Chaffee Transmission Questions

[Malcolm Towrie]

Hi, I got one of the GM Hydramatic transmissions off a M24 Chaffee apart and I have some questions:
- the tranny oil cooler has large ballooned spots in the cooler plates shown below. The cooler is on the suction side of the oil pumps so sees very low pressure, going on below atmospheric. Anyone any idea why has this happened?

- the front clutch pack is smoked including the aluminum apply piston. One of the return springs punched a hole through it. Who sells hard parts like this for these old trannies?

- who has Chaffees who could answer questions on these trannies?

Thanks,
Malcolm

[Bob Phillips]

why dont you compare a chaffee tranny parts book against a G749 hydramatic transmission book and see if there are common parts in both transmissions. If so call Brian Asbury who may still have some old rebuilt G749 transmissions available to strip for parts. Just a thought.

[Malcolm Towrie]

Thanks, Bob. My problem is I don't have a parts manual for the tranny. Also, I can tell from the photos and info in my 1945 Chaffee tranny manual that I don't have an original tranny. I assume it's a later model. And I'm finding that GM tweaked their newly-designed hydramatic every year, so by the time they were being installed in the deuces, there were a lot of differences.

Anyway, I got lucky. The damaged apply piston has the part number cast into the aluminum and I found a NOS one on eBay for reasonable money!

Rebuild gasket and seal kits and clutch plates are still available so I should be ok now, although the blistered cooler worries me. I'll just have to pressure test It (gently) and reuse it.

Fingers crossed the other tranny, which is also acting up, doesn't need any hard parts.

Malcolm

[Frank v R]

try calling Bob Rubino in NJ tell him I told you to call, Milspec Restoration
908-475-2799 he may be able to shed some light on the cooler , and if you need parts try calling Brent Mullins jeep parts, he does a lot of Armour and has lots of NOS parts
regards Frank

[Bob Phillips]

i used to have a couple of used transmissions for the Chaffee and I think they were shorter than most hydramatic transmissions and had no reverse gear, the reverse being in the transfer case. would a later transmission still work in a \chaffee or is this a non Chafee application?

[Bob Phillips]

So I just checked my G749 ord 9 and the oil cooler for the G749 which appears identical to the picture posted is identifed as G200-5608479 cooler assy, oil
This means it is the same in both applications. Used G749 transmissions are still widely available in Ontario junkyards, no need to go far. If you can't find one pm me for more leads.

[Malcolm Towrie]

Thanks, Frank.

Bob, these trannies are in a Chaffee. Yes, your right, the reverse gear is in the transfer case. The tranny connects directly to the t/c with a short stub shaft so there is no room for a reverse-equipped Hydramatic.

That's great info about the cooler because we have some old M135's here at the museum I can steal parts from. I'll check them out and see how easy it's is to drop the pan. I may even pull a tranny because the outer torus has worn splines and I'd like to replace it too.

Malcolm

[Malcolm Towrie]

Originally Posted by Bob Phillips

So I just checked my G749 ord 9 and the oil cooler for the G749 which appears identical to the picture posted is identifed as G200-5608479 cooler assy, oil
This means it is the same in both applications. Used G749 transmissions are still widely available in Ontario junkyards, no need to go far. If you can't find one pm me for more leads.

Bob, can you give the document number for the "G749 ord 9" you refer to? I'd like to get myself a copy.

Also, can I ask a favour, does the ord 9 show part numbers for the seals for the cooler? These seal around the two cooler nozzles, separating the water side of the pan from the oil side. Each nozzle has a flat fibre washer and an unusual chevron-shaped sealing ring.

Thanks, Malcolm

[Frank v R]

if you have problems with some of the seal number give me a call , I have a old school seal cross over book,

[rob love]

I have my Canadian deuce manual at work. If we are open today (the blizzard just ended a coupel hours ago) I'll look up the NSN for those O rings. They are good for searching for sources, along with alternate part numbers.

[BCA]

I have NOS oil coolers for Chaffee G200-56-08479/GM 8508471 @$120. ... Brian

[rob love]

The cooler number is the same as the G749 deuce.

From the parts manual, the seals are as follows:

#14 Retainer GM hydramatic pn 8602482 NSN 5330-00-534-2364
#15 Packing Preformed GM Hydramatic pn 8602366 NSN5330-00-534-2366
#16 Washer non-metallic GM Hydramatic pn 8606463 NSN 5330-00-291-8947

[Malcolm Towrie]

Originally Posted by BCA

I have NOS oil coolers for Chaffee G200-56-08479/GM 8508471 @$120. ... Brian

Brian, definitely interested. I'll get Ken Lee to give you a call.
Malcolm

[Malcolm Towrie]

Originally Posted by rob love

The cooler number is the same as the G749 deuce.

