Colby 04

That doesn't help me?

hog

Sure it does, 1:1 in 4th gear in a T-56 is teh same as 3rd gear of a 4l60e, except the manual trans doesnt have any torque multiplication but eh auto does.

With a 28" 325/40/15 bfg dr I trapped at 4900 rpm with a 4.10 gear and 4l60e, with the stock TC.

4.56's compared to 3.73's will have teh same amount of rpm drop at the shifts. The only thing that can affect rpm drop is the torque converter stall or teh actual trasmission gearing, not the final rear gears.

If I have a truck that has 4.10's and when I shift at 6000 rpm teh revs come back down to 4000 rpm in teh next gear, when I install 4.56 gear (or any other gear for that matter) teh revs will still drop 2000 rpm at teh shiftpoint.


peace
Hog

hog

Also although 4.56's would be nice for drag racing with a 4l80e, highway crusing would suck moreso than with the 4l60e as the 4l80e has the shorter .075:1 4th gear while the 4l60e/65e/70e's have the longer .070:1 ratio. 300 rpm is a biug difference when cruising. Thats why the OEM found it important to include a TCC to reduce pms by 2-300 rpm while improving effeciency.

I think that 3000 rpm at 70 mph is way too high a cruise rpm IMO.

peace
Hog

Lord Aries

iTrader: (6)

I am not bragging about my truck (nor have i ever 'Bragged" on this board), i simply stated that my truck pulls great from 45-120mph with my current setup and gearing... Everyones trucks are diffirent, I don't know what kind of "Proof" you are looking for. Don't expect any track slips anytime soon since i haven't been in almost two years, I didn't build truck to be a 1/4 mile queen...

Colby 04

a video would be nice

Lord Aries

iTrader: (6)

Heck yea it would! LOL

I am working on one at the moment actualy, just not done editing it. The local Avalanche club got to make some hot laps on the New Smyna Oval track a week ago, it was a lot of fun... Needless to say that since i was the only F.I. truck, i was the only one making hot laps. LoL

99RCSB

iTrader: (3)

I will be listening in on this. I might have to change gears with my 4l80e swap behind my 4.8 so i can regain some driveability.

LSInnovations

iTrader: (7)

To correct all the previous mis-information in this post.


You are much better off with a 4.56 gear with 30" tires than 4.11 /w 28" tires in most of your drag racing setups I see.

A 4.56 /w 30" will give you a deeper gear than the 4.11/28 but a 30" tire (my 30x14x16 M&H DOT's) grow right at 3" on the top end which takes away gear in the last 1/8th mile where I want it.

I can go through the traps at approx 125 without running out of gear. (I lock up the converter in high gear as well which gives me even more room)


<------408" /w 250hp spray in ECSB

James B.

iTrader: (1)

Be careful how much traction you bolt up with that gearing in a 10-bolt. Increasing the ratio puts more torque on the differential. In first gear it see's the most torque and if you have good traction in first the rear end has to hold against the full output torque of your powertrain. The Detroit will be solid but the housing isn't and will deflect causing the contact pattern between the ring and pinion to move out to the tips of the teeth. The pinion gear of an 8.6" 4.56:1 set is tiny.
As for the street and highway, 4.56:1 with 29" tires isn't that bad, even with a 4L80-E. I don't kick in the Gear Vendors until I'm past 65 to 70 and will be above that speed for a while. Personally I'd rather have 4.10:1 or 3.73:1 gears now. The 4.56 gear were great with less power but now I can't plant the extra torque anyway so the 4.56's are wasted really.

AustinDesigns

iTrader: (7)

You can plant any power you have, if you got deep enough pockets. Backhalf it!! But guess what, I aint got deep enough pockets to get it done right!! Talked to a chassis guy I know, and he said it would run me around $9000.