5 friction/clutch clearance issue in a 904

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bobscuda67 said:
I installed 5 discs in a 4 clutch drum in my 904. I had the pressure plate machined with a narrow groove so the snap ring could be installed with the proper clearance.
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Aaaand there it is. :D
I have done this on a bunch of different transmissions, and it works perfect.

Won't work for that drum obviously.
There isn't anywhere near enough room there for the extra clutch and steel and then the lock ring.
 
bobscuda67 said:
I installed 5 discs in a 4 clutch drum in my 904. I had the pressure plate machined with a narrow groove so the snap ring could be installed with the proper clearance.
Click to expand...

Nice Bob! I know it's a long shot, but do you remember what thickness clutches/frictions you used in your set up?
 
TrailBeast said:
Aaaand there it is. :D
I have done this on a bunch of different transmissions, and it works perfect.

Won't work for that drum obviously.
There isn't anywhere near enough room there for the extra clutch and steel and then the lock ring.
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TrailBeast, which drum have you used in the past?
 
67CUDA273 said:
TrailBeast, which drum have you used in the past?
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Stock forward drum with four discs and a solid band, and 5 thin discs and steels in the direct drum by taking a little off the piston if need be, and cutting the outer edge of the outer pressure plate engough to get the retaining ring in and have the approximate right clearances.

Don't get me wrong, I am in NO way a race trans builder or a major pro at them or anything.
It was required learning on all major brands of standards and auto's where I worked, and then the little things you can do to make it work how you want came into it over the years.
Of course I probably dont remember 3/4 of it now, but then it isn't real relevent information to most anymore. (outdated by 30 years)
 
In the front drum...I have had the pressure plate cut a few thousand to get the proper clearance plus a nice new shining surface. This is with 5 thin disc and steels in a 4 disc drum.
 
TrailBeast said:
Stock forward drum with four discs and a solid band, and 5 thin discs and steels in the direct drum by taking a little off the piston if need be, and cutting the outer edge of the outer pressure plate engough to get the retaining ring in and have the approximate right clearances.

Don't get me wrong, I am in NO way a race trans builder or a major pro at them or anything.
It was required learning on all major brands of standards and auto's where I worked, and then the little things you can do to make it work how you want came into it over the years.
Of course I probably dont remember 3/4 of it now, but then it isn't real relevent information to most anymore. (outdated by 30 years)
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you know, the stuff we learnt 30 yrs ago still works very well today. i think its one of those retro things, what was old is now new again.
 
zijmer said:
you know, the stuff we learnt 30 yrs ago still works very well today. i think its one of those retro things, what was old is now new again.
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The basic function and use of hard parts still applies, but springs have been replaced with computer controlled servo's. :D

You used to be able to add half of another governor spring in with the existing spring to raise the shiftpoints across the board, but only in the higher road speeds because the first part of the travel of the governor used the resistance of the existing main spring.
Now it moves about half way easy like it did until it comes up against the extra half spring and it resists the shift longer. (basically the driveline has to spin faster for it to shift than it did before)

Any more you have to program the computers to do it. (performance chips)

I don't do any of it anymore, except my own and maybe to help here if possible.
Sometimes I run stuff by (Tracy) Fishy68 in case I miss something stupid. :D
He still does 727's.
 
You guys are a fountain of information. The "1/4 of what you still know" is a million times more than I hope to have under my belt! I've been working long hours b/c my boss is on vacation so hopefully tonight I can get back at it.
 
My clutch disc measured .083 dry. My Koleane steels measured .066.
I used a .060 snap ring and the measured clearance was .057 wet.
I hope this helps you out.
 
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you can measure your thickness of the extra friction and steel and extra clearance if needed. then have the outer edge cut like above. select your needed snap ring and leave out the wavy one.
 
Alright, so mystery solved. I pulled everything out, dried it off, and measured my gear. The frictions were .061" and the clutches were .068" (exactly what 70AARCuda said). So I thought maybe it had something to do with my new 24 spring return module.

The snap ring that I received with the 24-spring return module was a double wound type. I'm assuming it is for an alternative clutch/friction setup. It was taking up WAY too much space for my setup. I swapped it for the original snap ring and the 5 clutches/frictions fit perfectly now with my stock drum. I have dried everything out, and the frictions are now soaking in ATF.

Thank you all for the help! Sorry I was a dingus and didn't catch my mistake earlier!
 

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isnt that spirol snap ring for you spring retainer? it shouldnt affect your stackup.
 
zijmer said:
isnt that spirol snap ring for you spring retainer? it shouldnt affect your stackup.
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Agreed. That snap ring isn't in any proximity to the clutch discs so there's no way it will affect the clearance. All it does is hold the spring retainer in place. It's double wound to provide extra protection against breakage due to the extra spring pressure in the multi spring pack
 
fishy68 said:
Agreed. That snap ring isn't in any proximity to the clutch discs so there's no way it will affect the clearance. All it does is hold the spring retainer in place. It's double wound to provide extra protection against breakage due to the extra spring pressure in the multi spring pack
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I'll double check it tonight to see what was causing it to not seat flush in the groove. I definitely need that security with the extra pressure.

Thanks again!
 
One note you may be aware of. Just because the snap rings fits doesn't guarantee enough clearance. Best to check with feeler gauge once assembled dry.
 
