4L60 Transmission (1 Viewer)

[EricG]

Hi folks - as some of you know, I've been plagued with a transmission leak on my truck for months now. I poked around with the borescope some more and finally think I found it. Looks like a crack in the actual transmission case not far above the pan, DS behind the shifter. No idea how or why it would crack there.

In any case, I was wondering if anyone happened to have a 4L60 around so I could lay eyes on this area and understand what's going on a bit better then I can through the borescope?

 

[Manitou Decline]

There isn't much on on that side that goes internationally to leak. There is the ring for the shifter shaft itself. I will see if we got one on in the shop to double check.

 

[Manitou Decline]

So it's number 82 on the diagram.

 

[Manitou Decline]

I know the ones we work on, they often develop leaks between the the transmission and adapter to the transfer. So look in that area also. Between the shift and that adapter there isn't anything above the pan that goes internally besides a cracked housing. Now it easy to crack the aluminum housings. Those pan bolts only get torqued to 10-12 ft lbs. You can crack it with over torqued bolts. But usually it just eats the threads.

 

[EricG]

View attachment 3732028
So it's number 82 on the diagram.

Thanks for the diagram. I thought it was the shifter shaft seal for a bit. But I took off my cat heat shield and pressure washed good up there and it's definitely not the shaft. And as you said, there's nothing else going on there.

Here's a pic of the crack. The other pic shows where it is and roughly how long. Leak is definitely getting worse.

 

[EricG]

So where would you guys go for a good rebuilt trans, with all the hardening done to it?

 

[Manitou Decline]

Thanks for the diagram. I thought it was the shifter shaft seal for a bit. But I took off my cat heat shield and pressure washed good up there and it's definitely not the shaft. And as you said, there's nothing else going on there.

Here's a pic of the crack. The other pic shows where it is and roughly how long. Leak is definitely getting worse.

View attachment 3732824View attachment 3732825

Ouch. Well at least you know now. As far as your new problem, I would suggest looking into a 4L80 isntead of another 4l60. Driving around in a 5000 lbs plus Cruiser already puts the 4l60 near its limits of 6000 GVWR. I also don't know your gearing. Gearing is different, completely different

If you're dead to nuts set on a rebuild, Transmission Clinic does pretty decent work. Also Precision Standard Transmission does well. We had them rebuild a couple transaxles for us.

 

[EricG]

Ouch. Well at least you know now. As far as your new problem, I would suggest looking into a 4L80 isntead of another 4l60. Driving around in a 5000 lbs plus Cruiser already puts the 4l60 near its limits of 6000 GVWR. I also don't know your gearing. Gearing is different, completely different

If you're dead to nuts set on a rebuild, Transmission Clinic does pretty decent work. Also Precision Standard Transmission does well. We had them rebuild a couple transaxles for us.

Yea, 4l80 swap looks like a lot of work, lol. new driveshafts, rework the cross member, wiring, programming, find one with a 27 spline shaft, etc. and don't know if it will bolt up to the transfer case adapter or fit width wise.

 

[Manitou Decline]

It is way more work than a simple pull and replace, yes. There are LS forums that give you details on how to exactly do it. One is rated for 6k lbs and the other is 8k lbs. My guess is you put a V8 In it and you like to tow. I have just seen too many of 4l60s eat their clutch packs cause 6000 gvwr means exactly 6000s. It's more of a longevity perspective. Also there is a shop downtown that shortened and lengthened my driveshafts for $100 each and a day turn around.

I know places like Summit sell the 60s with upgraded clutch packs in them. Maybe look into that route.

 

[EricG]

Looked it up - 4L80 needs a different transfer case adapter so another $1500

 

[LandLocked93]

So...4L80 is rated to 8K towing?
Or do I misunderstand?
Yes I know nothing of GM-speak.
What is the A442 rated for?

Hey Eric! Your 1FZ and A442 have traveled 3 states yet are still in my possession and in the same condition as when I picked them up.
Tho have to say I walked away envious of your up-power to the 5.3.

Followed for long time, still undecided.
Would the 4L80 fix the OD issues you were having when we last trailed together?
Or unrelated?

 

[Manitou Decline]

Yes, 8000 lbs towing. That's why you find them in the 2500 trucks/vans, Hummers, Rolls Royces. Need that extra extra ass.

I want to say the A442 is rated like 5000 lbs towing.

 

[EricG]

So...4L80 is rated to 8K towing?
Or do I misunderstand?
Yes I know nothing of GM-speak.
What is the A442 rated for?

Hey Eric! Your 1FZ and A442 have traveled 3 states yet are still in my possession and in the same condition as when I picked them up.
Tho have to say I walked away envious of your up-power to the 5.3.

Followed for long time, still undecided.
Would the 4L80 fix the OD issues you were having when we last trailed together?
Or unrelated?

So that 1FZ is still getting miles on it, lol.

The shifting problem in low range was caused by taking the speedometer reading off the transmission tail shaft. Switched to the transfer case sensor, with the help of a Dakota Digital converter, and it shifts much better.