Hello,
I'm converting my 58 from powerglide to turboglide. I need some info as to what is interchangeable between the two. I have transmission, torque converter and lower tin cover. I assume the flex plate, rear crankshaft bush, starter, cooler and vacuum lines, gear shift and accelerator rods are different, are there any other differences I have overlooked? Also, what other cars is this starter motor fitted to?
Any help with these questions or parts would be appreciated.
Ian.

Ian, I would like to know why you are converting to Turboglide, I doubt that many in the US ever consider making this change, we feel that the Powerglide is a better transmission. In my opinion the Turboglide was a failure back when they were new. I would hope that if you are changing from a Powerglide that you would change to a Turbo- Hydramatic, which is what Chevrolet went to when they made a change. My 68 Impala came from the factory with a TH400 transmission. Most of the US street rodders go to a Chevrolet TH350 or a TH400 transmission and a 305 or 350 Small block which is a good inexpensive setup. Many F0RD pre WWII cars and pickup street rods are "F0RD tuff, powered with Chevrolet stuff!"

A 305? Wow....none of the street rodders that I know in this area would even consider using a 305 in their street rods. I had a 305 engine and I couldn't even give it away for free to a street rodder, so the "boat anchor" went to the scrap yard.

Well the Street rodders here in Texas often use the 305 because of it's economy and because they are more plentiful and cheaper than a 350 used. They make a nice engine if you can find a low milage one in a car or a 1/2 ton pickup if you do a lot of tours and cruizes, also they are hard to tell if it is a 305 or a 350 in the street rod for an untrained eye. I know several builders that will buy one out of a wrecked Chevrolet Impala or Caprice old company cars from 1976 up thru 1993 and clean it off and put it in a street rod without even pulling the valve covers, they will "rebuild it" with a bright paint job and some chrome and away they go! I know several that have 15 or 20 old cars sitting in the back pasture as a supply for 350 transmissions and 305, 350 engines. It only takes a typo to make a 305 into a 350! Like JunkYardDog said they are CHEAP, and a good one will run for a long time if you keep it full of oil and coolant. I drove one in a 81 Chevrolet Caprice company car for 140K miles and it was still going strong, getting 24 MPG when I had to trade it in for a leased Ford Taurus v/6 powerless piece of junk with a 15 gallon fuel tank and it got 15 MPG.

By the way, I don't know of anyone that would swap a Powerglide for a Turboglide.

Hum.....I guess that dudes prefer things smaller in Texas, including engines. Yep, 140,000 miles on a 305 is pretty cool, but I have a 350 with 400,000 miles! I kept the 350 and junked the 305.

I also agree it is not a good idea to swap out a Powerglide for a Turboglide.

I think it was real great that both of you were able to spend all of this time bashing this guy AND NOT GIVE HIM ONE BIT OF USEFUL INFOMATION OTHER THAN YOUR OPINION OF WHICH HE DID NOT ASK FOR! Well do either of you two know the answer to his questions? If you do then why did you not answer them? other then a voice in your head telling you how did you know he had a 305 in his car

I am pretty sure the starter is the same as the later style I will look it it up later when I get home
John

Johnny 348, I am so glad that you are back around here taking time to be so nice and friendly...what would we do without you?

I think that we gave him some valuable advice. I had a 58 Impala with Turboglide for about three months, then traded it in on a Pontiac Booneville.....

By the way, you might want to read those other posts, and this time R E A D a little slower... I don't recollect saying anything about his car having a 305, that was another deal....

The best advice I have for Ian is , don't make that swap from a Powerglide to a Turboglide.....that wasn't intended to be me bashing Ian.... I hardly know the guy.

Are your installing a 1958 iron PG or a 1963 and up aluminum?
The aluminum PG is the most easy conversion. The iron would look more original.
I can give more info once I know whch PG you are using.

Hi John! You are right, he didn't ask for our opinion and we didn't ask for yours either! If you will go back and take the time to read the postings you will see that no one is bashing Ian at all. Regarding the 305, Mr. Mack mentioned both the 305 and the 350 in passing, not Ian, and I was commenting back to Mr. Mack about the 305 tongue-in-cheek. You would have realized that if you would have taken the time to read and understand the postings more thoroughly. At any rate, the "bashing' comment is both unfounded and unwarranted.

Now, back to the subject: Ian, if you want to do the conversion check with All American Classics in Vancouver, Washington. They seem to have lots of parts for transmissions. Here is their web site: http://www.allamericanclassics.com/

Thanks for your help guys. I knew that this conversion would cause some reaction, let me explain. My convertible is a one owner Californian car, traveled 72 000 miles, with ordinal paint, upholstery etc. The only down side is floor rust, no big deal to replace. I have owned and stored it for around 20 years and got it running after last year on her anniversary. I run it monthly around the farm (she is not road legal) last month the trans went bang, it was stuck in top gear, noisy and full of filings when brought the car. I can get the cast iron P/G here easily, but T/G never came here. I brought a T/G while in Rapid City out of a nice car. I want to test this trans in the car before I restore it to see if I like the trans.
Thanks for the help,
Ian.

