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Discussion Starter · #1 · (Edited)
I'll start:
1. Buy a real line pressure gauge. Do a check on the transmission as soon as you get the gauge and see what it's reading. WRITE IT ALL DOWN IN YOUR MAINTENANCE LOG so you can check it a year later without having to remember what the values were at different throttle positions and gears. If the shifts change, suddenly get smoother or softer, put the gauge on and see what the pressures are doing. It's likely they've dropped. I got mine for $55 off ebay. with 6' of cord, I zip-tie it to the windshield wiper like a hood tach and then go for a drive. I can see everything the line pressure is doing. Tunercat/Datamaster numbers have only a loose correlation with what's actually happening in the transmission.
2. Drop the valvebody and replace the EPC solenoid filter. The original design was the finest filter in the transmission and it tended to clog with crap and eventually gets completely blocked, then the screen ripped and would allow junk into the EPC solenoid. If this happens, you may want to start thinking about replacing the EPC solenoid too. IMPORTANT - replace this screen with the NEW design screen with a coarser (bigger) filter mesh), available only from GM P/N 24209145. As of October 2012, all aftermarket rebuild kits should include this screen but be sure to check.

For longevity, the things I usually see broken on stock 4L60Es:
0. EDIT - I firmly believe that the number one cause of failures in the 4L60E outside of hard parts like sunshell, broken 1-2 accumulator, etc. is low line pressure. Fix the line pressure, and a whole host of other problems go away. Low line pressure is usually a result of a worn boost valve (Sonnax 4L60E-LB-01 long version replaces it) or a worn pressure regulator valve above the boost valve (requires a reamer and oversize Sonnax valve, will likely need the pump to come out to install because it generates metal dust).
1. 3-4 clutchpack worn out. Replace with High Energy or Z-pack. EDIT - ALSO look at other areas that may cause leaks in the 3rd apply circuit. Sonnax has lots of fixes for these leaks: 77754-21, 77987-01K, 77777L-K, 77964-08K,
2. Sunshell broken or on its way out. Replace with reinforced one (either Beast, or a "reinforced" Taiwan sunshell, but if you look closely, they're both made in Taiwan). There's also a 4L70E sunshell that is heat-treated at the splines and uses a roller bearing instead of a thrust washer to cut down on particulate contamination generation at this location.
3. 2-4 band worn out. If you're going to replace this, if the drum isn't flat across the surface, replace the drum too. Can use a wide band but ONLY on a new drum.
4. Rear planet sungear's inner bushing is loose and is walking around. Replace with a Sonnax wide bushing.
5. Both the 1-2 and 3-4 accumulator pistons are worn in the center, and the 1-2 accumulator spring (the yellow one) is broken. Sometimes the 3-4 accumulator spring (purple) is broken too. Replace the pistons and the springs with GM parts or use the Sonnax pinless accumulators (best option) for better seal.
6. Pump spring has sagged and is allowing pressure to drop at WOT above 5500rpm. Replace with new spring or an aftermarket "high-rpm" spring but not one that basically is in coil bind. Sonnax makes one.
7. Pump stator shaft splines are worn where the converter engages them (from what???). If it's bad enough, replace the stator shaft. This is rare.
8. Tailshaft bushing is worn out.
9. Forward clutch piston tends to crack. Replace with '97-up stamped steel forward piston set (overrun, forward, 3-4). Requires spring compressor and snap-ring pliers to release them, and a feeler gauge to get the lip seals right. You'll need the later design return spring as well.
10. Sprag lays over. This is rare behind stock motors. Replace with dual-cage sprag.
11. The pump bushing walks out of the case and causes a leak out of the front of the transmission ONLY when the engine is running. You have to disassemble the pump and use a press to fix this (replace the bushing). If you grind out two divots in the pump housing, you can stake this bushing in place.
12. The 1-2 shift checkball is stuck in the spacer plate. Use a Fitzall VB-101 collar kit to fix it. The Sonnax 4L60E-HP-01 kit also includes plastic checkballs that eliminate further spacer plate wear.
13. Low line pressure due to worn boost valve. Use this new boost valve to not only raise your pressure when you need it but preserve this over the long haul.

