Power glide rear end swap

Discussion in '1947-1954' started by Chiro, Jan 25, 2008.

  1. Chiro

    Chiro Member

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    I have been toying with the possibility of doing this vs. going the Patirck's route (read EXPENSIVE here) to get a lower ratio in the back of the truck. I figure on saving the RPM's and engine life a little. The guy that gave me my truck just today dropped off an early birthday present to me. He brought by a torque tube rear from a '53 BelAir that had an inline six in it and a power glide. This rear end (if it is was it is supposed to be) should have a 3.73:1 ratio. While not as good as Patricks' 3.55:1, it is certainly better than the 3.90:1 I currently have. Free is for me. Rear was taken out of a running car just two weeks ago and the engine is already sold as well as the power glide.

    Question number one is; does anybody know if this will be a bolt up replacement or not?

    Question number two; if the splines on the shaft are different than those on my current torque tube, can I just take the yoke from the new torque tube and bolt it up to my current trunnion/u-joint at the ball seal. And...if that yoke does not mate up with the trunnion on my truck, shouldn't SOMEBODY make a yoke that matches the splines for the shaft in the torque tube and the trunnion on the truck and where would I find that resource? Driveshaft shop? I dunno??? I mean, this is GENEROUS MOTORS isn't it? Why would they make all the parts different?

    Question number three is; Where are the numbers on this rear and how do I decode them to find out what the ratio really is before I decide to do this or not.

    Point of information. Really good shop by me that can and will redrill the axles for 6 bolt pattern vs. the 5 bolt pattern on the car rear end.

    I have asked a similiar question on the Stovebolt site in the past and here as well, but now that I actually HAVE the rear, I need some more definitive answers.

    Help, I want to cruise in the fast lane without killing my engine. I don't want to fly mind you, just cruise at a comfortable 60, maybe 65 when needed to pass without red-lining my engine.

    Andy
     
    Last edited: Jan 25, 2008
  2. Kens 50 PU

    Kens 50 PU Member

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    Passenger car rear end ratios

    Andy, if my memory serves me correctly, standard transmission cars had 3.70 rear ends and automatic tranny cars had 3.55 rear ends. Look for a serial # on the passenger side of the carrier flange on the diff.
     
  3. vwnate1

    vwnate1 Member

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    Final Drive Ratios :

    Are always stamped in the edge of the ring gear and usualy also in the flat nose of the pinion gear .

    I don't know of the rear yoke's splines will match or not but I'd give it a look and maybe you can swap the output yoke of the tranny if needed ? .

    I'm keen to see how this turns out , as you said , it's a Generous Motors product so it may require some parts swapping but it _should_ be do-able .

    Good deal on the Bendix brake upgrade too ! .
     
  4. Chiro

    Chiro Member

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    I guess what I really need to know is if the part number for the rear yoke that goes into the torque tube is the same for both rear ends. Anybody have access to a parts book or know where I can look these parts up online? It's a '53 powerglide rear from a BelAir and the rear I have is a '54 1/2 ton truck rear. Is BIll Hanlon out there? I know he has a GMC master parts book. What about you, Ken? I know if it's on the web that you know WHERE on the web to find it.

    Andy
     
  5. Chiro

    Chiro Member

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    Okay, just did a little research on the Chev's of the '40's website. The u-joint rebuilt kit which consists of a new trunnion, bolts and hold-down clips is the same for cars and trucks. Sooooo.....it SHOULD follow that the yoke from a powerglide rear will bolt up to the trunnion for the truck. Only thing I need to know now is if the splines are the same for the torque tube rears for both rear ends as I do NOT have the yoke for the powerglide rear...yet. I asked the guy that dropped off the rear to me if that yoke was still around so I could match it up. He is going to get back to me. I hope this works. If it does, it will be a SWEET and cheap way to lower the rear ratio. Keeping my fingers crossed. If anybody out there has any more info on this, please let me know. Oh yeah, Chev's of the '40's also lists the ball seal kit as being different for the powerglide. Probably different in the way it mounts to the back of the trans. I'm figuring that I can just take the entire ball assembly with oakie bushing from the truck and all and swap it onto the powerglide torque tube as well if it actually is different. Also, if the yoke from the powerglide is not still available, my guy has another powerglide in a car in his yard and will pull the rear yoke for me if needed.

    Andy
     
    Last edited: Jan 26, 2008
  6. Kens 50 PU

    Kens 50 PU Member

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  7. Chiro

    Chiro Member

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    Ken,

    I KNEW you would know if it was online:D.

    Thanks,

    Andy
     
  8. Kens 50 PU

    Kens 50 PU Member

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    Andy, did some more research!

    In '53, chevy passenger cars had 3 different rear end set-ups. The sedan delivery had a 4.11 rear end, the standard shift cars had 3.70 and the powerglide equipped cars ran 3.55 rear ends. This info came from the "restoration pack" from GM on '53 models, so it ought to be valid.

    I'm a pretty simple minded fellow, so my obvious question would be: Couldn't a person simply swap out the gears in the differential and cruise on down the road? I KNOW someone out here will know that answer!
     