If the T.G. from Rapid City came out of a 1959-1961 chances are it will function properly. They were much improved over the 1958 units.

To install the cast irom P.G you will need;
Front drive shaft from a 1958 with P.G ...any engine
starter housing that bolts to engine
Long shift rod to trans
Shaft that bolts to flywheel housing and the kick-dow rod at the bottom of it
lever is probably on the side of the PG
(just about all the rods and linkage to P.G)
fly wheel
trans mount
I am sure I missed something

The T.G. works the best with a 348 engine. It requires an engine with more torque for the heavy 1958.
The T.G. does not shift, is completely smooth, and that was the advantage of that trans. It has a very exotic torque converter with a high stall speed and that is why it is so smooth. It must never be started off in the GR (Grade retard) position.

The P.G. is a simple 2 speed and torque converter unit. Gives fairly good performance and has just one shift and if linkage is correctly adjusted it is smooth. Works good with a 283 or 348.

Sorry _ originally I read that you want to convert a T.G to a P.G. I have never heard of any one converting a PG to TG.

If the TG "breaks" its almost impossible to find a rebuilder in this country (and the hard parts) say nothing about living in a far away country.

If it were mine I would keep a PG. A cast iron PG from a 1958-1962 will work.

For the TG you would also need the linkage bracket that is welded to the side of the frame rail and all the mentioned linkage. May be difficult to find.

And neither the P-glide or the T-Glide use a pilot bushing in the crank.
HOWEVER, a truboglide crank is drilled differntly than a P-Glide.
The problem is when you go to convert a T=Glide engine to a stick, it takes a different pilot bushing.
The problem with a lot of T-Glides is that it ran fine yesterday and this morning, it won't move. No warning given when they are about to fail.

If you are serious about this switch I would advise you to think this change over for a while, and while you are thinking try to locate a 350TH Hydramatic and the stuff needed to go that route, other wise get the PG rebuilt.
That Turboglide is nothing but a lot of work for you.
I think that you have doubts, because you sought our advice.

Yes, I forgot that problem. The T.G requires a larger pilot hole in the center of the crankshaft....and uses a different crankshaft.

Thanks for your reply's guys. I'm a motor mechanic and have experience overhauling auto transmissions, I have no experience with the turboglide though. People have told me that the T/G is unreliable, but they have not said what actually goes wrong with them. Is it through drivers pulling the transmission into GR while accelerating thinking it is a low gear? What was modified in 59 that improved the reliability? The transmission looks although it should be reliable, but you may be able to tell me different. If I don't decide to go with the T/G I will fit the cast iron powerglide.
Many thanks,
Ian.

he original 1957 and 1958 TG had cone type clutches for neutral, foward, and reverse clutch action. They were thin aluminum cones with clutch facing material bonded onto them. In 1959 the clutches were changed to much more durable multiple diisc type. The did make some change overs for 1958 that helped a little but the general construction of the transmission was still weak. It was suprising as the trans. didn't actulaat shift with the lever in Drive position. Any of the up-date parts for a 1958 would be almost impossible to find today. I would expect that even the rebuild parts for the 1959-61 would be difficult to come by.
In about 1964 Chevrolet sold an aluminum Power Glide along with the necessary parts to convert a TG car to the aluminum type Power Glide. This was much lighter than the old iron PG and looked more like a TG with the aluminum case and a removable pan.
There were very few mechanics that could rebuild a TG and even the experianced ones some times had to tear it down more than once to get it to function correctly.

Thanks for the explanation, that makes a bit more sense. I am one of those restorers who likes every thing to look 100 per cent correct, so it would be back to the cast iron powerglide.
I run a totally reliable non sifting powerglide in my 52 Bel Air, I assume that the 58 unit is more reliable. Also, is there a difference between the 283 and 348 turboglide. I would like to upgrade to he 348 before I restore the car.
Thanks,
Ian.

Both the PG and TG are the same for the 283 and 348.

I have been selling automatic transmission parts over 33 years and in all those years nobody ever wanted to or thought of putting a Turboglide in a Powerglide equipped car. The transmission fails too easily, almost no one wants (or can) work on them (I know a guy that just fixed a 1957 one 6 months ago, I supplied some of the parts) and the parts are hard to find.
The only reason to put a TG in a PG equipped car is if it came with a TG and it had been changed to a PG. And this would only be something you should do if you want a 100 point show car since it would hardly be driven anyway, if at all.
Dave

I recently watch a couple of very good examples of a TG on YouTube. It was especially interesting to me as I never had the chance to drive one or ride in one. I can't even remember one driving by, back in the old days. The car on YouTube is a '57. Let me know if any of you all need help finding it.

Bill

Thanks Bill, I'll have a look,
Ian.

Hello Ian,

I believe I read all the posts to your question and one thing is missing.....

You will need the crankshaft for the Turboglide.
Yes, you read that correctly.....the crankshaft needs to be compatible to the Turboglide torque converter. It has a more robust center hub due to its much larger size.

You can put a Powerglide in a Turboglide car no problem - but not the other way around.

Thanks Oliver,
I will keep that in mind,
Ian.