Category Archives: 4L80E Transmission

4L80E Transmission Facts

Rather than do an end to end anal exam with this transmission, i have to be honest…..compared to servicing a 4L60E this thing is not bad at all. if you can do a Th400, you can do this thing. for the most part it even shares the same gear ratio’s as the th400, reverse being a slightly lower ratio over the 400 though due to the overdrive unit.

first gear: 2.48:1

second gear: 1.48:1

third gear: 1:1

fourth gear: 1 :.75 – overdrive

Reverse: 2.08:1

 i am going to go over some of the things to look for and be aware of durning your build. most of these are outlined in your ATSG book. the first thing is that the later model transmissions were a different bell housing to accomodate the LS engine bell housing. the easy way to tell is it has the extra bolt hole at the top of the housing that older bell housing pattern housings did not have.

Starting at the front,S3700038 the overrun clutch assembly on earlier model trannys was known to be a problem area. in 2001 they changed the design of the overrun roller clutch assembly due to wear issues with the sprag. the new design set up can be retro fitted into older transmissions, however when they changed the sprag, they pretty much changed damn near everything you see in this picture to accomodate the change, including the input turbine shaft.



here S3700040you can get a good lookat the older style sprag to the right of the picture. it has a thick lip of plastic on one side. is this a real critical thing to have to retro fit into these, i don’t feel it is unless there is a wear issue when you do your tear down and inspection. that would be the time to consider the retro fit to the 01 and newer design.



moving to the rear, the front planetarydrum and clutch used a lip seal type piston up to 1996 or so, then they switched to a molded style piston. the direct drum and intermediate clutch pack is standard with a 4 disc clutch, 34 element sprag, and spiro clip retaining the sprag. like the forward clutch, somewhere around 96 they went to a molded…..or what is also called bonded piston where the seal is bonded to the piston and cannot be serviced separately.

when we move back to the center support, although it looks just like one from a th400 it is not. it fits into the housing a lot more snug than a 400 center support. in 1999 there was some what of an overhaul to the rear planetary design to beef up the rear planetary gearset. to do this….like the front overrun clutch assembly, several components also changed. the rear of the center support was changed at the torrington bearing.

the sun gear shaft changed 3 times. 91-96, 97-98, and 99 on up. they also changed the sun gear shell in 1997…..ironically reducing lubricating oil flow to the rear planetary.S3700030 the part that absolutely baffles me is that they made the rear mainshaft solid in 1997. between 97 and 99 they changed the torrington bearing set up a few times but to be honest, here you can see the bearing exploded out of this 99 unit due to lack of lubrication. basically, like in a demo car, if this is in a plow truck where 1st/reverse is held for long periods of time, this thing has no direct lubricating oil and fails……this is what failed in this particular 1999 unit. it trashed the rear planetary. for shits and giggles though i stuck some th400 parts from an old bop tranny in it to re-assemble it cause these were so trashed…..and they almost fit perfect. all i have to say is someone bought a gem of a core off me!


the S3700031rear output shaft is about an inch shorter than that of a th400, but has over 2 inches more of spline area. here you can see a side by side photograph as a comparison.





down S3700046to the valve body the first thing to be aware of is that there are two different force motors. my index finger is pointing to the force motor, the other is a solenoid. 91-93 models were different. the 94 and newer ones are different….and the electrical/case connectors also changed in 93. there are two shift solenoids to the rear of the valve body that also need to be checked out. like the 4L60E there is also a switch manifold that needs to be checked .



oneS3700045 thing not to overlook is the the shift solenoid feed filter found beneath this plug to the rear of the valve body. you can also see the two shift valves in this picture. like the 4L60E, there are concerns for valve wear in the aluminum valve body. be aware of it. if you have a clutch pack failure or a driveability problem, you need to look into your valve body if there is no other obvious signs of damage. for me, in this tranny the damage was pretty damn obvious and the valve body looked great. i would still clean it out and change the force motor.



the frontS3700044 pump is a cast iron pump with a pump gear set up similar to a th400. the regulator is in a similar mannor as a th400 and can be accessed from the bottom through the oil pan. in the picture i am pointing to your TCC valves that are, unlike the 4L60e or 700R4, located in the pump as well. the valve to the right can be seen like the regulator valve through the oil pan area with the pan off….the other valve i am pointing to is a converter limit valve. during pump service these should be removed and cleaned to insure proper function. also i should note that the drive gear does not have teeth on it like a th400 pump. it is driven by two flats on the converter hub. so if you look down the pump with a flashlight and don’t see any teeth to drive the pump…..don’t panic!

