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Discussion Starter · #1 ·
I have been researching this quite a bit, but have not found answers to all my questions so I thought I would ask here since this forum came up quite a lot and has helped me a ton already.

I am building a Powerglide for a 66 caprice. Swapping a mild 400 Horse 489 into it. I want to make the trans reliable. So I can drive the car without having to worry that it might blow up if I step on it. Have bought the Glide Bible, which is on the way as well as some parts. Namely a steel high gear hub and a new input shaft.

Now as for the clutches. I want to upgrade the high clutch pack from the 4 disks. I have heard conflicting things about the OEM drums. Are there different OEM drums? Can I fit 5 or 6 friction discs into the standard 4 clutch drum by just throwing the wavy washer out without having to turn down the piston?

The reverse clutch had me kinda confused as well. The pack I pulled out of there had 6 friction disks in there. Is that normal? Every bit I read talked about 5 frictions.

Thanks in Advance

-Tim
 

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True Hotrodder
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Wow, a 6 disc clutch is quite a find. Probably not really needed in a street 'Glide but no harm either.

Removing the washer does give you some space and you might be able to squeeze a 5th disc in there but it'll be tight I bet. You want to end up with .010 per clutch disc so the 5 would be looking for .050 clearance. You can run a little bit less but it can lead to other issues. Best really is to put the 4 disc together, measure the clearance then measure what a 5th and 6th clutch pack would require - then take that number and have the piston milled that amount. If you want to invest in additional steels, you can find some that are thinner but I still think machining the piston is the easier approach.

I assume you're popping for another converter which brings up the question of the input shaft. You can go with a stock style shaft and probably be okay but generally we switch up to a turbo shaft as it's an inexpensive upgrade. But, the converter of course has to be setup to accept the turbo shaft.

The last bit would be taking a good solid look at the pump. In as long as it's not damaged in the pump gear area, I would at least replace the gear set with new gears. Verifying that the stator shaft has not rotated in the pump is another item to look at, if it has already started to do so, then replace the pump.
 

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Discussion Starter · #3 ·
Wow, a 6 disc clutch is quite a find. Probably not really needed in a street 'Glide but no harm either.

Removing the washer does give you some space and you might be able to squeeze a 5th disc in there but it'll be tight I bet. You want to end up with .010 per clutch disc so the 5 would be looking for .050 clearance. You can run a little bit less but it can lead to other issues. Best really is to put the 4 disc together, measure the clearance then measure what a 5th and 6th clutch pack would require - then take that number and have the piston milled that amount. If you want to invest in additional steels, you can find some that are thinner but I still think machining the piston is the easier approach.

I assume you're popping for another converter which brings up the question of the input shaft. You can go with a stock style shaft and probably be okay but generally we switch up to a turbo shaft as it's an inexpensive upgrade. But, the converter of course has to be setup to accept the turbo shaft.

The last bit would be taking a good solid look at the pump. In as long as it's not damaged in the pump gear area, I would at least replace the gear set with new gears. Verifying that the stator shaft has not rotated in the pump is another item to look at, if it has already started to do so, then replace the pump.
Thank You very much for the input.
On the high drum, are all stock drums capable for taking more clutches by turning down the piston? I have read that some have a longer splined area for the steels to grip into.

I already have a good turbo glide converter, so I was gonna stick with that. I just got a basic nice steel input shaft for it.

Pump looks really good. I can still see all of the machining marks on it and there seems to be 0 wear. I got new pump gears just in case though.
 

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True Hotrodder
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The only drums that I know are different are the aftermarket ones however there might be some OEM out there. Sonnax has one that is deeper and depending on the chosen piston can take up to 10 clutches. I have a 555" BBC in front of one of my glides with 6 clutches - last rebuild was just a few weeks back and they looked fine.
 

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Some OEM powerglide direct drums are not cut as deep for frictions and steels. Get your parts cleaned up. Test fit dry to see what you have for space. The aluminum piston can only be machined down so far. You do not want the base steel plate to drop below the notches in the drum.

make sure your converter has a bushing on the internal turbine hub or you have a bushing in the end of the stator tube. If you have a bushing in the stator tube, the input shaft must have a hole at the converter end for oil flow.
 

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Discussion Starter · #6 ·
Thanks for the help, I got my overhaul kit and was able to fit 6 clutches in the high gear drum and get people clearance by running two steels stacked without machining anything. I used those 60 thou raybestos clutches.

Now I am assembling everything and have ran into another problem. The rear pump drive pin has gone to town on the hole in The output shaft as well as the pump gears. I am thinking about just eliminating the rear pump. What exactly do I have to watch out for when doing this? Can I just remove the pump gears and assemble, or will that cause some internal fluid leak?
 

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Burnt out transmission tech.
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Thanks for the help, I got my overhaul kit and was able to fit 6 clutches in the high gear drum and get people clearance by running two steels stacked without machining anything. I used those 60 thou raybestos clutches.

Now I am assembling everything and have ran into another problem. The rear pump drive pin has gone to town on the hole in The output shaft as well as the pump gears. I am thinking about just eliminating the rear pump. What exactly do I have to watch out for when doing this? Can I just remove the pump gears and assemble, or will that cause some internal fluid leak?
It won’t shift if the pump is eliminated.
 

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True Hotrodder
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Arrhh - maybe.

