Gearing with 700R4 transmission

[vfrdude]

I just converted to a 700R4. I currently have 3.08 gears. Right now I'm running at about 1600 RPM at 60 MPH. I'm thinking I should be closer to about 2000 RPM.

I'd like to know what gearing you guys are running that have a 700R4 transmission. It looks like 3.73 gears would be about right.

Thanks,

Rudy

[Tx Firefighter]

I've always used 3.73s with my overdrives. They match real well, super dooper acceleration and plenty of top end too.

[drink2mny]

I run 4.11's in my '72 with an overdrive.
I do alot of highway and I am always in OD for it. But around town or towing no problems at all..

[Mixup]

I've got 3:73 with a 700R4 and that combination works great.

[64fleetside]

I have 3.40's in my 64 w/700R4, with a 350 there is still plenty of low end. Great mileage. Brian

[hyperformance]

i'm gonna start with 3.73 but later i may run a tall tire and need 4.11. what solution did you use for the converter lockup? that and the stall rate of the convert would determine what gears. you wouldn't want the tranny in 4th going 60mph at 1600rpm and a 2000rpm stall converter. i'm still trying to get a good understanding of the 700r4, lockup convterter and how tire size + gear ratios effect this trans. so for now i'm using a stock converter in mine and the painless wiring lockup solution.

[vfrdude]

I actually paid to have the conversion done. I could have done it myself, but I'm in a time crunch right now as far as vehicles being down.

The way I understand it, when the converter is 'locked', it's a mechanical coupling, and the stall speed isn't a factor. The place that did the conversion said it was a 'one wire' hookup. I need to ask them more about this, because I recently read that with the converter 'locked', if the tires were stopped suddenly with the converter locked, (braking, causing tires to lock up), it could stall the motor.

I think I'll be going with the 3.73 gearing.......

[hyperformance]

yes, when the converter is in lockup it acts as mechanical coupling instead of a fluid coupling. if you were to slam on the brakes and told them for more than a second while the converter is locked up, the engine would most likely stall. the lockup is a one wire 12v circuit, it's either 12v on or no voltage, most poeple are just putting toggle switches in to supply the curcuit with 12v to lock the converter up (in any gear but 1st) but i think this could damage the trans or converter under certain conditions. EZ Wire (and Bowtie Overdrives) has a harness that sends the converter into lockup any time the trans is in 4th but this again is not how the trans was engineered. the Painless Wiring setup uses 12v and a vacuum signal so the trans can be in 4th and still go in and out of lockup. this seems more like it would function in a stock setup. plus a couple poeple i know used the painless stuff in 700r4 and said they drove better than any other 700r4 vehicles they'd dealt with.

[kwmech]

I have 4.56s with 31'' tall tires

[71Rat]

i built my 700r4 and put 4.10:1 in the rear.... i run a 28 inch tire and at about 80 i am running just over 2500.... i bought a TCI lockup kit.... in my opinion it is a just kit that was way over priced.... i am going to conver the trans to a non lock up..... i dont need fuel economy.... best of luck with your truck

[Longhorn Man]

The lock up is pretty much required (in an overdrive set up) if you want the tranny to live. The nature of spinning the drive shaft faster than the crank with no mechanical link will cause excesive slipping.

[poink 71 chev]

Where can I find the Painlees wiring setup for my 71 with a 700R4