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Discussion Starter #1
With all the excellent info available on this Forum on building a C4 maybe someone can help me out.My Morris early ('67)C4 has a false "neutral" on the 1-2 shift while racing. I leave in 1st and shift to 2nd @6000RPM and it goes into this false neutral and the motor revs to the moon because of no rev limiter.When I let off the gas and it slows down,2nd gear comes back and I can manually shift to high.It shifts manually 1-2-3 in the burnout box and when driving slow. In drive when driven slow it shifts 1-2-3. I tried leaving it in Drive at the track and it took off good in 1st and then instead of shifting to 2nd it hit this false neutral again so I let off and it went into 2nd and then 3rd.Instead of calling it a day I tried racing it by starting in 2nd and it acts like it starts in 2nd,momentarily goes into first,back to second and then can be manually shifted into third.The trans has a Transgo shift kit and H servo.I have put in a new shift cable and cleaned the manual valve in the valve body along with a new detent plunger and spring.Nothing seems to fix it.The problem has progressively gotten worse over the last few times out at the track.Sorry for the long post,but I 'm trying to give enough info for someone to help me out. Thanks.
 

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Discussion Starter #2
Can't anyone help me out here?
89coupe(Kent),Gregaust,Mario428,R code,Windsoreight and other C4 build experts where are you?

Since I posted this yesterday I have taken out the valve body and cleaned everything in it and found no problem. Since the intermediate band is only applied in 2nd gear I'm thinking it is related to that circut somewhere. I applied air to the servo port and the front band applies and releases just fine. Can't one of you guys give me some input on this?
 

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I wonder if your immediate band is bad/burnt or your forward drum is glazed or your immediate servo has bad o-rings or you don't have enough line pressure.

Might be a few other things also, such as pump sealing rings, worn pump, other seals or o-rings leaking off the pressure, etc. Not sure how new the parts are in your tanny.
 

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What are the specs on your trans. Does it have the stock valve body or a shift kit. It sounds like a loss of pressure. If the servo is air checking fine that leaves pressures. Have you looked at the valve body for wear or stuck valves. How is the bore in the case were the servo pin rides. I have seen the servo's hang up. Was there any debris in the bottom of the pan? What does the pump look like? How does the rest of the trans look(clutches, bands, etc)?

<font size=-1>[ This Message was edited by: windsoreight on 3/5/02 9:35am ]</font>
 

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Is your shifter linkage adjusted right? It sounds like its shifting half way between the detents on the 1-2 shift. Are all your mounts good or do you have the motor chained down? The motor and tranny torquing over real hard may mess with the linkage on the shift and cause it to not hit the detent just perfect.

Ok, I went back and read your post again. Make sure your downshift linkage is adjusted and hooked up right(is it pushing on the shift linkage for example?) if you still have that on there and make sure your modulator is good and the vacuum line is hooked up right too.



<font size=-1>[ This Message was edited by: Hottarod on 3/5/02 11:14am ]</font>
 

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Discussion Starter #6
Thanks for the responses.

I just went thru the trans in December. It missed the 1-2 shift on occasion before I went thru it. I assumed it was the linkage and readjusted it when I put the trans back in. I went thru it with all new seals,5 clutches in both clutch packs and a new "h" servo. It worked good the first time out at the track and has been acting up ever since.Everything checks good and there wasn't anything strange in the pan.It works OK when driven slow and also when manually shifted in the burnout box so I'm stumped.I'll try to check the line pressure but will have to get a gauge as I don't have one.
 

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Sounds like the seals in the servo are damaged or bad. Could be a bad band not grabbing the drum hard enough at full throttle and unable to grasp the drum. When you put the new clutches and "H" servo in, did you replace the seals in the servo and make sure the oil passages to the servo are clear. This is a strange problem I have not had. Usually the flareup on the 2-3 shift from band releasing before the hi clutches engage but never a 1-2 shift problem. The easiest thing to do first is to put a known good valve body(even stock will work but won't shift as hard from 1st to 2nd but it shouldn't flare up between shifts either) in it to narrow it down to rule out the possibility of it being the valve body. That way the trans doesn't have to come out in case it is the valve body. If another valvebody does the same thing, then remove the servo and see if the seals are damaged or broken. If seal are good, then the trans must come out. It sounds like it could be a valve partially sticking not letting full pressure or volume to the servo to "grab" the drum for 2nd. Like I said, it is a strange occurance for 1-2 shift to do that. Band could be burned up or glazed. There are many possible causes but one thing is known, you must let off the throttle to let the band finally grab hold of the drum and then it holds good enough till the 2-3 shift. Maybe somebody else here has had the same problem you have and can give better insite.
Good luck Jim.
 

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Jim,i've been holding out on this one as it is a bit strange.I was hoping someone else might have an answer.I don't really have an answer but something to think about.
Now if a c4 has a band prob or a broken band the trans will skip straight from 1st to 3rd.Is it possible that the servo is catching slightly on apply and confusing the valvebody between second or third.
Something else to look at but it may not apply to your v.b.
A while ago i rebuilt an early c4 from a 66 mustang that had the green dot v.b.I cleaned out the v.b and put it all back together the way i found it with the rubber checkball.3 years later it lost second gear.What i found is the rubber ball had worn enough to jam itself in the seperator plate and block the oil feed for 2nd.I was lucky the ball was stuck in the plate and it was easy to find.When i looked in the factory manual it doesn't show any checkballs so i left it out and all is going well.
This might not help directly but check the passages and checkballs in case one is blocking the oil somewhere.
 

