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Jim,this is getting stranger by the day.I feel it is a v.b prob.Have you got the transgo instructions just to doublecheck all the springs and checkballs are in place correctly.I can send if you havent for the 67-69 v.b.
I don't doubt everything isn't correct but something strange is going on.
For the trans to lock up it must be engaging something when it shouldn't.
Reverse uses low/band+hi/rev so if the trans is locking it must be the fwd clutch or band coming on somehow.
I have spent a bit of time going through the oil circuits and 2-3 backout valve has oil going through it for the shift to 2nd .There is also oil to the top of that valve in reverse and if it was say stuck down or the spring on the wrong side it would bleed oil the apply the fr band in rev.
It also has throttle pressure acting on it so may affect where the valve sits at different times.
Also for 2nd gear to apply this 2-3 b/o valve has to be in the correct position or oil wont get to apply the band.
I know the trans works ok sometimes but i am basing my diagnosis on the 2nd shift delay and the lockup in rev.
That's my thought so far but i'll keep thinking on it.
Please keep us posted on your progress..
 
Also ,on the pressure gauge,they sometimes do flicker around at idle but if you bring the revs up a little they usually smooth out.
I think the flickering is caused by the uneven vacuum from a modified cam acting on the modulator.
 
Discussion starter · #23 ·
Greg,
Thanks for the response. I replaced the valvebody with a 'new'one out of the '68 trans I got last week. Took the car around the block and all gears work and no lock-up. I'll find out about the 2nd gear problem Sunday if it the races don't get rained out.
 
Discussion starter · #24 ·
I give up.Went to the track today and thought I fixed the no second gear under power problem by replacing the valve body,intermediate servo and adjusting the front band and air checking it. If driven fast but not racing and in the burnout box it shifts really firm 1-2-3.Leave in first and shift to second and nothing.Instead of going home I raced it by starting out in second and shifting to third. It slips and grabs most of the way down the track until shifted to third. Now it acts like it slips in all forward speeds but I managed to go 3 rounds in my bracket but lost by braking out by .250. I'm going to go thru the new trans and put it in.Gotta pull the motor to get the trans out from the top. I just can't figure out what is wrong.
 
Hey Jim. B4 you pull, why don't you hook a vacuum gauge up remotely and go for a cruise with a buddy. Get him to watch the gauge and write down everything for readings ie:under full throttle, at 1000 rpm increments etc. it sounds more like a problem I had a few years ago and it came down to installing a Crane vacuum assist system. I think you said earlier that you have checked all the seals, did that include the piston seals in the intermediate clutch? You are getting your pressure reading right at the test port. Have you taken vacuum readings lately? Check them out at idle in park and at idle in gear. If the readings in N are 12lbs or lower and 9 lbs or lower in gear, you will probably want to get a vacuum chamber.


_________________

There is NO substitution for Cubes
1954 Mercury Pick-up Blown 525 BBF, Morrison pro street/ pro-gas frame,2 1/2" chop but still in pieces

<font size=-1>[ This Message was edited by: Blown54 on 3/18/02 2:43pm ]</font>
 
Discussion starter · #26 ·
Blown54,Thanks for your suggestion. All the seals and clutches are fresh in the trans,but the problem was there,although not as bad,before I freshened it up.It shifts fine while under slow and moderate speeds,which indicates it's not a vacuum problem. Under full throttle conditions there isn't enough vacuum going to the modulator to move the diaphragm which assists controlling line pressure.I've spent too many mornings getting up way too early to get to the track and race the car thinking the latest repair fixed the problem and finding out it didn't. The trans is history as far as I'm concerened.Better to start off fresh with a whole new C4.It would be nice to figure out what actually caused this weird problem though..
 
Anytime Jim. Another thing you may want to watch, in the way of pressures, is if you have a full manual valvebody with a reverse pattern, the pressure for ALL gears should be a steady 140-160 lbs.The thing I'm shooting at is making sure it is the tranny as you say you are gettign another, just don't want to see you grow any grey hair!
 
Discussion starter · #28 ·
Blown 54,what do you mean growing grey hair? It should be growing MORE gray hair.Hah.

I pulled the car off the trailer yesterday and it went in reverse fine,but it slipped so bad in any forward gear that I barely got it into the garage. Must have fried the direct clutch at the races with those 2nd gear starts. I pulled the motor to get to the trans and also got the trans out,which comes out the top not the bottom as a normal car. The fluid is smelly and dark maroon color not red.I'll pull it apart soon but want to build up the new trans first.The saga continues.
 
Discussion starter · #29 ·
I pulled the trans out and tore it down. 4 of the forward clutch frictions had all of the lining burned off and the 5th one had very little lining. The reverse/high frictions looked OK but showed signs of slipping. The intermediate band was burnt/fried and glazed up.All of the seals looked good as did the internals of the pump.I guess I'll never know what caused the problem.
I went thru my "new"1968 C4 with Red Eagle frictions/Kolene steels, new bands,thrust washers/bushings as required,seals,gaskets and an "H" servo.I set both clutches with .025-.030 clearance and the input shaft free play to .020. It should be all back together and running in a few weeks.I sure hope the new trans works better than the old one.I'm not too fond of the "pink shirt syndrome" from all the trans fluid.
 
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