transmission trouble

[iceman]

Hi every one.
I'am new to this forum, living overseas (Netherlands).
I own a 76 F100 supercab and a 77 F250 crewcab, both have a c6 tranny.
The F100 tranny fluid was'nt changed since I own it ( 8 yrs).
The F250 tranny fluid had amsoil in it wich is hard to get overhere.
So I decided to change fluids in both. I put atf f in the 76 F100 and it ran just fine (old fluid was soupy).In the 77 F250 I put dexron II, It runs ok when driving along normally , but when the tranny is warmed up and I hit the throttle it has a long shift from 2nd to 3rd with sometimes a rpm surge before shifting or no shift. Also the reverse gear starts slipping then.
Before the fluid change the tranny shifted really strong, when using more power the shifts became more positive.I'am wondering if its caused by the fluid change or a failure of some kind. The guy I purchased the oil from suggested , the new oil could have loosened dirt wich could cause problems in the valve body. The old fluid (amsoil) looked very clean and there was no debris in the oil pan.
All help is welcome and sorry for the long story

Thanks William

 

[flareside_thunder]

Hey thanks for joining and welcome to the website...trannies aren't my thing but I'm sure others will jump in and let ya know what your problem is. Get some pics up of those trucks too...especially the crew cab!!

 

[iceman]

Hi Junior
Hopefully they will, getting pictures on the the web isn't really my thing but I'll try
William

 

[Ranger429]

Why did you use Dexron? Should of went with Type F fluid.

First thing I'd do is drain the Dexron and refill with Type F. If you still are having problems check to make sure you have vacuum at the modulator valve or see if the hose is cracked.

 

[Mil1ion]

Why did you use Dexron? Should of went with Type F fluid.

First thing I'd do is drain the Dexron and refill with Type F. If you still are having problems check to make sure you have vacuum at the modulator valve or see if the hose is cracked.

Wrong.
Dexron II,III, IV, Mercur are the proper fluids for C6's. The 77 has a C6 in it

C4's use F type.

You use what it says on the dipstick..nothing else.

Try a trans additive to possibly help.
I use FORTE' products

You could also inspect the modulator for becoming faulty

 

[TexasRho83]

I'm used Type F in all my C6s...

 

[bigyellowtruck]

im getting the same problems in my c6 iv changes the oil a couple times and it ran better but then did the same problem i talked to a guy that knows all about the c6 tranny and he told he would replace the bands in it and should run good as knew they say they get like that after a long time
and welcome the website i hope this helps any

 

[Mil1ion]

 

[iceman]

Hi guys.
Thanks for all the response sofar.
Today I checked the modulator and it worked fine, vacuum is also ok.
Tomorrow I'll drain the oil and check the pan for debris and next I will remove the valve body for a clean up.

Thanks William

 

[iceman]

HI
problem still exists after oil change,It slips in 2nd and reverse (is there a connection?).First gear and 3rd are solid.
Anyone any suggestions ?!!.
Thanks William

 

[brentleedragon]

I am not sure but can't you adjust bands in the C6 to tighten it up? I had slipping in first when I first got my tranny rebuilt, and the guy said he tightened up the bands. I know new bands (adjusted) can be amazing, you might want to try that.

 

[brentleedragon]

On the C6, there is a side adjustment nut and bolt for band adjustment. Loosen the lock nut and back it off enough to tighten the adjusting screw to 10 lb/ft, then back out the screw 1.5 turns. while holding the adjustment screw, tighten the lock nut to 35 lb/ft. Make sure the adjustment screw does not move while torquing the lock nut.

There we go, thats what my buddy whose next to me and works on C6's said might help

 

[chuck101st]

I'd tyry some Lucas additive. I know a few people who swear by it. Never actually used it myself but plan on adding some when I change fluid in mine.
I do know of one guy that I work with had a 90's Dodge that the tranny was slipping and he added some and it is still on the road today and this was over a year ago.