Sad Transmission story,,,, help

[airemdwn]

My 700r4 in my 74 died last summer, thats ok it was due i had almost 10 years on it and lots of wheelin time with 38's and 42's. The guy who built that tranny retired and gave me another guy he said was really good. So i asked around and some Racers said he was pretty good, So i yanked out my tranny and gave it to him. I told him i needed it set up for towing. (after 5 trans in this truck i know from painful experience and my driving style that "towing" is the best way to go)

Well i installed it just b4 winter and Hated it. Wayy too high stall (he insisted on this new heavy duty one, as opposed to my old diesel one) and the 1-2 shift is so harsh it feels like its going to shatter the windshield. I called him back and he told me to bring it by. i left it there for 2 weeks and he said he fixed it?? well nothing changed. I ended up calling him a couple times and he said if i took it out he would work with me and only charge for parts.
Anyway long story short, or shorter. i dont trust him and its about time i get over my fear and learn these Transmissions for myself.

I see the videos for rebuilding them anyone have thoughts on which one is best or most informative, Where can i get a real GM manual for them?
I guess i trust the internal rebuild he did. Does anyone think i could just drop the valve body and do a shift kit to less the impact of the 1-2 shift?

 

[tRustyK5]

Are the shifts also delayed? it may be the TV cable isn't set correctly...

As for the convertor, why not just get a new diesel 700R-4 convertor for it if you liked it so much before?

Rene

 

[Fordum]

Actually it probably already has a shift kit in it, which is why its so rough.

First, ask around here for the correct way to set the TV cable. It is really really vital that it be set right.
Not only will it cause some of the things you are seeing, but will tear up the tranny if set wrong.

Now, if its OK, then it sounds like he has a heavy duty towing shift kit in it.
In a normal car or truck, when you go to shift, it kinda oozes from one gear to another.
While it is in-between the gears, the transmission is slipping. That is why it is so smooth. It gradually releases one clutch pack as it gradually applies the next.
For normal driving, that's fine.
But, you hang a heavy trailer back there, and you want to minimize the shift time. So the shift kits shift fast and hard.

I'm surprised he could not tame it some, but he is probably a by-the-book guy.

If you want to straighten it out yourself, ask him for the name and model of the shift kit he used.
If its a name brand, you can probably contact them and they can send you some different springs or whatever to put in the valve body to soften the shift.

I helped put a B&K shift kit in a friend's Camero in an apartment house parking lot one afternoon.
They made three levels for it back then, and he ordered the extreme.

When we got through, it would chirp the tires on every shift if he was on the gas even a little.

He loved it. But it was a rough ride around town.

J.

 

[Greg Ducato]

I am guessing he made some extreme modification to the 1-2 accumulator assembly if the 1-2 shift is disproportionately firmer than the other shifts. My advice is to pull the pan and remove the accumulator cover and piston. It is at the passenger side rear corner of the trans and secured to the seperator plate with two short and one long bolt, all with 10mm heads. Stock, the accumulator has a piston and a spring to control accumulator oil, which cushions the 1-2 shift. The stronger the spring, the less accumulator effect and thus firmer shift. I have seen some crazy mods to the accumulator ranging from solid bushings to limit stroke to lug nuts piled up instead of springs. The best shift is a clean shift without flare or slippage, extra firm shifts just break parts. Your best bet is a medium strength spring, I will be happy to send you one if you need it, just PM me. On the converter, the factory gas converter will stall about 1400-1600 in the 5.7 Blazer, the Diesel converter will be 1300-1400 so there is a difference. If you really notice a big stall change you may have gotten a converter modified for much higher stall speed. As far as books go, the factory GM manuals have a lot of good info and great illustrations, the ATRA and ATSG service manuals are also pretty good, though these are all geared for pro technicians a talented individual could build this trans with one.

 

[airemdwn]

Thanks for all the ideas. The 1-2 shift is seriously off. Im running an F.I. tourquey 383 with a 205 and 5.13's and its trying to twist the shaft right off the axle. That would be fine if i were 16 again running mud or in a drag car but its not what i was looking for. Power on upshifts 1-2 is out of the question in its current state.

Ive done shift kits in TH350's and 400's, but i never had a valvebody down in the 700. ive heard about the accumualtor and servo mods and with the electrics in the 700 i never tore into one, i always didnt have the time to really learn about them. Im not a novice with installs or setup. ive had it out more times than i care to remember and the 205 makes it oh so easy to drop, So i am familiar with the proper way to set it up and how and when it should be shifting. 2-3, and 3-4 +lockup work fine, except for the wrong stall.

Its already out of the truck to change the converter and while its on the bench i want to relax that 1-2 shift, I will check that accumulator and do plenty of research on rebuild vids and books.