C6 slipping

gamudslinger88

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My C6 in my truck is starting to slip so I think a rebuild is in order. My question is can I swap in an newer style overdrive tranny in my 85 4x4? I want to keep the auto becouse my other two trucks have the hog leg and im tired of shifting gears. SHould I just keep the c6 or would the swap to an od be worth it? I was thinking of a gear spliter unit but I dont have the funds for that so I will have to be resourceful on this one. Any advice would be greatly apreciated. sorry for the miss spelling , my fingers are could and dont want to work right.
 

Diesel JD

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You might do a search...a guy here said he was selling an OD unit that was a lot cheaper than the GV. I have no connection with him, nor do I know if he makes a good product, but he was on here trying to find out some IDI info or maybe drum up some business too. The E40D is a nice unit, buit you really need at least the 97 and up upgrades and if possible a BTS tranny or other built E4OD. The C6 is pretty tough, you should consider keeping it if you want to stay auto, but its pretty inefficient too. It is cheap to overhaul. I had mine done at a flate rate shop...COMPLETE hard parts, soft parts, everything, for $900. Completely burned up...would have been around $3000 for an E4OD. A soft parts overhaul at a shop like that usually runs around $250 + the labor to remove and install. If you are at least semi skilled shadetree mechanic you might be able to do a soft parts overhaul on a C6 yourself for pretty cheap. It may not even be that bad of damage. I'd say it warrants pulling the pan for a look see before you panic...and checking the VRV and vaccum pump....accursed VRV....that's one more reason I want to go manual. Does it still slip if you shift it manually?
 

NJKen

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The C6 has adjustable bands. A lot of times a simple band adjustment will take care of slip problem. The C6 is almost bomb proof.
Ken
 

suv7734

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It really depends on 'when' your trans is slipping. Hot/cold, 1 to 2, 2 to 3 etc. As mentioned the VRV is a huge culprit and there is an adjustment on the band as well as the vacuum modulator. A vacuum pump that is going out can also cause you problems in this regard. Going to an OD tranny will be a lot of work (computer controls involved) but can certainly be done (we're talking expensive depending on your ability). The C6 is a strong trans and can be rebuilt at a reasonable cost. Has to be your call.
 

smokin69

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I thought if you went with one of them Baumenator computers or whatever, that it had everything you need to put an E4OD in a truck.
 

suv7734

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Very true but since he has indicated there is a serious restriction on funds that unit will probably be worth about half or more of the C6 rebuild. Not to say it's not worth it in the least but he has indicated that this is low budget.
 

Diesel JD

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The Bauman computer is pretty spendy, the E40D isn't going to be cheap either. I say either a C6 with an aux. O/D or a manual is the best bang for your $$
 

gamudslinger88

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Well I plan on pulling and rebuilding myself. I have never put my hands in a auto trans but have pulled my fair share. I do however have a friend who has rebuilt a C6 before so I will have him help me.

I will check the bands and the vrv before pulling the tranny.

I just purchased this truck from a friend who just put a new(new to him but a good used) motor in it and hadnt worked out all the bugs. I now have her running good and took her for a run. I checked the fluid before leaving and it was about 2 qrts low. so I filled it up. She sliped and was trying to grab in reverse, had a hard grab and jerk fealing to it. when in drive I have to shift manualy till she warms up then she doesnt seem to slip as bad. After warming up its hit or miss on slipping. I parked her and havent tried anything else.

Do you think some lucas or other trans slip stop would help. I know its just a bandaid but just wondering.

A little off subject but funds are low but not broke as hell per say. I just bought a used Hypermax setup so my funds I have set aside for this project have dwindled somewhat. I also have a 91 chevy 4x4 solid axle swap in progress and a 81 toyota with 33's but have 39.5 TSLs and 9 more inches of lift to put on her first. Thats why My funds are low im trying to devide between 3 projects and one Ol'lady. I realy need a second job.lol
 

Mr_Roboto

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Definitely do your band adjustments, the VRV and add a bottle of Trans-X.

It sounds like you have some hardened seals that are losing pressure. The Trans-X will help that.
 

gamudslinger88

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I fooled around with the truck today but it got dark before I could mess with the trans. Can you adjust the bands from the bottom or do you have to pull the trans? Could someone supply me with a link with some information on adusting the bands and vrv. sorry for the dumb questions but im a diesel newbie here;Sweet

The trans fluid doesnt smell burnt. someone did loop the trans fluid cooler lines together though and there leaking so it could be that the fluid is new from topping it off.
 

Mr_Roboto

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Intermediate band is the only one that can be adjusted. Tighten the stud to 120 "inch" pounds, then back off 1-1/2 turns then tighten the jam nut.

Note that if the trans coolers are bypassed the trans will overheat FAST.
 

gamudslinger88

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Yea I think thats the culprit to the slipping. I am going to hook up the trans cooler before driving it any distance. Is there any particular brand of trans fix I should use?
 

lotzagoodstuff

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I wouldn't put any additive in just yet as you may have a leaking trans cooler as that's generally why people bypass them. I would pressure test the cooler before hooking up your lines as it's usually easier to find a leak with air or nitrogen than hot transmission fluid.

The good news is that you most likely found the cause of your slippage. C6's are pretty indestructable, but heat makes anything slip. I think the rule of thumb is every 20 degrees cuts the fluid life in half and belts start slipping around 260-270F.

Make sure nothing's leaking, and then get all the old fluid out of there.

Good luck, and report back with your findings.

R. J.
 

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