Replace Overdrive gear
Thread Starter
Teching In
Joined: Jan 2013
Posts: 39
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Replace Overdrive gear Would it be possible to replace the overdrive gear with a stronger one to utilize that OD ratio at speed? That would allow a higher top speed without breakage? My friends dad has a pretty sweet metalworking setup.
Are you asking the question based on the many posts about not wanting to have to shift into 4th to finish the 1/4 mile ?
4th gear and its' associated clutching was/is intended for freeway cruising at low torque demand.
AND because of its' .76 ratio, transmission output torque is lower than 3rds' 1:1 ratio.
Example,if with 3rd(1:1) tranny output is putting out 350 ft.lbs,in 4th(1:.76) tranny output is 266 ft.lbs..
4th gear and its' associated clutching was/is intended for freeway cruising at low torque demand.
AND because of its' .76 ratio, transmission output torque is lower than 3rds' 1:1 ratio.
Example,if with 3rd(1:1) tranny output is putting out 350 ft.lbs,in 4th(1:.76) tranny output is 266 ft.lbs..
Metalworking is all fine, but what about metallurgy
(bulk and surface)? Do you think you, or he, know
what it takes to make a cut gear survive for a
hundred thousand miles? And that's like 6-7 of
them, pinion, ring and planets, all perfect.
I'd bet there's someone selling different ratio
planetaries out there. At well less than one
screwup will cost you, even with metal shop
labor being "free".
(bulk and surface)? Do you think you, or he, know
what it takes to make a cut gear survive for a
hundred thousand miles? And that's like 6-7 of
them, pinion, ring and planets, all perfect.
I'd bet there's someone selling different ratio
planetaries out there. At well less than one
screwup will cost you, even with metal shop
labor being "free".
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Joined: Aug 2010
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From: Ann Arbor, MI
I'm very familiar with aftermarket 4L60E parts and there is nothing to chang the OD ratio.
There is a billet planetary set, which I have, which provides closer ratios for 1st and 2nd, but it does not change OD. Also, if still made, it costs $1200+.
4th gear (OD) in a 4L60E is known to be weak, but can be improved with a wide 2/4 band and a billet 4th gear servo. Drilling the 4th apply hole in the separator plate and a few other tweaks will help too.
With my 3.42 rear, I would hit about 135mph at 6500 RPM in 3rd. It will take 700+ HP to hit that in the 1/4 mile. I can see exceeding that in a road race course, but it otherwise seems like a theoretical issue.
There is a billet planetary set, which I have, which provides closer ratios for 1st and 2nd, but it does not change OD. Also, if still made, it costs $1200+.
4th gear (OD) in a 4L60E is known to be weak, but can be improved with a wide 2/4 band and a billet 4th gear servo. Drilling the 4th apply hole in the separator plate and a few other tweaks will help too.
With my 3.42 rear, I would hit about 135mph at 6500 RPM in 3rd. It will take 700+ HP to hit that in the 1/4 mile. I can see exceeding that in a road race course, but it otherwise seems like a theoretical issue.
Thread Starter
Teching In
Joined: Jan 2013
Posts: 39
Likes: 0
Was just a theory I had. The car isnt going to be for the strip, but more for DD/twisty roads. Just was wondering if fourth gear could be beefed up in any way so it could be used to prevent a loss of top speed with 3.73s.
EDIT: Once I get a job (Just moved to college), im looking at doing either a stall/gears, or a 6l80e. But either way its gonna be a few months to scrounge up that kind of money.
EDIT: Once I get a job (Just moved to college), im looking at doing either a stall/gears, or a 6l80e. But either way its gonna be a few months to scrounge up that kind of money.
Last edited by jericz28; Jan 25, 2014 at 12:24 PM.
