I put a 200-4R in one of my Buicks. It is the non-computer trans. I could use original driveshaft and trans cross member. I would do that research to help determine what makes the most sense.
1968 400 Coupe, verdoro green, black vinyl top 1968 400 Convertible, verdoro green, black top 1971 Trans Am, cameo white, auto 1970 Buick Skylark Custom Convertible 350-4(driver)
I put a 200-4R in one of my Buicks. It is the non-computer trans. I could use original driveshaft and trans cross member. I would do that research to help determine what makes the most sense.
Thanks for the input. Does the rear diff ratio factor in the selection?
Yes, it does a bit. 200 has lower final (0.67 to 0.70) and 700 has steeper 1st (3.06 vs. 2.74), 200 has better “spacing†between gears. Ultimately, I let no computer and less mods dictate choice. Either generally can be made to handle horsepowers involved.
Availability of Trans is also an issue. I hear the 200s are getting harder to find.
1968 400 Coupe, verdoro green, black vinyl top 1968 400 Convertible, verdoro green, black top 1971 Trans Am, cameo white, auto 1970 Buick Skylark Custom Convertible 350-4(driver)
I would go the 200-4r route (what I did) mainly because of gear spacing and BOP bolt pattern on case. You "should" be able to use your original crossmember and driveline (I had to buy a new crossmember and shorten my driveline since my original trans was a 2-speed ST300). Mine just uses a brake switch to lock out OD which is an easy install so it's not computer controlled. I went this route: https://www.bowtieoverdrives.com/catalog/catalog_inc/viewitem.php?ITEMID=12 and bought their TV made simple kit and transmission lines. The stage II is rated up to 450-500hp and 400-450 lb torque (which I may need to revisit with my new motor). If you do decide to go this route make sure you give the company your rear tire diameter and gear ratio so they can put the correct speedometer governor in the tranny so your speedometer reads correctly. Also, if you have a stock shifter you want to retain you can go to shiftworks.com and they have a kit to add the extra detents to your original shifter (I ended up going to an aftermarket shifter).
"With 3.08 :: 1 gears in the diff you can’t use OD at all. Your engine rpm at 60 mph would be 1600 rpm. Most gas engines barely make power down that low. You could use the 700 R4 if you change your gears to 3.42, 3.73, 4.11, 4.56, 4.88, 5.12 or 5.30."
Looks like I will have to up the diff to 3.42 or 3.73. He likes the 700 R4, why?
"With 3.08 :: 1 gears in the diff you can’t use OD at all. Your engine rpm at 60 mph would be 1600 rpm. Most gas engines barely make power down that low. You could use the 700 R4 if you change your gears to 3.42, 3.73, 4.11, 4.56, 4.88, 5.12 or 5.30."
Looks like I will have to up the diff to 3.42 or 3.73. He likes the 700 R4, why?
I think your tranny builder is correct. I would not put OD trans in unless you have gears in the 3:42 range or higher. I put a 2004R after I switched to 3:73 gears and it dropped my highway RPMs from round 3200 rpms at about 65 to right around 2100 RPM's. The 700R4 takes more to make it work in the FB. You will need an adapter plate to mate the trans to your engine (unless you have a Chebby engine...lol) and a computer to run it. You will need to shorten your driveline, but then again had to also since the th400 I was replacing was about an inch longer then the 2004R. I also believe you will need a new trans crossmember but you wouldn't need a new one if you put in a 2004R.
I went with the 700R4. I was told, by several knowledgeable mechanics(not hobbyists) that the 200 is just not as durable and won't handle the abuse. (I have a fairly stout build, and WILL abuse when I can)
Also added the lock-up convertor, which saves about 200 or so RPM at highway speed.
I have a 3:55 rear end. Changed to cross member, driveshaft, added adapter for bolt pattern, and added bracket and modified throttle linkage geometry to work with the TV Cable.
I'm a hobbyist. Not a professional. Don't be hatin'!
I've got 4.10 gears in my Firebird and at 70 mph it turns about 2000-2100 rpm on the freeway. Also, the 200-4r can be built to handle 1000 horsepower if so desired: http://www.cpttransmission.com/ .
I've got 4.10 gears in my Firebird and at 70 mph it turns about 2000-2100 rpm on the freeway. Also, the 200-4r can be built to handle 1000 horsepower if so desired: http://www.cpttransmission.com/ .
X2... I have a 2004R stage 2 built to handle up to 750HP/650TQ by Lonnie Diers at Extreme automatics. He is quite knowledgeable about them and he is also a racer.
"With 3.08 :: 1 gears in the diff you can’t use OD at all. Your engine rpm at 60 mph would be 1600 rpm. Most gas engines barely make power down that low. You could use the 700 R4 if you change your gears to 3.42, 3.73, 4.11, 4.56, 4.88, 5.12 or 5.30."
Looks like I will have to up the diff to 3.42 or 3.73. He likes the 700 R4, why?
Then ask him to explain the 1991+ Caprice with an anemic 305ci, 4L60E, and a 3.08 rear along with 27" tall tires back when the national speed limit was still 55mph? Your combination will be fine even with a .67 overdrive.
The 2004R is easier to adapt to a Pontiac, and has a better gear set than the 700R4 (some don't like the wide 1st to 2nd gear drop of the 700R4). And when upgraded, they're about the same strength.
Honestly, if a trans builder made that statement to me, I'd be looking for another builder.
"With 3.08 :: 1 gears in the diff you can’t use OD at all. Your engine rpm at 60 mph would be 1600 rpm. Most gas engines barely make power down that low. You could use the 700 R4 if you change your gears to 3.42, 3.73, 4.11, 4.56, 4.88, 5.12 or 5.30."
Looks like I will have to up the diff to 3.42 or 3.73. He likes the 700 R4, why?
Then ask him to explain the 1991+ Caprice with an anemic 305ci, 4L60E, and a 3.08 rear along with 27" tall tires back when the national speed limit was still 55mph? Your combination will be fine even with a .67 overdrive.
The 2004R is easier to adapt to a Pontiac, and has a better gear set than the 700R4 (some don't like the wide 1st to 2nd gear drop of the 700R4). And when upgraded, they're about the same strength.
Honestly, if a trans builder made that statement to me, I'd be looking for another builder.
I agree regarding finding a new tranny man. Check the rpm of any modern vehicle at highway speed.
Last edited by Bronze Bird; 02/18/1910:32 PM.
I'm a hobbyist. Not a professional. Don't be hatin'!
I suppose it might depend on the engine, the torque converter, and the amount of time one will spend at 70-75 mph.
A long stroke Pontiac engine, with a reasonable cam, can make enuff torque to drive down the road at 1600 rpm.
But, if you have a converter with enuff stall speed to slip a lot at 1600 rpm, it can build up extra heat, and possibly reduce converter life.
But, just because the trans has an OD high gear don't mean you'll have to run it in high gear when your engine is only turning 1600 rpm. You can just run it in 3rd gear til your highway speed is high enuff to need the OD. I suppose you could just think of high gear as something you only use when cruising the freeway, at 70 mph or faster.
The only reason I'd consider changing to a numerically higher gear ratio is if I wanted more acceleration in 1st, 2nd & 3rd gears.
Just curious. Are there gear sets readily available for the '65 Cat ? Don't know what rear end they had. I think '64 was the last year for the 9.3 chunk type rear end. Don't think they used the 8.2 BOP, like the A-bodies used. I read where 1 guy found some better gears for his big car, out of a Pontiac hearse.