I'm thinking of replacing my TH350 with a 700R4 to get OD. Quick search on the web brings up a lot of so called heavy duty units. Are they any good? What problems will I run into? Will a 700R4 hold up or is there a better option?
The car is not a Vette, it's a 73 Nova with a mild 454. You guys are the ones I trust:)
Al
73 Nova, 454, TH350, 4.89 9" Ford. 12.00 @ 113 MPH street car.you want a 4L60E, pretty much the same as the 700R4, much more heavy duty. just my 2cents!
troy
Troy,
Thanks for the reply. The 4L60E needs a computer to shift. 700R4 is old school.
Al > Very old school:)
700R4 and 4L60 are two names for the same thing. A 4L60E is also the same, but computer controlled (sorry Troy, it's not any stronger). Pre 1988 700R4's weren't perfected yet. Avoid them. So, 1988 and up 700R4/4L60 is what you're looking for. There were a number of different tailhousing lengths. Avoid a Corvette model as it probably doesn't have normal rear mount.
It should be a bolt in (SB and BB are the same bell housing, right?). Models with a mechanical speedometer drive should hook right up to the speedo cable. You'll need a Throttle Valve cable bracket (very different than your TH350 kickdown cable), a TCC lockup controller, a shorter driveshaft, and probably a new transmission crossmember. The shifter will work but won't reach down to 1st. Be very careful with the throttle valve operation and adjustment. You can toast a perfectly good transmission in one launch if it's wrong.
Summit Racing sells all these parts. They'll also have new 700R4's that are built to take the abuse of your 454 Nova. I'd be hesitant to bolt up any junk yard transmission behind even a mild big block.
Not only will you get a nice overdrive that sips gas, but the 700R4 has a lower first for better launches.
Would you not consider a 4L80E to mate up with a big block?
----------- Elbert snipped-for-privacy@me.com
Well, sure, but I don't know much about them nor have I ever seen one. Performance catalogs only seem to list parts for the TH350, TH400, and 4L60/TH700R4.
Strange: I brought my '99 Jeep Grand Cherokee to the dealer today to have the transmission computer reprogrammed. It was a 4-speed automatic when I drove it in, and a 5-speed automatic when I drove it out! Hard to believe! The '01+ models are 5-speed and the only difference was the programming.
There must be more to the jeep story... there is no such thing as a hidden electronic "gear"... The programming might have changed when the TCC engaged.. The mechanical parts have to exist in the trans to support 5 speeds.
Some places are selling something called a 4L85E as a HD trans. You have to use a controller on these transmissions unless you have the engine harness and PCM out of a matching vehicle.
----------- Elbert snipped-for-privacy@me.com
It's hard to believe, but a flash update really did add a fifth gear!
The 1999 and 2000 are 4 speeds. The 2001-2004 are 5 speeds. They're mechanically identical. The only difference is the programming. Fifth just never engages on the older ones. Only Chrysler could say why!
It didn't ADD it, it ENABLED it, Elbert was spot on. Just a guess but perhaps the earlier engines were having trouble pulling the taller gearing so it was disabled to prevent warranty issues from lugging and hunting.
Yes, very good guess. Bob's warranty concern may have been related to making it pass smog for
70K miles. Once they got mileage on a mule they may have had more confidence cruising it in 5th.-- pj
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