What is probable cause of transmission running w/ increased rpms (about 200 or 250 rpms less at 55 mph)?

Original 700r4 guessing tons of miles. changed trani filter & fluid last week - do so every couple years. never any metal in pan. just a little black particle that I wipe out of pan. Besides higher rpms the trani seems solid and doesn't appear to leak.

other than trani fluid /filter change and tv cable adjust I'm a transmission n00b.

Thanks for help

 

bump

We discussed the transmission problem at work and heard an opinion that dark coating is probably something like aluminum dust... not good. I guess. And perhaps a spring is weak?

What do you guys think? How much of a rebuild might be involved?

 

okay, temp was a coincidence (hole on underside of a vacuum tube causing lean condition/temp spike). Simple fix and car drives normal. Sorry for odd post about heat and rpms. Runs smooth but RPMs are still up.

Since my transmission is showing signs of wear have been looking & saw a transmission shop that looks good in NC (stage 1 up to 400 hp 700r4 at very fair price). Am planning on a L31 upgrade somewhere between 275-325 hp/~350 tq on a daily ride. Eventually upgrading to a mild posi. Plan is to enjoy short trips to from work, some highway runs and keep newer imports in rear mirror. LOL Some more transmission firmness would be great but the car's a daily driver forever. I'm sure the transmission shop will have advice but what stall would you recommend for that combo?

 

I'm glad you figured out your issues. I'm having that random problem now. Have to keep checking for hoses that seem to be going bad with alarming frequency. does your converter lock? You should notice it dropping down once you are cruising. With my 3.73 gears, I'm running right at 2000rpm at 55. If it's unlocked, I'm ru nning about 2300.

make sure that when/if you upgrade your transmission and get a good shift kit in it, you get a good trans cooler, one with a fan. Heat will kill your tranny.

 

Agreed, check converter lockup. Get up to 60 65, and give the engine enough time to settle out and cruise. With one foot on throttle, keeping the car at speed, reach over and lightly press on the brake pedal, you should notice an increase of ~250 rpms when the converter comes out of lock up.

 

Do what Heavy Thunder suggest. The rpm's should go up and down with the slight apply of the brake pedal when at a constant speed. The black stuff at the bottom of the pan away from the magnet is clutch and or band material. In this case it could be converter clutch material if you are having problems locking up the torque converter and the transmission is shifting fine.