tankerpilot01

My mechanic brought up the idea of me replacing my 4L60-E in my 2002 Tahoe with a 4L65-E. I tow around 7,000lbs (enclosed trailer and car) and he said it would betougher than the stock 4L60. There is a huge auto wrecking yard here in Spokane, WA (Spalding) and he thinks I could find a 4L65 withless than 1,000 miles on itfairly easily and that it would be a direct swap....electronics, etc would fit directly with no computer issues and would not affect my mpg. What are you guys' thoughts?

tankerpilot01

No transmission experts out there?

kpanza

The 4L65 won't be that much better than your 4L60...as far as dealing with towing loads like 7000lbs regularly. A 4L80 would be much better suited, but probably looking at adapters and electronic changes being necessary. If you do go with the 4L65, you should look into getting one from an aftermarket company who builds the internals with heavy duty towing in mind...and you'll of course want to get the biggest cooler you can find, preferably with a manually operated torque converter lockout switch, with a deep pan, etc...

I've got a built 700R4 (same basic tranny as 4L60, 65) in my K5 which has 42s, sees mostly offroad use...got it from Bowtie Overdrives in Hesperia, CA. There's lots of places that specialize in building up the GM 700R4/4L60/4L65 trannies...yeah, they're more expensive than just getting a junkyard tranny, but they'll last a lot longer in your situation. Heck, you could probably save some money and ship them your's to be rebuilt, or at the very least as a core in trade. Just FYI, but I paid about $1400 for my 700R4 to be fully rebuilt, with the special servos, stronger bands, lockout switch, etc all included...that was about 7 years ago, and it is still going strong in a rig that abuses it!

The 4L60/4L65s just aren't made to handle those kind of loads in stock form...they need some help to live longer.

tankerpilot01

Thanks for the words kpanza! Maybe just better off going as is, stock, until it dies...only 44K miles on it now....only started really towing in the last couple weeks.

kpanza

Yeah, might as well. But I would definitely recommend getting the biggest auxiliary tranny cooler you can get! And for even better results, stick an electric fan on the cooler for those times when it really gets hot (I've got one on my K5 and it helps a lot when I need it). Check your tranny fluid regularly - if you're towing quite a bit, change the fluid much more often than recommended - it's cheap insurance! Might also consider using synthetic, but I don't...I just change it regularly. Getting a deep tranny pan with a drain plug will make the job real easy, which will get you to actually do the job more often!