I have a 700R4 which needs to be rebuilt. I have been told that the tv cable on that particular transmission should probably be installed by a pro. I have also been told that the cost of rebuilding the 700R4 (including paying someone to properly install the tv cable) and purchasing a rebuilt TH400 (which I can install) is about the same.
If that's right, are there any advantages of one over the other? Which would you guys prefer? Is the tv cable all that tricky?
Thanks. Jake
I am not knocking a THM400 as it was a good tranny in its day but that day is long gone. The THM 400 (also called a 3L80) itself was replaced with a the 4L80 in 92 which is basically a THM 400 with a OD, a locking converter and a electronically controlled valve body. The
700R4 is a good trany when brought up to current spec and with a lttle work can easily handle a big block too.. Plus about a 700R4, on locking converter in 3 and 4th, no need for a computer for it to work, a wider gear ratio range from 3.06 first to .70 OD (a ratio spread of 4.37 to loweest to highest gear), and a deeper reverse too (2.29 vs 2.07). It is also a bit shorter than a THM400 too. Minuses of a THM 400, limited gear ratio rage of a 2.48 first to 1.0 drive (a ratio spread of 2.48) and no locking converter. In a 4x4 you can have your cake and eat it to with a 700R4 because you can run deep axle ratios for seriuos power and still cruise nicely in OD. An extreme example of this is that you can run 5.13's with a 700R4 and have a lower cruise RPM than with a THM400 and 3.73's. This means the with 3.73 and a THM 400 you first gear start up is 3.73 x 2.48 which equals 9.25 to one. Add a 2 to 1 converter stal that give you a maximum ratio factor of about 18 to 1 (300ft lbs in to tranny about puts 5400 ft lbs on axle shaft before drive train losses. With a 700R4 and 5.13's you have 5.13 x 3.06 equal 15.69. Add a 2 to 1 converter stall and you have about 31 to 1 startup ratio or 300 ft lbs in equals over 9000 ft lbs on axle shafts. High possible axle torque and lower cruise RPM than a THM400, this is why I say its day is passed.----------------- TheSnoMan.com
TY SnoMan, How about the difficulty of the tv cable? I have found several solutions online that promise easy install but the effort seems to be in "dialing it in". I'm a little nervous because one thing I read says the tv cable is vital for the survival of the 700R4.
SnoMan wrote:
The cable is not hard to adjust with a little trail and error and common sense. GM has been using TV cable since 69 when THM350 came out and it is not big deal to setup nor are you going to wreck your tranny dialing it in.
----------------- TheSnoMan.com
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