badtothe bone
Full Access Member
I thought I would share some of the inner workings of the 4L60E and 4L85E transmissions, and some of the common problems I’ve seen with them over the years.
The 4l60E, was introduced in 1993, is an electronic version of the 700r4, which was introduced in 1982. The 4L65E is heavy-duty unit for use behind the 6.0L engines, and was introduced in 2001. Some of the parts were improved to increase its torque capacity. Input and reaction carriers were changed from 4 to 5 pinion gears. An extra clutch was added to the 3-4-clutch pack, hardened input shaft, heavy-duty low roller clutch with wider rollers, and a heavy-duty sun shell and sun gear. All of these parts can be used in the 4L60E. I think they should've just used the 4L65E in all applications instead of having two versions of the same transmission.
The 4L80E has been around since 91 and is basically a turbo 400 with overdrive and electronic controls. A lot of the parts have remained virtually unchanged since 64 when the 400 was introduced. When the 4L85E came about in 2002 and had a higher torque capacity. Parts that were improved were the input and reaction carriers, from 4 to 5 pinions gears and an improved overdrive planatary and drum. The 4L80E in my opinion is a very strong transmission. It’s had its share problems over the years but currently is the best it’s ever been. One common complaint I see a lot is “no reverse”. In the 91-96 units I see a lot of direct/rev pistons broken in two. These are made of aluminum. In 97 they went to a metal piston with a bonded rubber seal. I have yet to see one of these fail yet and I use this type when I rebuild them. The reason the piston breaks is due to a high line pressure in reverse. The reverse boost valve wears out and causes a uncontrollable line pressure. I’ve heard of cases where the line pressure has exceeded 600 psi, and when this happens you can get some serious parts breakage. I’ve heard of cases splitting in two and have seen myself a direct drum, which is made from cast iron, split apart. Every time I see a unit with a reverse problem it always has a worn out boost valve. The latest 4L80E units I have worked on was a 2000 model with no reverse. I was a little surprised to see this complaint on a newer model transmission because I knew it had a steel piston with a bonded rubber seal, which usually does not break. I took the unit apart and everything looked perfect inside except for the reverse band which was burnt, usually that is not a problem with that model. Anyway the cause of the problem again was the boost valve. So if there is one thing that I would like to see improved with the 4l80E is if they would improve the reverse boost valve. Is there any drawbacks with the 4l80E? Not really, except maybe with the weight of the unit. The torque converters on these things weight nearly 70lbs! I think that there is quite a bit a horsepower that is being thrown away - with such a heavy unit.
As for the 4L60E, not too many changes has been made to the major components of the transmission (planets, drums, gears, etc.) since 82. A larger input sprag and low roller clutch is about all that’s been changed and that was back in 86-87. Once again “no reverse” is fairly common complaint with these, but for a different reason. I see a ton of broken sun shells. There is a splined area of the shell (splines on to reaction sun gear) that breaks clean off. This area is just not strong enough. So GM has come out with a redesigned shell in the past couple of years to help with this problem, it’s a bit thicker and has more of a radius where the splines meet the base of the shell. Well now guess what? Instead of breaking the splines , they are now striping out! I’ve seen this problem many times on the 2000 and newer units, and have heard this from other builders too. I am a little reluctant to get new shell from the dealer because of this current problem. I’ve heard from other builders that new shells they bought and put in have been striping out in as little as 20,000 miles! I think that the sun shell is the weakest part of the 4L60E. I have tried to use an aftermarket shell that has hardened splines whenever possible.
There are a few other common problems I see. One problem is that there is a check ball that likes to wear out the separator plate, it eventually blows down through it, but it doesn’t occure all the time. It might depend on how hard it is driven. In the mid 90’s, I saw quite a few bearings in the planetaries fail. Usually it would cause a lot of damage, but I think that it was due to a bad batch bearings.
In the quest for better gas mileage GM has changed the lock up strategy of the torque converter over the years. The original 700 and 93-94 4L60E used a on/off type lockup. Meaning it was totally off or fully on and locked.
In 95 they went to a PWM (pulse width modulated) lockup, which controls the aggressiveness of the apply and release of the torque converter clutch and it allows a little bit more slippage for a smoother feel.
In 1998 GM went to a different strategy called “Ec3”or electronically controlled capacity clutch.
This strategy has made a big difference in fuel economy by starting the apply of the TCC at a much lower speed and continually slipping it until it reaches highway speeds. It begins to apply in 2nd gear and slips up to 250 rpms depending on speed and engine output. In order for this strategy to work a new converter clutch lining had to be developed to withstand the slippage and heat generated. What GM came up with is a woven carbon fiber material that is very porous that allows fluid to flow though it for better heat transfer. This stuff is practically indestructible. One of the problems shops face is getting a replacement converter when doing a rebuild. GM holds a patent on this material. The aftermarket converter companies have been trying to find a suitable replacement material that will hold up. Several companies are very close to releasing their own material. Until then we have only two choices, get a rebuilt converter with a good “used” woven clutch or buy the converter from the local GM dealer. I personally prefer to go new. I just don’t trust a used lining although this stuff is extremely durable.
The 4l80E uses the PWM type strategy and uses a Graphite/ Kevlar composition lining for the TCC.
The 4l60E PWM units use this material also.
Both the units have been using a High Energy Graphitic lining on the clutch plates and bands for several years now. This material is very durable and can withstand high temperatures. It’s not uncommon to take apart a high mileage unit and find that the clutches still look as good as they day they were put in new.
