4L80E vs. TH400 with GV OD
the down side is there are no good/reliable trans brakes for the 4l80's yet from what i've heard. so if you are wanting one, look into the GV, or better yet IMO, the V2OD unit. it's nearly $1000 less, and can take all the abuse you'll likely ever throw at it. it's been tested to 1000+hp so far with no problems when run indirect, the same way the GV is measured. they are made by US Gear, the same company that Moser uses exclusively from what i understand. with that being said, they are a reputable company and the customer service is top notch. i had bought one for my vert. SS, but thought it did not fit due to where i measured it.
however, if a GV can fit in our cars, so can this as it's nearly identical in size. take a look at the pic. they also have a cable operated unit too that's the same price, and either a .80 od gear or a .70 gear too. hope that helps your decision some. btw, either a GV or V2OD can be used with a trans brake when they are not engaged.later,
Dave
btw....it weighs 50lbs. and takes an avg. of 1% hp to turn. i don't know the difference in weight of a 4l80 or if it takes more power to turn than just a th400. but even at 800hp, you'll only lose 8rwhp and have O.D. and a trans brake will more than make up that power loss off the line with the much harder launch.
Last edited by PRAY HRD; Dec 29, 2004 at 01:52 PM.
I bought a 1998 trans for my truck and it had some major wear in it with only 60,000 miles on it. I had to put $200 just for hard parts like the forward clutch housing, the center support bushing was worn with about 1/16" clearance in it. The clutches were still all good.
On the other hand I've got ahold of th400's with unknown miles, worn out clutch frictions and have just put a $120 rebuild in them.

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One thing to note about how it shifts though is that the GV uses an on/off solenoid. There is no line pressure control that can be based off throttle posistion or any of that. It engages and disengages very firmly, the firmness you FEEL will be determined by how much throttle you are putting through it at the time. At low throttle the tprque converter is more lose and with more throttle the converter gets tighter. The GV controller will always unlock the TCC (if you have one) to shift itself no matter what speed or gear the trans is in. These units cannot be used to split gears on a sprint. There are delays with engagement and with disengagement that are impossible to coordinate with trans shifting.
Given the choice of TH400+GV and 4L80-E, the 4L80-E has the advantage. It can be programmed. Shift points, shift firmness, TCC lockup, downshift heuristics, Line pressure vs. TPS, etc... the list of stuff you have control of goes on and on. Nice and soft around town, very firm and solid WOT = NO PROBLEM. (Just try to manually calibrate a valvebody on a non-electronic trans to give you that.) I figure if you're going to put something as heavy and parasitic as an automatic transmission in your drive train, the damn thing should shift itself and do it better than you could. Programmed right, the 4L80-E can and DOES.
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in essence, isn't what you're saying then is that the GV unit is basically OFF when your going down the quarter? so when racing, there is no realized benefit to having a GV over a V2OD if i'm understanding correctly. and yes, the 4l80E would be the best choice if this is still your everyday car, or close to it. but in my case, i'm going to put maybe 2500-3500 miles a year on the car, and wont do without a t-brake. so the 4l80E is out of the question. this is a good topic, and i've been waiting for one of these for a while now.
Dave
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in essence, isn't what you're saying then is that the GV unit is basically OFF when your going down the quarter? so when racing, there is no realized benefit to having a GV over a V2OD if i'm understanding correctly....
oh, and exactly! with either one of these OD's, definately set your car up for the strip as though it was not even there, since you will not be using it anyway. this will enable you to run the t-brake and go through the th400's gears like any other car that does not have an OD. then, pack up and drive home with an OD setup and smile....
you're living the best of both worlds!thanks,
Dave
curious. i don't have the time, nor the patience right now to figure out the mathematical equation to understand this comment on the D/S RPM's. shouldn't the OD reduce the speed at which it turns, as it does the engine and trans? that's something i've never thought about and any insight would be appreciated.
thanks,
Dave
Driveshaft RPM....
I have 29" tires and 4.56:1 gears.
29" tires do 11.59 RPM at 1 mph (88/(29pi/12))
take my average highway speed of 85, multiplied by tire factor os 11.59, and gear of 4.56 and it comes to 4492 RPM at the driveshaft! It doesn't matter what's in there for a transmission, transfer case, or an overdrive - that's what the driveshaft on my truck is doing at 85 no matter what. If I had a only a TH400 in there I would be seeing engine RPMs at 85mph even higher than that by a little bit in top gear since it can't lock the converter. It's scary to think I've had the truck up to the speed limiter of 128mph = 6764RPM for the driveshaft. I know that stock ones cannot do that.... With the 4L80-E OD gear ratio of 0.75:1 and the GV OD ratio of 0.78:1 combined with TCC lockup I can get those Engine RPMs down to 2628RPM at 85mph with this setup.
I stopped by Speed Inc last night, my old 4l60e was pulled and the Th400 was going in.
You are more than welcome to swing by or meet up and I will let you take a TH400 behind a 408 stroker to get a feel for it.
Depends on the day of the week, but I am frequently in Vernon Hills, Elgin, Schaumburg area.
I stopped by Speed Inc last night, my old 4l60e was pulled and the Th400 was going in.
You are more than welcome to swing by or meet up and I will let you take a TH400 behind a 408 stroker to get a feel for it.
Depends on the day of the week, but I am frequently in Vernon Hills, Elgin, Schaumburg area.
I personally really want OD cause spining at like 3500 while only doing 55-60 on the highway isn't to my liking among other things.




