C6 Gremlins

[mlcraven]

Continuing the earlier theme of C6 posts, seeking input on a couple of issues (possibly related) that I'm having.

Full disclosure: the transmission wasn't rebuilt when it was out of the car -- it worked before it came out and, when I dropped the pan there was minimal crud evident and the fluid looked and smelled OK.  On that basis I performed an exterior cleaning, installed a deeper pan and new filter, filled it with new fluid and elected to put it back in the car with the stock convertor.

The issue(s):
1 - won't downshift (as in go into "passing gear") under aggressive throttle application.  This issue came to light after my first interstate excursion but wasn't particularly concerning, insomuch as the car has great acceleration from highway cruising speed (2200 rpm and up) and was in any case attributed to a linkage adjustment issue.  I've had a number of goes at getting the linkage sorted but still nothing, so I'm assuming the problem must be something else.

2 - when driven 'enthusiastically' exhibits slippage on the 2-3 upshift.  Under normal conditions (i.e., mild throttle application) it's virtually undetectable; but becomes more pronounced with more aggressive throttle application.  It never fails to make the shift, but the rpm jumps 200-400 revs (again, depending on throttle condition) when the slippage occurs.

I am a newb when it comes to transmissions, but based on reading the shop manual and internet surfing am wondering if these faults are possibly the result of low line pressure and/or vacuum modulator issues?           

[Drew Pojedinec]

Are you running type F?

1. adjust kickdown, I prefer the lokar cable as it's pretty easy and fast to adjust and it works well with any headers.

2. Adjust the band


If you have an adjustable modulator try firming up the shifts too.  Worst case, rebuilds aren't THAT expensive, and you'll know a thing or two about automatic transmissions before you are done.

[mlcraven]

Yes, Type F.  I should have been more clear, it's the kick-down linkage that I've been playing around with, so far without any positive result. I'd really hoped that my days of crawling around on the garage floor underneath a car up on jackstands were over, but apparently not yet.

[machoneman]

Drew's got the 'right stuff' for you to look at.

If you haven't done so, have a pal mat the gas pedal inside the car while you inspect the action of the tranny downshift linkage (KD, kickdown) from underneath after the band adjustment. Sometimes even a hair's is more travel on old KD linkage will get same to downshift. Check too that when the gas pedal is matted, the carpeting under the pedal allows full gas pedal travel both under the dash and inside the carb (at WOT, throttle blades straight up and down) as that also can affect the tranny's kickdown.

Also, it might pay to get new linkage as the KD rod one on the tranny now may be bent....it's been known to happen.  Can't often tell unless a new link is set side-by-side with the old one. JMO! 

If you really want a do it yourself approach, a tranny gauge is pretty cheap. Just be sure to have the Ford manual data handy (forget what the test PSI's should be for a C-6) to do a diagnostic:

http://www.ebay.com/bhp/transmission-pressure-gauge

[Drew Pojedinec]

Where do you live Micheal?  You might not be willing to pull the trans and rebuild it, but I'd be happy to help if you are in Southern Georgia.
I'm offshore till Thursday and home for a month.

[mlcraven]

Thanks for the input Bob.  I'm kind of obsessively fixed on getting the factory set-up to work, but based on feedback received here have done some investigation of the Lokar C6 kickdown cable product, including a call to their tech line (very helpful gentleman patiently answered my several questions). 

I do have some suspicions about accelerator pedal linkage interference, namely, carpet and sound deadener, so am taking your advice to have someone sit inside while I check out the linkage action from below. l already did this earlier to ensure the carb went to WOT (it didn't and adjustments had to be made to that linkage) but at the time didn't think about the kickdown linkage.  Thankfully, my assistant is both enthusiastic and local. 

The 67 Cougar-Fairlane-Falcon-Merc Intermediate Shop Manual has a write-up (page 7-66, Fig 14 Throttle Linkage Comet & Fairlane with 390 CID Engine) on how to set everything up; it includes the downshift linkage.  Must confess, my male proclivity to ignore all written instruction is looking like a contributing factor to this predicament: it seems the accelerator pedal height, carb linkage and downshift linkage are all cleverly related and have to be attended to in a particular order and fashion (as compared to my "eyeball it-fiddle with it-drive it" technique).  and, as you have suggested, I have my suspicion that the kickdown linkage components aren't in complete conformance with their 'as delivered' shape.