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I have had problems like this, I do not like to discuss it because it ended up being so stupid.
I bulit this monster deep(4 inches)pan for my C-4. I welded an extension onto a stock pan and the pickup goes thru a hole in the old pan. The pickup was a pices of tubing I welded to a filter.
Anyway on a Friday I freshened the tranny and went racing sat. Tranny acted the same way but in both 2nd & high but mostly in 2nd.
Loaded up and went home, pulled the tranny, disassembled and found nothing. Tore the valve body down to castings, still nothing. Getting late so started to reassemble. When putting the pan on a guy remarked about how far I had the bottom of the pan pushed in. Turns out the pan was against the pickup. Cut some slots in the pickup and have had no trouble since.
In short form check to see that your filter is clean and can get sufficient fluid.
 

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Discussion Starter #12
Hey guys,thanks for the responses. qrtmiler,I'm sorry,didn't mean to leave you out.
I called around to junk yards today and found the going price for a C4 'core' is about $50-$75. I'm going to pick one up and rob the valve body out of it and put a shift kit in it and put it in the Morris to see if that's the problem.I also will go thru the new trans and build it up as a spare as both my cars use the same trans.I think if you ask for a good usable trans at the yards they charge you $175-$200 and say it's good,but if you ask for a core to rebuild they sell ya the exact same trans for $50 but don't guaranty it will work.The '70 and up trans is easier to find,but since I have good converters which won't work on the later 26 spline models I'm going with a '67-'69. The problem trans has all new seals,filter,front band,clutches,etc. for those who asked.It's not much fun getting up before the cows come home to drive out to the races and then have the trans act up. Hope I can fix it soon.
 

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Jim, hang in there pal, c4's are great transmissions, and this "setback" will be a learning experience for you, one way or another. I would be willing to bet you either have a valvebody problem or something similar. I still remember my first dealings with the c4's...needless to say, I got really good at pulling a c4 from a maverick, so good that I could pull it at the track, put forward clutches in it, and have it reinstalled in time for the next round! I finally broke down and bought an aftermarket valvebody, and it fixed the problem. I dont think your problem lies in the servos, because like someone else said, it would skip right through 2nd gear altogether. You probably have a sticking or leaking valve inside the vb itself.
 

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Discussion Starter #14
I haven't found any obvious problems inside the trans. I cleaned all the moving valves /parts in the valvebody and made sure it was super clean and all the valves moved smoothly.I also took the intermediate 'H' servo out and put an 'A' servo in with new correct fitting seals.The shift problem wasn't as bad with the 'A' servo.The band was adjusted to 1 1/2 turns out and checked with air pressure at about 35PSI and it applies and releases fine.I reassembled it all and fired up the car on the trailer and all the gears work.I haven't driven the car however as the problem only shows up at the track and a Morris Minor flying thru the neighborhood would bring out those guys who investigate UFO sightings.I borrowed a flex hose and 0-300psi gauge from work and hooked it up to the trans. I can't get a steady reading as the needle bounces all over the place.In reverse with the brake on at about 1500 RPM it reads 175-225 psi but bounces around so much it's hard to tell.Is the pressure supposed to fluxuate that bad or is there a malfunctioning relief valve or something? The gauge has a calibration sticker on it good until 2003 so I doubt it's the gauge. Any input from the C4 gurus would be welcome.
 

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The needles sometimes jump around like that. Don't worry about it. Your line pressure sounds ok. What was it at idle?

Range Minimum Maximum
Park 55-75 220-250
Reverse 150-175 235-280
Neutral 55-75 220-250
Drive 55-75 155-170
Second 90-105 110-125
Low 90-105 110-125


<font size=-1>[ This Message was edited by: windsoreight on 3/12/02 9:37am ]</font>
 

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Discussion Starter #16
So the gauge bouncing is normal then?The pressure was within the limits you listed which are similar to the manual I'm using.I checked it at idle with and without vacuum to the modulator and at about 1500 with and without vacuum.The car doesn't have a parking brake and only was kept from moving by some wedges under the tires and the trailer tie down straps so I was afraid to rev it up too much.Nothing like trying to explain how ya got run over while looking at a trans pressure gauge mounted so ya can't see it from in the car.I guess next time I shouldn't be such a loner and get someone to sit in the car and hold the brakes on.
 

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I cannot agree on the pressure gauge jumpimg around being an ok thing. I had a tranny pressure gauge permanently mounted in my car for a while and it did not do that. It will flicker but not 50 psi as you describe.
I have my pressure relief shimmed for 200 PSI at any rpm over 1500 and it is very steady at the 200. Slight boost in reverse but I did basically disable the reverse boost. Run the car in neutral at a good rpm where pressure maxes out. Run for a while to see if reading stabilizes. C-4's are notorious for dirt screwing up the valve body so you may have a problem with the relief. Since a relief valve is a controlled leak the spool can be looser in its bore than other valves and still work fine. You may have to pull valve body again to make sure it is free.
I did ramble a bit here but i hope it helps, good luck.
 

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Mario,what spring do you use for the pressure reg valve and how thick of a shim or shims roughly for 200psi?.Do you add the shims on the dished washer on the valve?
thanks..
 

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Greg I do not have my reference material here with me but. I put a spacer on the shaft of the relief and off the top of my head it was a 1/16 thick o-ring. I also put another o-ring of the same thickness in the reverse boost valve that is on the end of the pressure regulator.
I also used the stiffest springs I had found out of stock valve bodies. Do not remember colors.
I installed a 3 stage B&M kit in my brothers tranny with my manual valve body mods and there was stiffer springs in it for the strip mode. I have the lengths and spring rates but never got a chance to measure pressure on that tranny. If I could measure pressure I would know what spring rate is required for what line pressure.
Not much help here I am afraid.
 

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Discussion Starter #20
<font size=-1>[ This Message was edited by: Just Jim on 3/16/02 6:18am ]</font>
 
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