From the parts manual, the seals are as follows:

#14 Retainer GM hydramatic pn 8602482 NSN 5330-00-534-2364
#15 Packing Preformed GM Hydramatic pn 8602366 NSN5330-00-534-2366
#16 Washer non-metallic GM Hydramatic pn 8606463 NSN 5330-00-291-8947

Rob, this is the part I like least about working on these dinosaurs, finding parts.
Anyway, I found an M135 manual that gives part numbers for these coolers. I don't need the retainer, 5342364 (that's a solid steel ring), but I need the oil cooler mounting gasket 2918947 you listed, (which I could make out of sheet material if I have to), and I definitely need the shaped packing ring, 5342366 you also listed.

I've searched on these parts numbers and got a bunch of aerospace suppliers, which sounds expensive, but there must be somebody selling them for deuces. Anyone have any suggestions?

Thanks,
Malcolm

[Malcolm Towrie]

Here's a video of the front servo, which clamps the front band around the front drum, being tested with air. This is my first tranny rebuild and it's neat the way you can test various components with shop air.
Malcolm

https://www.youtube.com/watch?v=wY0o...ature=youtu.be

[rob love]

Originally Posted by Malcolm Towrie

Rob, this is the part I like least about working on these dinosaurs, finding parts.
Anyway, I found an M135 manual that gives part numbers for these coolers. I don't need the retainer, 5342364 (that's a solid steel ring), but I need the oil cooler mounting gasket 2918947 you listed, (which I could make out of sheet material if I have to), and I definitely need the shaped packing ring, 5342366 you also listed.

I've searched on these parts numbers and got a bunch of aerospace suppliers, which sounds expensive, but there must be somebody selling them for deuces. Anyone have any suggestions?

Thanks,
Malcolm

Not just expensive, but likely fruitless. They list every NSN under the sun, but don't actually have anything. Most of them are more of an expensive ebay for guys who buy up surplus parts and want to get decent money for what would otherwise be useless parts, often re-selling the same parts to the governments.

I think your best bet would be to find what company was rebuilding the M135 transmissions in the US for the collectors. Query the guys on steelsoldiers.com in the old deuce section....they will steer you in the right direction.

[Bob Phillips]

So again, if you have not actually made the call...phone Brian Asbury for rebuilt trany parts he may still have some units left.

[Malcolm Towrie]

I've posted on steel soldiers. And I'll phone Brian. Thanks.
Malcolm

[rob love]

This might be a source: http://www.fatsco.net/hydramatic.html

[Malcolm Towrie]

Originally Posted by rob love

This might be a source: http://www.fatsco.net/hydramatic.html

From my searches, the heavy duty cooler in the Chaffee, M5, and M135 tranny was unique to military applications and wasn't used in civilian cars or trucks, so Hydramatic parts suppliers like autotran and fatsco don't have cooler parts.

Malcolm

[rob love]

Fatsco tailor some of their kits directly toward the military trucks......wouldn't hurt to ask them. Then again, the military hydromatic is such a small segment of the market, it is hardly worth any companies time to have the parts custom made.

[BCA]

I am not sure if the G200 and G749 seals and gasket and retainers are the same. I don't have the full G200 Ord9 book to compare with G749 book.

[Malcolm Towrie]

Brian, this website below lists some specs for the 5342366 part shown in the G749 manuals. The cross sectional shape (u-cup) and the dimensions shown exactly match the ones I removed from the Chaffee,so I'm pretty confident these are the same part.

Do you have any?

Also part # 5342367?

Malcolm

https://www.wbparts.com/rfq/5330-00-534-2366.html

[Malcolm Towrie]

As a followup, I have ordered the cooler from Brian Asbury;. He also has seal and gasket sets for the G749 Hydramatic which include the cooler seals(and probably other gaskets and seals I need, because there are some significant differences between the civvy trannies and the military one) so I have ordered one of those. I think I'm good to go now.

Thanks for everyone's help, especially Brian.

Malcolm

[Malcolm Towrie]

To anyone with a Chaffee tank who finds this thread, the NOS G749 Hydramatic seal and gasket kit is useful because it has the round gaskets and v-cup seals necessary to seal the cooler in the pan (but see below). However, the pan and side cover gaskets don't fit. And the clutch apply piston rubber seals are the old style that need the brass expander so they still seal when they get hard and brittle after a few years. Modern Hydramatic kits have piston seals that don't require the expander.

The v cup seals for the cooler have the number AN6225-25 on them which is still available. Buy the 90 durometer ones in Buna N (nitrile).

The round gaskets can be made with 1/16" material.

Pressure test the cooler compartment to a few psi with air. The cover on mine was warped and leaked until I used RTV on the gasket. Dribble water into the two interspace drains and look for air bubbles.

Dribble water into the interspace drains and apply a couple of psi with a rubber -tipped blow gun to confirm the v-cups seal.
Beats finding the leaks when it's all installed in the tank.

Malcolm