C6 Trans Question

[wyazel1]

I ran my truck pretty hard today, this was the first time really running hard with the new motor. T case in 4LO and trans in 1 at 4.5k rpm this thing is alot of fun This motor kicks some serious a$$ I never did get stuck but came close due to going thru holes in 2wd to see if i could make it.

But the bad news is.....on the way home i noticed the trans slipping as it shifts from 1-2 and 2-3. It is doing it whether i shift it manually or if i let it shift automatically. The rpms surge momentarily as it shifts. I plan on dropping the pan and changing the filter, as well as adjusting the band as per my chiltons and haynes books. 10ft/lb then back it off 1.5 turns. Are any of the shift kits any good? What have you guys used in this situation? Im hoping the tranny isnt shot, but its definitely not used to 400+ ft/lbs of torque.

Hoping for some good advice here, thanks.

 

[SuperCab]

Hate to break it to you, but I'd bet any money your tranny is seeing it's last days...

The one in my truck did the same thing, and it never gets better...

According to my trans guy, you could take it apart, put thicker thrust washers in it, and it'd be good for several thousand miles more, but a rebuild is still inevitable...

Sorry to be the bearer of bad news...

 

[velocityboy]

I'm gonna be more of a "glass half-full" kind of guy.

I say you go ahead w/ the maintenance you mentioned, plus maybe change out the vac modulator (if I remember correctly, black band might be preferable in your case) and hose.

The c6 on our work van was acting all funky and I figured it was just about on its last legs. Went through and gave 'er a little TLC and it was all good... 100,000 miles later, not only is it still going, but I'd venture to say it's doing better than most of the rest of the van.

Even if a little general maintenance doesn't save your particular transmission, it can't hurt to try.

 

[wyazel1]

Yea I think I am going to try one of these

http://store.summitracing.com/partd...908331+4294925060+4294904004+115&autoview=sku

and i will also check the band adjustment and put in a new filter while i am down there. Thats all less than $100 total so its worth a shot i guess.

 

[LEB Ben]

You'll have to let me know how you like that shift kit...we have almost the exact same builds...and I've been debating about the B&M kits. So be sure to post the results.

 

[wyazel1]

You'll have to let me know how you like that shift kit...we have almost the exact same builds...and I've been debating about the B&M kits. So be sure to post the results.

ok i am ordering the parts from summit now. I am thinking i will be rebuilding /replacing the tranny soon though. My truck isnt near as nice as yours so i am very hard on it, thats what it is for. I really cant say enough how much i love this motor though, it got a powerband that reminds me of the old 2 stroke dirt bikes i used to ride. At about 3500 it really turns into a nasty beast lol. That along with how i like to run the piss out of it probably spells certain death for my all stock c6.

If/when i do rebuild or replace the tranny, what are some things that i will need to hold up to the abuse? I tend to shift it manually quite a bit, and wrap it up to 5k and shift it in each gear. I dont mind the column shift i want to keep that.

 

[dentside79]

Mine did this once, I found out the fluid level was low. I filled it up, and a day or two later it started slipping again. I checked the fluid level and once again, it was low. I park on a concrete drive and did not notice any leaks so I could not figure out where the fluid was going? I found out that my modulator valve was bad and it was sucking trans. fluid through the vacuum hose on the modulator valve then burning it out of the exhaust. Talk about strange I replaced the valve, and all was well. There are different modulator valves even for C6's. If this is your problem, make sure to match up your band color on you existing valve when replacing. It is RARE that you kill a C6. Low fluid levels will make it skip every time, even if its only a quart or two low. There are a few other causes for a C6 to slip. One is the pan magnet packing with metal shavings to the point it blocks the flow of fluid through the filter. Make sure the magnet is clean and positioned directly in the middle of the filter inlet hole. Another common problem is water in the fluid. This is usually caused by water running off between the hood and cab. Sometimes if the rubber seal between the hood and cab is missing or not sealing properly, water can run off into the filler neck of the transmission. The filler dip stick has a slot on top where the metal cap slides onto the stick itself. Water can run into this crack and mix with your trans. fluid. I also had this problem when I first bought my truck (mine was missing the seal). I changed the fluid and filter, ran it a day and then changed it again. Worked just like new. Hopefully one of these things is your problem because they are all easy fixes. Good luck.

 

[wyazel1]

Got my shift kit, filter and fluid from summit yesterday, the b&m kit has awesome directions. I will probably get the valve body out someday this week and get er all freshened up.

My fluid appears to be at the exact right level, checking it hot idling in P. Also appears to be red and doesnt smell burnt. I talked to a tranny shop, the shop that the engine builder recommended and he quoted me $900 if i bring him just the tranny to rebuild it stout enough to handle over 600hp he said. Or $1400 if i bring him the whole truck and let him pull it out and install it. He said if my c6 is bone stock and hasnt been rebuilt in years, then shifting it from 1-2 at 5k rpm with 350+ hp might be a little hard on it.

So as of now i am hoping to freshen it up and get it to last until fall or winter then have it built for the abuse. Also planning on getting 4.10's in the axles when the tranny is out. The tranny shop said that spinning 35" tires with 3.50 gears also adds unnecessary stress on a tranny..i had never heard that before but it makes sense i guess, especially in deep mud.