This may be a dumb question,but here goes. Has Chevrolet ever put a turbo 350 tranny behind a 6.2L diesel?
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This may be a dumb question,but here goes. Has Chevrolet ever put a turbo 350 tranny behind a 6.2L diesel?
Little late here but no, they have not. The 6.2L and TH700R4 came out together.
.......or the TH400 in 3/4 and 1 tons. No TH350.
Not from the factory, bunch of trucks running around with 'em in them though. They were "transplants" back in the day when someones 700R4 died and didn't want to pay to fix it, again. The main reason you'll find that someone put a TH350 in is that the length of the trans is very similar to the TH700.
My first 6.2L diesel equipped truck (a 4 year old GMC K1500 with 51,000 miles on the odo) had a TH350 3-speed automatic in it, though the truck had been equipped with a TH700R4 from the factory. The non-OD 350 worked fine for the 55-mph federal speed limit of the day. It took a few years before the 700R4 became the reliable transmission it eventually became. I re-installed a 700R4 in this truck in the mid 1990s, and was one of the best upgrades I could have done. The 700 first appeared in the 1982 model year.
Back in the day, a number of aftermarket companies produced adapters that made the downgrade easy.
Jim
I had an 82 K5 (Jimmy) with a 6.2 and the 700R
The tranny gave up and literally scattered all over the street in a splash of oil and broken parts.
The 700R was very expensive to rebuild then and finding a good core was tough too (at an affordable price)
I used a spacer and a slightly longer tail shaft (all came in a kit) and replaced the 700R with a TH350.
Truck got about the same mileage as it did with the 700R too.
Truck was equipped with 3.42 gears and I had oversized the tires some too, so the change in trannies was not a big deal.
The TH350 IMHO is a far better tranny that the 700 ever thought of being.
A 350 with just a shift kit added will outlive a 700R and take just about anything you can toss at it.
One box thats not talked about often is the TH350 C, these had a lockup converter, but were otherwise just like any other 350.
With the lockup conveter most of the mileage loss is gained back, unless you are running low butt gears.
My K5 always got about 20-24 MPG and it did about the same with the 350 as it did with the 700.
I sold that truck to a local fellow and he had a 700R put back in the truck and it died within a year, so they put the 350 that I sold it with back in.
As far as I know that same 350 is still in the truck today and this all took place in the late 80's.
Best tranny bar none for holding up and not needing any fooling around is the old TH400.
A 400 with a shift kit and cooler can take just about anything you can throw at it and shrug it off.
Now if we start talking DMax level power, then the Allison comes into view.
The only issue with the 400 or the 350 is that when used with the diesel engine, there is a need for some sort of vacuum and controls to handle the needs of the TV circuit.
The factory used a vacuum switch mounted to the IP that sent controlled vacuum to the modulator to maintain the correct TV pressure.
This system worked quite well actually.
Adjustments were either done by the seat of the pants or by a gauge setup.
I always used a pressure gauge and the old Butt dyno.
As long as the vacuum was not too low at moderate to heavy throttle, you were fine and the tranny was happy.
The reason for the 6.2 was really all about keeping the CAFE (corporate average fuel economy) numbers up and the 6.2 coupled with the 700R did a fabulous job at this.
Even a 2500 Burb 4x4 with 4.10 gears could (when new) pull down 20 MPG ++ out on the highway.
This was using a TH400 and not the OD trannies.
The 350 was pretty much phased out when the 700R came on the scene.
The 700 was used in almost all the rear wheel drive cars and 1/2 trucks and the S10 too.
The big difference was what they installed in the box in the way of clutches and the VB settings.
The cars and such got a very light duty 700 and the 1/2 ton pickups and Burbs got a heavier duty one. (dont confuse this with REAL HD)
Now, the truth is, the 700R as it hit the streets was an abortion, with more problems than anyone needed.
It was not until about 1987 after amny many changes and upgrades and the aftermarket folks had really dug in and got traction that the 700 finally became fairly reliable.
To some it up, the TH 350 will do an admirable job behind a 6.2
Just some thoughts.
Missy
My 1982 Suburban has a 700R4 transmission in it as well. The tranny died so I had it rebuilt. About 6 months later, I installed headers and high flow exhaust which increased power considerably. Not even a week later, the tranny scattered in pieces 1500 miles from home and was a total loss. So I had a 700R4 out of an 89 rebuilt and installed. Fast forward 10 years and so far, I haven't had any issues. I am careful with it and only tow in 3rd gear.
I am considering finding a TH-350C for my Suburban because I am just not happy with my 700. I don't like the way it shifts, I don't like the "flimsy" feel it has (I can't put a finger on that one; I just don't trust it) and I have a vibration at 60-65 MPH that I know has to be internal to the transmission. It's not engine speed dependent, but road speed dependent. I thought it might be the driveshaft, but I know it's in balance and my driveline angles are good, as well as my U-Joints. I even swapped it into my in-law's Suburban and took it for a drive and it was smooth as silk. The problem with this plan is my rear axle has 3.73 gears. Since I don't tow with this, and since this engine likes 2nd gear even from about 5 mph (1st is so low it's about useless) I intend to run 2.73 gears in the rear end. FWIW that will make the TH-350 2nd gear act like cruising with a 4.10 rear if I am driving up a steep grade, so I have no worries about it being underpowered. The overall effective ratio in top gear with the 700 is 2.62:1, so 2.73:1 without overdrive will work just fine. I actually know how to work on a TH-350, they are cheap, and I have never been let down by one. I like it better than the 700, and I wish I would have gone that route to begin with. When I do the diesel conversion to my F-150 (it will be getting a 6.2L someday) it will get a TH-400 since I use it to tow and haul alot. But my Sub is going to eventually get a TH-350C and I hope to have a Custom Cruiser Wagon with a 5.7L diesel and a TH-350C in that one too.
The fly in the ointment is that I have no VRV on my I.P., so I'll have to install a cable operated modulator and figure out how I can actuate it and the kickdown cable. I'll also have to install a reluctor wheel for the electronic speedo, which I'll have to re-program for the change in axle ratio. As for TCC engagement, I'll wire it with a 3rd gear pressure switch and a brake interrupt switch. I'll put a "highway" button on the dash, and it will be used only during highway travel.
Then I'll be as confident with the driveline as I am with the engine!
Need to know what transmission fluid to put into it and many more questions your the only person in 3 days searching who knows anything about these vehiclesQuote:
Originally Posted by Robyn
Dextron 2 or 3 should be good for the 400,at least it has been good in mine.
I have not tried any of the synthetic versions
As Yukon said
Dexron....2...3 all will do fine