I replaced my tranny with one from another 94 gt (auto). When I test drove it my mph were (and still are) off by 9. If my speedo says 79 my car is going 70....the other day I was driving on the highway cruise set at 80 on the speedo and my car shifted in and out of OD a couple times. Here is what I'm thinking. The car I got the tranny from had different rear end gears and it is fooling with my computer. If that sounds good let me know. I figured I would just take the speedo gear off my old tranny and put it in the new one and that should fix the off mph and the shifting in and out of OD.....and while we are on the topic of trannys and gears, I have a set of 373's to put in my car (bought before I knew what was in the car) but my car has 320 something (I think)(drive shaft spins 3 and 1/4 times to one revolution of the tires. My question is....will there be that much of a difference between what I have and the 373's,,,,I don't want to spend a couple hundred bucks and not see much of a difference. Thanks in advance.
tranny and speed gear question
- Thread starter Bigdaddy
- Start date
"shifting in and out of OD" was the beginning of the end on my box, after that it went downhill rapidly.
The speedo will be off till you fit something like a Speedcal, i found the plastic gears in box just chewed up after a while after i went to 3:73, if your speedo was ok before, the original gear should cure it.
The shift points do change when you alter rear gears, but i doubt the o\d problem will go away i'm afraid, there is a wide ratio box available and it has something stamped on it to identify it, JR will be able to tell you.
The speedo will be off till you fit something like a Speedcal, i found the plastic gears in box just chewed up after a while after i went to 3:73, if your speedo was ok before, the original gear should cure it.
The shift points do change when you alter rear gears, but i doubt the o\d problem will go away i'm afraid, there is a wide ratio box available and it has something stamped on it to identify it, JR will be able to tell you.
If you check there's more than a few threads here, you will find the aftermarket speedo gears do chew up, i went through 3 before i got a speedcal, that uses the stock gear though which does'nt have any problems.
http://www.sn95forums.com/forum/index.php?topic=25708.0
Well i dont know the guy who built your box, but mine was untouched from new with 50k on it, i was sure after a while that the box and the converter were shot, power was down, acceleration poor, but at least it went, until the o\d started jumping in and out.
I tried a few things, inc the o\d servo and accumulator pistons, fluid etc, in the end i got another built box and b+m converter which i should have done first.
I found with the o\d switched off the box still functioned as before, but with 3:73 at the back the revs were pretty uncomfortable except at 30mph.
http://www.sn95forums.com/forum/index.php?topic=25708.0
Well i dont know the guy who built your box, but mine was untouched from new with 50k on it, i was sure after a while that the box and the converter were shot, power was down, acceleration poor, but at least it went, until the o\d started jumping in and out.
I tried a few things, inc the o\d servo and accumulator pistons, fluid etc, in the end i got another built box and b+m converter which i should have done first.
I found with the o\d switched off the box still functioned as before, but with 3:73 at the back the revs were pretty uncomfortable except at 30mph.
Well, the gear that I'm going to put i is the stock factory gear that was on my original box. As far as acceleration, power and shifting are great. If I'm not going to notice a considerable difference between the stock 327 and the 373's I'm not going to waste my time or money making the switch.
"but with 3:73 at the back the revs were pretty uncomfortable except at 30mph. "
To be fair that was with no overdrive, with my new box and converter at 70mph on the motorway with o\d on its doing round about 2000rpm, which is fairly comfortable and i still get a few mpg as well.
"To be fair that was with no overdrive, with my new box and converter at 70mph on the motorway with o\d on its doing round about 2000rpm, which is fairly comfortable and i still get a few mpg as well.
Well mine was a puny 2:73 when it started out, its now a 31 spline 3:73, so yes i noticed a big gain, i think you would need to be looking at 4:10 [or more ] to get a worthwile gain over yours, i think if mine had been 3:27 i would have stuck with them.
] to get a worthwile gain over yours, i think if mine had been 3:27 i would have stuck with them.I think I will stick with what I have and sell my 373's. I'm not planning on raceing my car , its my DD and its almost all highway to work so I really don't want to go with 410's (mabey if the car someday becomes a peoject car). Thanks for the help.
