I am building my 406 next week and wondering what trans/ rear combo to go with this coming spring. I have two rear end and transmissions.

Rear 1: 4.10 ratio
Rear 2: 3.08 ratio

Trans 1: Turbo 400
Trans 2: 700r4 from a 90' firebird

Here is the engine specs

400 bored out .030 to 406, decked to 9.000 - zero deck with pistons.
H616P30 flatop pistons with four valve releiefs (6cc volume per fedral mogual) compression around 10.5 to 10.6:1
5.7 Eagle Sir rods and 400 crank, balanced.
Top line pro lighting heads, 72 cc chambers, 200cc runners. Chambers cleanup and bowl blending.
Victor Jr 2975 intake manifold
Mallory HEI
COMP XE294 cam, Magnum Roller rockers 1.55 ratio.
Hooker1-3/4 X 30 (2116) headers (yet to be purchased).

Pro/cons for how streetable with which combo would be great. Thanks - John

The 3.08's will be pretty doggy regardless of the tranny selected. An XE294 isn't going to like the lockup gearing with the 700R4, you'll have problems with bucking at low rpms.

If I use the overdrive, it will be for the cruising the freeway. Right now, I push around 4300 rpm at 75mph (4.10 rear and 24” dia. tire). Great for a short blast or two but sucks for any road trip - buzzing ears and numb hands. If I use the lockup, rpm would be around 3000 rpm. Maybe less if I go to a larger tire setup.

My opinion would be to go with 4.10 gears and the TH400. If you go with 4.10 gears and the 700R4 your effective first gear ratio would be way too high and would be tractor-like. A TH350 would be a better tranny for your setup, I don't think you need a TH400 with that motor...a TH350 would have less parasitic loss. But since you already have the tranny I'd go with the TH400. Get rid of those 24" tires (what tire size is that anyway?). Go with a 27"-28" tall tire...that will help drop your high cruising RPMs that you speak of.

I run 4.11 gears with a 4 speed and 27.3" tall street slick and usually turn around 3500RPMs @ 65MPH or so.

John..
I really think that you need to decide on what tire you are going to run in the long term first. Most aftermarket prformance tires are in the 26" range.
go with the 4.10's... sell the 700R4 and the Turbo 400 and buy a prepped Turbo 200R4.
The Turbo 200R4's aren't cheap $$$$. But they are a direct bolt in replacement for the powerglide, Turbo350, and Turbo400. They have the same desirable gear ratios as the Turbo 350 plus an overdrive.

*EDIT * opps.. The turbo 2004R doesnt have the same ratios as a turbo 350.. but they are not as much of a spread as the 700R4.

What are your goals with this car? Sell the 4.10's and the 3.08's and buy either 3.42's or 3.55's and use the 700R4

This one hits close to home. Hey Hoffbug haven't talked with you in quite a while. Your combination sounds very decent with less cam then mine and different heads, it is close for practical purposes. I ran a 3.31 gear with a 700R4 and a 25" tall tire previously which worked real well on the street and strip. This was from the 350 and used for a year with the 406. Highway cruising previously was good with the RPM's being acceptable usually around 2500 rpm for 70mph if I remember correctly. this past year i switched to a 4.10 and 28" tall tires, the car responds much quicker and is actually easier to drive IMO. Highway driving is still nice with RPM @2750 cruising 80mph. That is with the converter locked. One thing to know is that everybody has an opinion on this one and a lot of them are real valuable, just listen. I chose the 700R4 because it is a strong trans and there are a lot of things that can be done with it to make it stronger. I have done plenty to it, I can tell you if you would like. The 200-4R can be made to be a strong unit but will require a good deal of money, more than I would like to spend. I like my combo that I am running now so there is no intentions to change anything. For first gear reference the 700-R4 is a 3:08:1 while the 200-4R is a 2.75:1, so there is a spread but it is still very close, the big thing people comment on is the 1-2 shift drop since the 200's first gear is less the drop is slightly less than the 700 but if you are into it hard with plenty of power you won't much notice it.

Cheers

This one hits close to home. Hey Hoffbug haven't talked with you in quite a while. Your combination sounds very decent with less cam then mine and different heads, it is close for practical purposes. I ran a 3.31 gear with a 700R4 and a 25" tall tire previously which worked real well on the street and strip. This was from the 350 and used for a year with the 406. Highway cruising previously was good with the RPM's being acceptable usually around 2500 rpm for 70mph if I remember correctly. this past year i switched to a 4.10 and 28" tall tires, the car responds much quicker and is actually easier to drive IMO. Highway driving is still nice with RPM @2750 cruising 80mph. That is with the converter locked. One thing to know is that everybody has an opinion on this one and a lot of them are real valuable, just listen. I chose the 700R4 because it is a strong trans and there are a lot of things that can be done with it to make it stronger. I have done plenty to it, I can tell you if you would like. The 200-4R can be made to be a strong unit but will require a good deal of money, more than I would like to spend. I like my combo that I am running now so there is no intentions to change anything. For first gear reference the 700-R4 is a 3:08:1 while the 200-4R is a 2.75:1, so there is a spread but it is still very close, the big thing people comment on is the 1-2 shift drop since the 200's first gear is less the drop is slightly less than the 700 but if you are into it hard with plenty of power you won't much notice it.

Cheers

Well,

I will be getting rid of the tires when I upgrade my brakes. I picked up some 16" iroc rims and that would put it at a larger tire 26" or so. Still debating on using the rims though, I may go with something else if I don't like them when I mount them.

My goals are to have a fun weekend car but streetable enough that I can cruise around the cites and out to the country.

I had looked at some 200r4 but chickened out on the price but maybe need to go back.

Clean7T, if you could send some details on your combo, that would be great.

Thanks everyone for the input. - John

Enganeer,
I run close to the same displacement as you. The 700 works nicely with a 26" tire and 3.55 r 3.73 gear. It's a good compromise between cruise rpm and 1st gear being too low. It has worked well for me.

no problem

406 2 bolt block that has been studded
Forged crank
6" Fotged Rods
Diamond race pistons 10.63:1 compression
Racer Brown cam 252 degrees of duration w1.6 roller rockers .552 lift @50
Dart Pro1 AL heads 200cc with minor cleanup work to achieve comp ratio.
Edelbrock 2999 Victor Jr.
Holley 850 dp

That is the basics on the motor. The trans has quite a bit of work done to it. It has a 3400 stall billet converter and manual VB to name a few. Hope yhis helps if you have any more questions let me know.

I really think Chris and Tony nailed it with two viable options.

The 4.10's and the TH400 would make an awesome around town and strip car but won't be too happy for long cruises which it seems you're interested in.

I'd either use Tony's advice, although more expensive 4.10's with a 2004r would rip similar to the 4.10's and TH400 on the street and strip but will still cruise great on the highway.

Chris also offered a great option, if you dont have the cash to swing the 2004r rebuilding the 3.08 rear into a more mid 3's gear would give you great performance the the 700r4 you currently have and that will cost you less than a grand to put into action. If you were to go that route though I would definately NOT redo the 4.10 rear into that rear as down the road you may want to do the 2004r and 4.10's would be perfect for that and you dont want a double hit of another rearend rebuild along with the cost of the 2004r.

So, IMHO, given your current goals and aspirations for the car, I would indefinately take Chris or Tony's solid advice. Just depends if you want to spend ~$2500 for the 2004r or ~$1000 for the 700r4, rearend rebuild route.