I have the "bible" and need to look at that section on it. It's not something that I have run into before, but I'm thinking that I did read something about it - might have to block a feed hole at the back of the case but I'm not positive. I'll research it here in a bit and see what I can find for you.
 

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Discussion Starter · #10 ·
Arrhh - maybe.

I have the "bible" and need to look at that section on it. It's not something that I have run into before, but I'm thinking that I did read something about it - might have to block a feed hole at the back of the case but I'm not positive. I'll research it here in a bit and see what I can find for you.
Thanks for your effort. I have been leafing through Carl’s book and have just found info on doing a conversion for manual or trans break applications.
 

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Okay that's the same info that I have too. The only piece that caught me was "if the VB does not require the governor to work". Which brings up the question what is the difference in the pre-67 valve bodies compared to the 67 and later ones? The only thing that the rear pump was used for was the ability to push-start the car.

I found this old post:

"The aluminum powerglides were a single piece casting, as in the bellhousing was cast in one piece with the main body of the transmission. The tailhousing was a separate removable piece. Removing the rear pump involves disassembly of the rear governor and pump (inside the rear tailhousing) and making a thin round aluminum shim (.030 or so) that works as a gasket between the rear governor support and the rear of the transmission case. Throw away all of the rear pump parts except for the governor support casting. Two holes need to be drilled in that aluminum sheet (along with a larger center hole for the transmission output shaft) to allow fluid to flow through a crescent shaped slot in the governor support casting and back into a passage in the rear of the main case. You also need to cut a notch on the bottom side of the aluminum sheet to allow transmission fluid to flow back into the pan. Don't ask me for a whole lot more specifics, as I am recalling this from building a racing glide for my 67 Bel Air station wagon 45 or more years ago. Supposedly 67's didn't have rear pumps, but mine did. When you remove the rear pump assembly from your transmission I'm sure you will see the crescent shaped passage in the support. If your tranny case doesn't have holes that match each end of that crescent, you will need to drill the second hole. The aluminum gasket you are going to make will seal off any extra holes that are not needed. Good luck, but once you get in there I'm sure you will see what I'm describing."

I wish my pal Steve Oldani was still around - he could answer this in minutes. Steve passed away a number of years ago to cancer - RIP Steve - still miss you friend.
 

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Discussion Starter · #12 ·
I am willing to dive into this a bit. from what I gather the difference in the valvebody are the check valves which manage which pump supplies line pressure. I know which slot the post is talking about. It Transfers fluid up to the old case location to apply reverse.
The only problem Is that in doing as described pressure to the governor is cut off, so again it won’t be shifting.
Now I got to find out How the governor is supplied in the original later governor support. OEM gov supports seem to be readily available an pretty cheap.
 

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Discussion Starter · #13 ·
So looking at pictures of the newer gov support, it should be pretty simple to Convert away from the rear pump. Important being reverse and gov feed and return ports. Feed and return ports line up. The only thing that needs changing is the reverse apply. Like described in the book, capping the old piston feed and drilling put a new path to the reverse piston.
 

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Thanks for the help, I got my overhaul kit and was able to fit 6 clutches in the high gear drum and get people clearance by running two steels stacked without machining anything. I used those 60 thou raybestos clutches.

Now I am assembling everything and have ran into another problem. The rear pump drive pin has gone to town on the hole in The output shaft as well as the pump gears. I am thinking about just eliminating the rear pump. What exactly do I have to watch out for when doing this? Can I just remove the pump gears and assemble, or will that cause some internal fluid leak?
It would be much easier to get a newer transmission.
 

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Discussion Starter · #16 ·
I thought I would get back and share my findings to maybe help the next guy searching on google out.

To clarify the changes I made. I started with a 66 Rear Pump Glide, because of damage to the hole in the output shaft, which drives the rear pump, I was uncomfortable with the idea of just installing everything and hoping it holds. I did not want to change the output shaft and planetary assembly because of the cost. So I converted my Rear Pump Glide to a front pump only glide, while having it still having it shift by itself as it should. So if for any reason you want to convert a Rear Pump Glide to a Front pump only, while retaining the automatic function, this is how to do it.

First, you need to order the later 67 and up rear governor support. This will take place of the rear pump assembly.

Starting with case modifications. When using the later gov support the reverse piston apply hole in the case will need to be relocated

The hole next to the Horseshoe shaped indentation at 7 o'clock needs to be drilled through the case back behind the reverse apply piston. (Which should obviously not be in the case as it should be completely stripped to modify it. )
The hole at the 11 o'clock position is the current apply hole which needs to be tapped and plugged with a set screw.
Clean the metal shavings out of the case and deburr the holes. Now reverse will function with the new gov support.

The next Problem is the upshift.
Normally the rear pump provides pressure to the governor to let it control the upshift into high. When eliminating the rear pump the governor will no longer be supplied pressure and cant open the valve to apply the high clutch.
Now without the rear pump, the pressure will have to come from the front pump. To make a path for the front pump pressure the two check valves simply have to be taken out of the valve body. This will allow pressure to pass up to the gov support and feed the governor.

If you have the Powerglide Transmission Handbook by Carl Munroe (which you should when working on these transmissions and are a beginner like me) The case modifications are covered in detail in there.

I hope this helps someone even though the chances that this mod has to be made are slim.
 
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