I just ordered a very beefed up 700r4 for my 69. I was wondering if anyone could help on gear ratio? I have a 3.90 12 bolt right now, which with a 3200 stall, would be a stump puller. I really don't care to have a granny low 1st gear. lol...

I am putting in c-clip eliminators in it, so while I'm there... I should change the gear ratio... to make it more user friendly. My friend has a good set of 3.55's I could buy cheap from him, but not sure what that would do for rpms. It still may be a bit low for 1st gear, but not too sure. I am going to use a non lock up converter... with 255 60R 15's... Can anyone calculate rpm for me? Any help would be greatly appreciated.

The 3.55's will work out nicely with the 700r4.......but the non lock-up converter will most likely destroy the transmission. With the 3200 stall converter, when you are cruising in 4th gear the engine rpms will be below the stall speed of the converter and generate a TON of heat inside the transmission.

http://tri-5.chevyrides.com/rpm.php

Use the above site to figure RPM's. I run a 700r4 with a 2200 stall and 3.89 rear gears. Really gets out of the gate in low gear. (502 cubic inches) Be sure to run the lockup convertor or you will shorten the trans life with excessive heat as previously stated.

Wayne is right, at least lock it in 4th (od) or the cruise RPM will generate too much heat... It's a simple 1 hot lead connection that you can run through a switch at the brake pedal to unlock it as you slow down.

Who are you buying the trans. from? they might have a lock up accessory kit as well. Mine did!

So... i'm kind of confused here... I had the trans converted to hydraulic lock up, so I still need a lock up convertor, but will it lock down pretty much the same? I didn't order the convertor yet, so I can still order what ever I need... Pretty much was just going to order that stall speed, because of the low first gear...

I will be running 4.10's with mine. Who cares if 1st is granny low. Your not doing the shifting ;)

Well I hope I'm doing the shifting... I don't want it to shift at around 5K.. lol

3.42-3.55's seem to work best all around for street cars with 26" tall tires. If you have 28" tall tires then 3.73's to your current 3.90's would be fine.

I have 26" tall tires and wish I never replaced my 3.73's with 3.42's. Not a lot of difference in 1st with the 3.06 but the rpm drop in OD means keeping it in 3rd on city streets when cruising around town in 35 - 45 mph zones. It also means some extra shifting when you are in traffic doing 55 mph and hit a hill... With the 3.73's the extra couple hundred rpm was all it needed to be in the torque curve under these conditions.

As far as lockup, I thought the older 700r4's used hydraulic controls to lockup the converter, then they went to electric for a while and finally computers to control the lockup in the more recent versions.

I have 26" tall tires and wish I never replaced my 3.73's with 3.42's. Not a lot of difference in 1st with the 3.06 but the rpm drop in OD means keeping it in 3rd on city streets when cruising around town in 35 - 45 mph zones. It also means some extra shifting when you are in traffic doing 55 mph and hit a hill... With the 3.73's the extra couple hundred rpm was all it needed to be in the torque curve under these conditions.

As far as lockup, I thought the older 700r4's used hydraulic controls to lockup the converter, then they went to electric for a while and finally computers to control the lockup in the more recent versions.


Quite possibly.. I am totally clueless on this trans... I always knew it was so weak that no one ever wanted to use them. Well times have changed, and so has parts, and these can be made MUCH stronger, and I need the overdrive instead of running 3700 rpm down the interstate.. THat sucked...

The builder told me that you have to use the 87-up 700, or else it is very weak.. I believe a 30 spline instead of a 27? I am going to get a lock up converter now, as I was totally clueless to this as well... I was just going to order a converter from Art Carr, but I haven't talked to them yet... I may just try the 3.90's and see how it works before I change them... I just figured while I am installing the c-clip eliminator kit, that it would be the time to do it.

I appreciate all the help from all you guys... It's obvious.. I am clueless about this tranny!

