i am starting to shop around for a new tranny that will handle some serious power. i see all the top dogs running a th400 or 350. i am sure this is because the 4l60e is much weaker. what is the difference between the 400 and 350? what all does it take to bolt this up to a ls1/lt1? what are the pros and cons on a streetable car? anyone have a website i can go to for the answers? thanks alot

Paul

 

I have just gone from an M6 to a TH400 so have thought a lot about this. You really don't include enough information about your car and how you drive to respond except in generalities. So, in general, I'd say don't bother with a TH350. It isn't really any stronger than a 4L60E and you lose the OD. Without OD, you need a Gear Vendors OD to preserve reasonable rpm on the hoghway, and this adds >$2,000 to the cost!. The TH400 can be made "bullet proof" in terms of anything a small block can throw at it. Of course, it also lacks OD. Any of these tranny will bolt up without much difficulty. But like most of these projects, can get expensive, especially as the hp/performance level increases. For example, a basic race TH400 is in the $1,200-1,400 dollar range. But to this you need converter, spedometer speed sensor, oil pan, dipstick, and a shifter. Add a bit more for a transbrake. Good converters start in the ~$500 range and go up from there. A TH400 and converter for a hi-po setup runs in $4,000 range (don't ask me how I know, my checkbook is still whining).

Tell us more about your car and how you drive it. Does it have an A4 or an M6 now?

Rich Krause

 

right now i have a 94Z a4. i will probably be throwing in an ls1 before too long (yes i know the lt1 is good, i just want an ls1 for many different reasons, but i want MY car). in doing this, i will need a new tranny. the car will be used as a streetworthy driver and i dont want to have to hesitate to use it on the road. at the same time, i eventually plan on going the full bolt on and a power adder route (650+/- rwhp). my car has had 3 trannys already (160000) and from what i have read the 4l60e is only reliable up to certain points. so i figured whenever i am ready, i will throw in something more worthy in the long run. thats why i was thinking the TH 400 or 350. like i said i see the big boys running them. what are my options? what all does it take to have a great streetable yet powerful tranny? is the th400 the best route or is there someone with a good 4l60e that is capable. i havent thrown out the m6 idea, but i just feel a nice stall would be more fun to drive than a m6. plus the m6 isnt as consistent and i am worried about missing shifts with that much power. thanks for the response

Paul

 

Well, I really prefer a manual and used the T-56 with 733+rwhp. But if you want an auto with 650+rwhp you are talking TH400, and if you really want to use it comfortably for long distance highway travel, you will need the GV overdrive as well. This is a fine solution, except for the cost. I am not getting the GV this year, there's a limit to what even I am willing to dump into the car. And when I think back to the 60's, we drove around a lot in cars with 1:1 high gear and 3.73's or even 4:11's. With my 3.42's it may be livable after all.

To be sure I'm being clear, I do not think that any 4L60E is up to the kind of hp you are talking about. The TH400 simply has bigger, stronger parts. With that kind of hp, you can get away with the "basic" race TH400, you won't need all the billet stuff. But you are still talking at least $2,000 for everything you need. And you will still have a 1:1 top gear unless you spring for an overdrive unit.

I am no auto tranny expert, so hopefully others will chime in. But your story of "three transmissions" is one that many people have experienced with both TH350's and 4L60E's.

Rich Krause

 

thanks for the ffedback rich, thats what i was looking for. so you really enjoyed the t56 with that much power? i just firgured it would be hard to handle with the that much power and getting through the rpm band so quickly to the next shift. also i figured launching with one is reather tricky. so why are you going with a TH400 after all if you liked the m6 setup so much? if i was to go with a th400, what all i do i need to convert the ls1 to it? just adapter plates, ds, speedo sonsor, and optional gear venders OD? what else am i missing? what about a transmission crossmemeber or something to bolt it in? i think the biggest thing i am unclear on is how all the electronic controled computer knows how to shift and when with a non electric tranny, is that what the speedo sensor does? any help is appreciated, i am brand new to this idea and am considering to start my shopping when i find good deals.

Paul

 

For the most part, most people wear out auto tranny’s, not outright break them. You could build any one of them to handle the power you’re talking about, it’s a matter of for how long will it hold it.

The 350 vs. 400 debate is light and efficient 350 that will need to be rebuilt regularly vs the bullet proof 400 that will suck up power. You’ll run faster with a 350 but not as long. Building up a 4L60e could be considered the worst of both of those worlds discussed, not very durable, fairly heavy but still somewhat more efficient then the 400, but with the advantage of an overdrive for street driving.

If you poke around the SyTy groups you’ll find a bunch of builders claiming reliability for the TH700r4 (old name for the 4L60) with their aftermarket parts in the 800+hp range. I’m not sure that I believe it but I really haven’t seen one in person. GM has also released some stronger/more reliable parts for them and is marketing them as the 4L65e truck tranny.

You pretty much have to evaluate the importance of each of the qualities and make your own decision.

I, myself am trying to find the most efficient setup which will handle 800+ hp and usable in OD (I’d like to run land speed type stuff at Maxton on top of the typical drag race and even some road course use), which unfortunately appears to mean skipping on efficiency and either using a 400+gear vendors or a 4L80. I’d love to hear of an answer if someone has one. One other thing I’m considering is a 350 + GV and just keeping a couple of the around, 350’s are cheap and trannys aren’t as hard to rebuild as people make them out to be.

