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C6 Transmission woes... **(update, I think I know why!)**

Re: C6 Transmission woes...

Sorry to read that. Occasionally that would happen if the valve body didn't have a low-band hold feature and we were using a transbrake. My memories of that stuff was why I always did high gear burnouts in the race car, meaning I'd shock the tires loose in high gear with the converter or, at most, start out in second with the solid band. The rear sprag was even weaker on the C4 which is what I used. I used a reverse pattern manual body with the hold and transbrake.


Check to see if your new valve body has a low/reverse band hold feature. If it doesn't, get one that does or modify it. Imagine like it's in manual low whenever in low gear, even in drive range.


Good deal on the used C6; hope it works out.
 
Re: C6 Transmission woes...

I'm not sure I follow you. The C6 doesn't have a low/reverse band like the C4. It has clutches for low/reverse and only a band for 2nd. If the low/reverse feature you speak of in the VB works on the clutches though, how would I check that?
Thanks
 
Re: C6 Transmission woes...

I finally got time to prep the trans for the swap. As I was taking the Mustang specific parts to switch over, I observed the tailshaft is too long! :rant

so I took it apart to get the parts I need, I will put my old trans back together... I had to disassemble it completely to swap the output and tail shaft so I decided to just put the low/reverse clutch hub and one-way clutch in my trans
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Re: C6 Transmission woes...

anybody swap E4OD/4R100 planetary gears into a C6? I can't find any specifics on the swap but plenty of stuff on the web saying it can be done...
 
Re: C6 Transmission woes...

Now might be a good time to consider an AOD transmission. The C6 can handle a lot of horsepower of course, but it's well known for its appetite for gasoline (inefficient) and is a horsepower black hole as well.

Z
 
Re: C6 Transmission woes...

an AOD won't bolt up to a 429, might not hold up to one either...
the E4OD is the only OD trans made for the 385 series big block and they are HUGE!!!
My goal is a TKO 600 5 speed but that conversion will cost in total about $6K. The C6 has to to do until then...
 
Re: C6 Transmission woes...

Good deal. Keep your eye on the prize and don't get too carried away with spending unneeded money on the current trans setup :thum

Bill
 
Re: C6 Transmission woes...

"tarafied1" said:
I'm not sure I follow you. The C6 doesn't have a low/reverse band like the C4. It has clutches for low/reverse and only a band for 2nd. If the low/reverse feature you speak of in the VB works on the clutches though, how would I check that?
Thanks
Click to expand...


Sorry for the band/clutch brain fart.... in the C6, the clutch performs the same function as the band in the C4. In Drive range, the one-way sprag takes the stress until the trans shifts to second and the intermediate band takes over.


Looks like you got the trans fixed up. Assuming it's your race car and automatic operation isn't necessary and a manual valve body or shift kit is in the trans, you shouldn't have any more issues of that sort. Weak links in the chain and all that.


Drag racing tip: If you're not already doing it, when you exit the water box in high gear with tire speeds approaching or exceeding 100mph+ and the slicks start to recover, release the throttle. It's not as impressive but transmissions last a lot longer. That and other little 'tricks' are why I never lost a C4/converter during 20+ years of racing. Kinda boring but easy on the wallet.
 
Re: C6 Transmission woes...

I was reading about "spragless" converters and they say the sprag fails due to tire shake....
http://www.raceshopconverters.com/sprag-vs-spragless-vs-mechanical-diode/
A sprag is simply a one way clutch. It works the same way as a ratchet; locked in one direction and turning in the other. Sprag assemblies are often damaged when initial tire shake occurs during a burnout. Internal components are loaded and unloaded quickly during the tire shake, causing the sprag to wear unevenly. This will eventually lead to failure of the sprag design, if it is not simply broken from the power output of the engine.
Click to expand...

do you think this hold true for the one-way clutch (sprag) in the trans too?
 
Re: C6 Transmission woes...

