Powerglide vs. TH-350

I have asked this question awhile ago, but did not get too much responce so I figured I would try again. I have a completely stock 60 bel-air with a 283 2bbl and a cast iron powerglide that I am using as my daily driver. I have a spare th-350 short shaft out of a 70 nova just laying in my garage and I was wondering two things. First, how easy of a swap will it be. I have heard the th-350 and the powerglide are the same size, use the same mount location, and same driveshaft and everything. Should be a direct swap. Is this true. Second, is there really any advantage to switching to a th-350? I figure three speeds are better than two, even though they both have 1:1 finals. There is nothing wrong with my cast iron powerglide, I was just wondering if it would be better on say gas mileage and for the car to have the three speed th-350. Thanks

 

Well, I can only give you an impression. I've got the same powerglide and several 350's lying around and they are very close to the same length. I haven't thought to compare mounting.

As you noted, they both have 1:1 finals so it's going to be shift points and how you're going to drive it that makes the difference. I don't see a particular advantage except maybe weight. Also, many racers use the alum powerglide for the two gears (note not stock form).

Ease of change?? i can tell you the PG is a PITA to take out from under the car and even out of the car it wasn't easy when on the ground.

 

T-350 has much lower ratio in 1st gear than PG, and you can run a higher gear in the rear axle without it being dead off the line. The racers who run PG are using strong engines, light bodies (usually), and low gears in the rear end.
I can't comment on the installation difficulties.
Dave

 

powerglide needs a bell crank for trans pressure
put in the 350 and save yourself some head aches
tk

 

A low powered street car will run & drive much better with the TH350, plus it'll shed 75 lbs.

As noted, gliders work great for high power, high stall, purpose built drag cars. IMO in a 283 street car they'll make an otherwise peppy car feel like a slug.

 

Changing will lead to two major problems.

1. You will shed rear tread depth much quicker.
2. You will wear out the carpet under the gas pedal much quicker.

The first gear ratio will liven up that tank.

 

You'll love the extra gear and kick yourself for not doing it earlier.
r

 

Being that you're dealing with a '60 283, make damned sure that the block has starter mounting provisions before you go through swapping to a TH350, only to find that you no can no longer bolt a starter to it.

 

I have an aluminum Powerglide and love it..... so much I removed the motor and trans for me to keep.(when I sold my last car) I would only switch things up if I where going to a 700r. what's the reason for the 350? A Powerglide and a low gear ratio 3rd member work just for the highway...

 

You will be amazed at how much more versatile the car is with the extra gear of a TH350. That and the weight savings add up to a win/win.

Frank

 

i run a powerglide in my 31 coupe behind a almost stock 327,love it, no problems,quick off the line . i have run powerglides in many hot rods in the past without any problems.

 

Thanks for all the fast replies guys. I will weigh my options and go from there. Thanks you have all helped me out a great deal. I think th-350 here I come.

 

Just so you know the front yoke on the drive shaft will have to be changed. Otherwise it is fine. My '55 chevy had a glide and I changed it to TH350 and once the yoke was changed the length was within 1/4 inch of where it should have been.

Now in Hotrod, like my roadster the glide is the way to go for period correctness, plus I love the whine!

 

Ahhh...but a coupe is a LOT lighter than a '60 Belair.
I'd dump the 'glide.
Don't know about the install ease, but, you will like that first gear...

 

But, like Heathen said; early small blocks used a starter that bolted to the bell housing, no turbo350 ever had that.

 

I do believe the 350 trans was availible starting in 58 as an optional trans, but not many were sold. I do remember having starters that were block mounted for them. So it's possible all blocks were drilled, even tho the majority of cars had the flange mount starter.

But that is the first thing to check before making any decision.

Frank

 

The switch from PG to TH350 really improved the performance of my pickup. Like, night and day.

 

Sorry Gas Pumper, but you are thinking of the Turboglide. The Turbo Hydro 350 came out later in the 60s, like circa 65. The Turboglide was an option in 58 thru 60? and was a strange beast with many a problem from what I understand. Anyway, I removed a Powerglide in my 64 Impala SS and replaced it with a TH 350. I did not have to alter the drive shaft, yoke or the transmission mount. It all bolted up fine, but it is a short shaft TH 350. The only thing that I had to mess with was the shifter. I had to weld on it some and modify it, I can't remember exactly what I did to it though. The driveability is much better now with the 3rd gear, and she will bark a third gear scratch as well. Go for it. BlackCherry

 

Here is a link to Transmission dimensions

http://www.tciauto.com/Products/TechInfo/trans_dims.asp

 

I don't know about changing just for the sake of change but if the Iron glide is going bad I would make the change for sure.

