C6 done... seeking advice on options

[DuRolf]

So on my long arc to Lake Tahoe and back from Colorado in my 1989 Ford E 350 Born Free RV with a 6.9 IDI / Hypermax Turbo'd rig I have run into transmission problems. When trying to reverse the engine roars but maybe 1% of the force actually gets to the wheels. I was barely able to back out of a parking spot with a slight uphill grade in Wells NV, and quite a burning smell ensued. Tranny fluid level is fine. I was able to go forward, at highway speed, to get into Salt Lake City and the in laws house.
I am sure I need at least a big transmission repair on my C6, and maybe a new one.
I am wondering is there anything I could do to make the transmission system more heavy duty? Is a repaired or replacement C6 the best I can hope for? Are there mods down the road that will make things better? Or is there someway I could make a choice at a transmission repair shop tomorrow that would make the system more heavy duty?
Reading this forum suggests the C6 is a pretty good transmission already, and maybe better than the overdrive model that came later.
Usage of my rig includes crossing mountain passes and towing trailers.

regards

Rolf

 

[OLDBULL8]

As long as you can go forward OK I wouldn't worry about not backing up. I would say the reverse clutches are burnd up. Previouse owner may have got stuck and burned them up.
Too rebuild a C6 completely is relatively cheap, You can prolly do it yourself. If you have many more miles to get home, you should change the tranny fluid, since it smelled burned. Check the dip stick to see how brown the oil is, if it's still a bit red, don't be concerned about it. A thought, possibly the trans. was not shifted all the way into the reverse detent, meaning worn shifting bushings under the RV.

Here is one. http://www.makcotransmissionparts.com/C-6.html

Another: This is where I get my parts from. http://www.transmissioncenter.net/C4_C6.htm

 

[OLDBULL8]

Here is the linkage I was talking about. Without the engine running, shift into reverse, crawl under and see if you can shift it further into reverse detent. I don"t know why I can't upload a C6 pic. Maybe your intermediate band is slipping, can't remember if it's in play in reverse, you can try and adjust it anyhow.

There is a bolt on the side of the tyranny with a lock nut, loosen the nut, tighten the screw in, caution, not real tight, just so it bottoms out (feels tight), then back it out exactly, one and a half turns, tighten lock nut.

EDIT: Tighten bolt to 10 Ft Lbs.

 

[OLDBULL8]

Ran into another place, don't show for a 6.9 but might call them. Couldn't upload pic from my pictures, so I uploaded from webshots.
This website is so screwed up since they changed, takes forever to navigate, let alone trying to upload pictures. Just about to say to hell with this OB, takes too much time to do anything on it now.

You must be registered for see images

 

[DuRolf]

OB8, you've been a font of information. I have learned a lot already. Thank you!

 

[DuRolf]

Well, here's where we're at: I took it to Aamco in downtown Salt Lake City. They replaced the C6. The old one had a burnt out reverse clutch, and much damage to the second band and the forward clutch. The culprit according to them was a vacuum line that had been routed straight from the vacuum pump to the old transmission, bypassing the vacuum switch. They said this would feed constant high vacuum to the transmission, making it think I was in idle all the time and upshifting too fast. Since the new C6 the rig runs with much better pep and speed.
I talked with the guy who installed the Hypermax turbo, and he said "that was me who routed the vacuum line straight to the pump, per Hypermax instructions".
I talked with an old time Ford dealership mechanic, who got his start when 6.9 IDIs were the latest thing. He said he had never heard of bypassing the vacuum switch. And furthermore, in that brief window when the 7.3 IDI was turbo charged in the factory, right before the Powerstroke era, C6s always had the vacuum line go through the switch.
Has anyone heard of bypassing the vacuum switch on a C6 attached to a diesel? Is there any reason a Hypermax turbo installation would require that?

regards

Rolf

 

[DeepRoots]

you shoulda rebuilt it yourself. For $600 you can have the most bulletproof c6 available and you'll at least know how it works next time.

and yeah, you need a VRV

 

[franklin2]

Has anyone heard of bypassing the vacuum switch on a C6 attached to a diesel? Is there any reason a Hypermax turbo installation would require that?

Rolf

I believe the previous owner is mistaken. A "automatic" transmission needs some input info to make decisions about shifting. It needs to know the road speed(governor inside the tranny) and it needs to know the load on the engine. The vacuum switch is what is used to measure the load, though in this application it's really just measuring the throttle position. As was mentioned, high vacuum means the throttle is mostly closed, which means not much demand, not much load on the engine. So as the tranny guy said, this causes quick soft shifts, which can hurt the tranny if it's under a high load.

Low vacuum means the throttle is open fairly wide, which means a high demand on the engine. This will cause delayed shifting and higher harder shifts, since you want the engine to rev up a little more to get everything moving, and you want the hydraulic pressure in the tranny to be higher so there is less slippage during shifting.

You really can't run without the vacuum control.

 

[OLDBULL8]

Man, ya just never know what ya got with a used vehicle, the PO is prolly lying and wants to blame his screwup on Hypermax, they would never never say to do anything like that. Did Aamco install the VRV? Surely they did. If not I have one. Here is how they have to be adjusted.

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[DuRolf]

Aamco hooked the VRV back up and tested it. The rig is now running better than it ever did.
Agreed there is no substitute for fixing things your ownself. I'll have the tools and expertise some day, maybe soon.

 

[OLDBULL8]

Forgot to mention if you don't have a VRV, you have to get the one with the Black strip for a diesel. White strip is for hi altitude and green strip is for gassers.

Whoops shoulda read the thread, VRV was there, just not hooked up. Oh well glad you still had it.