The 4l60E, was introduced in 1993, is an electronic version of the 700r4, which was introduced in 1982. The 4L65E is heavy-duty unit for use behind the 6.0L engines, and was introduced in 2001. Some of the parts were improved to increase its torque capacity. Input and reaction carriers were changed from 4 to 5 pinion gears. An extra clutch was added to the 3-4-clutch pack, hardened input shaft, heavy-duty low roller clutch with wider rollers, and a heavy-duty sun shell and sun gear. All of these parts can be used in the 4L60E. I think they should've just used the 4L65E in all applications instead of having two versions of the same transmission.
The 4L80E has been around since 91 and is basically a turbo 400 with overdrive and electronic controls. A lot of the parts have remained virtually unchanged since 64 when the 400 was introduced. When the 4L85E came about in 2002 and had a higher torque capacity. Parts that were improved were the input and reaction carriers, from 4 to 5 pinions gears and an improved overdrive planatary and drum. The 4L80E in my opinion is a very strong transmission. It’s had its share problems over the years but currently is the best it’s ever been. One common complaint I see a lot is “no reverse”. In the 91-96 units I see a lot of direct/rev pistons broken in two. These are made of aluminum. In 97 they went to a metal piston with a bonded rubber seal. I have yet to see one of these fail yet and I use this type when I rebuild them. The reason the piston breaks is due to a high line pressure in reverse. The reverse boost valve wears out and causes a uncontrollable line pressure. I’ve heard of cases where the line pressure has exceeded 600 psi, and when this happens you can get some serious parts breakage. I’ve heard of cases splitting in two and have seen myself a direct drum, which is made from cast iron, split apart. Every time I see a unit with a reverse problem it always has a worn out boost valve. The latest 4L80E units I have worked on was a 2000 model with no reverse. I was a little surprised to see this complaint on a newer model transmission because I knew it had a steel piston with a bonded rubber seal, which usually does not break. I took the unit apart and everything looked perfect inside except for the reverse band which was burnt, usually that is not a problem with that model. Anyway the cause of the problem again was the boost valve. So if there is one thing that I would like to see improved with the 4l80E is if they would improve the reverse boost valve. Is there any drawbacks with the 4l80E? Not really, except maybe with the weight of the unit. The torque converters on these things weight nearly 70lbs! I think that there is quite a bit a horsepower that is being thrown away - with such a heavy unit.
As for the 4L60E, not too many changes has been made to the major components of the transmission (planets, drums, gears, etc.) since 82. A larger input sprag and low roller clutch is about all that’s been changed and that was back in 86-87. Once again “no reverse” is fairly common complaint with these, but for a different reason. I see a ton of broken sun shells. There is a splined area of the shell (splines on to reaction sun gear) that breaks clean off. This area is just not strong enough. So GM has come out with a redesigned shell in the past couple of years to help with this problem, it’s a bit thicker and has more of a radius where the splines meet the base of the shell. Well now guess what? Instead of breaking the splines , they are now striping out! I’ve seen this problem many times on the 2000 and newer units, and have heard this from other builders too. I am a little reluctant to get new shell from the dealer because of this current problem. I’ve heard from other builders that new shells they bought and put in have been striping out in as little as 20,000 miles! I think that the sun shell is the weakest part of the 4L60E. I have tried to use an aftermarket shell that has hardened splines whenever possible.
There are a few other common problems I see. One problem is that there is a check ball that likes to wear out the separator plate, it eventually blows down through it, but it doesn’t occure all the time. It might depend on how hard it is driven. In the mid 90’s, I saw quite a few bearings in the planetaries fail. Usually it would cause a lot of damage, but I think that it was due to a bad batch bearings.
In the quest for better gas mileage GM has changed the lock up strategy of the torque converter over the years. The original 700 and 93-94 4L60E used a on/off type lockup. Meaning it was totally off or fully on and locked.
In 95 they went to a PWM (pulse width modulated) lockup, which controls the aggressiveness of the apply and release of the torque converter clutch and it allows a little bit more slippage for a smoother feel.
In 1998 GM went to a different strategy called “Ec3”or electronically controlled capacity clutch.
This strategy has made a big difference in fuel economy by starting the apply of the TCC at a much lower speed and continually slipping it until it reaches highway speeds. It begins to apply in 2nd gear and slips up to 250 rpms depending on speed and engine output. In order for this strategy to work a new converter clutch lining had to be developed to withstand the slippage and heat generated. What GM came up with is a woven carbon fiber material that is very porous that allows fluid to flow though it for better heat transfer. This stuff is practically indestructible. One of the problems shops face is getting a replacement converter when doing a rebuild. GM holds a patent on this material. The aftermarket converter companies have been trying to find a suitable replacement material that will hold up. Several companies are very close to releasing their own material. Until then we have only two choices, get a rebuilt converter with a good “used” woven clutch or buy the converter from the local GM dealer. I personally prefer to go new. I just don’t trust a used lining although this stuff is extremely durable.
The 4l80E uses the PWM type strategy and uses a Graphite/ Kevlar composition lining for the TCC.
The 4l60E PWM units use this material also.
Both the units have been using a High Energy Graphitic lining on the clutch plates and bands for several years now. This material is very durable and can withstand high temperatures. It’s not uncommon to take apart a high mileage unit and find that the clutches still look as good as they day they were put in new.
Interesting post nonetheless.