4L80E Transmission Teardown


Well, although i have had this core for quite a while, i finally had the time to take the thing apart, document it, and most of all LEARN from it. this one in particular was a core out of a dumpster that i paid fair price for. it was missing the wiring harness and filter so basically what you see here is what i saw. basically the overall scheme of this tranny is a th400 with an overdrive unit glued infront of the front drum. the valve body is very similar to the same appearance and function of a 4L60 or even a 4R70W Ford. it is an aluminum valve body with a PWM, two shift solenoids, and a pressure switch manifold. what is absent though from the 4L80 that you find in the 700R4/4L60E is the TCC solenoid. the pressure regulator like the older th400’s is in the front pump. in addition there are also two TCC valves located in the front pump. i will get into detail on this a bit later, along with some model year stuff. unlike the 4L60’s and 4L60E’s, there isn’t as much info on these trannys easily found like there is on most others.

first thing to come off is the outer switches and cooler line fitting, specifically the rear cooler line fitting. there are two speed sensors to the left side of the case that you shoud remove to replace damage. also the shift position sensor. basically they moved it from the steering column to the side of the tranny and made the shift selector shaft longer. it has nothing to do with the internals of the tranny. you would also remove the rear cooler line fitting from the case. it protrudes into the center support and will make removing the rear planetary gearset damn near impossible. since the overdrive unit interrupts lubrication circuits that would have flowed similar to the th400, they re-routed the lube return fluid directly to the center support. anyways just don’t forget to remove the fitting.

After the pan and wiring harness removal,  the pressure switch manifold is next at this point. like the 4L60E, this is the signal manifold the connects to the ECM S3700022to let the on board computer know what the hell is happening in the tranny….and signal shift or set off idiot lights accordingly. it is help on by 6 bolts that go all the way through the valve body to the case and are an 8mm head. next is the clamp and steel lube line to the rear housing bushing and seal area. this is a 10mm bolt and clamp and is easily removed. anfter all that, you remove the rest of the valve body bolts and lift off the valve body assembly.


This leaves you with the valve body passage containing 8 check ballsS3700023, the low 2/front band servo, and you can also see the rear servo cover assembly like the th400 and center support bolt, but there is also a front support/fourth gear piston housing bolt as well. it is a torx head bolt.






hereS3700048 is a picture of the front bolt locationunder the valve body to be removed like the rear center support bolt on this tranny….and the TH400 trannys. at this time i would also go ahead and remove you rear servo assembly from the case so that there is no hardware left to interfere with the rest of tranny disassembly. the rear servo is VERY similar to the Th400 in that the rear band pin is an adjustment, but the piston, accumulator, spring, and cover are different. so don’t get the brilliant idea to interchange the parts.


Next, i pulled the tail housing. it is 6 bolts and although a similar pattern to a th400 tail, it is not the same. S3700028some of the 4L80’s used a tin oil shield like the older Th350 tranny’s did, some did not. they all had an internal oil seal thought. it may look like a roller bearing but it’s not. the rear bushing is actually smaller than a 400! if you have a tin shield it has to be removed, the seal does not. it can be removed and replaced later.



time for the front pump to come out.S3700026 first and foremost, remove the input shaft o-ring so you do not pull the guts out all over the shop floor. remove the pump bolts and like i do on the th400…..coax it out with a large screwdriver. pictured is what you should see. this is the front of the tubbine shaft/overrrun clutch assembly, and 4th clutch assembly to the outside of it. the center assembly pulls out like a forward drum assembly on a Th400. the 4th clutch assembly is held in by a snap ring and can be removed next.


the 4th gear clutch assembly housing/piston assembly can be removed and you are now down to the forward clutch. from here back it is damn near identical to the Th400 transmission. now although they may seem identical to the th400, not all the components of the aft assembly interchange. i will get into this in other articles. here you remove the forward drum, direct drum, low 2 bad, 4 disc intermediate clutch, and rear planetary/center support. the center support on these fits pretty damn tight to the case. they make a tool for removal, however i used a lead hammer and tapped it out of the case. i also used a big brass drift to coax it back home into the case during assembly. use good judgement when doing this if you are worried about it….don’t ram rod it!

Parasitic Drag/Oil Shear Effect on Clutch Packs

so something i have been trying to find a happy medium on transmission builds is what is largely known as parasitic drag. this is the amount of power it takes to make the transmission function. on a stock th400 it is around 30-35hp it taxes off the engine, whereas a th350 is about 10hp less than a th400 on the average.

parasitic drag i always thought was due to rotating mass and power requirement of the hydraulic pump. simply put, a hydraulic pump needs power, and the resistance to flow creates a power loss as well. you also have slippage in the torque converter as it is a fluid coupling(essentially a pump). internal components also have some weight to it. basically the more it weigh’s- the more it takes to get it moving. i’ll spare you the law’s of physics.

there is also something i have been trying to deal with lately called oil shear. on your clutch packs, oil circulates from the center out for lubrication and cooling. when the clutch is not applied, the surface area of both the clutches and steels are still covered in circulating lubricant oil. now, if we are spinning a dissengaged clutch pack at any kind of an rpm, the oil will sling to the outside…..literally sucking the flat clutches and flat steels together and causing them to drag. i want to say it is fairly similar to a kind of capillary action caused by centrifugal force. obviously a dragging clutch pack will increase tranny temperatures, and if severe enough, clutch failure.

the solution is basically put a relief area in the clutch pack for the fluid to escape. the easiest way to battle this is to loosen up your clutch pack clearances. this though is a catch 22 as if your clearances are too loose you will have other consequences.

the use of radial grooved clutch discs and waffle clutch discs are the best solution to resolve the problems caused by oil shear on most of your older trannys. gm did it on different clutch packs in both the th400 and the th350.