I took off the snap ring, pressure plate, clutches and frictions. I compressed the return spring module down and removed the single snap ring. I put the double wound snap ring on, and this time it seated correctly. I measured the outer snap ring, and found it's at .076". I re-installed that snap ring and measured for clearance. According to the ATSG manual, I need .075" to .152" of clearance with the 5 clutch/friction set up. With my .076" snap ring, I'm only currently getting .020". It looks like .060" is the thinnest snap ring I can get, so that will put me at .036" of clearance. Close enough? Maybe machine down the pressure plate .045"+/-?

It looks like the clearance really matters at the rear clutch, and I'm good at .046".
 

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Another thing I noticed was that the snap ring was a flat snap ring, and not a waved snap ring like the book calls for. Any problems running this? From what I've read it sounds like this will bang 3rd and reverse a bit harder. Thoughts on this?
 
67CUDA273 said:
Another thing I noticed was that the snap ring was a flat snap ring, and not a waved snap ring like the book calls for. Any problems running this? From what I've read it sounds like this will bang 3rd and reverse a bit harder. Thoughts on this?
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the wavey snap ring was used as a cushion for reverse. using a flat snap ring will firm up the apply. a stall convertor eased the shock a little. rule of thumb is about .010 clearance per friction, so you need at least .050.
 
67CUDA273 said:
I took off the snap ring, pressure plate, clutches and frictions. I compressed the return spring module down and removed the single snap ring. I put the double wound snap ring on, and this time it seated correctly. I measured the outer snap ring, and found it's at .076". I re-installed that snap ring and measured for clearance. According to the ATSG manual, I need .075" to .152" of clearance with the 5 clutch/friction set up. With my .076" snap ring, I'm only currently getting .020". It looks like .060" is the thinnest snap ring I can get, so that will put me at .036" of clearance. Close enough? Maybe machine down the pressure plate .045"+/-?

It looks like the clearance really matters at the rear clutch, and I'm good at .046".
Click to expand...

.036 is definitely too tight. Sounds like there's no getting around getting the pressure plate milled. Personally I like to see .015 per clutch disc. in the front carrier so you need to get the pressure plate milled approx. .040" if you plan on using the .060 snap ring. .055-.060" if your wanting to use the .076 ring.. The high limit of .152 in the ATSG book is real loose for a performance build. The ATSG book is just a copy of the factory serv manual and factory specs vary greatly thus the reason for the wide range of tolerance. .046" is real good for the rear clutch. I usually run flat snap rings in any performance build. Like Zijmer said a loose converter will absorb shock so you don't usually feel the difference between a flat and wavy ring if you have a high stall converter. With a stock converter I'd use a wavy ring.

BTW: how much power are you running? I see in your tag line you say your engine is a 273. Is that correct? If so why are you fretting with installing 5 discs? 4 discs are plenty for anything short of a blown or nitrous injected 273 IMO
 
i was wondering the same. 67cuda had said at the begining he had a mild 273. but its been one heck of a learning session hasnt it!
 
fishy68 said:
.036 is definitely too tight. Sounds like there's no getting around getting the pressure plate milled. Personally I like to see .015 per clutch disc. in the front carrier so you need to get the pressure plate milled approx. .040" if you plan on using the .060 snap ring. .055-.060" if your wanting to use the .076 ring.. The high limit of .152 in the ATSG book is real loose for a performance build. The ATSG book is just a copy of the factory serv manual and factory specs vary greatly thus the reason for the wide range of tolerance. .046" is real good for the rear clutch. I usually run flat snap rings in any performance build. Like Zijmer said a loose converter will absorb shock so you don't usually feel the difference between a flat and wavy ring if you have a high stall converter. With a stock converter I'd use a wavy ring.

BTW: how much power are you running? I see in your tag line you say your engine is a 273. Is that correct? If so why are you fretting with installing 5 discs? 4 discs are plenty for anything short of a blown or nitrous injected 273 IMO
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The 273 is going to be a mild build at first. I'm thinking of having it bored .030" with the goal of trying to get as much power out of it without going crazy. Eventually I want to step up to a 340. YES this has definitely been a great learning session!
 
Fishy and Trailbeast were invaluable when I did my 904 , I bought a forged drum with a relocated groove with my kit and was able to get 4 thick and 2 thin in it , 6 are better than 5 eh LOL , most people I spoke with before doing mine said they had to machine their drums so I figured it was worth the extra cost to just buy a drum designed for what I wanted to do , the mixing and matching of clutches allowed me to avoid the search for the proper snap ring and pressure plate combo . 3 years and a lot of beating later it still shifts strong without slipping .
 
What about finding a 999, throwing in the lower gears, using the front drum and pump with his 904 input shaft to build a non lockup 904/999. Not so much for the five clutches, but for the lower gear for that mild 273. I agree that there is really no need for a five clutch setup on a mild 273.
 
cannucky said:
Fishy and Trailbeast were invaluable when I did my 904 , I bought a forged drum with a relocated groove with my kit and was able to get 4 thick and 2 thin in it , 6 are better than 5 eh LOL , most people I spoke with before doing mine said they had to machine their drums so I figured it was worth the extra cost to just buy a drum designed for what I wanted to do , the mixing and matching of clutches allowed me to avoid the search for the proper snap ring and pressure plate combo . 3 years and a lot of beating later it still shifts strong without slipping .
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This entire FORUM is invaluable for the amount of help, tips, and advice I've already received..and I'm just getting started. Hopefully one day I'm able to give back as much as I'm getting from all of your guys.

I'm going to have the pressure plate machined, but before I do so I'm going to get a wavy ring and re-measure the clearance. At this time I don't plan on upgrading the converter.
 
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