Improving C6

[mj05]

The whole problem with fabing up a lockup converter on the C6 is establishing the fluid path for the clutch assembly in the converter...

You would need a hollow input shaft on the transmission and some way of directing fluid into a channel in the TQ to apply the lockup. Then have a dump valve inside the tranny to release the lock up.

If someone really wanted to, it could be done, but you would still be stuck with only three speeds...

Good info! I know the c6 is a tough, dependable ole tranny, so I figured I'd ask you gurus if there was a way to better it for efficiency and driveability sake. Thanks for the input guys!

 

[david85]

The C6 in my truck had "1986" printed with ink on the face of the converter so I think it had a stock setup. Our steep driveway required abour 1400 RPM to climb out and with a heavier load would go above 1600.

When I had a custom converter made for my E4OD, I asked for a low stall converter and under the same conditions, 1000 RPM is enough to get the truck rolling, give more power and the truck starts moving faster instead of RPMs drifting up first. Under load going down the road, the practical stall spees still seems to be around 1400 though. That is lower than stock but I still wish it were lower.

The difference I notice on the driveway was also partly thanks to the slightly lower 1st gear ratio of the E4OD.

If comparing a slush box to a stick shift, the auto will always feel, well, sushy off the line.

 

[franklin2]

The difference I notice on the driveway was also partly thanks to the slightly lower 1st gear ratio of the E4OD.

I forgot about that ratio difference, which reminds me can't you put those E4OD lower gears in the C6? That would help the whole situation out I would think.

 

[trackspeeder]

I forgot about that ratio difference, which reminds me can't you put those E4OD lower gears in the C6? That would help the whole situation out I would think.

You can. You can spread the gears out by lowering the 1st and 2nd gear ratio. 3rd remains the same.

 

[RLDSL]

THis may be what you need . Allison spec built torque converter for a C6

Before I found a clutch that was easy enough on my knee, I was contemplating throwing a C6 that i have in and was looking at these things.

 

[mj05]

Good web sight. But for some reason they don't list the stall speed for the low stall converters?

 

[idiabuse]

I have been building the C-6 since I was 18, always had great luck with these units.
I learned one thing first,
1) remove the OEM valve body intstall reverse manual.
2) remover servo install R servo with adjustable release springs.
3) oversized oil cooler
4) 3/8 1/2 cooler lines
5) synthetic fluid

The rest of the unit can be OEM and set up with the above parts
will never fail, miss a shift, never slip under any condition.
Best of all you can leave it in 3rd gear all day long and drive around due to the low RPM torque of the IDI.
and when pulling a heavy load the reverse manual valve body will have enough pressure at excessive operating temperature to still shift positively.
The oem valve body I never liked, too many valves to hang up and cause erratic shift pattern.
Javier

 

[bud48fla]

I use the ATI converter and the C6 with the lower gears from the E4OD in my 88' and have Doug Nash OD.

 

[idiabuse]

I use the ATI converter and the C6 with the lower gears from the E4OD in my 88' and have Doug Nash OD.

what year did u but the ATI? I only use ATI from now on cause I can afford to do it once, I cant afford to do it over and over.
I have the same low gear set in my truck, but I wonder if it actually makes my trck slower up to 40mph, it revs up too quick IMO in 1st and 2nd gear.
I think the 2.40 first gear would be better for the low RPM torque the IDI makes, and respond better to the load.
Javier

 

[smolkin]

I just got my c6 rebuilt, and boy do I wish I'd known about lower stall converters. And since I'm mad at the shop that did it (long story, almost Hall of Shame worthy) I'm looking around for a good local go-to tranny guy, this thing just won't shift right. I can't find anyone who knows how to adjust the vacuum, is it something I can do properly? Also, what is the correct color modulator, not sure but I think they put the wrong one on...?

 

[franklin2]

I just got my c6 rebuilt, and boy do I wish I'd known about lower stall converters. And since I'm mad at the shop that did it (long story, almost Hall of Shame worthy) I'm looking around for a good local go-to tranny guy, this thing just won't shift right. I can't find anyone who knows how to adjust the vacuum, is it something I can do properly? Also, what is the correct color modulator, not sure but I think they put the wrong one on...?

They have this procedure to adjust the variable vacuum gizmo on the throttle, but you need some special vacuum tools to do it. I would just slowly adjust it one way or the other to get the shifting rpm you want.

Most modulators are adjustable. You take the vacuum line off and stick a screwdriver up in the nipple and make small adjustments. Problem is, this will affect your adjustment on the throttle, so it's sort of a juggling act between both.

 

[david85]

I have been building the C-6 since I was 18, always had great luck with these units.
I learned one thing first,
1) remove the OEM valve body intstall reverse manual.
2) remover servo install R servo with adjustable release springs.
3) oversized oil cooler
4) 3/8 1/2 cooler lines
5) synthetic fluid

The rest of the unit can be OEM and set up with the above parts
will never fail, miss a shift, never slip under any condition.
Best of all you can leave it in 3rd gear all day long and drive around due to the low RPM torque of the IDI.
and when pulling a heavy load the reverse manual valve body will have enough pressure at excessive operating temperature to still shift positively.
The oem valve body I never liked, too many valves to hang up and cause erratic shift pattern.
Javier

How do you get the bigger lines on? I've been wanting to do that for a while on my E4OD.

 

[idiabuse]

How do you get the bigger lines on? I've been wanting to do that for a while on my E4OD.

remove OEM steel lines, purchase pushlok 300psi rated hose and AN style pushlok fittings for hose, cooler and trans case.
This usually cost around $200
Javier