tranny swap and rear end ratio

oldjunk · April 22nd, 2009, 08:46 PM

Hi Guys!
I am restoring a 1972 cutlass S 2 door. I am replacing the 350 with a stock 455. I want to replace the TH350 transmission with an overdrive, either a 700 4R or a 200 4R. I currently have 2.73 rear gears, and I am wondering if this rearend ration will work well with the 4 speed. This car is going to be a driver, not a drag car. Any opinions are greatly appreciated.

J-(Chicago) · April 23rd, 2009, 12:42 AM

It should work well for a cruiser.
The 7004r will need a chevy conversion mounting plate, and the driveshaft will need to be shortened.
2004R should bolt to the motor , but your transmission mount and crossmember may need to be moved back or swapped out for something else.

joe_padavano · April 23rd, 2009, 07:48 AM

Quote:

Originally Posted by J-(Chicago)

It should work well for a cruiser.
The 7004r will need a chevy conversion mounting plate, and the driveshaft will need to be shortened.
2004R should bolt to the motor , but your transmission mount and crossmember may need to be moved back or swapped out for something else.

Neither the 700R4 nor the 200-4R will survive in stock form. Since either one needs to be modified, the 200-4R is the easier swap. Your stock driveshaft will work fine. Your stock crossmember will also work fine, though you will need to move it rearward. Your frame is already drilled for this rearward location since it is the same as used on the TH400 that was available in 1972. You will need to get the throttle vavle cable and bracket from a 1980s Olds with the 307/200-4R combo.

J-(Chicago) · April 23rd, 2009, 11:55 AM

Thanks for the correction, Joe.
I do believe a 700r4 could survive fine if it is just a driver, though.
I'll have to get back to you guys on that one.
We just put a motor that ran 12.40's in front of a 700r4.
I'll let you know the outcome after the racing season is over, or as soon as it shatters into pieces.

mugzilla · April 23rd, 2009, 12:28 PM

Quote:

Originally Posted by J-(Chicago)

Thanks for the correction, Joe.
I do believe a 700r4 could survive fine if it is just a driver, though.
I'll have to get back to you guys on that one.
We just put a motor that ran 12.40's in front of a 700r4.
I'll let you know the outcome after the racing season is over, or as soon as it shatters into pieces.

With me I like having the trans as the weakest link as the labor and cost of a replacement are relatively cheap.

I'd rather break a trans than the engine or rear end ...

J-(Chicago) · April 23rd, 2009, 03:38 PM

Quote:

Originally Posted by mugzilla

With me I like having the trans as the weakest link as the labor and cost of a replacement are relatively cheap.

I'd rather break a trans than the engine or rear end ...

X2

oldjunk · April 23rd, 2009, 08:00 PM

Thank you very much for your comments. What kind of modifications do you suggest I make to the 200 4R to make it more durable?

88 coupe · April 23rd, 2009, 08:19 PM

http://www.cpttransmission.com

Norm

mugzilla · April 23rd, 2009, 10:38 PM

Quote:

Originally Posted by oldjunk

Thank you very much for your comments. What kind of modifications do you suggest I make to the 200 4R to make it more durable?

I bypass the radiator and plumb the lines directly into the biggest transmission cooler I could find ...

Heat is the enemy ...

jaysun · April 25th, 2009, 08:51 PM

some reading

http://www.turbobuick.com/forums/tra...ing-2004r.html

mugzilla · April 26th, 2009, 12:31 PM

Quote:

Originally Posted by jaysun

some reading

http://www.turbobuick.com/forums/tra...ing-2004r.html

I'm checking the linkbacks. I am checking out interchanges like universal bell housings when this popped up ...

Quote:

Originally Posted by megaladon6

i 4l60e, it's basically a 700 with computer control. plus, you can get the shifter paddles on the steering wheel

Kind of takes the hassle out of shifter locations...

...

ThyPlumber · April 26th, 2009, 02:55 PM

Try a 4L60 should be reasonable on price, think the final drive ratio was around 0.60, dont forget to replace your spedo gear, might want a tranny shop to mach it up.

mugzilla · April 26th, 2009, 11:26 PM

Quote:

Originally Posted by ThyPlumber

Try a 4L60 should be reasonable on price, think the final drive ratio was around 0.60, dont forget to replace your spedo gear, might want a tranny shop to mach it up.

I use the guy that calibrates the chip speedos' ...

April 22nd, 2009, 08:46 PM	#1 (permalink)
oldjunk Registered User Join Date: Apr 2009 Posts: 16	tranny swap and rear end ratio Hi Guys! I am restoring a 1972 cutlass S 2 door. I am replacing the 350 with a stock 455. I want to replace the TH350 transmission with an overdrive, either a 700 4R or a 200 4R. I currently have 2.73 rear gears, and I am wondering if this rearend ration will work well with the 4 speed. This car is going to be a driver, not a drag car. Any opinions are greatly appreciated.

April 23rd, 2009, 12:42 AM	#2 (permalink)
J-(Chicago) Seasoned beater pilot. Join Date: Jan 2007 Location: Chicago Posts: 2,697	It should work well for a cruiser. The 7004r will need a chevy conversion mounting plate, and the driveshaft will need to be shortened. 2004R should bolt to the motor , but your transmission mount and crossmember may need to be moved back or swapped out for something else. __________________ I'd rather have a numbers matching poker hand.

April 23rd, 2009, 11:55 AM	#4 (permalink)
J-(Chicago) Seasoned beater pilot. Join Date: Jan 2007 Location: Chicago Posts: 2,697	Thanks for the correction, Joe. I do believe a 700r4 could survive fine if it is just a driver, though. I'll have to get back to you guys on that one. We just put a motor that ran 12.40's in front of a 700r4. I'll let you know the outcome after the racing season is over, or as soon as it shatters into pieces. __________________ I'd rather have a numbers matching poker hand.

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April 23rd, 2009, 08:00 PM	#7 (permalink)
oldjunk Registered User Join Date: Apr 2009 Posts: 16	Thank you very much for your comments. What kind of modifications do you suggest I make to the 200 4R to make it more durable?

April 25th, 2009, 08:51 PM	#10 (permalink)
jaysun ate glue as a child Join Date: Feb 2009 Location: madison wi Posts: 75	some reading http://www.turbobuick.com/forums/tra...ing-2004r.html

April 26th, 2009, 02:55 PM	#12 (permalink)
ThyPlumber Registered User Join Date: Apr 2009 Posts: 34	Try a 4L60 should be reasonable on price, think the final drive ratio was around 0.60, dont forget to replace your spedo gear, might want a tranny shop to mach it up.