Hawaii89vette

I have an 89 Coupe. Seems as though the previous owner had put in a 350 Auto Transmission in my car. The original trans should have been a 700R4 4speed trans instead of the 350 3speed trans. My question is what would be the major differences between both. Also, if I wanted to change to the 700R4, what would I need to know about the 700R4 to install it. Like any specific connections, input/output shafts, drive shaft length, differential, etc, etc.

Thanks for any info

-Tim (mariah@hawaii.rr.com)

dtorc4

If you wanted to switch back to the 700, it should be a direct bolt on. Even if the driveshaft lengths are different, you could get a driveshaft from a variety of places since it is stock. I don't think you would have that hard of a time w/ a "retro" swap. :cheers:

Hawaii89vette

Would there be any benefits for me? Would overdrive give me better mileage? Would it give me more or less power, if any? Cost wise, I can get a recently rebuilt 700R4 for really cheap. It comes complete with valve body and stock torque converter. Would I want to change any of these for more low end power?

-Tim (mariah@hawaii.rr.com)

jimfl

The 700R4 that should be in your car is a great transmission which allows these cars to have excellent performance and still deliver 25-29 mpg on the highway. The big swap these days is to replace the 350 with a 700R4 in C3 cars. On the subject of how to restore your 89 I yield to the experts on this forum. regards, jim

65Z01

I think the 350 had closer ratios which is a benefit in racing.
You might check on the differential ratio, as it may have been changed too.
There's also the issue of what TC is now used.
Check under the hood to see if the TV cable is still there; I'm not sure if it's used on a 350 but the 700R/4 needs it. It attaches to the TB near the throttle cable and passes through a bracket attached to the left side of the plenum.

All the connections the the TC's lockup clutch and shifter electronics should be in tact if not now used.

mean8t

I may be able to help a little since I just put a 700r4 in my 80 vette in place of the old 350. The 700r4 is a better tranny in some ways and not quite as good in one particular way. The best thing about it is the overdrive and the 3.06 first gear compared to the 2.54 (I think) first gear in the 350. BUT as was said the wide ratios on the 700 causes a huge drop in RPM on the 1-2 shift, which will lead to a slightly slower 1/4 mile. Also you have to contend with whatever mods where done to the car to make the 350 fit. The 350 never came in a car with a torque arm so some sort of crossmember must have been fabed up. If there is some mod one to the car it may be easier to swap in a 200-4r which is a direct bolt in replacement for the 350, and with a few mods and a correct rebuild is just as strong as a 700. In addition to this it has a slightly higher (lower numerically first gear), i think it is 2.80 something. This will provide good acceleration of the line without the huge drop in RPM's the is part of the 350. All said if I could have do it all over again I would have put in a 200-4r in my vette. I hope this helps in making a decision.

edited to say: the 350 does not use a TV cable, it uses a vacuum modulator and a kickdown cable. The 200 uses a TV cable just like the 700, in fact you could use the stock 89 vette TV cable for the 200-4r


[Modified by mean8t, 12:00 PM 1/29/2002]

Vic'89

Are you sure you have a Turbo 350 in your car ?

Why would the previous owner do this ?

The 700R4's best feature is the overdrive, 4th gear !

Vic

Hawaii89vette

I'm not sure why the previous owner changed it to the 350 Trans. But I guess must have been because he wanted to race it.

-Tim

TIMSPEED

Why didn't he just put a PG in it then? :eek:

CFI-EFI

Rule of thumb: Glide isn't an advantage in a car over 2500 lbs.

mean8t

Some people believe that the 700 is a weak tranny. And actually it is, the 4L60 is the better version which came out in 89. Maybe this guy didn't know that much about the 700.

Hawaii89vette

Do you mean that my 1989 Coupe Supposed to have a 4L60 Trans?

Does anyone know what it supposed to have?

-Tim

Vic'89

The 89 Vette has a 700R4 from the factory or the 6 speed manual Tranny.

Vic