Hey Ya'll
How many of you have C6's in your trucks and swear by them?

I bought my truck in May 04 and 2 weeks later it started slipping...
I called around and found a rebuilt C6 at Transmission Trading company in Longview, Wa I put it in and it still did not shift just right so I went and bought that trans vacuum Shift control valve and it seems to shift ok for about a week and during a trip to Seattle it overheated and lost first gear.

I took it back to Trans Trading company and he installed a trans cooler and fixed it. But you know it just don't seem to shift right. the guy at the said shop says its good. but you know it just seems like it shifts too early. except when I hammer on the accelerator then it seems to do just fine..

Also anybody know where I can pickup or have you laying around a Fan shroud for my 88 F350 7.3 L IDI ??

Any guidance would be highly appreciated

My Passion Her headache

 

tou could adjust your kickdown linkage to shift later than it does now by losening it up a bit. i had a buddy that had a 83 with a 302 and a c-6 and he was never nice to it, burnout-romp in the mud, etc, etc, and he never burned his up, but i have a 89 with a 351 and a c-6 and 60,000 original miles, i lost first gear just driving around town normal-like. i took it apart and found the clutch packs were bad for 1st and 2nd gear. 50 bucks for a tranny rebuild kit wasn't bad at all. i had it back in in a day and after that, it didn't shift too good for about a week, then it started working normal like again. and we will see how it works this go-round, i put 500 miles on it and its doing great

 

I had 88 with c06. had a problem and replaced band for one of the gears without removing the trans. had second problem a little later --- rebuilt the trans. still not right, shifted early and did not "drive" the rear wheels like i thought it should - slippage?? talked to many people, they told me the clutch packs are different in the diesel c-6 than a gasser. I even installed one of them ball bearing heavy duty whoopty doo converters, same nonsense. SOLD!! I suggest you find a better trans shop that understands the diesel applications. just while you're talkin with them, ask if there is a difference in the diesel trans and the gas trans. If you get that deer in the headlight look, tell them you'll check back later. AND DONT. Good luck.

 

Last night I just finished a C6 for a 88 F-250. Internally there is no difference from any other C6. It does have an extra reverse/high clutch and the snap ring groove in the drum is cut higher. However the valve body is set up different. The kick down is just that, it moves the trans to a lower gear if the valve body will allow it. The modulator and governor control the upshift. Most modulators are adjustable thru the hose nipple on them. It uses a hex key to adjust the shift point. The Vacuum control on the injection pump also must be adjusted to send the correct vacuum to the modulator. It must have been quite a feat to change the band without taking the front pump out. Hope this helps...Don

 

Hey Don Thanks for the insite. Shy of putting the vacuum gage on the line What is the correct reading of vacuum to the modulator. The guy at the Trans shop said 18-25 so I set it at the max the vacuum switch would allow.
How do I adjust the modulator I know where you said it was but how much is enough? Should I turn and drive? Turn and drive? This incorrect vaccum thing is what burned me up last time..

Thanks for the info guys...

89Ford73 That kickdown linkige is a waste of time on this trans.... They should rename that linkage to higher rpm linkage cause thats all it does for me is drop to an unproductive rpm raising something er other. lets just say I don't pass nothin.... even empty I have experanced in my 2000 F150 that passing gear should release a bit of quick power but in a 6000 rpm Gasser its ok for that but in a 3.75 redline deisel its usless.

My passion her Headache

 

I have a 89 Factory manual,but they don't give specs. (That's in a different book) If you have a means of supplying external vacuum to the VCV regulator at the injection pump, try adjusting it down from where you are now. The diesel C6 valve body functions no different from that of a gas engine. High vacuum at the modulator means low load and lower shift. Low vacuum means higher load and higher shift points. The modulator also controls line pressure which adjusts pressure to the clutches and bands. This gives the clutches more holding power when it is needed. As far as adjusting the modulator, that is more trial and error than anything else. Usually they are set from factory. There is a spec that says that at a certain Hg. of vacuum there should be a certain amount of Line pressure. I don't have that information for your application.
At any rate a little less vacuum from the VCV control won't hurt anything.
Hopes this helps at little...Don

 

Thanks Don
I will try tomarrow to adjust it down a bit. today between repairing my compressor and the Hunny do list I was rather overwelmed. (didn't have Truck time)
Tomarro I am off and the women have to work so bye bye soup bowl...

 

sorry bout that, i didn't know it had a vacuum thingy on the i.p. i guess its kind of a throttle position sender for the tranny??i dunno what to tell you, loosen the modulator thingy on the tranny all the way and see if that helps.... thats wut i'd do if it was my truck anyways.

 

This info may help..........if applicable.

How to adjust VRV

You don't have the engine running for the test, you need to apply 20" vacuum to upper VRV port and attach vacuum gauge to lower VRV port. The lower port is the one that goes to tranny, the upper to vacuum pump.
You have to maintain 20" througout this test. If it drops off you need to pump it back up.
Remove throttle return spring, cycle throttle lever 5 times from idle to WOT. Make sure 20" vacuum is maintained on upper port side.
Move throttle so it is 0.515" (33/64") from wide open (they make a tool for this). Vacuum gauge should read from 6-8" of vacuum. If incorrect adjust VRV to 7".
Again apply 20" vacuum, cycle throttle from idle to WOT 5 times. Return to idle. Gauge should read at least 13".

It says if you can't get the 7" or the 13" to replace the VRV. If VRV checks out maybe the diaphragm (modulator), line from VRV goes to the vacuum diaphragm I believe. Can't find any adjustment for the diaphragm but I think there is a little.

Basically all you need for the test is a vacuum pump (handheld type), vacuum gauge and a ruler to measure 1/2" or a 33/64" drill bit in lieu of the .515" tool. And a screwdriver for any adjustment needed.
Good Luck
James

 

Wow James Thanks for going to the trouble of looking that up.... I felt like I was reading out of a Tech manual...

I don't know about the 33/64 but I will go give it my best shot and see how it does

Bare with me I might get that done today... We managed a heavy frost so I just went out and pluged the ole girl in so in a couple hours well see. I assume it needs to be warmand not froze cold...

Anyway thanks again James...