later model 4L80E’s and 4L60E transmissions used what is termed as turbulator steels. basically they are steels that have an oblong hole in the middle to relieve the oil shear caused by centrifugal force. they are found in the 97 and newer 4L80E’s in the overdrive clutch packs.

on the 96 and newer 4L60E’s , they used turbulator steels in both the reverse input drum and the low 1/reverse drum. ironically it is erie similar to the same areas that fail on a th350 in a demolition derby….anyways the late model turbulator steels can be swapped into earlier 700R4’s as an upgrade.

now as an example of oil shear. on my 1st/reverse th400, i got a guy that gives it time to shift, but floors it from one side of the track to the other all night in forward. after 40 minutes of running the piss out of his suicide lincoln……he loses reverse or it starts to slip. upon teardown there is nothing wrong with the seals- the seal rings-the pistons- the forward clutch is fantastic- gearset is fine. the direct/forward clutch is burnt to a crisp- i mean no linings. on a 1st/rev the direct drum spins just as fast in the opposite direction but dissengaged. even when using stiffer trans brake springs to keep the clutches dissengaged- the discs still suck together!

this is chronic oil shear….and can happen on ANY transmission used for demo derby. even with the use of waffle clutches, chronic oil shear still can happen. we are experimenting even to this day with combinations of different linings-number of discs vs number of steels, different fluids/additives, and clutch pack clearances to prevent this. there is no answer at this time for derby transmissions.

GM 4L80E layout of components

well, i have also been doing some research into the 4L80E, which is the later 4 speed computer controlled version of the TH400 starting around 1992 to present. i ran across a forum where another gentleman had done a disassembly and pictoral layout of the internals on one of these trannys. i copied it to help me during disassembly and to be honest thought it was pretty good cause it’s an actual picture not a drawing.  i copied it and posted it to my blog. due to the format of my blog, you may have to copy the pictures to your computer and blow them up to read the numbers.   i give credit to whoever put this on an open mechanic’s forum i ran across on the internet.  BTW, i did check my service manuals and the labelling on the components is correct. 



Number listing for rotating assembly 4l80e

4: complete pump body assembly
504: 502: housing assembly overrunning clutch and turbine shaft
529: 4th clutch housing
529: 4th clutch
602: forward clutch housing assembly
623:628 direct clutch & forward band
632: intermediate clutch
640: center support
651: reaction drum and carrier assembly
657: rear brake band assembly
661: 662: 668:671:ect:
Carrier output assembly, main shaft, rear rear internal gear, output shaft assembly , ect


Number listing for valve body assembly 4l80e

301: valve body
302: force motor feed filter screen
303: coiled spring pin
304: check ball plug
305: .375 diameter check ball
306: 3rd reverse check ball bushing
307: o-ring seal
308: 3>4 shift valve
309: 2>3 & 3>4 shift valve return spring
310: solenoid bolt
311: 2>3 shift solenoid
312: 2>3 shift valve
313: 1>2 shift solenoid
314: 2>3 shift valve
315: 1>2 shift valve return spring
316: shift solenoid feed plug
317: shift solenoid feed filter
318: low/reverse check ball sleeve
319: manual selector valve
320: variable force motor (can)
321: force motor retaining clamp

322: PWM solenoid retaining clip
323: PWM solenoid assembly
324: TCC regulator apply valve
325: TCC regulator apply valve spring
326: actuator feed valve bore plug
327: actuator feed valve limit spring
328: actuator feed limit valve
329: accumulator valve bore plug
330: accumulator valve spring
331: accumulator valve


Number listing for Accumulator housing assembly 4l80e

49: 4th clutch accumulator piston spring
50: 3rd clutch accumulator piston spring
52: accumulator housing to valve body bolt (Long)
53: accumulator housing to valve body bolt (short)
402: snap ring
404: 1.615 square cut seal
405: 3rd clutch accumulator piston
406: .859 square cut seal


Number listing for pump assembly 4l80e

202: 4L80E pump Body
203: 4L80E Oil Pump
204: Driven pump gear
205: pump drive gear
206: Pump cover
211: coiled spring pins (3 total)
212: converter limit valve bore plug
213: converter limit valve spring
214: converter limit valve
215: spring retainer sleeve
216: TCC enable valve spring
217: TCC enable valve
218: thrust selective washer
220: M8 x 1.25 x 40 mm bolts (5 total)
221: snap ring
222: TCC valve bore plug
223: TCC valve
224: TCC valve spring
225: TCC valve bore plug
226: retaining ring for boost reverse valve bushing
227: reverse boost valve bushing
228: reverse boost valve
229: pressure regulator spring retainer
230: pressure regulator spring
231: pressure regulator valve
232: pressure regulator plug

I.D. your tranny according to oil pan shape

1 Aluminum Powerglide
2 TH200 (Metric), TH200C (Metric)
3 TH250, TH250C, TH350, TH350C, TH375B
4 TH375C, TH400, TH475, 3L80, 3L80HD
5 TH200-4R
6 TH700-R4, 4L60, 4L60E
7 4L80E