave cylinders and relined brakes for other forum users.

There is a separate sub-forum for Thiokol/DMC/LMC. Sometimes posting Thiokol questions there gets more responses.

 

[Snowy Rivers]

I have used Pat for parts.....Good folks to deal with.

 

[Bombi1]

"Hoping for better results from this post than the last one with zero answers out of 114 views. lol"

Comments like that are probably not going to help you get the answers you want.

 

[vintagebike]

 

[Snowy Rivers]

I am not too quick to criticize.....I think I saw the first post......Not having had any first hands on with the 15 I just passed it over...

Figured that others that were more in tune with the OC15 would chime in.

Lets try and help this fella.....Some time the actual feelings displayed in these text forums can come across a tad tart....and not mean to.....

Lets move ahead........

 

[modifier]

"Hoping for better results from this post than the last one with zero answers out of 114 views. lol"

Comments like that are probably not going to help you get the answers you want.

Really? Is that what people are like here? You make a joke about the truth and people are like, screw him. I've actually been warned about forumforums from some of the old guard who have been helping the Thiokol community for many years, so you might be right.

 

[modifier]

Another place that does very good work on Thiokols & OC rear ends is https://spryteimp.com/ (Snowcat Pat). They rebuilt my brake slave cylinders and relined brakes for other forum users.

There is a separate sub-forum for Thiokol/DMC/LMC. Sometimes posting Thiokol questions there gets more responses.

Thanks. I did talk to him a couple weeks ago and he offed some good info I did not know. Like how OC-15 bands are wider and have brass at the ends to keep the friction material from wearing down as quickly or unevenly. If I can't find anyone else he can have them relined for me once I get them out.

 

[modifier]

Even the OC12 has to come out of many chassis to be able to service the bands easily.

Drop the tracks and a few bolts and a big floor jack.....that bad boy will come out.

Once the top is off the bands will be quite easy to get at.

I personally have not worked on a 15.....but the 12 brake bands can be removed pretty easy.

Unhook the internal linkage (Taking care not to drop any washers or cotter pins or other small parts) then the bands can be rolled out of the case.

The bands can be relined.

I had my OC12 bands relined by a specialty friction shop up in Portland.....
I drilled the heads off the brass rivets and removed the old lining and then cleaned the bands up well before taking them to the shop.
No sense in paying them to do what I can do.........

We discussed the usage and we picked the type of band material to use (Take a piece of the old stuff with you)


Good luck

Thanks. I've had people tell me the OC-15 bands are hinged on one end and pinned on the other and they can come out without removing the diff. I've also been told by others I have to remove it. I can gain easy access from the top, so if the band are hinged like the guy who said he has worked on many OC-15s, Nodwells run them, then it should not be too hard. If not hinged then I will have to pull everything apart.

 

[modifier]

Thanks to those who offered help or advice. I think the number of Thiokols with OC-15 rear ends is pretty small, so most don't have any experience serving them, and the 15s are quite a bit different than 12s or 4s. 600 series are probably the only ones with 15s. 601, 602, 603 & 604s. Not many of any of those still around.

 

[PradoTDI]

Here are a couple of photos of the inside of an OC-15. Looks like the brake bands are hinged. https://www.forumsforums.com/threads/thiokol-601-restore.7484/post-78695

 

[Snowy Rivers]

Just a word of caution here.

With all the rust showing up top.....

Personally ....I would pull that bad boy all the way apart and check ALL the bearings......
After rust starts in a roller/ball bearing it's only a matter of time before the bearing surface starts to break down and then "SHELL OUT" FOLLOWS.....

These machines are noisy enough when everything is perfect that a bearing failure will go unnoticed until the carnage is WAAAAAAAAAAAAAY too far gone ....and or a major failure occurs......

As the bearings go away and start shedding pieces ...then junk starts going through the gears......It takes very little running through the R&P to destroy them....Quickly too.

You would be best to just drag that big bad boy out and spread it apart.....

Examine everything.......

HINT/......BEARINGS ARE SPENDY....BUT ARE ALL STANDARD NUMBERED PARTS.

EBAY can yield very good prices on NOS parts

The inner pinion bearing on my OC12 was quoted at $700.....I bought the very same part off ebay (Box was a bit tattered...made in 1976, but perfect) $20 to my door.

Getting your diffy in top shape and all cleaned up will be a good thing......Failure out in the brush in the cold....not so good..
PICCY
One of the bearings that came out of my 12.....
The balls had already broken up and luckily the pieces had not gone through the R&P....Or anything else
Pretty sure this bearing was on the top gear...outside.....
The pic with the one bearing missing the balls is out of a drop box.
Shot of the pinion with lotsa orange.......

Water is an absolute enemy of these gear boxes (Any gear box) and with cold snow packed in and around these suckers..
as the inside cools after a run.....water can get sucked in through seals, vents and other places too.....
Condensation from moist air getting in from the vent.......
With any appreciable use ...drain and refill with fresh oil before storing for the off season.....OIL IS CHEAP.....PARTS ARE NOT

Anyway.....my 2 cents worth.......good luck and have fun.

 

[northfork]

GREETING SUCH A WONDERFUL THREAD THANK YOU, MAY I ASK IS THERE A GASKET BETWEEN THE COVER WHERE THE BEARINGS CAMP OUT FROM I’D LOVE TO TAKE LOOK SEE I ‘M JUST AFRAID I WOULDN’T FIND THE GASKET, THANK YOU

 

[mtncrawler]

So Modifier, what did you find out with changing your OC-15 bands? I've been told that the axles need to be pulled and the center section lifted out to get the bands off. I, for one, would appreciate learning from your experience with this.

 

[northfork]

Hoping for better results from this post than the last one with zero answers out of 114 views. lol

I'm completely rebuilding or replacing all the serviceable parts of the brake system on my 604. All slave and master cylinders will be renewed and I'll also have to disassemble and rebuild the dual hydrovac system if I find it needs it. I'd like to have the brake bands relined while I'm at all the rest so there is no chance of scoring the machined surfaces if the linings wear thin. The OC-15 is pretty different from the more common smaller rear ends, as I understand it, but there must be some similarities. I've taken the cover off and looked inside, and it certainly isn't obvious how to get the old ones off to inspect and rebuild if needed. It doesn't look like there is any room to work without removing a lot of other major parts. I find it hard to believe the rear diff as to come out to service the brakes.

601s have the same rear end, so maybe someone here can share some instructions on what it takes to do this. Hoping.

Here are a few picks of it in the shop and up on jack stands. Since those were taken the tracks are off and the wheels and sprockets were removed.

Greetings a couple things that is one unique snowcat amphibious ? crazy question HuH? I own 602 with OC 15 l was wondering if you rebuilt the slave cylinders or just replaced them my cylinders are original ones still, thank you

 

[Snowy Rivers]

If the Cylinders are not scored or rusted/pitted ....Just replace the seals....

 

[northfork]

Snowy Rivers thank you very much for your reply, I haven't removed them yet their both original its a slow leak, I see the drip leak, as l steer it must increase, I replenish the master cylinder often, at times twice a day I'II most likely have a rough time finding a seal kit, I'II give it a run thanks again