Any ideas what would cause my transmission to slip in first gear?

I was driving today and out of the hot burning sun the transmission started slipping as I pulled from the stop, the engine would rev and it felt like it was low on fluid.

It did this for about 2 miles until I stopped and picked up some fuel, I checked the transmission fluid and it was fine and did not smell burnt.

So I was going to chance it and go home but was ready to call for a tow truck and when I pulled out of the gas station the truck shifted perfectly all of the way home.

The only thing I did differently was to turn on the fan on the trans cooler.

Any ideas what could have caused it do this? I do not know how hot the fluid was

but it was 106* today and I had the AC on high all day with the temps running normal.

Of course tomorrow is Sunday but I am going to call the transmission shop on Monday.

I have an A-727

Jim

 

The forward clutch and the 1st gear sprag clutch are what make 1st gear happen. Does it pull OK in 2nd and 3rd, or were you babying it to try to limp home? If it shifts to 2nd and starts pulling normally, it's the sprag clutch.

If you can get it to do it again, dump it in Low to apply the low/reverse band. If it hooks up, the sprag clutch is dying (and putting metal in the pan). If it keeps slipping, the forward clutch is toast and you will eventually lose all forward gears.

 

Could the low reverse band be out of adjustment?

 

Nope. Low/Reverse band only applies in Low (1 on the shift quadrant) and Reverse. The sprag clutch holds in Drive 1st.

 

The mechanical gov could have hung up, and you were getting a 2nd or 3rd gear start. Another possiblity. But pulling it down into low, should give you an indicator, if its not starting out in first.

 

One of my trucks did the same way. I took it in, babying it. Changed the filter
and it has been ok, .........but I wonder for how long.

 

Dave,

Yes, second and third did seem to be OK once I got up to speed if I recall correctly, I was a bit agitated at the moment.

When I tried to pull out from a stop the engine would rev up and the truck would accelerate real slowly, just like a slipping clutch on a manual or low fluid in an automatic.

It was 106* out My Low Fuel was on and I was on the way to get fuel when it happened and I didn't want to run out of fuel.

So I made it to the station and got some fuel and then that is when I checked the fluids and they were ok so I smelled it to see if it was burnt and it was also ok.

So I already had my AAA card ready to call a tow truck but I thought I would at least head towards home since it wasn’t burnt.

While I was at the island I ran it through he gears a few times between forwards and reverse while giving it some throttle and it then did engage hard into “D” so I headed on home and at first it was a bit sketchy but after about a mile it was working fine.

I was a bit hesitant to give it much power but I did and it still shifts ok now.

One thing that I do remember though is that for the last few days when I would accelerates hard I would notice a faint shudder while it pulled in first gear but I passed it off as being pinion inclination because I just worked on my rear springs.

So far it is now running fine but I do not trust it. So today I am going to call the transmission shop and see when I can have them check it out.

BUT the guy who rebuilt the transmission closed shop is now in Afghanistan, I got his name from the technicians from Banks Engineering so first I will stop back in and find out who they recommend now.

In the next few days I am going to install my remote filter system for the transmission that I took off my other truck, at least I will keep the fluid clean.

Last time when I had it rebuilt, the magnet was full of metal filings like as if you drug it through the floor of a machine shop, I did nasty things to my torque converter.

Do you have any idea what the cooler line size in for the 727, ˝”?

Thanks Jim