Tranny- Rebuild or replace with other? Please advise!!

[g.gifford]

My ailing tranny finally went yesterday on my '90 Grand. I am curious if there are other compatible trannies that I could consider as a replacement (like something with an overdrive) as opposed the the standard 3 speed automatic. I do mostly city/ highway driving and less revs at speed would be nice (and better for mileage?) Or is it better just to rebuild the existing tranny? Your advice/ comments are appreciated.

[Will Morris]

There's no easy bolt in solution. I'd rebuild the existing one as the TF727 is a very heavy duty transmission, and it would take you a couple years to get back the money for an overdrive swap based just on fuel economy. However if you're willing to shell out 2k or so, and want to be able to drive faster with less engine noise, overdrive is the way to go. Besides, unless you have made a gear change, you'll have 2.72s or 3.31s which would make an overdrive pretty useless because the engine would be out of its power band on the highway because the revs would be so low.

Will

[g.gifford]

So the only real solution to getting less rpm's at speed is to swap for an overdrive unit? Do you know manufacturer's/ model #'s of overdrive units that might work? These are in the 2 K range you say? Ouch. How much should I reasonably expect to pay for a 727 rebuild?

[andy d]

my brother paid 900@ for a complete overhaul. didnt do a thing himself but wince when he paid the bill. at best you have a 3.31 axle ratio, more'n likely, its a 2.73. those are tall. to put an overdrive on them is to lose any accelleration at all. it would kickdown at the least incline. so there you are back in 1:1 again. to use an overdrive effectively, you would need to go for a higher axle ratio too. simpler to save the money for gas or a more efficient daily driver. theres no such thing as a free lunch, tnstaafl

[Will Morris]

Well these are inherently fuel inefficient vehicles, but if you do a search in the Tech forum for overdrive transmissions, you should get a lot of info. Tire size or gear ratio changes will also affect your RPMs. I haven't had a TF727 rebuilt, but I'd say probably around $500 maybe more or less dependingon shops in your area.

Will

[gsmikie]

rebuild and put fuel injection on it

[mechanic58]

Overhaul your torque-flite. Prolly one of the best automatic transmissions ever made.

[Ralph]

Prolly one of the best automatic transmissions ever made. ...except for that dad-gummed reverse band!

[ February 23, 2003, 11:11 PM: Message edited by: Ralph ]