So that's what I've seen on stock 4L60Es behind relatively stock motors. Anybody with modified motor experience want to discuss?
 

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Great info Joel! I've got a question for ya:
I have a GM SRTA Trans/torque convertor (95 Caprice LT1) in the garage thats NEVER been in a car yet since it's rebuild. I bought it from a guy a couple of years ago. It's had the Transgo fix kit installed in the valve body (Not the shift kit) but that's about it. My car has a Stock LT1 in it. Any suggestions as to what you would do to this trans to extend the life and prevent any of the known failures of the 4L60E Before I install it in the car in the future? I'd rather put in ALL the needed fixes now, then have to pull it in the future and repair the trans. Again, the car is a Stock LT1. Thanks for any suggestions you have......Mike
 

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Hd2!

Mike,
..excuse me for butting in here. :)
Based on outstanding service from both of my stock 4L60E's, I'd say without a doubt to install the full Transgo HD2 kit. Since it sounds like you're going to run a stock TC, use no shims in the 1-2 accumulator and go with minimum recommended hole size for the 2nd gear apply in the separator plate. I also wouldn't run without the 093 (Vette) servo. I tried it once without and could not get a 2-3 shift that satisfied me. I'm not sure if the servo is a durability upgrade behind a stockish engine.
 

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Thanks for the reply and tips Pat. Yes, it is a stock TC that came with the SRTA trans. We have the tools, and can do pretty much anything at the house inc engine rebuilds and installing transmissions......But rebuilding them is something I've never tried before however, I have a very competant local rebuilder that's fixed several different transmissions for me so.......All I need to do is give him the info as to what I want done....Thanks again.
 

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Well, I just have to say that everything you wrote is what the local trans guy told me and are some of the upgrades he did on my build. I have to say they made a world of difference to the SOTP feel in my car. Only mods I have are the original SRI and a PCMforLess PCM. Although, my wife doesn't like the harder shifts.
 

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IMO there is only one guy that can build a 4L60E to levels no one else thinks they can take and that is Carl Rossler. What you get from him is not a kit installed but custom changes/parts that make it possible to do what kits are not able to do.

Still not sure if it will live in a Impala the weighs more than a stock one trying to run 8's but if will live at 9's all day. 9"s is more than most people will ever do. There is a reason Lingenfilter is using Rossler in all his twin turbo corvettes.

This is not needed in most Impala's out here but why mess with tranny problems when you could do it right the first time and let your friends have all the problems.

When a 4L60E fails don't blame the tranny, blame the builder.
 

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Jeff,
I think roadracing and aggressive street driving is harder on these tranny's than pure drag racing. I know even Rossler has problems making them hold up to roadracing. I wasn't aware till now that you use his 4L60E build, so that's definitely a good data point for him!
I don't know of any others using it for high hp drag racing,....do you?
 

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Not that I know of and there are not any others near the top of the ET page. I don't raod race so your point is taken. Do you know what fails on the road race version?

One note I left out was the tranny is much like the LT1 engine and the right tuneup/program can be the difference in them living or not. One item that has worked good on my tranny is not jacking the line pressures too high. What I have seen is if the pressure is too high it will break parts like drums. Drums are the one part that no one has made a bullit drum to replace the cast one. I do use a 4L70 drum instead of what came in our trannys. I bet I run less pressure than a lot of people but thats why it doesn't break those parts. Hook a pressure gauge up to the port on the drivers side of the tranny and see whats really going on and not just rely on what you are programming into the computer tables. What number you put in the table may not be the number on the gauge. These trannys are not like the old TH400 so what your program is telling them to do can kill the best built 4L60E you can buy.
 

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........ Do you know what fails on the road race version? .......
We'd have to ask Doc (John Dougherty) about that. It's more than just clutch/band wear, because he's had at least one build that failed before he made it to the track, and he's not one to horse around on the streets.
 

