C6 Behavior

[Thumperbird]

A couple questions on expected C6 shift behavior:

I have a Broader wide ratio C6 built 1 step short of full manual, say 4 of 5 for shift firmness.
After sorting out torque converter size and stall I am happy with the setup with a minor exception which may or may not be a self-induced problem, looking for feedback from the collective here.

Issue is that at WOT and ~5500 RPM shift point my 1-2 and 2-3 manual shifts are a bit soft, takes a solid 1/2 second to make the transition.  Not saying I feel much slipping but it just seems soft and I have to modulate the gas some times to get it to go.

Under light and moderate acceleration the shift is very firm and crisp/fast.

I had modulator tied to vacuum pump, Jay said that was stupid, don't do that.  Problem is I do not seem to be able to adjust modulator and or the vacuum it sees and ever get a solid thump shift whn under heavy load.

No kick down, Hurst shifter, seems like cable is adjusted correctly.  This is all behavior with manual shifting, I never go hard in drive mode, need to try that sometime though.

Thoughts?

Thanks.
 

[e philpott]

first off the Vacuum Modulator controls Pump pressure , high vacuum equals low pressure from the pump for cruising  , low or no vacuum is the highest pressure from pump for maximum clutch holding power  hence why Jay said it was stupid to drive it with a vacuum pump so you can full throttle the vehicle with the pump giving the lowest pressure possible giving you the best chance of burning up your new transmission from clutch slippage .. A full manual valve body eliminates the Modulator and Govenor all together and just runs full Pump pressure all the time

If I had to guess on your shift problem I would say that the governor is not ready to shift at your 5500 rpm full throttle shift point so its delayed shift , but I have never used a Broader valve body so I don't really know his product or how it's supposed to work . What did Jay tell you to do ?

[Falcon67]

X2 - ask Jay what to do about it. Your shift time should be well inside .4 seconds, .2 more like it with proper pressure.  If the C6 works like the C4, any delay on the 2-3 shift is going to start burning clutches.

[e philpott]

  If the C6 works like the C4, any delay on the 2-3 shift is going to start burning clutches.

not always on the burning clutches , the TCI trans brake VB for example had a delayed shift sometimes from the 2-3 caused by check ball cavity aka Bath Tub being to big which made the check ball sometimes take longer to find the hole in the separator plate , the farmer Frank Merkil (sp?)on 460.com figured it out and I have actually talked to him about on the phone back when I first got a TCI TB VB in the late 90's , I changed so much stuff trying to fix that darned " sometime delay" that 30 seconds into talking to him on the phone I knew he was right about the Bath Tub cavity being too big I just didn't think about or put 2 + 2 together on the check ball not finding the " hole " consistently until he mentioned it , it was a DUH moment for me lol

[fryedaddy]

i dont know much about the C6,but i had one rebuilt in 1986 for my 66 comet and they drilled a few holes in the vb and it has done good for 33 years now.with a 3500 converter it shifts so smooth at cruise you dont even feel it shift,but at wot it shifts very hard and fast.i have been hard on it for many years.i have been waiting on it to tear up so i can change back to a 4 speed like what came in it originally.

[RustyCrankshaft]

Could be a lot of stuff going on here, but start with something simple. Have you driven it with the modulator plugged off (no vacuum?) and does it change the shift behavior?

As was mentioned, you could have VB issues, gov problems, etc. Simple test with no vacuum to see if the modulator is even influencing the shift problem.

[Thumperbird]

Modulator does influence shifts, early to late, downshifts on decel, etc., but have not found a configuration where it will consistently shift fast and snappy on command under heavy load.  Don't get me wrong, it plays very well overall, not bashing Jay's trans in any way just trying to understand normal and expected behavior, or how to dial out the part of th trans where it has a mind of it's own, I slap it and it does not respond instantly.

Jay just told me to hook up vacuum normally, which I have again and had before.  While manifold vacuum may cause a slightly quicker shift it is still not a hard snap and sometimes I need to tweak the gas to get it to go.  I've never really let it wind out in drive to check that behavior, suppose I should.  Daily driving shift points are about where I want them speed wise and firm.   

Maybe I am expecting too much out of a non-manual valve body trans., just not sure.  Should I have to play with throttle at full load up near 5000 RPM's to cause a 2-3 shift?  All of this discussion is around manually shifting from 1-2-3 using console shifter.

Thanks.

[338Raptor]

If you want it to shift automatically you need the downshift linkage connected and the vacuum modulator connected to engine vacuum, not a vacuum pump.
If your 1-2 upshift is firm at low to mid RPM and 3-2 down shifts don’t bind up it sounds like the intermediate band is properly adjusted. This possibly sounds like a valve body issue. But before disassembling anything get the down shift link and the vacuum modulator working properly.

By the way, I’ve had the best luck using a cheap Transgo shift kit. I’ve used it with large capacity drums with excellent results.

[Thumperbird]

Ran with modulator vacuum disconnected.
Automatic up shifts (drive) were higher in RPM, too high really for 2-3, did not adjust modulator.
Light and moderate load 1-2 manual up shift about the same
2-3 manual up shift was much more inconsistent, more throttle modulation required to get it to go.
Not concerned about kick down, disconnected.

I feel like modulator is behaving properly, trans just does not have that .2 second 2-3 shift under heavy load at high rpm, more like .3/.4 seconds after playing with it some more and still throttle tweak needed some times to get it to go.

Overall, like I said it behaves well, maybe I need to lean it out a bit more, rich under hard accel. still.

Thanks.

[cammerfe]

Back in the day, we put a quarter-turn valve in the vac line. With no vacuum, the shifts were both too high and too brutal for comfort when just cruising. When pulling out of Tel-Way to go out for a run-off with money on the line, it was time to shut off the vacuum. At that point the shift point was controlled by the secondary valve in the governor body. (There was a machine set up in the experimental section at T&C Livonia that was all arranged to whittle on secondary valves---to get the weight just right to get the shift point where you wanted it.) The regularly-street-driven TP 427 in Brother Lon's '67 'Mustang liked to up-shift at 6500 RPMs. Take the weight out of the big hollow inside of the valve.

KS

[e philpott]

Which Servo are you using ? What procedure did you use on Band adjustment ?

X2 on the Trans Go Kits

[wayne]

I read Ohio Georges book and he tells about ford guys came to watch him run and ask how do drive it and shift to.Tell us how you want it to shift at and we will set it up for you.They did one for him it shifted at 7500 i think it said he just put it drive and and let it shift its self from then on.The ford boys new how to make them do what you wanted