Powerglide 1.76 Gearset Diagnosis - Impala Tech
Transmission & Driveline Transmissions & Differentials

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  • 1 Post By Deadwolf
  • 1 Post By Big Dave
 
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post #1 of 5 (permalink) Old 07-14-2019, 04:47 PM Thread Starter
 
 
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Powerglide 1.76 Gearset Diagnosis

Hey everyone. First post on here, though I've been a member for a while and it has been an excellent resource. Anyway, I began the teardown on my powerglide this weekend in preparation for a rebuild and noticed some serious discoloration on the gearset carrier (image attached). I just wanted to double check here and make sure this isn't from the brazing process during manufacturing. As far as I'm concerned it's evidence of severe overheating, but I wanted to double check before I try to source a replacement. It's the earlier 16 spline output shaft version so I don't think finding a replacement will be too easy. Thanks for any and all input.
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post #2 of 5 (permalink) Old 07-14-2019, 09:17 PM
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Welcome to the Team!

I have never played with a PG as they are just a broken TH350 in my opinion. I assume you want to keep it all original. but even so a newer stronger PG out of a 1968 would be a better choice than trying to rebuild the older one you have.

Even car show judges rarely compare casting dates and casting numbers. They just look to see if it is a PG or not.

Big Dave
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post #3 of 5 (permalink) Old 07-15-2019, 06:59 PM Thread Starter
 
 
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Quote:
Originally Posted by Big Dave View Post
Welcome to the Team!

I have never played with a PG as they are just a broken TH350 in my opinion. I assume you want to keep it all original. but even so a newer stronger PG out of a 1968 would be a better choice than trying to rebuild the older one you have.

Even car show judges rarely compare casting dates and casting numbers. They just look to see if it is a PG or not.

Big Dave

Dave, thanks for the advice. I'm already committed to putting this one back in the car but I appreciate the information regarding the limitations. I'll definitely keep that in mind going forward and keep my eyes out for a good 350.



I've spoken with a few older techs who all said this looks like it's just from the manufacturing process where the output shaft is brazed to the carrier. Going to gather a few more opinions and move on, just thought I'd share this info in case anyone ever finds themselves in the same place/with the same question. Gear endplays checked out and no other damage found so assuming all signs point to 'normal' I'll put it back in for the rebuild.


Thanks again
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post #4 of 5 (permalink) Old 07-16-2019, 09:41 AM
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I had to rebuild my PG out of a 66 I had when I was in high school a couple of times. Stock parts don't like hard launches into a low rear gears. That isn't uncommon from what I have seen and should do just fine.
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post #5 of 5 (permalink) Old 07-16-2019, 11:38 AM
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Problem with the PowerGlide is it is weak. People hear of race cars using a PowerGlide in their 2500 horsepower Top Alcohol dragsters but fail to realize that the only part of a Chevrolet produced PowerGlide is the name. They do not have a single stock power glide part (not even the oil pan as it is replaced with a deep cast aluminum finned one to reinforce the strength of the case).

The PG started out as a transmission for a six cylinder. It was never intended to be used behind a V8. Because a 283 can break one; Chevy had to redesign it three different times making parts bigger and stronger from 1950 when it was introduced as an air cooled transmission to allow mom to drive the car, to 1973 when it was discontinued it got better.

The six cylinder PG was rated at 177 ft/lbs while the V8 was rated at 215 ft/lbs back in the late sixties.The V8 PG has a bigger pump for higher line pressure, and additional clutches in the drums to transmit torque. Intermediate shafts where different also.

Big Dave
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carrier, gearset, overheating, powerglide, transmission

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