Joined
·
9,369 Posts
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?
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?