  9. Chiro

    Chiro Member

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    Yeah Ken,

    You would think that would be the easy way. However, I know that if I wanted to go with Patrick's gearing I would have to use a carrier from a '47-'53 truck as his gears do NOT work with the carrier for the '54 and 55.1. I believe the axles splines are different from cars to trucks as well so the whole rear would have to be swapped.

    Andy
     
  10. vwnate1

    vwnate1 Member

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    Torque Tube U-Joints 4 Trucks

    Andy ;

    I don't have catalogs but IIRC , the Torque Tube U-joint for a three speed 1/2 T. truck is the same as Passenger Car but the one for a four speed 1/2 T. truck is different...

    Of course you know better than to trust my memory , I'm sure if you collect enough parts you'll be able to piece it all to-gehter just fine :)

    To-day I got lost and spotted a complete '55 ~ '57 Task Force with Service Bed and a DeLuxe Nu-View '49 sans bed that looked pretty clean , not much paint left tho' .
     
  11. Chiro

    Chiro Member

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    Nate,

    Got the 4-speed for my truck from a hot-rodder in CT, from a '49 I think. Parts truck still had the 3-speed in it connected to the torque tube. I used the yoke and u-joint from the 3-speed for my (monstrously heavy) 4-speed when I put it all back together. Fit perfect. I knwo some catalogs list different part nimbers for 3 and 4 speed trannys, but the 3-speed joint worked fine for me.

    That's exactly what I'm doing right now. Collecting parts and taking measurements. Still haven't measured up the powerglide rear yet to see if the perches, drum to drum width and length of torque tube all match up yet, but it sure eyeballs like a match. Besides the measurements, the only question is the splines on the yoke for the powerglide rear. Should know soon as I am going to have my guy pull the yoke off the powerglide in his yard and see if it matches up to the trunnion in my truck.

    BTW I have a question about that zerk fitting near the ball seal on the 4-speed. If that was used to fill the trunnion area with gear oil at the factory, shouldn't I fill the ball area from that fitting with gear oil when I put it all together? I can't see how that area gets lube from the tranny as it seems to be on a much higher level than the oil level in the main part of the trans.

    Andy
     
  12. vwnate1

    vwnate1 Member

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    U-Joint Ball Zerk

    Yes Andy ;

    You can remove that and fill the cavity with gear oil .

    In general use , a small amount of gear oil dribbles through the rear bearing in the tranny .

    It's a mediocre design and is why so many Torque Tube U-Joints explode ~ lack of lubrication , it's critical to get the ball's fittment and seal " JustSo " so it won't leak out the small amount of lube it contains .

    I meant to mention that part about the different catalogs having different listings too but I forgot .

    At least there's still plenty of good N.O.S. ones on E-Pay and occasionally one of the Argentine ones from Jim Carter , is properly machined .

    OCCASIONALLY :rolleyes:
     
  13. Chiro

    Chiro Member

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    Okay sir.

    Then exactly how much gear oil should I put into the area upon re-assembly? I just put in a "goodly" amount by my judgement the first time. since I will be taking it apart again when I do the powerglide rear swap, I figured I'd ask. It was bugging me from time to time.

    Andy
     
  14. vwnate1

    vwnate1 Member

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    A goodly amount is fine , excess will leak out not to worry :rolleyes:

    Better too much than too little .
     
  15. Thunder54

    Thunder54 Member

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    Andy,
    You can fill your sm420 from that top zerk hole if you try (really slow, and not necessary). The manual says the tranny is full cold when the oil level is 1/2 below the overflow plug. Full hot when level to this same point.

    I am very experienced here.

    Jim
     
  16. Bill Hanlon

    Bill Hanlon Member

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    Would that be an English goodly or a metric goodly??
     
  17. Chiro

    Chiro Member

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    Powerglide rear swap is now a moot point. Took measurements today and the spring perches do not line up and the powerglide rear is a full 3 inches narrower than the truck rear drum to drum. Since the shock mounts just barely clear the rear now, it would be impossible to fit this rear under my truck. Nice thought while it lasted however.

    Andy
     
  18. vwnate1

    vwnate1 Member

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    OOps

    That was a no coffee yet , 1/2 asleep , 1/2 a$$ed answer on my part ,
    is what it was .

    I usually fill through the side fill port untill gear oil burps out , then let it sit for 15 mintues whilst I go cleanup or have coffee etc. , this allows the gear oil to (ever so slowly) flow through the rear bearing and fill the U-Joint cavity , then I give the pump a few more strokes untill it burps again and it's good to go .

    Too much tranny oil will leak out the open from bearing (there's NO seal on the input shaft) and thence all over your flywheel and clutch , sometimes it'll cause terrible clutch chatter (correctly called " Judder ") that will last until you wash the clutch plate & disc , do-able in situ but not a lot of fun .

    Sorry , guys .

    -Nate
     
  19. ol' chebby

    ol' chebby Member

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    Look into a Dodge Dakota rear end...6 lug and about the same track width. Switch out to an open shaft trans...cure all those problems quickly.
     
  20. Chiro

    Chiro Member

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    Thanks Old Chebby,

    Already working on a Muuncie SM420 open driveline trans. This is a swap that will have to wait for know. The truck runs and drives as is. gives the kids something to work on later on as they gain skills.

    Andy
     

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