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The 1960 Cadillac utilizes the four speed Controlled Coupling Hydramatic (a.k.a. Jetaway) transmission. It has a reputation as a troublesome transmission, but with the 4:1 first gear ratio it really moves out especially with the 3.21 ratio rear end that they used in air conditioned cars.
The Jetaway can be a tricky beast - I ended up pulling it three times.
First Pull
After doing some research, I decided to rebuild the transmission myself since no local shop seemed up to the task. I ordered the kit from a prominent supplier, but I would order from David Edwards at http://www.autotran.us" onclick="window.open(this.href);return false; if I could do it over again. The kit that I ordered from the prominent supplier had an incorrectly sized oil ring which caused me all sorts of problems – a problem I didn’t discover until my third transmission pull.
After tearing down my transmission using the Cadillac shop manual, I discovered where the noise was coming from: The output shaft support bearing was coming apart. Also, the wave spring on the reverse cone was broken which explains why I really had to rev the engine to get going at times – my transmission was fighting the reverse gear at times. (Bruce Reynolds in Tasmania tells me that some drag racers intentionally apply the reverse gear in a technique known as a reverse brake.) In addition, the clutch plates were shot – which also explains some of the slipping.
Notice the broken parts – especially the output shaft bearing.
Parts Explosion – and these are just the main parts which come apart as well.
I cleaned all of the parts using Simple Green. I filled up an old cooler with three gallons of the stuff and let the parts soak. After a good soaking, I rinsed the parts in warm water and sprayed them with WD-40 so they wouldn’t rust. For smaller parts I used mineral spirits.
Upon disassembly, I noticed that the pump pressure regulator was assembled backwards and was jammed. I noticed that the Cadillac parts manual shows the incorrect assembly of this part when compared to the service manual from Cadillac.
As illustrated in the parts manual – incorrect assembly.
I’ll bet that somebody serviced the transmission using the parts manual as a reference and, therefore, assembled the part incorrectly. When I assembled the part according to the service manual, it didn’t jam.
Second Pull
The second transmission pull took place in May 2004 after I thought I had the car all together and ready to drive. I noticed that the engine was pulling some heavy duty RPMs at highway speeds (over 3,500 rpm ) instead of the 2,500 rpm where it should be. Here’s a handy formula to determine your engine rpm speed based on tire size and rear end ratio (I got this after I made an inquiry on the CadillacLasalle Club bulletin board:
(rear gear ratio) x mph x 336 / (tire diameter) = rpms
In may case:
3.21 x 65 x 336 / 28 = 2500
The 235x75x15 tire is 28 inches in diameter.
When the transmission was cold, I’d pull 2,500 rpms at 65 mph. But when she heated up, the RPMs would go way up since I wasn’t getting fourth gear. I also noticed that I wasn’t getting second gear. I consulted the Cadillac service manual transmission troubleshooting section and the most likely scenario involved a stuck valve or the front coupling unit staying in reduction. I dropped the pan and cleaned the valves and still had the problem. I also did a pressure check on the transmission and the pressures were normal. I decided to pull the transmission.
This pull was different since I wanted to leave the engine in the car. Be sure to support the engine with a floor jack under the oil pan. Don’t leave the floor jack under the engine for a long period of time as it will eventually leak down – support the engine with something solid like wood blocks:
Coming out again.
Upon partial disassembly (I only removed what I needed to get to the front coupling unit and the pump), I noticed the cover of the front coupling unit had a number of small cracks that I missed the first time around because they were so small. But I was tipped off to look for these cracks as the aluminum cover is a weak point in the design of the Controlled Coupling Hydramatic / Jetaway transmission:
The cracks were really small and get lost in the .jpg compression.
In addition, the bushing in the pump housing had spun and was stuck on the end of the driven torus. The driven torus had to be replaced because the spun bushing took about .006” off of the shaft.
Bushing stuck on torus shaft.
The bushing should be in the pump housing – and it should be in there tight.
I ended up ordering a complete front coupling unit (driven torus, driving torus, coupling cover) from http://www.autotran.us" onclick="window.open(this.href);return false;. The driven and driving torus were N.O.S. in the original GM packaging. The coupling cover was a first rate reproduction – every bit as good as the original. I heard about David Edwards from another fellow in the Cadillac club and I can highly recommend him. He’s open in the evenings which is very convenient for the hobbyist. If you need a small part he’ll toss it in a padded envelope and you’ll get it in a couple of days – very convenient when you realize you missed a small part.
Here I am inserting the new bushing. I used to Permatex sleeve retainer to make sure it would not spin loose again:
Bushing going in to pump housing.
And here’s the front torus going together. This step can be a little tricky. I recommend using a screwdriver as shown to hold the driven torus in place in the coupling cover. To get the driven torus in the proper position requires that an oil seal on the driven torus shaft finds it’s way into the cover without breaking – you’ll know what I mean when you try to put one together.
Drive torus held in place with screwdriver.
And the next step is to squeeze everything together. The service manual tells you to whack the whole thing together, but you’ll see that this can result in a broken oil seal. Be sure to lube everything up with Vaseline. The o-ring seals (called spaghetti o-rings) for the coupling cover come in various sizes. Ask for the thicker ones as they are less likely to twist – if you order from David Edwards at http://www.autran.us" onclick="window.open(this.href);return false; he’ll know what you are talking about.
Coming together – squeeze carefully making sure nothing binds.
I also replaced the bushing in the bell housing and front unit drive gear because they were a little sloppy.
