• Welcome to ClassicBroncos! - You are currently viewing the forums as a GUEST. To take advantage of all the site features, please take a moment to register. It's fast, simple and absolutely free. So please join our community today!
    If you have problems registering or can't log into your account, please contact Admin.

C4 Reverse Vibration

dirtbikedad

Jr. Member
Joined
Jan 16, 2010
Messages
97
Loc.
Athens, AL
Transmission shifts into reverse ok and seems ok when cold but after driving a while and put into reverse it vibrates the whole truck when you actually start moving. Any ideas what it could be causing it to act this way.
 

Viperwolf1

Contributor
electron whisperer
Joined
Aug 23, 2007
Messages
24,316
2 possibilities I can think of.

The direct clutch or rear band are slipping. Adjust the rear band. There is no clutch adjustment.

Shifter adjustment at the trans is off making the park pawl drag when in reverse. Adjust the linkage correctly.
 

Bajabrewer

Contributor
Bronco Guru
Joined
Jan 28, 2012
Messages
1,435
I had a C4 that was doing this & it turned out one of the pinions was starting to eat it's self. I hope Vipers adjustments work for you - if not then you may need a rebuild.
 

Rustytruck

Bronco Guru
Joined
Feb 24, 2002
Messages
10,875
if adjusting the band doesn't work before dropping the trans I would check the reverse servo. this can be pulled while the trans is in the truck but there is a special proceedure to do it.
 

Broncobowsher

Total hack
Joined
Jun 4, 2002
Messages
34,833
Outside the transmission...
In reverse the pinion on the rear axle moves down. This could be enough to put the U-joint into a bind. Easy check, remove the rear driveshaft and back up while in FWD (Front Wheel Drive). If it goes away it is a driveline issue, if not then transmission.
 

BwoncoHowie

C-4 Wizard
Joined
Nov 11, 2002
Messages
3,571

Wrong!
That additive is for TCCs where MERCON-V is called for. Adding this to a C-4 is a mistake. The chemical was developed for late model transmissions like the AODE/4R70W and will not cure the root cause. It could possibly worsen the condition of your C-4.

Do like Viper says... and I would add to his advice, also check the rear servo piston to make certain the rubber is still soft and pliable.
 
Top