If one final adjustment effort, this time following the advice received here and the factory guidance, doesn't solve things I'll go the Lokar route.  Sometimes repair by replacement is the least frustrating option, especially for that significant percentage of amateur gearheads addicted to shiny new parts (guilty as charged).

Drew's got the 'right stuff' for you to look at.

If you haven't done so, have a pal mat the gas pedal inside the car while you inspect the action of the tranny downshift linkage (KD, kickdown) from underneath after the band adjustment. Sometimes even a hair's is more travel on old KD linkage will get same to downshift. Check too that when the gas pedal is matted, the carpeting under the pedal allows full gas pedal travel both under the dash and inside the carb (at WOT, throttle blades straight up and down) as that also can affect the tranny's kickdown.

Also, it might pay to get new linkage as the KD rod one on the tranny now may be bent....it's been known to happen.  Can't often tell unless a new link is set side-by-side with the old one. JMO! 

If you really want a do it yourself approach, a tranny gauge is pretty cheap. Just be sure to have the Ford manual data handy (forget what the test PSI's should be for a C-6) to do a diagnostic:

http://www.ebay.com/bhp/transmission-pressure-gauge

[mlcraven]

Drew: many thanks for the kind offer. I'm in Hampton Roads, SE corner of Virginia, very near Norfolk airport.  Bit of a haul to/from southern Georgia.  Based on the input received from you and Bob I have an action plan for the kickdown issue, which I've set as the first priority.  I'm planning to go to the East Coast Drag Times show in Henderson NC in mid-Oct and don't think the 2-3 upshift slippage will prevent that; as indicated before, it only becomes significant when the tom-foolery factor is present.

But if you're agreeable, I would v much appreciate the opportunity to put more questions to you as I move to sort matters out over the next few months.

Where do you live Micheal?  You might not be willing to pull the trans and rebuild it, but I'd be happy to help if you are in Southern Georgia.
I'm offshore till Thursday and home for a month.

[Drew Pojedinec]

sure man.  I'm certainly not an expert, just happened to tear a few of these apart in recent history.
Yeah, I know where Hampton roads is.... my company has a shipyard in Portsmith and I think I've driven around your area.
Dunno man, sounds like a fun road trip :-)   I only work 6 months a year anyhow

Remember from 2nd to third, to the best of my understanding, the band stops one drum and hydraulics engages the other.  Timing is key, if the band releases too early it feels like the engine freewheels for half a second before third slams into gear.  Of course this late timing is better than third engaging before the band hasn't released yet, that'd suck, something would break or the band would wear out.

I suspect a lot of band failures are caused by this.  I find the factory manual is handy for setting initial band adjustment, but after a rebuild and/or shift kit, I really need to go for a drive and adjust as needed, i suspect a shift kit changes the timing slightly.

[e philpott]

how are you adjusting the Kick down ?? ...... the carb should be full throttle , the adjustment screw should be adjusted so that the kickdown is withen .050 from being bottomed out .... is that how your doing it ??

[mlcraven]

I'd like to say that's how I thought I was doing it, but in truth suspect it is not actuating to within the .050 spec you mention.  I'm hoping to get at it in the first half of next week.  What with non-negotiable commitments Thurs/Fri night, the MIR Budds Creek 'Legends' event Sat, and a work social function on Sun afternoon, there's no room in the calendar until after this weekend.

how are you adjusting the Kick down ?? ...... the carb should be full throttle , the adjustment screw should be adjusted so that the kickdown is withen .050 from being bottomed out .... is that how your doing it ??

[e philpott]

.050 is a starting point , you can go tighter for earlier down shifts or looser for later down shifts ..... you could go .010 but it will probably down shift to much every time you tip in the throttle ..... but it's easy adjustment to play with , also make sure the carb opens all the way while your partner is holding the throttle open (engine off )  , sometimes they need tweaked a bit too