Hey gang, I realize that in order to obtain my goal of having a 9 second street ride, I will need to ditch the 4 speed for a 3 speed.

Which one is the desired tranny? I see more 350's than 400's. Why is that? What makes a 350 stronger than a 4l60 or 4l65e? I'm no tranny guy, so explain this to a simpleton. lol.

Aside from crossbrace, torque converter and driveshaft- does anything else need to be swapped?

Steve

 

TH350's are abundent and easy to swap. They can be built to be about as strong as a TH400 but at a higher price than building a TH400. The TH400 is heavy, longer and needs a special tranny yoke for the driveshaft plus usually a shorter driveshaft.

If you tear apart both of them, you can see how much stronger and better designed the TH400 is but that better design also means a lot of weight. The TH400 tips the scales at 130 pounds. It also eats up 44 hp just turning the internal mass. The Th350 isn't that much lighter and doesn't need as much hp to turn the parts.

If you have enough hp/torque to run 9's then you don't need the low first gear of a 3 speed. Get a good Powerglide. The PG weighs 97 pounds and only uses up 18 hp. It's as simple to swap into a car as a TH350 is.

Another option is the Metric 200 (TH200c). It's a 3 speed tranny that is sort of similar to a TH350 but offers roughly the same performance advantages as the Powerglide with the extra gear.

There are kits available to remove a 4 speed automatic and install a TH350/TH400. Each has their own way of having things hooked up. The TH350 uses a detent cable (not the same thing as the TV cable). The TH400 uses an electric kickdown.

 

I have a TH400, reverse manual, transbrake, billet input shaft, and ultra bell.

Best mod you can do for any Fbody running 10's or lower.

 

Steve: I am not so sure about needing an auto for a 9sec street/strip car. My pig of convetible weighs 3,850 minus driver and went as quick as 10.66 with a granny shifted, stock T56 and it never broke. At this point, the car is not fully sorted, so I haven't come to a firm conclusion. But as of now, I wish I'd kept the T56. An auto with a race converter eats up a lot of hp (approaching 10%) and no OD is a major PITA on the street, even with 3.42's.

Stephen's post has some good info. But I disagree with the idea of a PG in a 4th gen. The car is just way to heavy to get away with a two speed. If it were purely a track car, with every possible weight reduction mod, and you were running a big nitrous shot then maybe, just maybe, you could get away with a PG. But as I understand your plans, it's gonna have a Vortech and be a street/strip car, so you won't have the huge torque hit of nitrous to get all that mass moving. I am still figuring out how to get mine to launch hard enough with the TH400. Clearly, with the blower alone and no N2O it doesn't launch hard enough. I am going to be playing with the niotrous and both together should do the trick. BTW: that's from a 4,200rpm launch against the brake, so I can't see the higher first gear of a PG working out, even with a car that's a couple of hundred ponds lighter.

If you are dead set on an auto, I'd say TH400 is the way to go. A big part of the reason to switch is to get something that won't break, and a TH400 is just plain stronger than a TH350.

Rich Krause

 

I'm sorry....could you say that again Mr. Krause.

 

Sorry,sorry, sorry, sorry.........

Rich Krause

 

From my experience and research i have found that no matter what ya do to a 350 it will only be reliable to 750 lbs torque. Thats with a 3200 lb car. Put that in a light car 2800-2900 and you can get away with it longer. For what it cost to build a 400 and what you get as far as Hp capability it far exceds everything out there. If ya know a buddy who is willing to do it for you then it can be made to handle 1000 lb tq for about 500-650$ with a trans brake. All a 400 needs to handle that is a good sprag and clutches and a manual or transbrake valve body. If ya really need a OD put a gearvendors OD on it. If your building a spray motor then your gears and converter are generaly low and tight enuff to do street duty at a small cost in cruising speed.

As far a Powereglides go my buddy has a 18* headed 406 in a old Iroc that has full powerevryting weighing in at 3650 and runs 9.60's at 142 all day. They are much more efficient in a lighter car but if its got he power and it suits the application then roll w/it

 

Don't knock a TH350's or even the T200's ability to handle hp in a fairly heavy car. You need only look at the stock and super stock ranks for validation of that. You will of course need a bit more than a street/strip type build but a car as fast as you're talking really should have a well prepped tranny in the first place. There are many GM racers in those ranks running the 200 behind BBC's in the SS and GT classes. And I'm sure you can figure the reason why these guys look at the "lesser" trannies, less wt always equals less hp loss. There are plenty of really good parts available for these trannies now. Billy Lynn, JPT, McClay, etc are all excellent pieces, you should call them for prices. Weighed against trying to run a street/strip type tranny vs what some of these guys charge for their pieces you'll find them to be pretty reasonable.

 

Has anyone tried the new (or relatively new) 4L65-E?? (yes, 65, not 60). It's supposed to be offered as a GM performance part (like their crate motors) and I've read a couple articles lately about it claiming that it's a much heavier duty version of a 4L60-E, with stronger gears, input/output shafts, etc. One of the articles said that it's currently the transmission in Escalades and vehicles of that sort, but in a car like the F-body, it should be capable of handling "roughly" ~400 lb-ft of torque vs. the ~360 lb-ft rating of the 4L60-E.

Maybe it's still not as strong as a TH350 or TH400, but it's probably a good alternative to get a stronger tranny, yet maintain the O/D option and the electronic controls.

 

Exactly the reason I got a TH400 for my Nova... I'm good at breaking things.

 

For starters, I have friends running bottom 9's with 350's- so I am sure whatever I give it will live.

I did see an article on the 65, but was curious how well it'd take to mods and torque. I make 400 ft/lbs at the wheels RIGHT NOW, so it'd be a waste if that would just pop.

Also- how does the 65 compare to the 80? The 80 is a pig, that sucks HP, and weighs too much. Any stats avail?

Steve

 

Sorry, I don't have much detail on the 4L80-E transmissions, but AFAIK, they're the new electronically controlled, O/D version of the TH400, whereas the L60/65's are based off the 700-R4, which is basically an O/D version of a TH350 (hence the weight difference between the TH350's / 4L60-E's and TH400's / 4L80-E's).

The mag. article I read said that the weight difference was roughly ~55 lbs.

 

Steve,
I just bought a 94Z28 w/TH400. If you want a speedometer/odometer, you'll need either an aftermarket electronic speedometer or a GM reluctor/sensor from an older car. I've been weighing the options lately myself.

 

I think that guy above made a good point about the T350 only being good to a certain point.

4L65E is supposedly good up to 400 ft lbs of torque so it would not be adequate for your needs.

S/E and S/S guys weight like 3200 raceweight and run like mid 10's down to high 9's, but mostly low 10's.

 

It depends how much you want to spend. I have betwean $4,000.00-$4,500.00 in each of my TH-200/350 set-ups and have been unable to kill one yet. I freshen them on a regular basis because I don't run a cooler and wear out the high gear clutches, but for me that is regular maintenance.

Daren