[69428HOj]

Have 69 GP 428 HO with BOP 8.2 10 bolt 3.23 limited slip and th400. Motor being rebuilt at DCI and expecting 425 hp and 480 torque. Want to enjoy car on street but also want to cruise at reasonable rpm. So thinking of putting in taller gear rear end (3.73) with overdrive tranny (art Carr th200r 4 speed). What do you think?

[TedRamAirII]

Use this to figure it out. 200r Has a .67 overdrive. With a 4.10 gear....that would be a ripper!

http://www.wallaceracing.com/gear-speed.php

[Navy Horn 16]

If you put sticky tires on that thing don't expect that 8.2/10 bolt to live very long.

[RocktimusPryme]

There are a few people on here who are running from pretty insane times with similar engines who went to a lower (numerically) gear.

You will probably get alot of people who tell you to stay with the th400 but go to a 3.08. After seeing what others have done with that combo Ive decided to try that route first rather than shelling out the money for an OD conversion that will stand up to 600 ft lbs

There are also going to be people who tell you if your dead set on OD to step up to the electronic 480Le

[69428HOj]

I have seen these 2 schools of thought. I am thinking because of the great torque going to 3.08 is a good approach but would the 3.73 or so with overdrive be more fun...albeit more expensive.

[Overkillphil]

3.73 would be "shorter". I have a 3.42 in one of my 200-4R equipped Pontiacs with a 462 and it's too much gear with the 2.74 first. But I run 26.4" tall tires and may be able to cure with a talker/stickier tire later. With your 428 I'd stick with your current gear and use street tires so you don't destroy your 8.2 rear.

200-4R is no problem provided it's built by a knowledgeable builder and TV cable setup is right (it's NOT difficult). Art Carr loves the 200-4R and you have to make sure you're dealing with CPT (the real Art Carr) and not the one who bught his name.

My first choice however is always Lonnie Dyers (Extreme Automatics) and there are others after that who are extremely competent with the 200-4R. However, there are many more who can barely build a mild daily driver yet claim to be experts. Stay away from those shops. There are a few members here who unfortunately got burned by subpar 200-4R builders and as a result feel compelled to steer others away from using the trans. Which is a shame because it's a great unit IF built by a true expert.

[geeteeohguy]

RocktimusPryme nailed it. I'm in the 'install 3.08 gears and be done with it' camp. Your 428 will still shred the tires and you'll be great on the highway, and be able to keep the strong TH400. If going to an overdrive, he's right on the money with the 4L80 trans, as well. You don't want to be cruising so far below the powerband that you're lugging the engine. I installed a 2.56 rear end in my '67 GTO convertible with the TH400, and have the stock but lowered compression 400 engine. It burns posi rubber easily, but it's slower than when it had a 3.36 gear below 60 mph. After 60-70, though, watch out!

[Matt Meaney]

unless you have your heart set on doing this all at the same time, i'd try it out with the th400 and 3.23's first to see how you like it. that 428 will move the Gp around like it's a much smaller & lighter car than it is and you could be ok with the high way rpm that the 3.23's turn. if not, than go with the trans. the 2.74 first in the trans will give it even more get up and boogie with out changing the rear and let you leg it up even faster on the highway.

the 2.74 & 3.06 first gear trans' mated to 3.73 rears were in the '80's when you had anemic small block chevy's powing cars. kind of overkill for a 428.

[racegto65]

How about a 3.08 with a 2.75 gear set in the turbo 400?
Lower 1st and 2nd, still manageable on the freeway.

[shedgpeth4]

how tall are your tires?

[Formulajones]

Originally Posted by 69428HOj

I have seen these 2 schools of thought. I am thinking because of the great torque going to 3.08 is a good approach but would the 3.73 or so with overdrive be more fun...albeit more expensive.

I go through this with customers all the time. Right now currently doing yet another AOD in a 57 T-bird. The overdrives are pretty much the way to go in almost every case I see.

Some things to keep in mind. The 400 turbo with 3.08 gear camp (I have a car of my own like that) that are going pretty quick at the track are also running a low 1-2 gear set in the trans so the car will launch like it has 3.42's. That gear set will set you back ~$500-~$750 alone. So don't be fooled when people tell you, yeah I'm running 10's with 3.08's because Pontiacs make so much torque. Well that's not entirely true, there's a little fudging going on there, and some money sunk in the trans to do it.

Also, yes the 3.73 with overdrive would be the cats meow. You have a relatively low 1st gear in the 2004R trans already (2.74), coupled with 3.73's gives you an effective 10.22 overall 1st gear, perfect range to shoot for that gives excellent out of the hole acceleration. The .67 overdrive will cruise nice with that.

I would also suggest maybe just doing the 2004R swap first and leave your 3.23's for now. See how you like the 2.74 first gear with that, and see how the car cruises on the highway with it. My bet is a torque abundant 428 probably won't mind lugging down the highway in OD and it will likely pull the car fine without downshifting. If you find it's not to your liking, only then would I look at a little more rear gear.

As far as 2004R's go, take Overkill's advice. I know Lonnie personally and lived up the street from his shop. He builds 2004R's that live behind 8 and 9 second Grand Nationals that make crazy power. So he can build one to live behind your Pontiac no problem.

[ponjohn]

I was pleasantly reminded in a thread i started about how quickly a 200r4 will fail with sticky tires.

I would use a 4L80e.

[Formulajones]

Lonnie apparently didn't build it

His street/strip GN's will drag the back bumper, he can incorporate transbrakes etc.. and still loaf down the highway in overdrive.

[ta man]

I think the biggest issue with the 200r4 tranny choice is trying to hook up or use first gear when coupled with a 3.73 rearend.Just way too much gear for any 455 making decent power.

[Formulajones]

If ultimate 60 foot times were the goal then one would just need to spend some time dialing in a suspension and tire setup to exploit the power and effective gear ratio.

Taking an advantageous gear combination out of a car because it doesn't hook generally isn't the best approach to best times.

Since I don't think routine quarter mile passes are in his game plan, he may as well enjoy the gear multiplication on the street and the fun factor it will provide.

[69428HOj]

Thanks guys. Just be clearer, I will not be drag racing or looking to burn tires off ad nauseum. What attracted me to Pontiacs was the pull/torque they have. The setup in the car prior to this rebuild was kinda dissapointing but I dont have a lot of experience to compare it to. Hard to explain but looking for a hard pull from idle to 4500 rpm. And want to be able to get on a highway without hitting 3500rpm. I don't have access to test drive different setups so all your input is appreciated. Seems to me that higher numerical gears with overdrive would be a good step.

Currently as 14" Rally II, TH400, 3.23, 428 HO (getting rebuild).

[Overkillphil]

69428HOj, where are you located? If near SE PA you're welcome to ride/drive one of mine.

[FrankieT/A]

Nobody likes the 700R4 ?

[69428HOj]

I like the way you think Formulajones. Thanks for the offer Overkill.

[RocktimusPryme]

Originally Posted by FrankieT/A

Nobody likes the 700R4 ?

I think it's mostly a matter of the 200 bolting up without an adapter.