Before me, I have a very toasty and well used C6 behind a code H 390.
I want to do a good build on the C6, and have been wondering what
peoples' experience has been at using an AOD (or equivalent) front
gear set in a C6 to give a 2.78 first vis à vis 2.46. I understand
it's a "drop in" mod but the valve body has to be worked at bit
(softer 1-2 and 2-3 springs) to get the shift points right. Anyone
If so, and furthermore, has anyone replaced most of the thrust washers
in a C6 with Torringtons to reduce drag? I hear that setting proper
clearance can be tricky and that while lessening drag, the Torringtons
have a finite service life.
I've talked to local shops, and I usually get a blank stare when these
ideas are posed. 'Net sellers gladly hawk the parts, but give a
paucity of info.
All comments welcome.
I have built a few C6's but, it has been severl years. I
routinely used the Torringtons instead of the OEM's - never
had one go down with them and never had to replace one
during rebuild even after a season of dirt tracking. Thrust
setup is done just like the OEM's. I usually set them up on
the tighter side of the clearance but made damn sure it was
never less than minimum since they do not give like the
plastic stuff. You may notice a bit louder thunk when
engaging since they don't absorb much noise especially if
you decide to go loose. Once you get it back tigether,
don't forget to check the overall thrust. You should do that
before you tear it down. Ford recommends you shoot for the
same setting when you are done. The only thing I concerned
myselt with was the min/max's when using the Torringtons.
As far as the gearset, I never did one since the AOD was
fairly new when I did my last one. If I ever go back into
my old Torino again, it think I would give it a try to help
the 351CJ off the line a bit. If you come up with the right
combo to make it shift just firmly - not hard - please pust
it back for my info.
LAstly, you are reading from my very old memory. Always
double check everything by the Book. ATSG has a good manual
on the C6. If you are going to use AOD gears in it, I
suggest you also get that manual. Find yourself a good
trans parts house. The one I use here in Atlanta has a
parts guy that isdamn close to being an encyclopedia of
trans knowledge and builds a few units for their companies
dirt cars and a few others. He always seems to know what
fails and how to fix it.
Thanks for that. I figured that the Torringtons would set up just
like the flat washers, but I would think you have to really make sure
all the slack is taken up when taking thrust readings. I'll just
shoot for what it came out of the vehicle with by using the right
selectives. I've heard that with Torringtons, you should go just a
TAD tight, but not by much.
I'll let you know what happens. I haven't decided whether to go with
a TransGo or Superior kit and just keep adding "stages" until I get
the right shift feel. I've read here and there where a firm band
apply is a must for the AOD mod, as the increased torque will make the
usual C4/C6 "flare" on part-throttle 3-2 even worse, and stock C6s,
unless they had the R option, weren't very good on band apply, anyway.
The big issue here is that the 1-2 and 2-3 points have to be
reprogrammed to prevent redlining, since the bigger ratios will wind
up quicker. No one's got a "kit" for that, so it'll be an engineering
I have a local guy who's getting the gear set for me, and according to
him and a couple of others, the AOD drum is a drop in...same
clearances, dimensions, etc. I do have a Ford and an ATSG manual on
the C6, and I've certainly done more complicated transmissions, the
Dual Coupling HydraMatic being one. The worst nightmare ever was the
Chevy Turboglide...yeeesh, what WERE they thinking??? Fords, I've
done FMs, an FMX, 2 speeders and a few C4s, only a couple of C6s,
nothing newer than that.
The C6 was evidently good enough to stay into production into the '90s
behind International diesels, and for every day small truck use, they
hold up well, if factory or done with a good kit. I think
Torqueflites are a better machine, but...everyone's got an opinion,
you know. Either's better than anything GM cooked up after around '64
or so, the THM400 being the last "good" GM box. Why people like 350s
is beyond me, and it just got worse from there after GM shut down
Detroit Gear Division and let Chevy start making transmissions for the
whole bunch. Cadillacs with Chevette trannies...what a joke!
Thanks again for your input, and I'll get back to the group with the
One more thing you may want to look at. IIRC, there was/is
a large bore servo available for the 2 band which may help
in lockup with a lower pressure. You may have to bore an
orifice to get it to apply quickly enough to prevent flare
along with a little extra pressure to really hold tight.
Another thing that can help lockup is using bands and
clutches from a post 76 trans and filling it with type F
fluid if you can still get it. The friction material is
different. You may have to play with the second accumulator
to help smooth it a bit. I think for an allout performance
build, I would go with the Transgo kit. It seems to be
timed a bit quicker on the shift which may help flare.
Regular heavy duty builds work well with the Superior. I
don't know if he is still in the shop at Transgo but, Gil
Younger was still taking tech calls at Transgo a few years
ago for unusual buildups or problems.
There are a myriad of after market clutch/band options for all C6s
now, but the general direction is to do just what you said, using the
I'm looking into the Type R servo, as I think I'd need the extra area
of that piston to get the pressure I'd need with a higher (numerical)
gear ratio. Most say it's a performance-only mod, but for
truck/hauling/towing, it's also a must on a C6, as 2 band apply is
always on the weak side at part throttle in them. Most CJs came stock
with the R option and the longer band strut, if I remember correctly.
Gil isn't in the shop all the time anymore, but still consults and
handles oddballs. He helped me out on a Chrysler A-904 modification
to add part-throttle TCC release to an earlier case and knew exactly
how to set up the "cheese plate" bores to get exactly the right apply
force. He's even a wiz at old cast iron HydraMatics, even though he
hasn't touched one for decades.
I had the truck version (bigger case, heftier gear sets) in my '62 GMC
P1500...no better truck auto box ever produced until the Allisons came
out in pickups, and even that's debatable. Only problem was that the
tranny weighed in almost as heavy as the 305D V6, making the total
power plant/tranmission package tip the scales at a hefty 1100 lbs! I
had put a Brownie on the back of mine, making it even heavier, but I
had 8 forward speeds (actually 6...some overlapped). With only 145
BHP, I could easily haul a loaded four horse trailer up a stiff grade
at the speed limit while the 4 bbl Chevies were throwing rods and
overheating trying to keep up. The secret there was that 4 5/16" bore
and 2" stroke...unlimited torque.
The crank in the V6 couldn't be turned by any but diesel shops, it was
so large. Helluva engine for pulling, though...as long as you never
went above 3400 RPM! If you did, things would start to come apart
fairly fast. Operated properly, the old V6s (and the V12s, as well as
the Chevy-only 45° V8) would last at least 300-400K miles without much
attention. Big design goof was the pot metal rocker shaft end stands;
if they didn't fit snug, oil would drool onto the end cylinder intake
valve guides and you'd have an oil burner, even with snug guides and
good seals. I used to pack them with Permatex #3 on assembly and
never had a problem.
Back to Fords, the GMC V6 and the Ford FE have one common design
factor that made them great for truck use...the Y block and all that
cast iron. Most Ford FEs in pickups and medium trucks would easily
outlast a small block Chevy in the same usage about 4 to 1. Mine ran
250K before tear down and it was still running well, while a friend
had put that many short blocks into his Chevy in only 175K. Experience
does tell! Biggest problem was throwing rods in the Chevy if used for
heavy towing, even with their overrated "4 bolt mains." I personally
think small block Chevies make great doorstops, not much else. People
like them because parts are cheap and there's a galaxy of aftermarket
performance stuff for them. As far as being a long lived workhouse,
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