Ford Muscle Cars Tech Forum banner

1 - 12 of 12 Posts

·
Registered
Joined
·
862 Posts
Discussion Starter · #1 ·
OK So i rebuilt a 1975 C4 stock trans, (first time) for my '69 302 stang. Checked and double checked clearances, assembly everything..Put trans back in. I can move the car in reverse, 1st and 2nd from a standing stop. I can shift from 1 to 2 no problem while moving. If I try to move the car in Drive from a stopped position, the car shakes like hell. If I shift from 2 to Drive while moving, the trans slips out of gear, unless I speed up, then it will catch. Seems to have enough oil (type F). Any ideas?

<font size=-1>[ This Message was edited by: fnracing on 5/22/02 8:52am ]</font>
 

·
Registered
Joined
·
862 Posts
Discussion Starter · #4 ·
Both tightened to 10 lbs. Then low-reverse band backed off 3 turns, and intermediate band backed off 1 3/4 turns. UPDATE: Took it out for 2 hour ride on highway. When under load (uphill) runs ok, once load reduces, slips out of gear........

<font size=-1>[ This Message was edited by: fnracing on 5/19/02 5:09am ]</font>
 

·
Registered
Joined
·
5,551 Posts
I had a maverick do the shake once. It was due to a valve stuck in the valvebody. at certain times, the low band would try to engage while going downtrack--causing the "shake". Actually, it was trying to engage low and high at the same time, effectively locking the trans. I would suspect the valvebody--either get another one and bolt it in, or take yours out and look at EVERY valve in it. I'd be willing to bet the 2-3 shift valve is stuck.
 

·
Registered
Joined
·
862 Posts
Discussion Starter · #6 ·
Will try replacing the valve body this week with another one i have. Thanks for the help.
 

·
Registered
Joined
·
94 Posts
I am not sure what is causing your problem. I was just wondering if you installed a shift kit? I just installed one and the band adjustments were different then what was in the manual. It changed from 3 turns off to 1 1/2 to 2 and from 1 3/4 to 1 1/2. It was a transgo shift kit.
 

·
Registered
Joined
·
862 Posts
Discussion Starter · #8 ·
No shift kit, but I did open it up and clean it out as well.
 

·
Registered
Joined
·
107 Posts
Well, for all wondering, this is what is wrong with this transmission:

He has no governor pressure and is bleeding off the line pressure as well.

The reason he can shift it in manual 1st and 2nd is the VB is forced to go to the gear selected - it overrides the govenor pressure.

When he shifts to "D" the transmission is actually shifting to 1st as there is no govenor pressure. It feels like it is in neutral b/c of the road speed - like shifting into 1st at 50mph, but without any engine braking (low band isn't applied in "D&quot
so the one-way clutch just overruns. When he revs up the engine it seem to "catch". In reality it just caught up to the ratio.

The shutter when put into gear is a result of not enough line pressure so the forward clutch isn't holding. When you put it in manual 1st the line pressure is boosted enough that it holds... just enough - nail it to the floor and I'd bet the forward will be toast in short order.

I've seen this many times before and every time it was either a govenor not assembled correctly, loose govenor bolts, or broken rings on output shaft. This causes two things to happen, 1st no govenor pressure, and 2nd a leak which bleeds of the line pressure. Naturally, with much effort one can goof up the VB and cause this too (but it requires much effort
).

Just my 2 cents


Steve S.
 

·
Registered
Joined
·
862 Posts
Discussion Starter · #10 ·
Steve I think you're right. I tried another VB, one that hasn't been touched and I have the same result. I did not r/r the govenor, but did replace one broken ring. Lesson learned, should have checked the govenor completely before assembling. Thanks for your explanation.
 

·
Registered
Joined
·
557 Posts
I had this very same problem after installing a B&M trans kit. I did everything the instructions said to do...it had the very same problems you are having. I pulled it out and tore it down again, double checked everything, it all looked good, so I cleaned it all out and reassembled it....same thing!
Pulled it out again, started getting very intracate in measuring every part of the trans...found the problem: one of the metal seal rings that was supplied in the B&M kit was a few thousandth's smaller than a stock one, thus, it was letting the fluid pressure leak past it, and would not seal tightly enough against the inside of the hub.
Got all factory seal rings from local trans parts supply house, and measured them and installed them, put trans back together and it works like it should!
Thats alot of back-busting work and frustration to go thru...but its all good now!
Hope this is "only" the case with your trans.
 

·
Premium Member
Joined
·
4,416 Posts
Stanley,just wondering which ring you had trouble with.Was it the govenor or stator rings..
The later c4's and c5's use a wider ring on the end of the stator support for the fwd clutch than the earlier c4.I have pulled a few c4's apart that have had the incorrect rings fitted.The trans seems to still work but there is always signs af slip on the fwd clutches from the loss of pressure..
 
1 - 12 of 12 Posts
Top