In comparision to a TH350 375 or 400 where does the stock 1500 tranny rate as far as design toque handing ability? ? ?
The 4L60E (electronic 700R4) is actually about 25-30% larger than the TH350, and about 40% less in size than the TH400 ...
I have been doing a lot of research on the 4L60E, and the various electronic trannies lately just to find out if what is always inferred as the 4L60E being a P.O.S. weak slush box... I mean a lot of research ! ... ?
The 4L60E tranny is a Medium Duty tranny period... With some good understanding of how to treat an automatic and what not to do with it, you will not likely have any issues IMHO (don't shock load it too much) ... To put it into perspective, the Ford and Dodge offerings in the half tons are not even close to the 4L60 in longevity ... With proper maintenance, a 4L60 should go 100,000 plus easy ... The Ford trannies will do on the average of 50-60K and Dodge trannies can have big issues as early as 30-40K ... These are all on the average; some folks will get lucky and not be so lucky... A lot of the recent issues that have hindered the reputation of the 4L60 is when GM made it electronic in 1995 ... They had issues in '96 due to this also ... 1997 was finally fairly clear and when they went with a 2 piece case/seperate full bell housing in 1998, they really got on the ball ... If GM was losing money on the 4L60, they wouldn't put it in a 6,000 pound truck and give the truck an 8,000 pull capacity ... Of recent, GM has gone with a variable lock-up strategy by the addition of an INDESTRUCTABLE converter clutch ... It varies lock-up based on driveline load and engine RPM/vehicle speed ...
The 4L60E as equipped in the avalanche is factory rated for up to 360 Ft Lbs ... The RPO code for the 4L60 is M30 ... There is a beefier version of the 4L60E called the 4L65E ... It is a little different, and is found behind the 6.0 engine in the GMC C3, Denali, H2, SSR, and Escalade 4x4's ... The main differences are an added 3-4 clutch, the use of 5 pinion planetaries vs. 4 in the 4L60E, and I think the input shaft is stronger ... There's a couple other things, but that's the main stuff ... The 4L65E is rated from the factory to handle another 20 Lb Ft of torque... The gear box max torque is 670 LB Ft for the 65E and 610 for the 60E ... It is interesting to note that the max RPM for the 60E is 6100 RPM and the 65E is 5600 ... I wonder why ... Both trannies share the same 300mm converter ...
Anyways, to finish this bunk... The 4L60E is a good tranny, but it will not take hard abuse in a 6,000# truck... The newest versions don't have heat/cooling issues as they once did, but they now continue to have minor hard part issues when they decide to give up the ghost ... They are IMHO at their max duties in the 1500 avalanche, and I wish they put the 4L65E's in them instead along with the 6.0 ... Rumor was circulating when the av was a concept, that it was going to get the 6.0 as a base engine, but apparently the production output on the 6.0 was not up to the roll-out numbers chevy needed due to the new lines being offered by GMC and Cadillac ... Shucks ... The good news is, that when the 4L60E breaks, there are a plethora of aftermarket companies that offer good parts at good prices... Whatever you do, don't do a stock re-build unless it's a warranty job... If you are gonna foot the bill on a rebuild, it is better to spend a little more for a strong rebuild... It's not that much more to do her up bulletproof ...
Some things you can do to take some strain off the beast is to increase shift quickness/firmness with a programmer or by running tow/haul all the time, don't lug the truck at all whether you are pulling or not, and if you are pulling in rolling terrain or mountains, run tow/haul and 3rd gear only ... And reduce your speed ... I would also consider it good measure to install the GM auxillary cooler for $75... As the 1500 has none... Maybe a Denali or 2500 cluster with the trans temp gauge too !
Oh, almost forgot... Drop the pan every 20-25K and install a new filter and clean the pan well... And don't overfill... This alone helps a lot... If you take the truck to have a full evac done, MAKE SURE YOU STAND AND WATCH... MAKE SURE THEY KNOW WHAT THEY'RE DOING... I have little faith in this procedure vs. dumping the pan every 20K ... IMHO ... ?
11H