"Fst Blk" said:
Good deal. Keep your eye on the prize and don't get too carried away with spending unneeded money on the current trans setup :thum

Bill
Click to expand...
thanks Bill, it's just so tempting since the TKO is probably a long way off... $$$$$
 
Re: C6 Transmission woes...

"tarafied1" said:
I was reading about "spragless" converters and they say the sprag fails due to tire shake....
http://www.raceshopconverters.com/sprag-vs-spragless-vs-mechanical-diode/
A sprag is simply a one way clutch. It works the same way as a ratchet; locked in one direction and turning in the other. Sprag assemblies are often damaged when initial tire shake occurs during a burnout. Internal components are loaded and unloaded quickly during the tire shake, causing the sprag to wear unevenly. This will eventually lead to failure of the sprag design, if it is not simply broken from the power output of the engine.
Click to expand...

do you think this hold true for the one-way clutch (sprag) in the trans too?
Click to expand...


Once the tires hit the VHT, all bets are off. My main experience was fixing other people's problems so I really didn't have a hard and fast read on their driving style unless witnessing it personally. About all I could do was watch my own, experiment and observe the results during the semi-annual teardowns to see if what I was doing was OK or wearing things out. I had two early small input C4 twins that I played with most of the time. I never graduated to a C6 like yours and was planning to stick a PowerGlide behind the next engine when I quit racing, so it never got done.


My supposition was that 'slip-stick', or tire shake in applications where it was a problem (not so much in mine) transmitted stress points throughout the drivetrain so I sought to limit it as much as possible. That's part of why, though certainly not impressive, my car was over-tired, had a four-link and an instant center pretty far forward, so it hardly lifted the wheels at all. I set it up like, and generally mimicked, the old Pro Stock cars of that era. Those were the days when one could talk to Pro Stock drivers about their setups and look at stuff, long before the 'business of racing' took over.


C6's are generally a really reliable and 'bulletproof' transmission but nothing is unbreakable and stuff does wear out, like that OEM one-way clutch. Think of all of the service it saw before it broke. Pretty impressive. With the C4's, they were always carefully blueprinted and massaged but I'd likely not check/do any of that stuff with a C6. Check the gross tolerances, stick it together and go have fun :)
 
Re: C6 Transmission woes...

thanks!
I think I will be a little easier on it this time around (at least I am telling myself that!). And yes, this trans has been in the car over 20 years and has had a lot of use and abuse so I guess I can't really complain!
 
Re: C6 Transmission woes...

Wow, that sounds awful but glad you found one and are ready to get it back in. I am clueless about Transmissions but maybe one day ill find someone doing a swap and i can help and figure it out
 
Re: C6 Transmission woes...

I took mine apart, swapped out the broken stuff, put it back together, then put it back in!
It's alive!
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My youngest son helped me put it back in today, so I let him drive it. You know, I have had this car over 24 years and never rode in the back before...
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Re: C6 Transmission woes...

well I made my first long journey since putting the trans back together. I drove it out to my dad's and back (around 200 miles). With the temp gauge working, I think I now know why it failed. On the way out, I was driving in the rain and it was cooler weather but it still climbed to 210* F
On the way home today it was warmer (upper 80's) and sunny. It climbed to 240* F. That was driving at 75/80 mph.
Way too hot. Need to replace trans cooler. When I replaced the radiator before Power Tour I didn't run the lines thru the rad. The trans cooler is obviously not up to the task :rant
 
So are you gonna get a larger cooler and bypass the rad. again or run it through the rad.? Today mine was running about 190*, I use synthetic fluid and it goes through the rad.


Sent from my iPhone using Tapatalk
 
well the engine runs around 190/200 so I would think it would be better to not run it thru the rad. We don't get very cold down here. I could see if I lived up North where you do, that it might need some heat in the winter from the rad but I see no point for me to do it.
I'm looking at trans coolers now...
 
At mercedes , they just cool the transfluid threw the radiator.
Maybe you can run it : from trans to radiator to extra cooler and back to trans.
And check out which type of transfluid you can use. Maybe their is a difference in heat absorbation or extraction ??
Somewhere between 180°F - 195°F should be your goal I guess.
 
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