Hydramatic Repairs

[LEWISMATKIN]

great idea James. however, the manual you found is for the 315 hydramatic (commonnaly called the Jetaway or controlled-coupling hydra-matic) and was never installed in a truck. It came in 1956-60 oldsmobiles, 1956-64 cadillac & pontiac automobiles.

[James]

I did not know that. Thanks for the update.

[jbgroby]

OK, we decided upgrade and change the tranny out to a 700R4 (non-electronic) We have a source (unless one of the club members has a good one they want to sell. However, I will neet a cross member.

Does anyone have a suggested part number so I can begine a search.

Thanks
Jake

[AZKen]

The crossmember is easy, Have you already determined the bellhousing/flexplate, shift linkage, driveshaft yoke/length and overall adapting procedure to a 305? With all the hearsay, urban legend stories and different "adapters", I would sure mock it up or take your adapters and try them on a 700r4....... and try it on your motor before buying a bunch of stuff and find out it won't work. Unless, of course, you know what you are doing.

Buying things on ebay for a V6 from someone who says it fits is no guarantee. Little is posted about 700r4 to V6. Check with Lewis Matkin, Ed Snyder, BigBlockV6 and GMCNUT. I have yet to read a trusted 700r4 to V6 story. But I could have missed it.

Anyway, I like this kind because they are modifiable and bolt on. There are several versions and many sellers of this tubular type.

My experience (not V6) is: I buy a running trans for $100-300, get it rebuilt for $300-400. Sometimes I take a chance and run it without rebuild, just refreshed. There are lots of very experienced, retired or health issue or Military Vet, trans mechanics who work from home.

The 700r4 is a very good choice. The theory would be that all these "Chevy" transmission's have the same bolt patterns for tranny and torque converter, so adapter parts will work for them all.

[jbgroby]

Hi AZ,

I was able to score on the needed adaptor for upgrading to a more modern to bolt up to the V-6 (THANK YOU ED SCHNIDER FOR LOCATING IT!) I too would like to save funds, but I think I’m stuck with having to pay someone to install it, I simply do not have needed experience NOR lift. I’m trying to find a local good installer. I really only want to do this once, the trans should last the life of the truck. Checking several sites for 700R4 (Summit, TDI, etc) they are in the avgerage range from $995- $1300), you also have to make sure they come with the torque converter or you’re out another $150-200. I found some deals on eBay from Jegs/Summit, shipping is free. I just have to wait till Sept to do the deal.


I saw that adaptor and suspected it would work too, but never having bought one, its ALWAYS good to opinions.
Thanks

[jbgroby]

Trans-update.

Ok, I picked up a 700R4 and I had a torque converter built. Next week I'll bring in the torque converter and OEM flex plate and flywheel to the machine shop to have them cut a new flex plate to matchup with the original crankshaft holes. The flex plate is nothing fancy, just a perfect circle with the holes spaced right. The flex-plate I have now is shaped like a curved triangle, but I don't need to copy the pattern exact, just a plain circle will do.

I found the torque converter, which is custom made at

www.americanhotrodsolutions.com

I ordered a 12" diameter 2000 stall for the 700R4

$200 plus shipping, and MADE IN USA. Check out their website. The TC are made heavier duty than other brands.
I'll try to get pictures at the machine shop if I can but once I get all the parts in I'll post pictures.

I also picked of a new shift linkage.

[lizziemeister'sV6]

Was wondering why you considered/purchased a 2000 rpm stall converter? Being a V6 is such a low rpm running engine wouldn't any kind of a stall converter cause an annoyance due to excessive rpm of an engine that red lines at 3200 rpm? This is something you should consider before you continue on your conversion by asking an transmission shop/rebuilder what they think. What do the rest of you GMC V6 people think?

[bigblockv6]

Considering the fact that Jake is running a rear axle ratio of 3.23, an overdrive transmission and the 305 that makes maximum hp at 4000rpms, he should have no problem at all with a 2000rpm stall converter

[bigblockv6]

Maximum engine speed for the 305 V6 with no load is 3700 rpms not 3200.

[James]

When I get around to it, I am going to place my truck on a chassis dyno. I wanted to know how much and where my torque band is. If I was to go with an automatic transmission I think I would try to place it stall speed at max torque (I would like to put a camper back on so I think getting max torque to get the truck moving with a heavy load). This is just my opinion and way at looking at my setup. Every truck is different and have their own requirements.