hey all,

my Z71 5.3 is losing reverse. it has 165k miles, but has always been babied.

it revs up like its in nuetral, and moves backwards reeeally slowly. just enought to get out of my garage. it wont go uphill at all. however, sometimes... when i rev it high, it will slam violently into reverse, sometimes spinning the tires a bit, and i will have reverse like i never lost it....

all my forward gears work great, and ive been driving the truck around like this for about a month. i just changed the tranny filter and fluid but no improvements.

i just got new tires, and decided to climb a small snowbank the other day, in 4WD. after that my reverse was working good for a while, hooking up without me having to rev it up high....

any thoughts??? i just bought a used tranny with 80k on it for $250. i am going to put it in soon, but wanted to give this one a final chance before i do.

 

I think that you have a seal leaving you. One of these days, it's not gonna back up at all.

Allan

 

sounds legit to me. a guy at work said the same thing. i have been prepping the replacement the past few days and will be putting it in soon.

 

Could be rear input clutch assembly seal, lo reverse clutch seal or 2-3 shift solenoid stuck or damaged reaction sun shield, which is know to be a POS and one of the most likely parts to fail on a 4L trans....

 

yup pretty common on the 4l60s they have a TSB for an updated beefier part

 

Hey tony onething you might consider is to rebuild the transmission. The transmission you bought for 250 may have some problems of its own. Another thing you can do is take your truck in to a transmissin shop and have them do a diagnostic on it some shops will do this for free. This will give you a starting point on what the problem might be.
Their is alot of info on how to rebuild these transmissions. I rebuilt mine about two years ago and haven't had a problem yet. I had somewhat of the same problem as you my sun shell was the problem the gears had stripped out. I wound up buying a DVD on rebuilding the 4l60e and buying a rebuild kit that came with everyting you need to rebuild it including the beefer sun shell and the upgraded parts. Here's were I bought my kit from 700R4 & 4L60E Automatic transmissions specialists - ProBuilt. The guy specializes in these transmissions and is very helpful. If you have time I recommend checking it out.

 

I agree that the tranny has probably got to come down out of the truck to make 'er well again.

However, he says that all the forward gears all work as they should. Therefore, the reverse input shell has got to be functioning.

Allan

 

Thank you both for the responses! Very helpful


Since i already bought the tranny, and my buddy will help me put it in for free, i am going to throw it in just to atleast find out.... Whether it works or not, i can rebuild my original tranny in the meantime while its out, with no rush...

As far as the replacement tranny, im praying its good. I got it from a rolled trucks at 80,000 miles..... my truck had 165,000, so i figure theres hope.

 

Before you heist it up in there, pull the pan and the filter. Break open the plastic on the filter so you can get to the paper. Unfold it a find out what's inside.

A tiny bit of metal is normal. But, if it has rubber seal material or flaked off clutch material, it's in need of repair itself.

If it's clean, a new filter and 'bout 10 quarts of oil and the chances of it being good are very high.

Allan

 

Diagnostics from the service manual:
No Reverse or Slips in Reverse


Input Housing Assembly (602)
• 3-4 apply ring stuck in applied position

• Forward clutch not releasing

• Turbine shaft seals missing, cut or damaged

Manual Valve Link (89)
Disconnected

Valve Body Assembly (60)
• 2-3 shift valve stuck

• Manual linkage not adjusted

• Spacer plate and gaskets incorrect, mispositioned or damaged

• Lo overrun valve stuck

• Orificed cup plug restricted, missing or damaged

Reverse Input Clutch Assembly (605-614)
• Clutch plate worn

• Reverse input housing and drum assembly cracked at weld

• Clutch plate retaining ring out of groove

• Return spring assembly retaining ring out of groove

• Seals cut or damaged

• Restricted apply passage

• Porosity in piston

• Belleville plate installed incorrectly

• Excessive clutch plate travel

• Oversized housing

Lo and Reverse Clutch (694-696)
• Clutch plates worn

• Porosity in piston

• Seals damaged

• Return spring assembly retaining ring mispositioned

• Restricted apply passage

Reaction Sun Shell (670)
Broken spline on reaction sun shell/replace shell