I've been running my mouth about it,now I'm going with 4.56 gears with my 4L80E.I'm hoping the close ratios will offset any power loses from using the bigger transmission.Any thoughts?I just hope I'll need 4th at about 110mph to finish the 1/4th mile.

 

Do you still have the 10 bolt? I think the 4.56 uses a smaller pinion than 4.10's in a 10 bolt. That'll definately test the 10-bolt's power handling capability.

 

The 10 bolt in our trucks is way stronger than the 7.5" 10 bolt the fbody guys keep breaking.The 8.6" ring gear in the truck is nearly as strong as the lengendary 12 bolt rears 8.8" ring gear and not nearly as big and heavy as the 9.5" 14 bolt in the heavy duty trucks.If you are running an Eaton or Auburn Pro with a quality ring and pinion set it should hold up to a lot of power probably 900 to 1000 hp.

 

Thats good to hear! I've always worried about my rear end.

 

the 9.5 inch 14bolt is the light duty 3/4 ton axle. on 88-98 trucks it is a 6 lug(5lug for 454SS) and semi floating. its considered an extreme upgrade in strength over the 10 bolt.....in 00 or 01 it was changed to 8 lug.

the one ton trucks use a 10.5 inch 14bolt that has long been a full floater 8 lug.

anyways enough of that useless info.

TONS of lifted guys run 4.56s in these 10 bolts and have zero problems with strength. many many people do agree tho that it is the limit of low gears for the 10 bolt tho. any lower and the pinion is way to small to be strong enough and the contact patch isnt enough either(5.13s have like 1 tooth at a time connecting EEK)

i think you will have no troubles

 

Will you be able to make a good comparison to the gear ratio you have now?To find out if you really do lower your ET?

 

The 1st gear with the 4.56 geared 4L80E is about the same as 1st gear with a 4L60E and 3.73 gears,but all the other gears are much closer spaced.

 

Reason i ask is because i have seen guys install 4.56 gears and not drop there ET.Do you plan make a compairison to what you have in there now?

 

Now,I have 3.73s with a 4L80E transmission,1st gear shifts at 55mph with the 4.56s it will shift at 44mph.There's no need to make a comparison the truck needs more gearing.A stock 4L60E has a 3.06 1st gear and a 4L80E has a 2.48 1st gear.I'm not suggesting that those who have a 4L60E should even consider a 4.56 gear.

 

i have the stock 3.42's iin right now but i am going to go to 4.10 in the summer. i have a built 4l60e and a 5.3. i have 275/55/20 tires which are 32 tall like the ss's. keep me posted on the install and results. thanks