700r4 and ford 9in

I plan to use a SBC/700 r4 and a 9 in ford rear with 263 gears in a 51 Merc. Is the overdive and the 263 gears to much? Should I stick with a th400 with that rear end?

 

With those gears a 400 would be better. If you have an engine with any kind of cam, the best gear for a 700 would be a 3:73.

The downside to the 400 is the ****py low gear. With 2:63s it will be a slug off the line.

 

I have 308's and a 700. It barley gets into 4th at 75-80. Im changing something in mine unless I plan on going for a speed record at Bonneville....

 

700's are commonly paired up with 3.42 gears from the factory. Depending on tire size it will put you around 2000 rpms at highway cruise speeds.

3.73's were used in performance combos and towing packages for the most part when coupled to 700's.

 

I have a 700r4 with 3;55 in a 9 inch, works perfect

 

I have 300's in mine and I'm hopeing it works out.I asked alot of questions before I bought my gear.Just hope it paid off.Will find out soon.

 

Same as "GearheadForever" and mine also works great. Not that it matters, but it gets kick a$$ gas milage....

 

I have 2:88s behind a 454/700R4, it turns 2000 RPM @ 80 MPH. I'm going to change to 3:54s, because I usually lock the OD out unless I'm over 60 MPH.

I'd keep the 700R4 and change the rear when you can. If you can't afford the gear change, just don't use OD. The lower 1st in the 700R4 will help a lot with that tall rear gear.

 

http://www.csgnetwork.com/multirpmcalc.html

I use calculators like this alot when I am picking combos.

 

Thanks. great link Turbo! Sounds like since it is easier to change rears I should hang with the 700r4.

Any other feed back?

 

I have 3.25 gears in my 9 inch and a 700 r4 trans with a 26 inch tall tire, Does anybody think that it will be alright?

 

700R4 gearing:

I think 3.42-3.73's with 28's.

 

9 inch rears have been built so many times you can get a different ring and pinion for a song and dance in just about any ratio you want. I would definitely keep the 700r4. They are super stout, especially the later 30 spline ones, and the first gear ratio makes for killer burnouts while still having a nice 4th for highway cruising.

 

454, 700R4, 3.42 gear, 255/60 X 15 tire. Runs at 2000 rpm at 70mph and done as high as 19.6 mpg. I would go any higher than that. 3.42 - 3.73 is a great gear range for the 700R

 

How difficult is it to change the gear ratio in the 9in? Any special tools? Or just change the hogs head?

 

You have to change the ring and pinion. If you are mechanically inclined it would be straightforward.

To OP, I would not do 2.63's for a big heavy car like that, converter might never lock up or worse it might go in and out. I don't think it would drive all that nice.

 

The specs on the rear is 2.75, not 2.65. Not that it would make a big difference.
I gave the spec of 59 in Hub to hub for the 51 merc, his measurement was 59 in backing plate to backing plate...I intend to measure it but off hand does anyone now if that will work?

 

measure you stock rear wheel mounting flange to wheel mounting flange so you can compare that to any potential rear end choices. what size wheels/tires should factor in too. what wheels will you be using?

about 20 years ago , a friend installed a 350/350 with a 9" in his `51 mercury. i went to the junkyard with him to get a rear and i believe we got one out of an early 70's Econoline van. it was the perfect width to use with his stock wheels/tires , had the 5-1/2" bolt pattern , and had 3.50 gears...which would be great with your 700R4 . with his th350 he always felt he wanted to go 3.00 ,but never did

don't hold me to the year/model of the rear end , my memory is a bit foggy sometimes...that's why i suggested measuring your existing rear end ,and then make a trip to the junk yard with a tape measure

if you get the perfect width rear , but doesn't have the gears you want...changing the pumkin is no big deal. you have to know 28 or 31 spline

 

I just changed ******s and rear gears....had a TH350C and 2.50:1 9" and changed to a 700r4 with 3.50:1 gears. Tires are 25.9" dia. :
Much more gooder pickup and I end up with nearly the same rpms at 70 mph.

 

Leadsled, I'm not trying to hi-jack your thread but does anyome know how much horsepower it take's to run/turn a 700R4, I read that it takes 44 horsepower to run/turn a TH400 and about 32 horsepower to run/turn a Th350? And what the weight of a 700R4 is?
Thanks,
60'

 

I'm not sure what the horse power is but I was told the AOD draw less than the 700 r4

 

You'll be OK, as long as you're not pulling a trailer with a lot of wind resistance.


BTW, for discussion's sake, I ran the Jag XJS with 454, 700R4, 2:88s, and 26" tires over the same 150 mile highway trip twice, once using OD as much as possible, and once with OD locked out. I got 21.5 MPG both times. The OD did nothing for mileage in that instance.

Gets 13-15 around town. Stock 454 p***enger car engine w/quadrajet, unknown mileage or year.

 

Thanks for the advice. I won't be pulling a trailer though it is in a 1959 rambler american wagon?

 

If you're in the habit of running 75-85 MPH or more, you'll love it. As long as you have a torquey engine.

 

10.2 compression, 406 cu. in. sbc, 750 holley, with 2700 stall, 700R4, and 3.70 gears. Ran 13.0@103 and got 17-18mpg @ 70mph.

 

I believe that with the overdrives in 700 4Rs and for that matter AODs the gear ratio you need is around 3:43 / 3:50 for optimum performance with a 21 to 26 inch tire. the danger of too high of gears is that at cruising speed your converter will be constantly going in and out of lock up which Will over heat the oil in the transmission.

 

I have that setup but with 27" tires.
I just keep the shifter in D around town so it can't jump up into overdrive by itself and then when I get out on the highway I select the OD. It is a HUGE jump up to the OD with that ratio, but it sure is nice to fly down the interstate at 75mph+ with the rpm at 1,800 while getting 20+mpg.
The rest of the gears are just fine with that ratio.

 

This is what I have been told too..and what I plan on running in my A

 

I ran a 700R4 in my heavier '57 ford, but for my lighter '33 Olds, I'm going with a 200-4R. The 1-2-3 gears are almost identical to a turbo 350; with a 30% OD.

 

I had a 700 R4, 9" inch with 3.70 gears and 30" tall tire in my roadster. Worked great and got 18 mpg.