Jeremy - here's some reading on converters and why to use a lockup converter... http://700r4.com/faq/whatlock.shtml

This could be like what you are having done to your trans and explains how the mid year trans could use a hyd lockup..
The lock-up valve and sleeve was used in early valve bodies 81 through 86. The later valve bodies, 86 through 89 kept the valve bore, but were non-functional. 90 through 93 valve bodies were produced without the valve bore. As long as the bore is in the valve body, the hydraulic package will apply.

http://www.superiortransmission.com/products/high_performance/700-r4_hydraulic_lock-up.htm

Jeremy - here's some reading on converters and why to use a lockup converter... http://700r4.com/faq/whatlock.shtml

This could be like what you are having done to your trans and explains how the mid year trans could use a hyd lockup..


http://www.superiortransmission.com/products/high_performance/700-r4_hydraulic_lock-up.htm

Wow Thanks Dennis... Definitely some good reading, and teaches things I never knew about this tranny... Absolutely need a lock up converter.... especially with a fairly large stall.

Okay with the roller 468 that I have... should I stay with the 3.90 gear?

I ended up ordering the 3200 rpm stall with lockup. Thanks guys... I almost made a HUGE mistake! No electronics, they are converting it to hydraulic lockup. Should be fun... Now I'm just trying to figure out which drag radial to run... I think the only company that makes 255/60R 15's are M/T...

Jeremy, Good stuff on the converter. I think it will work great for ya. I still think the 3.90's are going to be to much for it if you plan on trying to get it hooked up at the track. Your first gear reduction is 11.93. This is equal to a TH400 with a 4.81 rear gear. To top it off you are running a pretty small and narrow tire with 468 bigblock that makes alot of torque.
But shoot they are already in there so see how it does! If may be just fine but I dont think it will. My sbc 408 with 8.8 gear reduction had a hard time hooking at anything but a good prepared track. This was with 275/50/15 MT DR's. Again this is JHMO.

Thanks Ron. I know I'll be limited to traction big time with the 3.90's... It will shift so quick out of 1st gear. I have some 3.55's on stand by. I just don't want to change them this year... I want to run a larger tire, and I could run a 275/60R 15 which would help some... but then I would have to buy a 8 in rim, which are hard to find especially in the polished Centerline Auto Drags. I also want to put 17's on it next year, so I can't see spending much on 2 wheels just so I can run the size I want... I'll just have to see what the M/T drag radials work like in a 255/60. I am unsure if I want to run open headers or if there is enough benefit to run open headers... It may be enough with the exhaust hooked up. Can't gain a whole lot of speed spinning... lol

Thanks Ron. I know I'll be limited to traction big time with the 3.90's... It will shift so quick out of 1st gear. I have some 3.55's on stand by. I just don't want to change them this year... I want to run a larger tire, and I could run a 275/60R 15 which would help some... but then I would have to buy a 8 in rim, which are hard to find especially in the polished Centerline Auto Drags. I also want to put 17's on it next year, so I can't see spending much on 2 wheels just so I can run the size I want... I'll just have to see what the M/T drag radials work like in a 255/60. I am unsure if I want to run open headers or if there is enough benefit to run open headers... It may be enough with the exhaust hooked up. Can't gain a whole lot of speed spinning... lol

Yeah for sure give them a try. They may work fine. But if this is a street/strip car without a full on drag suspension it will be tough to get it to plant the tires. I have a friend with the 255/60/15 MT's and its hooking great. But he has a small block/TH350/3.90's. As far as the open headers unless your exhaust is a major restriction I would leave it hooked up. What does your exhaust system consist of right now??

Yeah for sure give them a try. They may work fine. But if this is a street/strip car without a full on drag suspension it will be tough to get it to plant the tires. I have a friend with the 255/60/15 MT's and its hooking great. But he has a small block/TH350/3.90's. As far as the open headers unless your exhaust is a major restriction I would leave it hooked up. What does your exhaust system consist of right now??

The exhaust is just 3 in exhaust with Flowmaster Super 40 series mufflers dumped at the rear end. Extremely loud inside, and on the outside... but I like it... I really don't want to rejet the carb several times either until I get a good mixture with open headers.

One my last Camaro, I was running 3.90 gears in a built 700R4 & 406ci combo. Tires were 255/50/16 (26in). I liked it. I had a one wire switched to lock up the converter.
Launches took some touch and a quick **** out of first....
Either way... your gonna love it!!!

The exhaust is just 3 in exhaust with Flowmaster Super 40 series mufflers dumped at the rear end. Extremely loud inside, and on the outside... but I like it... I really don't want to rejet the carb several times either until I get a good mixture with open headers.


Your exhaust is fine...I would leave it hooked up.