gear ratio swap

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BarryC

BarryC

'74 Duster 360
Joined
Jun 30, 2008
Messages
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Location
Leitchfield, KY
Hey guys. Hoping to get some good feedback. I am going to go from 3.91 gears back to the factory original 2.94 to get some better cruising. I have an old Fairbanks converter in that is rated at 3000. Against the brake it goes 2700. When I used to have 3.55's in it, the converter work the same. I was wondering if you guys thought I would have any problems when I go to the 2.94's with the converter being too loose. I do know this car originally came out with a factory high stall converter in it. Not sure what they where rated at. Any you guys running the same or similar setup? Also, I'm still using the stock in-radiator cooler and want to stay with that. Thanks.
 
I don't know how it will drive but I am interested in the replys because the I am thinking of doing the same thing. We may have to keep it from shifting into high gear in slower traffic and up hills. I think it will cause more tranny slippage.
 
Im sure it will seem a little loser for the simple fact it will effcetly add more load to tun rear wheels. now by how much? i have no idea each car/converter combo is diffrent. yes it will make some more heat depending how your driving style is. The more its lugged i higher gears with low road speed the more heat. i would add an aux cool in addtion to your factoy cooler it can never hurt to have more cooling capacity.
 
Thanks. I do run an additional cooler. It will feel kinda sluggish.
What do you think, BarryC?
 
If you are going to run an old Fairbanks 3000 stall converter against those steep gears, it's going to raise your transmission temperature and have lots of inefficiency at cruise.

Modern torque converters are much better designs and my recommendation would be to contact Precision or another quality torque converter company and get their recommendation. The new style converters are dramatically more efficient than they were even 15 years ago.

Sure it's an extra $400, but the car will run and perform better without cooking your trans. You should also run an additional cooler after it goes through the radiator and perhaps a deep pan.
 
Thanks,
It makes sense that a better converter would be required.
Make one change and it often requires another. Next we will want a lockup...haha.
 
you wont like it. it will be a dog out of the hole, create to much heat for your stock cooler and give you poor mileage. the factory highstalls were around 1800. that and a 3.23 gear would be better imo.
 
I better rethink the gear change then. My transmission temperature often approaches 200 degrees as is.
 
Can't run aux cooler, no room. I already have a condenser in front of radiator. I thought the hi stall was looser than 1800. I think the Fairbanks converter I have is still a 11" converter. It acted the same as it does now when I had 3.55's. Creeps away at an idle, barely have to give any throttle. I'll probably try it and see what happens. Might have to swap with my old man, his is a 340 car with a really tight converter I use to have. Might be 1200, pulls when put in gear.
 
Sorry it took so long to reply.
Sensor is in the line coming out of the transmission because I wanted to know the temperature of the trans and not the cooled fluid.
 
zijmer said:
you wont like it. it will be a dog out of the hole, create to much heat for your stock cooler and give you poor mileage. the factory highstalls were around 1800. that and a 3.23 gear would be better imo.
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i dont think you will like it either,maybe with a 6 speed
 
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