 

My own personal experience maybe 25 years ago. Rebuilt a 283 and put it and its powerglide in a 37 chevy sedan. Drove one season and thought something was wrong with motor.....real doggy and sluggish. The engine shop put a "corvette" cam in it during the rebuild. I thought maybe something serious was wrong. Could not spin tires unless pavement was wet. Changed the powerglide out for a 350 the next year. Drove like I had a different motor. Easy to peel a little rubber and felt overall much faster. As said here allready day and night difference. Steve

 

Black Cherry, Your'e right. I remembered turbo something anyway.
But I think I;m right about a different starter. Maybe

Frank

 

I have a Powerglide in my 50 Merc fodoor it came out of a 63 Impala SS <br> with the 327/300 hp and No Problem It lunches Great <br> just my 3 cents

 

I've got an aluminum one behind the 389 in my Pontiac. I built my engine pretty strong, not to mention Pontiacs put out a lot of torque.

I have an Art Carr shift kit and stall converter that locks up at 2500rpm. It has taken a beating over the years, up shifts from low to high around 80mph, lots of drag racing and it has done so without problems. My experience has been that they're nearly indestructible.

I don't see the need for a 350 turbo unless your car is geared really low and you need to lower cruising speed rpm's.

 

The Powerglide to 350 turbo swap was the best thing I ever did to my 66 Camino. Everything bolted up easy, but I used an aftermarket shifter so I didn't have to modify that. Made my car a lot funner to drive.

 

will a 350 with a 2 stage shift kit in it stand up to alotta down shifting?

 

Turboglide was available from 57 to 61 on both 283 and 348 engines. It had a block mounted starter. I would think that all blocks manufactured from 57 up would have the holes for the block mount starter. TH350 came along in the early 70's, superseding the Super Turbine 300 2 speed automatic, and of course the Powerslide.

 

I have done a few th350 swaps in place of glides in mid 60s impalas. Every time the car felt a whole bunch better to drive. These weren't high powered cars either. Mostly 283 or 327 cars and a couple also got upgraded from 2bbl to 4bbl (the cars that got the trans and intake/carb swap felt like 'racecars' compared to stock form.)

Not to mention the early glides took more hp to spin than the alum cased ones due to heavier internals.
I would do the swap in a minute, infact I am trying to get a friend to swap his iron glide out of his 348 powered 59 Impala and go to a th350 (or 700r4).
The lower first gear can help fuel economy especially if you do a fair amount of stop and go driving.

Adam D.-
The shift kit will not help the trans hold up to down shifting at all. In fact it could make it worse. The bands hold the drums during manual down shift( or upshifting) and these are usually what burns up first. I would go with a Kevlar band if you plan on doing much forced/manual downshifting under heavy load. But, I do run a th350 with stock replacement parts (and a shift kit) in the 54 and usuall manually shift up and down. I have had no trouble with it-it has been on the road 3yrs and is driven nearly daily from spring to fall.

 

If its weight your worried about, then you shouldnt be driving a 60 chevy. The powerglide should be just fine for what you need. If it aint broke, dont fix it. I vote for the 2 speed

 

Did this conversion to our '62 Chevy truck that had a 283 and cast-iron powerglide. Yes, it is well worth the effort, but beware.

When you hear it is a direct swap they seem to be talking about aluminum powerglide to turbo 350. The two problems you will run into with the cast-iron unit is the drive shaft length and the transmission mount/crossmember.

The cast-iron glide took a longer drive shaft length. Had to have ours cut down and of course balanced. That is $125 current price.

The trans mount was also a problem. On the stock crossmember it was too high and in the wrong location. Had to fab a cross member out of 3/8 steel that effectively lowered the crossmember height so that the mount could fit in between it and the trans. Not as bad as the driveshaft, just the expense of the steel for this and 5 drilled holes. Very simple, very strong. Been on there for 4 years now.

Tony