Transmission Problem

[EM1Pete]

Sorry, I'm sure this has been discussed ad nauseum, but I need some help.

Basics: 2002 Yukon XL SLT 4x4 174,000 miles

Symptoms: While driving to work today, my front end shook hard just one time and the truck basically fell out of gear. All it would do was rev. I can still drive it in 1, 2, and 3, but "D" does nothing but rev.

I'm pretty sure you're just going to tell me it's time for a new transmission, but I thought I would just throw this out there just to make sure. I don't have any experience at all with high mileage cars, so any help you can give me is great. Please don't be afraid to "dumb it down" for me because I really don't know much about this stuff.

 

[07Burb]

You don't need a new tranny but sounds like you definitely are due to have your current one rebuilt which is common for these transmissions especially with the mileage you have on yours.

 

[blueflamed03]

yup...sadly, the 4L60e is pretty weak for these heavy trucks.

Sound slike time for a rebuild. Expect around $1200-$1500.

 

[Jay]

Forward sprag let go. The reason you can still drive in 1, 2, and 3, is due to the overrun clutch being engaged.

Rebuild needed. Make sure the builder uses the Borg Warner 29 element double cage sprag (DO NOT use the aftermarket versions... the cages break and let the shoes flip). Install an 8-pack 3-4 (direct) clutch set to .030" clearance (i like the BW High Energy clutches FWIW) while you're in there. Replace the check ball capsule in the case behind the servos (need to drop the VB). Corvette 2nd servo, sonnax 4th servo, and sonnax .490" boost valve are also good things to make a solid 400hp reliable trans. Above that and valvebody modifications (mainly feed/bleed hole mods) will be needed.

 

[07Burb]

Jay, do you do tranny rebuilds for a living? You seem to know your stuff!

 

[blueflamed03]

no kidding,..................... Jay?

 

[07Burb]

no kidding,..................... Jay?

That's the user's name from post 4

 

[blueflamed03]

I know...was aksing like "well Jay, do you?"

 

[07Burb]

I know...was aksing like "well Jay, do you?"

feel free to just smack me when I post stupid crap like that...

 

[Jay]

Not for hire, sorry. I built a couple for friends of mine back when I had all the specialty tools, but did quite a few of my own for two of my drag cars. In ~3500lb cars, 600hp is about the limit for reliability in 60Es, a little less for heavier trucks.

The problem is when you get above the 600hp range you have a hard time keeping the aluminum input drum and steel output shafts (even 300M versions) from breaking. The only way to keep them alive is soften up the shifts, but then the 60E's relatively weak clutch packs just can't take slippage (especially the direct clutch). Just too much stress for the size of parts in this trans.

That's why as soon as anyone says they want over 600hp, especially in a truck, I immediately say convert to a 4L80E. After repeated 60E failures at 6-700hp I went to mildly built 80Es and went to 1000hp+ with ZERO problems for the last couple of years I raced.

The 60E is a hard trans to build right. It's a lot more than just parts swapping to make them live... there are a lot of "builder's secrets" when it comes to making the 60E reliable at reasonable power levels. Mostly with clearances and internal vavlebody modifications. While the guys in business won't give these out, as it is their trade they have to protect, I don't mind sharing some of what I learned.