Topic: 3.73 rear end

[Rebel 5150]

You have to remember that the 301T runs out of breath early, so I don't know if a 3.73 is that great an idea.  Joe (jjr) may add to this later.

Is the 200r4 an easier swap?

The 200-4r is a direct bolt up as it has the BOP pattern and is the same length as the TH350.

[bad76]

I have a 455 with 550 horse tied to a 700r4 with a lock up convertor and at 80 mph I turn about 2700 rpm. The 200 is a much eaiser swap because you use your old driveshaft and crossmember but the 700 does have a better 1st and 2nd gear.    

[tribute]

Try this site for information on the strength of the 2004R.  In stock form it has quite a few weaknesses but they will tell you how to strengthen it to hold up.  http://www.turbobuick.com/

After much research on my part, I decided to have Brian Hofer build mine.  He is out of Ohio and frequently posts on turbobuick.com.  I have yet to hear a negative thing about him or his transmissions.  Unfortunately, I am still awaiting my engine to test the strength of the 2004R he built for me but his customer service and communication has been great to this point.

I chose the 2004R for the more even gearing and the .68 overdrive.  I can still run my 3.73s that I'm adding and not be turning any more rpms than what I was with the 2.56 stock rear.  I also have the shiftworks kit for the shifter.  Only downside is that even though it will work with a slapstick, the slapstick portion will no longer be functional.

[O'Neall]

Be careful going with more gear on a 301T motor... the 301T runs out of breath over 4000rpm and with 3.73s you're going to run right thru the powerband really fast and you'll likely actually hurt performance.  The factory chose the 3.08s pretty wisely when it comes to the 301T because they knew it made it's power at low rpm.

[bad76]

The only issue I have heard about the 200 is that high torque is what kills them.   

[Rebel 5150]

The only issue I have heard about the 200 is that high torque is what kills them.   

That's why you have them built really well!    Look at all the ones that are living behind 10-11 second Buick GNs.

[bad76]

they may be running them in a 10 second grand national but they will never make the torque of a pontiac. They get down the track on pure boosted horse power rather than allot of torque. 

[WarbirdTA]

A lot of my friends out in Los Angeles use the 200 trans.
Works with their cars.
400 and 455 Pontiac powered.

George 

[Keith]

So, in the 200 vs the 700 debate:

Is the install any easier one way or the other?

It must be because I'm seeing / hearing about / lots of 200 installs, but no
one with a 700 has stepped up yet.

Personally, I'm not going to race. The only 2 requirements are that my wife wants to be able to smoke the tires, and we want to be able to take trips and cruise comfortably at 80mph.

[brian c]

By memory....using a 700R4 over a 200R4 will require the following:

Adapter plate if you're using anything other than a sbc/bbc
Shortened driveshaft as the 700R4 is longer
Possible modifications to the tranny tunnel as again its longer than a 200R4
New/modified tranny cross member (with the 200R4 I've heard the stock TH350 just needs to move back an inch or two).

I'm eventually going to swap from the TH350 to a 200R4 - might be sooner than i expect too as I'm not happy with the yahoos that rebuilt my TH350.

[Keith]

By memory....using a 700R4 over a 200R4 will require the following:

Adapter plate if you're using anything other than a sbc/bbc
Shortened driveshaft as the 700R4 is longer
Possible modifications to the tranny tunnel as again its longer than a 200R4
New/modified tranny cross member (with the 200R4 I've heard the stock TH350 just needs to move back an inch or two).

Thanks Brian, I really appreciate that information.

I had been leaning towards the 700R4, due to it's lower 1st and 2nd gears. But it sounds like a lot more work than the 200R4, which I think is easier to find anyway.

And, now that I think about it, I want my engine/drivetrain set up to make more power at lower rpms, which the 200R4 will suit just fine.

Thanks again for the info,and sorry to hear about the yahoo that set up your 350.

I may have a TH350 with 79k miles on it for sale,,,,,,,, or trade for a 200R4.




I'm eventually going to swap from the TH350 to a 200R4 - might be sooner than i expect too as I'm not happy with the yahoos that rebuilt my TH350.

[bad76]

When i installed my 700 I had to get a new driveshaft, crossmember and adapter plate. You do not have to do anything to the trans tunnel. The only reason I went with a 700 over a 200 was because of advise from my trans guy, he runs a 6 second firebird and said that any torque over 500 will just kill a 200 plus he knows that i drive like a maniac.

[LOMILETA]

Well, I have a 2004r, it was Built by Janis Transmissions in Ohio. He builds strickly 2004r's and turbo 350's. He has cars running in the 8 second range, and assured me ( with a 3 yr warranty) that a 2004r will withstand my cars 575hp and 565 lb/ft of torque. My car doesnt really have a torque curve, it starts at 515 at 2500 and ends at 530 at 5800. The only thing to installing a 2004r is the trans crossmember has to be moved about 3 inches back, You can use your stock driveshaft, and it also has a cable operated downshift c just like the turbo 350.  I also went with the shiftworks kit, which allows you to utilize your stock shifter with an overdrive trans. That was about a 30 minute install.