4l60e reverse problem

Ronnie Gaines · February 2, 2020

My transmission was rebuilt 1 month ago. Every gear works great. Reverse is slow to engage. Could this be caused by the band not working properly?

Doug_Scott · February 2, 2020

Possibly, should be under warranty, I hope. Don't waste anytime getting it back to who rebuilt it. The same band is also used for manual low. If you shift the transmission to 1 or L while driving at 10mph, you should feel engine breaking, you may need to go 15mph depending on final drive ratio.

Ronnie Gaines · February 2, 2020

23 minutes ago, Doug_Scott said:

Possibly, should be under warranty, I hope. Don't waste anytime getting it back to who rebuilt it. The same band is also used for manual low. If you shift the transmission to 1 or L while driving at 10mph, you should feel engine breaking, you may need to go 15mph depending on final drive ratio.

Ok what is engine braking

Ronnie Gaines · February 2, 2020

What is engine braking?

Ronnie Gaines · February 2, 2020

38 minutes ago, Doug_Scott said:

Possibly, should be under warranty, I hope. Don't waste anytime getting it back to who rebuilt it. The same band is also used for manual low. If you shift the transmission to 1 or L while driving at 10mph, you should feel engine breaking, you may need to go 15mph depending on final drive ratio.

If it does have engine braking is that good or bad ? Would that mean that the band is loose?

Doug_Scott · February 3, 2020

15 hours ago, Ronnie Gaines said:

If it does have engine braking is that good or bad ? Would that mean that the band is loose?

When your shifter is in Drive and you lift your foot off the gas pedal, your truck will coast to a stop, eventually. If you watch the tach you may even see the needle drop to the idle rpm, and stay there as the speed drops and the transmission automatically downshifts. If you pay attention you will find that when push the gas pedal at approximately 10 mph, the engine rpm will jump to about 2,000 rpm before it feels like the engine has caught up to the wheels. The transmission will be in first gear, and the low/reverse band will not be applied.

If you put the shifter into the lowest position, at about 10 - 15 mph with your foot off the gas, you will notice that it feels like the engine rpm will follow the speed of the truck. If you step on the gas and take the rpm up to 3,000 rpm and let off the gas, you will feel the engine slowing the truck down. You can accelerate, lift your foot off the gas pedal and the engine will feel like it is connected directly to the wheels. That is engine braking. The difference between the two positions is that in manual low(shifter in 1st), the low/reverse band is applied. If the band is very loose, it may not be able to stop the drum from spinning, making reverse feel like it is slipping. In manual low it may feel like it is slipping on deceleration.

I don't know the line hydraulic pressures of this transmission, but, in the Chrysler torqueflyte transmissions, line pressure will be double when shifter is in reverse.

Using manual low is a handy way to help diagnose low/reverse issues.

Ronnie Gaines · February 3, 2020

1 hour ago, Doug_Scott said:

When your shifter is in Drive and you lift your foot off the gas pedal, your truck will coast to a stop, eventually. If you watch the tach you may even see the needle drop to the idle rpm, and stay there as the speed drops and the transmission automatically downshifts. If you pay attention you will find that when push the gas pedal at approximately 10 mph, the engine rpm will jump to about 2,000 rpm before it feels like the engine has caught up to the wheels. The transmission will be in first gear, and the low/reverse band will not be applied.

If you put the shifter into the lowest position, at about 10 - 15 mph with your foot off the gas, you will notice that it feels like the engine rpm will follow the speed of the truck. If you step on the gas and take the rpm up to 3,000 rpm and let off the gas, you will feel the engine slowing the truck down. You can accelerate, lift your foot off the gas pedal and the engine will feel like it is connected directly to the wheels. That is engine braking. The difference between the two positions is that in manual low(shifter in 1st), the low/reverse band is applied. If the band is very loose, it may not be able to stop the drum from spinning, making reverse feel like it is slipping. In manual low it may feel like it is slipping on deceleration.

I don't know the line hydraulic pressures of this transmission, but, in the Chrysler torqueflyte transmissions, line pressure will be double when shifter is in reverse.

Using manual low is a handy way to help diagnose low/reverse issues.

It

17 hours ago, Ronnie Gaines said:

If it does have engine braking is that good or bad ? Would that mean that the band is loose?

17 hours ago, Ronnie Gaines said:

What is engine braking?

Thanks

Ronnie Gaines · February 3, 2020

Thank you

carkhz316 · February 3, 2020

There is no "reverse band" (it's the 2-4 band) used in this transmission, just a reverse input clutch and a low-reverse clutch . Probable causes are either bad low-reverse clutch or low line pressure rise from the boost valve. Take it back to the rebuilder for repair/ warranty.

Ronnie Gaines · February 3, 2020

Will extending the Corvette servo pin tighten up the reverse band?

Ronnie Gaines · February 3, 2020

2 hours ago, carkhz316 said:

There is no "reverse band" (it's the 2-4 band) used in this transmission, just a reverse input clutch and a low-reverse clutch . Probable causes are either bad low-reverse clutch or low line pressure rise from the boost valve. Take it back to the rebuilder for repair/ warranty.

What does the 2/4 servo and band do? Do they control the reverse?