Author Topic: C6 Problems--Advice Needed  (Read 2479 times)

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cjshaker

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Re: C6 Problems--Advice Needed
« Reply #30 on: September 27, 2020, 01:58:11 PM »
Those symptoms sound like seal or valvebody issues. It used to be common to experience the same issues on old C6 transmissions where the seals were getting hard and losing their sealing ability. One of the old "tricks" used to be to put about half a teaspoon of dishwashing liquid in, which would soften the seals a bit and get it to work better. It actually worked for me once, in an old 460 Mercury stationwagon. It only lasted about a year though before they just stopped working altogether. By that time, the clutches were pretty much toasted from slipping. Not saying that's the issue, but I'm sure there are a lot of guys here who have experienced it, back in the day.
Doug Smith


'69 R-code Mach 1, '65 427 MR, 2x4, 4-spd, 4.30 Locker
2 1965 Galaxies with 390s
1970 F-350 390
1958 Ford Ranch Wagon 390

RJP

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Re: C6 Problems--Advice Needed
« Reply #31 on: September 27, 2020, 02:10:04 PM »
If you do a complete rebuild I would check to confirm the forward and hi/rev clutch packs have an adequate amount of clutches, those would be the frictions, not the steels. Hi/rev should have 4 for a mildly built 390 and there should be 5 clutches in the forward. If clutches need to be added it is not a big deal if you have access to a shop with a lathe. The thick backing plate in each clutch assembly can be machined to add an extra friction and steel. Some people get away with regrooving the drum but that can lead to problems if the old groove interferes with a steel plate. It can hang up causing the clutch pack to drag or if it aligns up with the groove the steel will be useless, it will float. I've always done the backing plate machining. If you have access to a hard parts vendor you can use the beveled pressure plate that is found in the forward clutch that acts directly against the Belville spring. It is important to add here that setting your clutch clearances to spec. is very critical. I use the ".008" to .010" per friction clutch" rule. That has always served me well. I recently finished building a C6 for my 66 Galaxie 428. I started with a core that was from a low hp/tq. 352 or 390 2V. It had a 4 clutch forward and a 3 clutch hi/rev. I upgraded to a 5 clutch forward [machined backing plate method] and I had a couple extra 4 clutch hi/rev drums from some other cores I had. If you want to overkill this you can still buy a 5 clutch hi/rev drum new. It was OEM in a 428 CJ/SCJ and some Lincolns. I think it is still available from Ford or it is available thru some of the A/T parts vendors.     

shady

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Re: C6 Problems--Advice Needed
« Reply #32 on: September 27, 2020, 03:44:15 PM »
you might want to make sure that the filter didn't fall to the bottom of the pan.
What goes fast doesn't go fast long'
What goes fast takes your money with it.
So I'm slow & broke, what went wrong?

Diogenes

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Re: C6 Problems--Advice Needed
« Reply #33 on: September 30, 2020, 10:44:31 PM »
I plumbed an old Stewart Warner gauge into the cooler line, which indicated around 60-62lbs at idle. I can't speak to the accuracy of the gauge, but clearly there is ample pressure.

What does this possibly point to? Previous posts state a converter or broken input shaft--is this all that it could be?

Again, thank you for all the feedback.
« Last Edit: September 30, 2020, 10:49:42 PM by Diogenes »
1966 Galaxie 500 390 C6 Traction-Lock 9in.
1985 Toyota Celica Supra
71 Montego MX wagon 351C Toploader Detroit Locker Cyclone competition gauge/dash bucket seats/console
89 Texas DPS Police Mustang
71 Torino GT 351C 4V AT
68 Cougar 351W Toploader Traction-Lock 8in.
89 Dodge Omni modified 2.5 turbo from hell

manofmerc

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Re: C6 Problems--Advice Needed
« Reply #34 on: October 01, 2020, 02:44:23 AM »
Is that in park ? I believe for a stock valve body 90 psi is normal .A valve body with a shift kit would be more than 90 .probably in the 120 range or higher .You can use your gauge and check the pressures in low second drive and reverse to isolate each gear and find if either one is leaking .To me 60 is low .I recently rebuilt a c-6 that had 50 psi in park the clutches were fried in it .Check your pressures in the different gears and get back to us .Good luck Doug!

Diogenes

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Re: C6 Problems--Advice Needed
« Reply #35 on: October 01, 2020, 02:57:12 AM »
Yes, it was in park, low idle. I only have an old engine oil pressure gauge up to 80lbs to check.

