2speed powerglide transmission pros & cons [Archive] - Impala Tech

: 2speed powerglide transmission pros & cons


Skyverado13
01-18-2010, 06:17 PM
HELLO ALL I HAVE A 62 IMPALA WITH A 283c.i.d. AND A 2 SPEED CAST IRON POWERGLIDE MY QUESTION IS SHOULD I CHANGE MY ORIGINAL 2 SPEED FOR A 350 TRANNY OR OTHER I HAVE HEARD THAT THE POWERGLIDE USES UP MORE FUEL DUE TO IT ONLY HAVING 2 GEARS AND ALSO IT PUTS MORE STRESS ON THE ENGINE? NOW I WILL ONLY USE MY CAR ON WEEKENDS AND ALSO WILL PRETTY MUCH JUST BE CRUISING RACING OR ANYTHING I WOULD REALLY LIKE TO KEEP THE ORIGINAL TRANSMISSION IN PLACE BUT IF ITS NOT WORTH LEAVING IT IN I AM PROBABLY GOUNG TO REPLACE IT...THANKS.

Big Dave
01-18-2010, 07:15 PM
First thing to answer is this a six cylinder cast iron air cooled PowerGlide or a V-8 version that has hydraulic oil cooling lines running to the radiator? If you have tranny cooling lines at your radiator and a cast iron case it is a V-8 version. If it is a V-8 version sell it to an early model figure eight racer as they can use it to push start the car with that transmission and they only use two gears for racing anyway. If it is the air cooled six cylinder version only the scrap dealer wants it as it is not very strong and overheats if pushed hard.

A PowerGlide transmission is a TH350 with a busted first gear. You take off in second gear every time. As you can imagine starting out in second gear is not going to win you any races. And yes it does strain things as the irresistible force of your two barrel 283 exerts itself against the immoveable object of a two ton Chevy full size car.

The TH350 is identically the same size as the PowerGlide and it interchanges with it directly bolting into place. The only difference between the two transmissions is in the shifter mechanism. You can still reuse the PowerGlide transmission shifter if you want to fore go the ability to manually select first gear, and just leave it in drive (it will down shift and up shift automatically which is why we call them automatics :) in the first place).

There is another option available to you. It is the 200R4 transmission. It is also identically the same size as the TH350 or the PowerGlide. You will need to move the transmission mount to the rear of the car the same distance as that used by the TH400 transmission (you may need a replacement cross member as the TH400 was not introduced until 1965 so your 1962 will not have holes already drilled in the frame to accept that transmission cross member being moved back like in newer cars will).

The 200R4 has four forward gears with high being an overdrive ratio that cuts your rear axel ratio by one third which results in a one third savings in your gas mileage. It also has a steeper first gear than the TH350 for better acceleration off of the stop light. This is the transmission that Buick selected to stick behind their GN and GX turbocharged V-9 engines that were faster than the Corvette the year it was introduced (those plain black V-6 powered cars beat up on a lot of V-8's back then). The 200R4 is found in Chevy full size police cars from 1987 to 1990 and many other applications (search 200R4 as I have typed out a full list of applications before on this board).

Big Dave

jayoldschool
01-18-2010, 10:34 PM
The 200R4 is found in Chevy full size police cars from 1987 to 1990

Only in 305 cars. 350 cars got the 700R4 because the 200-4R wasn't strong enough (torque capacity).

You can also find 200-4Rs in 82-90 full size RWD Cadillacs with the 4100 or the Olds 307.

Big Dave
01-18-2010, 11:05 PM
The 200R4 can be built as strong or stronger than the 700Rr transmission can. This guy has transmissions he sells prebuilt to support any level of power you can imagine.

http://www.cpttransmission.com/

But if you are running a cast iron PowerGlide now a stone stock 200R4 will be able to keep you happy as is.

Big Dave

Jeff406cid
01-19-2010, 07:33 AM
When wanting to move weight off the line, you want gearing. The 700R4 has the best first gear out of all the GM trans'. It has an great kicking the pants off a dead start. I pulled a best of 1.8sec 60ft times with my 70' Imp at @4,100 lbs.

novadude
01-19-2010, 10:55 AM
For cruising around town w/ a stock 283, there is NOTHING at all wrong with a Powerglide. Millions of 283 / PG combos went 100,000 miles or more in daily use, so don't worry about wear and tear on the engine. If performance is not a major concern, don't waste your money on a swap.

If you want performance, then look into a 3 or 4 speed automatic.

dcairns
01-21-2010, 05:53 PM
I would say if you are going through the bother to change the transmission, skip the TH350 and get the 200r4 or 700r4. The lower first gear and overdrive are great. As mentioned, the old Powerglide works fine, but if you want better accleration and quieter highway driving, the 4 speed overdrives are the way to go. Or if you really want a TH350, I will sell you my old one... in the process of dropping it now.

BA.
01-22-2010, 12:53 AM
I agree with all of the above and will go on record to say that IMO the 2 speed just doesn't have enough nuts with most stock small-blocks to get a heavy Impala off the line very well.

drabina
01-22-2010, 10:06 AM
Don't forget to check your rear gear ratio. I was thinking of swapping my TH350 for overdrive transmission but with my 2.59:1 gear ratio, it did not make any sense. With TH350 I am cruising at 60mph with less than 2000RPM on the tach.

csf64ss
02-17-2010, 11:57 PM
you guy's are the best!.....i enjoy your posts so much............so much info here.....

sandiegohat
05-20-2010, 01:19 AM
how many shifts do you feel on the tranny when you are driving it?

palalt
05-20-2010, 11:32 AM
how many shifts do you feel on the tranny when you are driving it?

Hec. You raised this question on another thread so I guess you need an answer. The Powerglide is a 2 speed transmission. Therefore, it only shifts once. You pull away from a stop in low gear, then it shifts into high gear. One shift. It's done.

05snopro440
09-07-2011, 02:09 PM
Although this is an older thread, I wanted to make a correction for anyone referencing it.

The 64 and earlier Powerglide transmission has the mount in the same location as the powerglide, but the tailshaft is 3 inches longer. the 65 and later powerglide is the same length as a TH350, but for 64 and ealier, changing to a TH350 from a PG you will need to shorten the front driveshaft.

Also, as Big Dave was mentioning about the 6-cylinder powerglide being air-cooled, this isn't true for a '62. My 62 with a 6-cylinder and a powerglide used the transmission cooler in the radiator. However, the bellhousing had a different bolt pattern for the 6-cylinder.

I also wanted to point out that top gear in the 2 and 3 speed transmissions is all the same, 1.00:1. In a powerglide, you are basically starting off in second gear when compared to a 3-speed (TH350 or TH400). Changing to a TH350 from a Powerglide will only make the car faster off the line, and will make absolutely no difference in your highway cruising RPM.

Another thing to be thought of is your engine's ideal RPM. A lot of guys change to a overdrive thinking they'll get better mileage, not thinking the cam in their engine needs higher RPM and now they're running at 1800 RPM on the highway and getting terrible mileage. It's a good idea to check the specs on your engine parts before reducing the cruising RPM, as you may be making it worse.