From my memory you want to be at the top of the 1:1 gear crossing the 1/4 mi traps. 4.56:1 would kill any fuel economy you have (if you care about that stuff) but once you got past the 1st gear it would be similar to 2 and 3 with the 4L60. I'd say you would be close to 6700rpms or so (just a guess from power and motor wise) if not higher with those 4.56:1 gears crossing the traps. Basically you may be overgeared for your application.

A low geared 4L80E would be a killer trans for your setup. The slightly lower 2.75:1 first will drop your 1st to close to a 3.73:1 final ratio but the 1:1 is still a 4.10:1. This is pretty much a wash on what to do right now.

It sounds like you toasted your 3-4 clutch pack. Do you not have OD either?

How fast are you running in the 1/4mi anyway? What are your WOT shift RPMs?

 

It depends on what kind of MPH potential you have in a 1/4mi,from the kind of power you are making I would say you probably have the potential to run over or near 120mph with a 300 shot and I would suggest that a 4th gear change with 4.56 gears would give the best 1/4mi times.With 4.56 gears and 26" slicks you would be running 5500rpm at 120mph,right in the motors sweet spot.With 31" street the 4.56s would br livable.

 

the smaller gears are stronger, thats probably one of the reasons why they are used in the 4L80.

also 4.56s wont hurt your mileage as much as you think, but if you have a pretty fast truck, your gonna run out of gear, and shifting into OD isnt a smart idea if you ask me

 

The Ford 4R100 (E4OD) uses 2.71:1 first gear and can use 6 pinion planetaries (I think the later model trans use the 6 pinion), those are behind Powerstrokes and Lightnings...those make assloads of power. Those transmissions need a 45 element sprag, TransGo, and extra clutches in direct drive to be bad to the bone.

I still think over gearing the truck is a bad idea. I would never shift a trans into OD at WOT. I can see that band anchor being ripped right off and that does happen. Could you even get traction with a 4.56:1 on slicks with a 300shot sprayed out of the hole on a 408? That may make you shift gears on the 60' run and that would slow you down a bit also.

 

ya, It has only a little of third. Third works up to a 1/4 throttle. Anything past that just revs up like it is in neutral. Plus there is no overdrive. Some of you guys are saying that overdrive is to weak for this setup. Has very many people tried to use od with a large amount of power.

By the way that 300 hit really hard. I was impresses when i first hit it. The 200 was a decent hit, but the 300 was a completely differnt ball game. It was fun for the first couple of secounds. My buddy and i were very surprised on the difference an extra 100 hp added.

 

Well hell you just toasted the 3-4 clutch pack, I see if you could just rebild that and be off to the races again. It won't hold forever but with 8-10 clutches it should be okay.

The OD trans is not too weak, the acutal 3-4 shift into OD is at WOT. That band is not made for such an upshift at that speed. And yeah bigger shots of spray are addictive...I used to run a car with a 100 shot then jumped to a 175 shot, huge difference with that. I can only imagine what a 200 then to a 300 would be like.

 

"Red Eagle clutches and band, Kolene steels, rated at 900 + horse power and has full throttle 3-4 up-shifts." from >> http://www.transmissioncenter.net/4L80E.htm

they are saying 900+ shifts into 4th, now my question is would 4.88 gears be much faster than 373/410 gears asuming you could get traction(4wd + lockers front and rear)

i am leaning toward a HD wich will have 4.10's, probably just stick with those for awhile and if i run out of gear in 3rd then decide. if i want to go STEEP.

 

I dont know. I really think that if i lowered the ratio that low, there is no way i could ever hit the button in first gear. It has decent traction, but i dont think it would ever hook with that setup.

 

Parish8,according to everything I can find about the 4L80E,75% of TH400 parts fit it and the transmission is plenty strong to take full throttle shifts into 4th gear.

 

Well ya a 4L80E is basically a TH-400 with electronic controls and an OD...hence why most of the internals are the same.

But it would be tough to run out of gear in 3rd with 4.10:1 gears and ~31" tire, you will need some really hard-core power to do that. If you are going to be making all out power 600rwhp+ you'd light up the 4.88:1's even in 4Hi...hell you were doing that in the other truck in 4Hi, granted the front was open one more tire with way lower gears will spin.

Can you keep Torque Converter Lock-Up out of 4th at WOT? If not running a non-lockup converter will be your only option and create excessive heat and lower efficiency.

If you want to shift into 4th at WOT, you will need to get a set of gears that will be close to the top of the powerband at the end of the run also.

Either way if this trans is setup with a 4th gear band for OD, it has got to be really strong to do those upshifts. If the anchor on the band won't go then if there is a 3-4 clutch pack that would be next up. I am not totally sure of how the internals of the 4L80E work but those are just educated guesses.

Let me put it this way, I would not risk it. I trust no one's claims. That "900hp" WOT shift could be in a 2800lbs race car, but in a 5500lbs truck that could drop drastically to 600hp or so. That is only the OD shift, others should be okay.