Reverse shudder

[scotto0609]

I have a 88 6.2/400/205 combo and I noticed on the beach while trying to reverse it would not budge. Engine would load up truck just would not move,forward was fine. Drove the truckthis week and everything is fine on street except a little shudder in reverse but it does move. Any input? thanx

 

[4xcrazy]

Sounds like a similar issue I was having with a recently rebuilt 700r4, it would shudder when going into reverse and hitting the gas.

Unless I rev'd the motor a split second longer to basically/seemingly build line pressure, it would shudder, if I rev'd or let it sit for a split second longer in reverse, THEN hit the gas to move, it would be fine.

The rebuilder has already agreed that once I get it back to Phoenix, he's going to rebuild the whole thing again and use better quality seals. He mentioned something about a valve/piston or something, (been awhile since the phone call) that was essentially leaking past while in reverse, causing this shudder. He seemed like he knew what I was describing and talking about and had no problems with redoing the repair for free. heck he even offered to just have me bring the truck in and he'd do the R & R for me

Anyways, not sure how closely the 400 and 700 are internally, just thought I'd throw out an idea.

Also he did tell me that it will not last a "normal" lifetime with this issue either, it will eventually get worse.

 

[K588]

I am not an auto transmission expert, but when my TH400 went it would shudder in reverse and then I completely lost reverse then 3rd then 2nd. Limped it to the shop in first <10 miles on the shoulder. Transmission shop said that reverse was usually the first to go then 3rd etc. I would get it looked at sooner than later, just my opinion.

 

[Greg Ducato]

If your modulator is an adjustable type, try screwing the adjuster screw in a couple of rounds. Put a vacuum gauge on the line and check to see if you are getting a drop in vacuum as you open the accelerator. Without a drop in vacuum the modulator cannot raise line pressure and this may be contributing to your shudder.