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Discussion Starter #1
Hi guys!

Well, I've come to a point with my 68 firebird where I either need to replace the th400 with a 200r4 or change out the rear end gears. Right now I've got a 455 bored +.030 and I've been told I'm getting around 375-400hp at the rear wheels (haven't had a chance to dyno it yet). My rear is a 4.10 ford 9in. Gas being what it is, I'm looking to get my cruising rpms down to a reasonable level. Right now, I'm turning about 3800 at 60mph.

If I go to a 200r4, I'll get pretty much what I want, about 2250 at 60mph (according to the charts). But and this is a big but---that will run about $3200 to get one with a new yoke, 9" torque converter and installation.

The other way to go is to get 3.00 gears for the rear. That will put me down around 2500 at 60mph. I can do that for about $500.

My question is...what will the car feel like at launch? Am I really going to dog the vehicle with the 3.00 gears? I'm not racing it so I'm not sure I really need the 4.10s anyway, but I do like the fact that if I want to take it down to the track I could. The one thing open to me right now, is that I would keep the 4.10 gears and if I decide to go to the track, I could put those in rather quickly.

What do you all think? Will I be ripping the guts out of the 462 if I change to the 3.00 gear ration?

Jerry
 

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The 455 makes a lot of low end power. The 3.00 gears would be my choice. An overdrive is a good idea just a little pricey.
Bob
 

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new trans or change rear end ratio

first things first,either you have very small tires or your tach is reading wrong. 3800 rpm @ 60 mph with 4.10 does not seem correct.but to answer your question,this motor should have a bunch of torque,a 3.23 rear would be a good choice,kinda the best of both worlds.i have a transmission shop and we do a lot of conversions to overdrives,so my first inclination is to suggest a trans change,but that is big bucks.by the way,if you do decide to go that route i suggest a 700-r4 not 200-4r{adapter plate or bell housing} 200-4rs dont like a lot of torque.i am really curious to see which choice you make.
 

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Discussion Starter #5
Hi guys!

Well, my speedo is sure enough off, but I checked my speed by having another driver pace me and we talked back and forth via 2-way radios. As for small tires, I guess I do have small tires--265x50x15s. They measure 25.4 in diameter and the standard tires for the 'bird is 26.2. I'll be changing them as soon as these wear out (not too long as they break loose pretty easy :)

Anyway, briscoe, a local tranny shop here suggested the 200r4 that they custom build (the reason it's so costly) for high hp. If the 700r4 is better, where would I pick up one of those (I'm only interested in either a newly rebuilt or new tranny) and what would the cost be?

Jerry
 

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Hey Henkelphoto Rich here.My 700r4 came out of a 91 suburban and was built by beach at Expert transmission.I always ran turbo 400's in my trucks with tall tires to get the freeway gas mileage but that killed my mileage in town.The 700r4 gives me the best of both worlds.!4 mpg at 70 mph and 9 mpg in town and I am running 4.56 gears.I can still afford to drive it around town but I can jump up and run away from Beach's 66 nova any time I want to(Beach really hates that).The overdrive trans was well worth the money.That price of $3200 is too high it should be closer too $2500.Check out Raptor Transmission.There web site has allot of information.There prices are a little high but it will give you a good Idea of what options are available to you. :thumbup:
 

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new trans or change rear end ratio

hey henkelphoto,sounds like your prepared to spend the bucks for a trans.i agree with doubledick,raptor has a good reputation,good choice.however we have a speed shop right beside us,so they send us a lot of performance transmission work,in fact some of the guys they send us had bought performance units that were shipped to them with problems,so then its back and forth with the company to get it resolved,so finding a shop that does performance work and likes doing it would be best in my opinion.a few years ago we developed a rear planetary for the 700-r4,.the car we tested it in had over 550 hp and almost as much torque,i would be glad to share with you what worked and didnt work.
 

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Discussion Starter #9
Thanks for the info guys! As mentioned above, this is a pontiac engine, do either of these tranny guys make the 200r4 or 700r4 trannys for bop install?

Jerry
 

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I think the 200-4R has a "any GM" bolt pattern. I bought one from them for my 64 El Camino, and it had a lot of mounting holes that I didn't need.
I assumed they were for BOP application.
JA
 

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The 700r4 only comes in a Chevrolet bolt pattern ... :embarrass
 

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The 2004R vs 700R war rages on ;)

There's a huge debate on a good built over drive transmission.
Guys's that build the 700's think the 200's are weak and the guy's building 200's think the 700's are weak...

I've had both and would choose the 2004R. We use them in back of our Buick GN's that turn 9sec passes. If you don't think a 231cid turbo motor makes torque off the line you have'nt seen one run :)
A 200 will not hold up with out the right person putting it together and the right parts. (like anything else I guess)

For your application i'd put in a 28" tall tire with a 3:50 gear for your 9" ford rear end... That'll put you right in the middle of the road with performance and driveability. If you decide to go with a Trans later i'll just make it all the better.
If you can't put a 28" tire then the 3:23 ratio would be better. *some ford gears are expensive once you get down past 3:50*
Your making alot of torque down low... don't throw it away with a tall gear ratio (in the 4's) It's not a SBC that needs to spin a bunch of rpm to create torque... Heck you proably make over 300ft/lbs at idle :thumbup:

That's my .02...
Good luck
Scott~
 
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