How much tranny slippage is bad? - Diesel Forum

goldenfox · 03-10-2005, 12:03 AM

I had my tranny rebuilt about 5 thousand miles ago, with stock parts. I have noticed a couple of times that when I am in the throttle hard when it shifts it will rev up a little then shift, obviously slipping. And I have also noticed a few times where when accelerating it will go to say 2600 rpm and basically stay there, even while I am speeding up, is this normal or do I throw someone a beating? I know the converter locks and unlocks and so rpm's can be wierd, but with it slipping a little sometimes I am worried about another rebuild. I was hoping to make it til the end of summer before I called ats or suncoast. [img]/ubbthreads/images/graemlins/crazy.gif[/img]

SteveIn29 · 03-10-2005, 01:25 AM

Short version....any beyond what happens in the torque convertor is bad. It generates HEAT and heat will kill an automatic quickly.
Fluid temp-185 degrees = tranny life-around 100,000 miles.
300 degrees = 300 miles

Your power mods and large tires are basically too much for a stock tranny to live with especially if you have a lead foot.

GrampyJim · 03-10-2005, 01:46 AM

I can agree with a lot of what Steve says...... factory strategy is to defuel the motor at the time of the shift. This way, engine torque is reduced until the shift is completed and clutch apply pressure is up to the level needed. This reduces internal stress and delivers a smoother shift.

Power programmers change the fuel and shift strategies.... not much Ma Ford can do about that... If you want to boot-f**k somebody, it should be someone that had to do with one or more of the mods..... The engineers design these things to live in stock trim (and even then, they can miss the mark). Adding torque and/or abuse is going beyond design limits and shouldn't be blamed on the initial design.

Whoever repaired your transmission is going to install stock parts if it's repaired under warranty.... If the mods ate the transmission before, they WILL eat it again.... and again...

roofeditor · 03-10-2005, 06:44 AM

Slippage is very bad. Suncoast is having success with upgrades.

Canyonero02 · 03-10-2005, 08:59 AM

Was it rebuilt by ford under warrenty?? if not then whoever rebuilt it 'aught to be held responsible. If 1 stock tranny went then whats to keep another one from going. I would get it rebuilt right to handle the extra power and bigger wheels.

Also, if you never regeared for the larger tires that also puts alot of extra stress on your trans.

goldenfox · 03-11-2005, 12:58 AM

There has been mods added bck to the truck since the rebuild, I have been waiting for a trans program first, before putting any power adds back in. as far as the first time, the planetary thing came apart and shredded everything. I am kinda aiming toward the tech who rebuilt it, I pulled the filter off and looked in and there is a ton of metal in there. I am guessing he didnt flush the tranny out or the cooler before he put it back in, but a lot of slipping can obviously cause that too. I am gonna take it back and see what happens. worst case scenerio they say "eat it" and I'll call suncoast before summer instead of after. my biggest thing is it lasted 5 thousand miles! the first one had issues and lasted way longer than that.

GrampyJim · 03-11-2005, 03:21 AM

goldenfox.... while there may be a concern with the rebuild, Ford has some pretty strict rules about what we're supposed to do when we find metal in the pan. I would hope that your tranny tech would follow these rules.

The OTA cooler is supposed to be replaced, the OTC cooler and lines are supposed to be flushed and good housekeeping during the rebuid process is a must.

If the truck was in stock trim at the time of the rebuild and remained that way up until the transmission failure, you have a legitimate gripe and they should bend over backwards getting you on the road again.

AllOutFirefighter13 · 03-11-2005, 10:09 AM

Does anyone know if Suncoast, or anyone for that matter, has developed the proper torque specs for re-assembly?