 

I am upping the power this year by another 100-200hp and the T56 is simply not man enough for ~1000hp, that's why I am ditching it. It takes more skill to launch than an automatic and I wouldn't advise powershifting it. So an auto will likely be quicker, if not faster. But I was getting pretty consistent 60' in the low 1.5sec range with a 26" ET street and a "road race" type suspension, so they can launch hard with enough practice.

As far as the LS1 goes, I am not sure. But if the 4L60E bolts up to it, the TH350 or 400 ought to also. A TH400 is NOT an electronically controlled tranny. The speedo sensor is similar to that on the elecronic trannys though. If you want it to shift automatically, it will be controlled the old fashioned way with a throttle valve cable and changes to the valve body. Most hi-po units are manually shifted. Yes, a new driveshaft will be needed.

Rich Krause

 

ok so what exactly are most people with lt1/ls1 going with? why are they manually shifted if they are autos? does that mean its a gate type straight forward and back shifter? i never understood that. my ultimate goal for this car will be a street racer/drag/cruise car that will run low 10s or hopefully high 9s on direct port nitrous (i think). it seems i dont want the th350 because i dont want to have to rebuild it all the time. so what do you guys think? stick with a 6 speed until i get the money for a th400 and a gear venders OD? is that the most streetable and dragable setup for my application? thanks for all the help

Paul

 

If you want a 9sec car you will need a TH400. I have looked into all of the options, and it makes the most sense. I seriously considered going as far as a Lenco. But a five-speed Lenco costs more than $5,000 and to that you have to add a couple of thousand in parts and custom work to get a clutch to work with it. And it's HUGE. Would require major mods to the tranny tunnel, and more problems as well. So, a TH400 is really the most practical option for a super hi-po car, IMHO.

The typical hi-po TH400 is a "reverse shifted" manual. 3rd is all the way back. The shifter moves in a straight line: P-R-N-1-2-3. They shift hard, BTW. But if you've ever tried to drive a car with any kind of a race tranny smoothly, you will know that except for WOT speed shifts, it's impossible. You are venturing into a realm of hp that was never seen on the steet until recently, and transmissions just haven't kept up. One option is the super-strong T-56 that Tremec made for the Viper LeMans cars. I looked into this too. $25,000 for one, with a discount if at least 10 are ordered! I bet Tremec could sell quite a few of these at $5,000 apiece, but I couldn't convince them of that. Lot's of people out there who like a reasonably compact 6-speed that could handle 850+ft.lbs (that's what they rate them for).

So, in context, a $2,000-4,000 TH400 setup isn't so out of line.

Rich Krause

 

GM made another awesome automatic that people sucessfully race with, it's called a powerglide They are smaller and lighter than a 6 speed and can handle well in excess of 1,000hp with even a stock case.

I have one and it's definitely not as friendly for daily driving as an OD but it's alot easier and more consistent to race with. If on the odd chance you do break something the transmission is so light most people can remove them with no help.

Another nice thing is that my boost level stays the same all the way down the track, from launch to when I let off. There is no power lost on the shift.

If you are insistent on a th400 then Madman offers a complete bolt in kit that is very reasonably priced. I nearly bought one until I found the swinging deal on my glide.

 

what are you guys talking about, these trannys arent friendly to daily driving? do you mean they shift super hard or the cruising rpms are super high? it sounds more and more like a 6 speed is what i will need for the near future, then move up to a powerglide or th400 later. how much did your powerglide run you and where did you get it?

Paul

 

As a two-speed tranny, a 'glide has a major disadvantage in a 4th gen. The power:weight ratio just isn't high enough to get away with using a two-speed tranny. The only way around this would be to use a very loose converter, which would be a real PITA on the street.

Just IMHO.

Rich Krause

 

a 'glide will be a pain unless your car is light and high powered.

The reason that they are calling the auto trannys that we're discussing not street freindly is that they are mostly modified to apply as much pressure to the friction surfaces as quickly as possible in an effort to make them live under the big torque that we're talking about. That results in a tranny that shifts hard all the time, which is not exactly pleasant for daily driving.

That being said and based on the questions you're asking I've got to ask, why are you shopping for a tranny? Sounds like you really want a street setup and don't currently need anything seriously heavy duty. Why not just stick with whatever you've got till it proves insufficient and then worry about upgrading.

 

The TH400 can be built to take huge torque and HP loads.... at least the ones I have seen. I can't see using a 2-speed Powerglide on a 3,600# car. When you have enough torque/HP to destroy a well-built TH400, you are probably at a point where you should be using a clutchless manual box.

And if you are used to a manual tranny, using a "manual" shifter on a reverse pattern, manual valve body automatic isn't going to be that traumatic. Seems to me like a lot of the harshness is proportional to load... snaps your neck under full power, just a little jolt at normal street driving loads, and its cushioned by the loose convertor. And the Gear Vendor has similar properties.

The problem with trying to have a setup that responds well both on the track and on the street it the huge difference in requirements. Big HP cars are going to be running large diameter slicks, pushing toward 4.11 and higher rear axle ratios. Put a 25.6" street tire on that car, and its going to drive you crazy with the buzzz, even with a GV. The GV only comes in one ratio... 0.78:1, so it is not going to be compatible with the expections of the typical T56 user with their 0.50:1 top gear.

If there is a downside of a manual valve body for the former M6 user, it is the complete absence of engine braking under decel.....

 

Fred: Carl Rossler is setting up mine to have engine braking in second as well as third gear. Some magic with the valve body, or something? Auto trannys are a "black box" to me.

Rich krause