When I reinstalled the transmission, she worked like a champ….for a while.
Third Pull
So I’m driving along on a nice hot summer day and sure enough the tranny starts to slip out of fourth gear and settle in third gear. Needless to say, I’m about ready to pull my hair out. For whatever reason, the front coupling unit was losing pressure again, but why?
I proceeded to attach a pressure gauge to the transmission which was very revealing. When she was cold, the transmission would maintain pressure as per the service manual. However, when she was hot and got ready to shift into fourth, the pressure would drop below 30 PSI and then pop back up to 60 PSI and the transmission would stay in third gear. By design, the transmission was cutting off fluid to the front coupling unit (via the limit valve) since it could not maintain pressure.
So I pulled the tranny again (I was getting really good at that). I applied compressed air to the front coupling unit signaling passage and I would hear a lot of compressed air leaking. I noticed this the other time I had the transmission out of the car, but I figured it was by design. I started to think that perhaps something was wrong because I didn’t get much air leakage at all when I applied pressure to the other passages. On a hunch, I ordered a N.O.S. front pump cover oil ring from http://www.autotran.us" onclick="window.open(this.href);return false; to compare to the one that I had. Sure enough, the one that I had was slightly smaller. When I assembled the transmission with the new oil ring, I had no more compressed air leakage from the front coupling unit signaling passage. When I applied compressed air, the exhaust valves would close.
The following pictures illustrate what I did to confirm my problem:
Here’s the culprit – the oil ring was not the correct size.
To confirm my theory, I wanted to bench test the front coupling unit. Here’s the assembled coupling unit:
Assembled front coupling unit.
Next I installed the front pump cover with the correct size oil ring. I used clamps so the compressed air would not blow the cover off. When I applied compressed air, the exhaust valves would close. To further confirm my theory, I put the old (undersized) oil ring back on and air would leak and the valves would not close unless I applied a LOT of air. Oh Happy Day….it felt so good to find the problem. This explains why the tranny would work when it was cold – the oil was nice and thick and could build up enough pressure to close the exhaust valves despite the leak from the oil ring. When the tranny heated up, the oil thinned out and could not maintain enough pressure to keep the exhaust valves closed.
Applying compressed air to verify closure of exhaust valves.
Since I had the transmission apart, I noticed some galling inside the pump. Since David Edwards had some N.O.S. pumps on the shelf, I figured I might as well eliminate the possibility of my pump being a problem as well (after all, I was not going to pull the tranny for the fourth time). I took the old pump down to a local tranny shop and they said it looked worn out. Here are some pictures of the old and new pumps:
Old Pump: Notice the metal galling which was deep enough to catch your fingernail on.
New Pump: Notice the smooth surfaces. You can even see the original grease pencil writing from the factory.
Notice the metal galling on the old pump roter to the right.
Here’s another tip: I noticed that the filter element in my filter had come loose. Upon disassembly, I noticed that elements are glued to the housing. Since the metal on the housing is smooth, it is no surprise to me that the element came loose. You will notice four dimples on the bottom part of the pump, but the dimples are not tall enough to support the element from underneath.
Notice how the element has come loose on the old filter.
I ordered a new filter from http://www.autotran.us" onclick="window.open(this.href);return false; and it was the exact same type as my original filter which I ordered from another source. To avoid the same issue with my replacement filter, I inserted some springs to support the element from underneath (ACE Hardware has these springs). This is a design improvement that the manufacturer should adopt in my opinion. I’d be interested to look at a filter manufactured in the 50’s and 60’s to see if the design would allow the element to come loose:
I used four light weight springs.
And I pushed them in so they would center over the indentations.
I’m an expert at installing the tranny. Here’s a step by step sequence:
Looking to the left, the engine is supported by the oil pan.
I re-purposed the jack from our Toyota minivan and slipped under the bell housing. I used a floor jack for the rear of the transmission.
Up, up, up
When she was high enough, I inserted the tranny jack.
It is not difficult at all to get everything to line up using a tranny jack on wheels.
As I write this, it’s been about a year since I last installed the tranny, and she’s working like a champ!
What I Learned
Rebuilding the transmission was not as intimidating as I once thought it would be. Sure, I didn’t want to have to pull it three time, but I’m told that even the best don’t always get these things working the first time around. If you keep track of the parts you’ll be in good shape. If you take the time to learn how the transmission works, you’ll avoid mistakes and appreciate what sort of mistakes the more casual mechanic would make. You can test the function of the coupling unit, clutch packs and reverse cone using compressed air.
The service manual calls for a number of specialized tools, but I was able to fabricate most of the tools that I needed. Here’s an example of a rear clutch spring compressor tool that I built:
Example of tool that I fabricated to compress rear clutch spings.
However, there is one critical tool that one needs to rebuild the transmission properly and that’s the Front Unit End Play Checking Gage. I was lucky enough to find the tool (Kent Moore J-6282) from a gentleman that specializes in old Kent-Moore tools. You can contact him at: toolzguy@aol.com. If you hire somebody to rebuild your transmission, ask if they have this tool. Without this tool there is no way to accurately ascertain the proper selective washer to use on the front coupling unit (David Edwards at http://www.autotran.us" onclick="window.open(this.href);return false; has these washers by the way). You also have to use this tool with a No. 1 1956-57 selective spacer part number 8616703. Again, David Edwards has that part.
Here’s the section of the manual that addresses Front Unit End Clearance.