C4 problems

C4 problems

Joined: November 10th, 2010, 2:49 pm

November 10th, 2010, 2:55 pm #1

64 1/2 Mustang cruise-o-matic,no low gear, just lost reverse. fluid looks good. I recently rebuilt it (apparently not very good) also has a fluid leak from undetermined location, possibly the vent on top of case. Leaks after you park it.
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Mac
Mac

November 11th, 2010, 2:46 am #2

No low gear in drive or no manual low gear?
Mac
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Joined: November 10th, 2010, 2:49 pm

November 11th, 2010, 3:47 am #3

no low gear in drive
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Joined: January 1st, 2004, 2:15 am

November 11th, 2010, 5:33 am #4

64 1/2 Mustang cruise-o-matic,no low gear, just lost reverse. fluid looks good. I recently rebuilt it (apparently not very good) also has a fluid leak from undetermined location, possibly the vent on top of case. Leaks after you park it.
The reason Mac is asking Drive vs Low is how the trans operates.

In "D", 1st gear only uses the forward clutch and the one-way roller clutch.
In "1", 1st gear adds the low-reverse band as well.

The fact that you lost 1st in "D" hints at the one-way clutch.
The fact that you lost R also hints at another problem "rev-high" clutch is bad also.
This second case would mean you would not get high gear either.

So, what to do? Best thing right now is to pull the pan and start inspecting. Pull the valve body off and perform the factory air test -- that will reveal a lot about the sealing of the rings/seals and how well the clutch packs/servos are working.

Are you ready to get dirty?
Last edited by stuart40a on November 11th, 2010, 12:15 pm, edited 1 time in total.
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Mac
Mac

November 11th, 2010, 3:48 pm #5

If you lost the sprag you would have a no move condition in drive but would move forward in manual low or 2nd. If You move in drive you are probable takeing off in 2nd. If so it's a governor or v/b problem. If you have hi gear then the reverse problem as the rear band.
Mac
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Joined: November 10th, 2010, 2:49 pm

November 24th, 2010, 3:44 pm #6

I air checked the reverse servo and everything seemed fine, it engaged and held with no leakage
Last edited by DrCobra on November 24th, 2010, 3:45 pm, edited 1 time in total.
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Mac
Mac

November 24th, 2010, 4:25 pm #7

Put the pan back on and fill wuth fluid. Tighten the rear band adjusting screw to lock the band on. Start the engine in neutral and shift to reverse. If it backs up the high clutches are ok. Shift to drive. It it moves forward the forward clutches are ok. Accelerate slowly untile it shifts to second. If it binds up or locks up when it shifts, the front band is OK. Shift back to manual low so you dont damage the front band. Adjust the rear band back to spec. If you lose reverse the problem is in the rear band circuit even though the servo air checks. If it pases this test then all the friction elements are working so the problem is hydraulic,V/B, governor ,seals or gaskts. Sometimes when diagnosing it helps to find out what is right as this directs you towards what is not right.
Mac
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Joe
Joe

November 25th, 2010, 4:18 am #8

I did this swap on my 69 mustang several years ago..that's how I found this site..could not of done it without these guys..Stewart, Allenman, Silverfox just to mention a few...do it..its worth it...you do not have to shorten drive shaft..only change the yoke ....will have to change flex plate and torgue converter,..buy a new cross memeber for the swap..they are cheap and readily available...or cut and weld as you please...can re-use the gear shift rod after some tweeking..also the AOD dip stick tube with some bending but new flexibles are cheap and easier to install...get lokar cable and put a return spring on the trans end of the lokar, prevents hang ups when you relaese the pedal, especially cold weather... get the geometry corrector if you have a Holly, definitely worth it and necessary. Also need to splice in the AOD neutral safety switch.the speedo cable plugs right in. Do get an external cooler for better flow since the C4 lines are smaller..can do the Stewart trick and use an AC condensor off an old import...cools great!..Also to make things easier, I put a small pipe extension, with a 90 degree elbow pointing downward, in the pressure test port in place of the plug..it extends out past the side of the pan...so when I am through adjusting all I have to do is un-plug the pressure gauge(which has a female pipe thread end) and put a pipe cap on it....no more burned hands and jacking up the car!!! hope this helps...many THANKS, again to you guys on this site!
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