RJP posted this response a while back "At low idle there should be 60-65 lbs pressure."
1966 Galaxie 500 390 C6 Traction-Lock 9in.
1985 Toyota Celica Supra
71 Montego MX wagon 351C Toploader Detroit Locker Cyclone competition gauge/dash bucket seats/console
89 Texas DPS Police Mustang
71 Torino GT 351C 4V AT
68 Cougar 351W Toploader Traction-Lock 8in.
89 Dodge Omni modified 2.5 turbo from hell

RJP

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Re: C6 Problems--Advice Needed
« Reply #36 on: October 01, 2020, 12:08:44 PM »
Pressures should be checked using engine vacuum as your guideline. I'm not going to post the entire chart as it is quite comprehensive. At idle in drive, low, 2nd with 17" or more of vacuum @ 29.5 barometric pressure] there should be 51-66lbs of control pressure and 72-108lbs in reverse only. Next pressure check is done at 15" vacuum @29.5 BA/HG, press. should be 70-78lbs. and so on. All the way down to below 1.0" vacuum where press. should be 157-172 lbs [drive, 2nd and low gear] reverse should have 230-252lbs of pressure. This is specification for a STOCK built C6, not with a shift kit or any other valve body modifications. If you have the pressure you have found I'd be looking into the input shaft, broken, stripped splines or any other mayhem in the input shaft, forward clutch splines, etc. Not having reverse tells me the forward clutch could still be functioning, maybe not 100% right but when only the forward clutch fails the trans will still have reverse as rev is the only "in gear" position that does not engage the forward clutch, hence the name "forward". Most of the forward clutch failures I've dealt with are broken or hard seals that won't hold pressure. When that happens the forward clutches go south very quickly as they are slipping.  My comment regarding "At low idle there should be 60-65lbs press." was a guesstimate that should have merely proven the front pump was still working. IMO, You should pull the trans and with the converter removed grab hold of the input shaft and pull it out as there is nothing holding it in such as a snap ring, etc. Let us know what you find.

Diogenes

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Re: C6 Problems--Advice Needed
« Reply #37 on: October 02, 2020, 11:19:49 PM »
"If you have the pressure you have found I'd be looking into the input shaft, broken, stripped splines or any other mayhem in the input shaft, forward clutch splines, etc."

Would any of these possible failures in the transmission cause the vibration I experienced?

I drained the pan in preparation to pull the trans. The magnetic drain plug had, what I assume, some black metallic "paste" on it, but there weren't any large metallic pieces on the plug or in the fluid. I won't pull the pan until I get it out of the car.
1966 Galaxie 500 390 C6 Traction-Lock 9in.
1985 Toyota Celica Supra
71 Montego MX wagon 351C Toploader Detroit Locker Cyclone competition gauge/dash bucket seats/console
89 Texas DPS Police Mustang
71 Torino GT 351C 4V AT
68 Cougar 351W Toploader Traction-Lock 8in.
89 Dodge Omni modified 2.5 turbo from hell

RJP

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Re: C6 Problems--Advice Needed
« Reply #38 on: October 03, 2020, 12:16:17 PM »
It is very hard if not impossible to diagnose problems such as this on line with any accuracy. At the point you are at now your only option is to pull the trans and tear it down. Since you have the pan off remove the valve body [8 bolts] and look for any obvious damage, likely there will be nothing visible short of a broken sun shell or a hi/rev drum that has come apart also look for the drive lugs on the hi/rev that engage the sunshell, there could be damage there too. Beyond that it is time look further and to pull the front pump as little more is visible at this point. Remove the pump bolts and with the trans up-side-down take a long screwdriver or small pry bar and wedge in between the forward planetary gear set and the sun shell, pry forward and the ft. pump should pop out. It may require a bit of force if the trans has been together for a long time. Now you will be able to remove the hi/rev drum, band and forward drum. As I said in a previous post when the converter is removed the input shaft end is now visible, inspect splines and look for debris on the ends. Now just grab it and pull straight out. If there is damage to the input either stripped, broken or whatever. If nothing found it is time to tear down your sub assemblies, the forward and the hi/rev. With the problems you are experiencing I think it is rather moot to attempt an air pressure test but if you want to it should be done before the front pump is loose. A good shop manual will have instructions for a air pressure test. I usually reserve that test for when the trans is being assembled and the 3 clutch assemblies, band servo and governor are air tested to confirm they hold pressure and are functioning.    Post your findings and we can go from there.

fryedaddy

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Re: C6 Problems--Advice Needed
« Reply #39 on: October 03, 2020, 12:29:47 PM »
time to pull her out,if you want to find out whats wrong,and fix it.