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Maybe he will see this and chime in. I just I'm a little supprised because it takes my tires out on the street as there is not enough traction. That is a easy win for a tranny and no where near what it would see at a track when it's hooked up and the tranny has to take the load.
 

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Making a 4L60E last??

This has gone into major detail on internal modifications - great info but to step back to some basics: REDUCE HEAT - with a stock stall and essentially stock engine Impala SS / 9C1 coolers are adaquate.
Install a deep - (OEM Truck Pan)
REMOVE the torque Converter dust shield!

Change fluid regularly!

I have a bolt on 96 (Never had a valve cover off) - Currently 228K.
@ 130K It was Dyno'd in Tulsa in 2003 at 256HP and 298TQ to the rear wheels and it was over 100deg outside. The car has lost a bit of power especially on top - best ever 1/4 mile was 14.32. Best I ran last year was 14.67.

The transmission was replaced at 36,700 miles with a Factory exchange transmission (Good Will replacement!)

Street driven daily!, I have put over 1000 miles of road race and Auto X time on the car & a few hundred 1/8 and 1/4 mile passes.

I pull the pan and replace fluid and filter at least every other year, sometimes annually. I run Redline Dextron III, and have used ATP filter kits all changes.

Using old hypertech scan tool - transmission will typically run 20 degrees cooler than engine temp when cruising at 80MPH on interstate even in the summer - When racing at Hallett I have seen it get maybe 20 degrees hotter than engine. (Engine with 160 stat runs at about 180.)

The only other trans modification I have is one of those B&M shift firmness swithces - It will reduce the 1/8 mile of 1/4 mile time on my car exactly .10!

I am approaching 200K on this trans and I would admit it has not seen an easy life but it has been maintained as well as possible.
I would guess I'll need a tranny replacement in the next year or two.

Future motor plans will dictate if I get another GM one or step up to a "more modified" trans.

I have to agree with Jeff comment about not blaming the Trans :)
 

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Tranny in my car was installed 6 years ago today. I told Dana that about 360fwhp was my ultimate goal cwm9. Apparently he didn't believe me because all I have done to it since is redrill the 1-2 feed hole after the heads and cam almost 4 years ago and it gets Walmart fluid, tried a half fill of Dex VI once and noticed no difference.

It comes down to Jeff being right about use a good builder. This tranny is NOT real dependant on lots of expensive parts. I still have a stock sunshell in mine, Vette servo, drum is NOT sleeved, think the only cryo'd part is an accumulator piston. NOTHING fancy here other tham maybe the vacuum modulator.

I do have plans for a super duty tranny to replace this one, but this one has worked so well and is working so well I have not moved forward on the replacement yet.
 

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Discussion Starter · #13 ·
Todd, thanks for pulling me outside of the case. :)

Another thing to note is the stock B-body external transmission cooler is located behind the bumper. This is great for safety and survivability, but not so great for airflow, particularly at low speeds.

I installed a Cyberdyne digital transmission temp sensor into the pressure test port on the upper driver's side of the transmission. Just unscrew the plug, screw in the sensor, and wire it up. The hottest my transmission ever got was idling in the staging lanes on a hot day at the drag strip. It actually cooled down while racing. The only caveat is that I don't know how much of that was actual transmission heat and how much was just being radiated off the exhaust pipe nearby. Once the car is moving, airflow will eliminate the exhaust as a heat source.
 

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FrankenTimmy
1/1/2000 install / build at 60K
to
present 2009 110K

Build *loosely based off of George Debskis build sheet
-TransGo HD2 Full install
-TransGo No Yo yo Hi Rev Kit with hard stop in the hi rev spring
-TransGo Vacuum Modulator
-Y-body 093 servo
-beast sun shell
-Sonnax 3rd accum check ball capsule
-Sonnax .500 boost valve
-alto red wide 2/4 band
-alto red commercial 3/4 9pack
-TC feed in seporator plate drilled over recomendation
-flats ground on tcc valve for cooler flow
-edge small body converter
-OEM radiator cooler, OEM aux cooler, full radiator height B&M cross flow cooler
-Spin on filter @ frame rail!!!!
-VDO temp gauge
-VDO pressure gauge
-NO SCREENS! thru out trans only the noid sreens remain
*spin on filter keeps the fluid clean
*new fluid every three or four oil changes

reused from OEM build
-forward clutchs
-reverse clutchs
-all pistons and accumulators except servo
-forward sprag
-planets
-input hub
-reverse drum
-ouput shaft
-pump body
-and OMG the OVERUNS are still stock and pristine
see my youtube and wonder why?... OMG!

