Customs rear end help

a buddy of mine has a 63 chevy impala with a very tired 283 pg combo in it. he wants to go 350 700r4 and a 3.27 gear. does that gear seem a little high for this car?pretty heavy car. i told him i would ask you guys. i think a 3.54 would be a better choice your opinions please.

 

Depends what he wants that sounds like a nice combo to me.

 

3.36? 3.55? Either one would work. The 700 has a steeper first gear ratio than any of the other GM automatics, helps it get moving. Tire size makes a difference too, they were pretty small originally on those cars, what does it have now?

 

Had a brand new 63 Impala 283 w/ PG and stock rear moved it along then, a 350 can only be better. 283's had 195 horse a 350 w/ 4bbl has probably 215. I don't see a problem.

Pat

 

The overdrive is the difference.

As soon as we know the tire size, we can figure it all out.

 

called him up he said 235 r75 15

 

That is a taller tire than it came with so that has the effect of a higher gear ratio. '63 Chevys came stock with 14" wheel.

 

That's an SUV tire size. Talk him into running a more proper size. He ain't going off roadin'.

 

Warm up the 283 and keep it, 700r4 and a 4.56 gear.

 

I run 225/75 15 with 3.36:1 rear with T700R.

works fine for me.

 

My 48 coupe weighs 3250 lbs. I run a 350 sbc , 700R4 with 3:55 gears and 235/70-15 tires. Goes great !

 

he should run some scenarios through a gear calculator, there's enough of them online, just plug and chug until he gets what he wants. Really helps to narrow down the choices. But a 235 tire is pretty tall for a '63 Chevy. My gear choice with that tire would be a 3.90 or 4.11.

 

your final drive numbers should be above 2.40:1 final ( 3:42) as you will have just enough torque to pull the car , .
as we keep saying, gear the final number at the base to middle of your torque band at cruising speed ib o/d ( 45-60 mph ) for best mileage and acelleration .

 

I run 235:75:15 rear tyres in my 35 tub with 3.54:1 Jag rear. Turns roughly 1,800rpm at 60mph with 700R transmission. Good low first with legs on the highway. Your engine RPM at cruising speed (6omph) should be between 1800rpm and 2100rpm.


3.06 1st,


1.62 2nd,


1.00 3rd and


0.70 OD

 

You'll be back with more questions when you see what that LONG 700r4 does to driveline angles on the 2 piece drive shaft.

 

thanks for the help guys i was thinking 3.54 myself. models 916 i hope he has thought through that part of it

 

I would recommend putting it all together and not changing anything in the rear gearing until he's driven it awhile. It's not going to be a case of doing anything twice if he waits, so no reason to change things until he's driven it. He can always change later if he wants to.

 

A stock PG goes either 25.31" or 28.31" long. The 700R4 is 30", the TH200 is 28.25" but mounts up the same as the PG at 22". So that may be the way to go.
http://www.maliburacing.com/auto_tranny_id.htm

 

bobss 396 will tell him about the th200 i know he hasnt bought a tranny yet.

 

Just don't call it a TH200. You go to a yard looking for one of those, and you're gonna' be sorry.

It is a TH200R4.

 

I replaced TH 350-2.42 with 700r4-3.23
28" tire cruises at 60mph/2100rpm (23% mileage improvement) improved acceleration
Stock 350" with q jet in 78 El Camino, perfect for me
If you have a warmed over engine (cam carb etc.) you would want 3.42 to get in higher torque band
Just put a toggle switch wired through brake switch so you control converter
Never mind the vacuum switches/speed sensor stuff-just complicates things
The BEST money I ever spent on a street car! you'll luv it.

 

gimpy, oh dont worry he doesnt buy anything from yards unlike me. i told him about the th 200 4r and he went on line and looked up bow ties trans he will probably buy one of those.

 

Wrong
It is a 2004R

 

That is the best advice to answer the question I have read yet,other than crunching some numbers with pen & paper.

 

The GM service manual calls it a Turbo-Hydramatic 200R4.

 

to be a proper HAMBer, he should go 2.73 with the od...that way, theres no chance you'll wet your depends when you go WOT. Remember, safety first...

 

Can you still get 1.95 s
Not everyone is headed for the salt or has a push car.

 

That tire size reminds of the jacked up rear ends in the 70's - mid 80's. Boy, we screwed up some nice cars.