67xr7cat

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Re: C6 Problems--Advice Needed
« Reply #40 on: October 03, 2020, 06:39:00 PM »
"If you have the pressure you have found I'd be looking into the input shaft, broken, stripped splines or any other mayhem in the input shaft, forward clutch splines, etc."

Would any of these possible failures in the transmission cause the vibration I experienced?

I drained the pan in preparation to pull the trans. The magnetic drain plug had, what I assume, some black metallic "paste" on it, but there weren't any large metallic pieces on the plug or in the fluid. I won't pull the pan until I get it out of the car.

How did the fluid look?

Diogenes

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Re: C6 Problems--Advice Needed
« Reply #41 on: October 04, 2020, 03:35:35 AM »
It looks dark red. After draining the drip pan, it had what was obviously some friction material at the bottom of the drain pan. I dragged an old hard drive permanent magnet on a wire through the drain pan and picked up some black "dust", but nothing more. Fluid isn't burnt smelling but dark. I've gotta drop the pipes before I can drop the trans, still have some work to do. I hope to have it on the floor by Monday night--schedule permitting.

« Last Edit: October 05, 2020, 06:59:26 PM by Diogenes »
1966 Galaxie 500 390 C6 Traction-Lock 9in.
1985 Toyota Celica Supra
71 Montego MX wagon 351C Toploader Detroit Locker Cyclone competition gauge/dash bucket seats/console
89 Texas DPS Police Mustang
71 Torino GT 351C 4V AT
68 Cougar 351W Toploader Traction-Lock 8in.
89 Dodge Omni modified 2.5 turbo from hell

Diogenes

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Re: C6 Problems--Advice Needed
« Reply #42 on: October 05, 2020, 07:16:19 PM »
I've got the trans out--the input shaft looks good. I likely won't be able to work on disassembly for about a week.

Any suggestions on what kit to purchase/who to purchase from? I've yet to find a stock converter for $140-160. I don't believe this is a stock converter, but the stack of receipts that came with the car doesn't have a receipt, just paperwork from the manufacturer. Would a stock converter be fine with the below specs?

CR 9.75:1
Bullet cam 230/230 dur@050 524 lift @050
3.25 or 3.50 gear (not certain, but believe its 3.25, I'll have to count)
66 Galaxie

UPDATE: I identified the torque converter, a JW Performance Street Lethal 60442-LP, says stall speed is 2400-2700. Seems unnecessary??
« Last Edit: October 05, 2020, 10:02:41 PM by Diogenes »
1966 Galaxie 500 390 C6 Traction-Lock 9in.
1985 Toyota Celica Supra
71 Montego MX wagon 351C Toploader Detroit Locker Cyclone competition gauge/dash bucket seats/console
89 Texas DPS Police Mustang
71 Torino GT 351C 4V AT
68 Cougar 351W Toploader Traction-Lock 8in.
89 Dodge Omni modified 2.5 turbo from hell

Lowrider

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Re: C6 Problems--Advice Needed
« Reply #43 on: October 07, 2020, 08:34:09 AM »
Suggestion. If you haven't done it, turn the input shaft and see if it feels like it's turning the planetary in the trans. Next pull the input shaft out and stick it in the coverter and see if its turning and not stripped. Myself, I like to know what happened to it when something goes south on me.

RJP

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Re: C6 Problems--Advice Needed
« Reply #44 on: October 07, 2020, 10:54:48 AM »
Suggestion. If you haven't done it, turn the input shaft and see if it feels like it's turning the planetary in the trans. Next pull the input shaft out and stick it in the coverter and see if its turning and not stripped. Myself, I like to know what happened to it when something goes south on me.
X 2... As Lowrider suggested use the input shaft to see if converter and forward clutch hub turn smoothly. You may not be able to see if the planetary turns as the input shaft engages the forward drum hub only and motion may not be transferred to the assembly behind the forward clutch. Also turn the output shaft, it should turn rather easy in forward [drive] rotation but it will be much harder to turn in reverse. It is for that reason there is much more line pressure needed for reverse.