100-110PSI idle
250-260PSI WOT
VDO electric sender gauges in the dash are key.



Broken so far
-2004 / reverse lip seal
*never replaced from the factory build

-2006 / pump rotor
*install issue improper TC depth into pump needed shim / my fault

-2009 / failed forward input sprag
*OEM sprag failed after power threshold was exceeded post new long tube tri-ys and built motor
**apart right now for sprag
installing Sonnax 77754-41 to keep overruns applied in 3rd! :)

Performance
A full shelf full of auto cross trophies all locked in second gear!

hundreds of 1/4 mile time slips many in the 12.s NA

12.1s on .040 pill


I have a side yard shed full of blown up so called Pro Built transmissions. Thanks BTOD. cwm8

FrankenTimmy has been stellar for the money I have spent.
But, I still worry!
 

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Discussion Starter · #15 ·
The 093 servo comes stock in all LT1 4L60Es. Tad, you probably know this, but it's worth pointing out for everyone else.

Another longevity tip: Don't change from R to D or vice verse while moving. It just puts extra wear on the clutches. Come to a complete stop, shift, left the shift finish, then start moving again.
 

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Does driving in the third gear instead of overdrive (town, hilly terrain) add to the longevity of transmission?
Thank you.
 

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Does driving in the third gear instead of overdrive (town, hilly terrain) add to the longevity of transmission?
Thank you.
Only if your tranny would otherwise be shifting in and out of overdrive would that possibly be an issue.

If under those conditions (in town or over hills), you drive with the tranny set in overdrive but the tranny stays in 3rd gear.......no problem at all.

KW
 

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4l60

My 4L60 lasted 82,000 miles behind a mostly stock LT1. It was autocrossed to death and saw hundreds of track day miles. I ran a cyberdyne temp gage off the test port and would end a track session early when the gage hit 300 degrees. (it would read HIGH) and that was my notice to quit and cool things down. I changed the fluid yearly or any time I really cooked it. Also ran a huge Earls cooler that hung down below the bumper and had a scoop for air. What seems to happen running track days is the heat builds up from session to session, so by the third session the tranny is cooking in 5-10 minutes where as in the first session you might run 20 minutes of a 30 minute session before it boils.

FWIW the tranny only started to slip and clunk after I put a stroker in it. The tranny ended up with Grant Rimbach who told me that when he took it apart it only needed clutches, seals and the normal maintence stuff. Listed in the first post. Basically it still worked but was showing wear which led to more heat and therefore more wear.

Doc told me that he never ran a temp gage on his tranny. I would venture based on my temperature records that he just cooked the fluid and kept going until the tranny failed. I do know that when new the tranny ran cooler longer than it did as the miles accumulated and I speculate that as the internal parts wore, the line pressure drops and the heat increased. I know it would peg the temp gage much faster the last year I ran the automatic than when it was new.

What really kills the tranny in road racing/track day use is the constant locking and unlocking of the torque converter. Every time you down shift and unlock the converter the transmission fliud temperature will jump twenty degrees or more.
 

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Discussion Starter · #20 ·
Does driving in the third gear instead of overdrive (town, hilly terrain) add to the longevity of transmission?
This used to be a big problem with 700R4s - they would shift themselves to death and burn up the 2-4 band. I think Sonnax makes a 4-3 downshift valve that eliminates the problem. I don't know if the '91-93 B-bodies had that problem but my dad's '86 Caprice wagon was terrible like this.

The 4L60E's shifts are commanded electronically, so there's really no problem driving in OD all the time. The programming is setup from the factory to keep this from happening. You can screw it up if you're not careful with the shift tables though.
 
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