Automatic Transmission Shudder 2.8ltr 1993 Campervan

Having had my bus for some time, I was alarmed by the development of a shudder when starting off. Harsh acceleration got rid of it but a slow take-off produced symptoms of a engine mounting failure, shaking from stem to stern, especially on an uphill slope.

The autobox was changing smoothly - fluid was red and unburnt & frequently changed, the kick down cable adjustment was per specification (The cable ferrule being 1mm from the end of the red boot-35mm from ferrule to housing on full throttle) but something was amiss.

The line pressure was to specification, no leaks and once the bus was moving a smooth as silk.

The problem seemed to be Kick-Down cable related, it appeared to be smooth in the cable sheath, no obvious fraying and visibly undamaged from autobox to throttle arm. Having played for many hours I concluded that the slack in the cable was ok to produce smooth running but as the ferrule was butted up to the cable housing the cable length between the auto valve body hidden behind the sump pan and the ferrule may be the cause of the vehicle shake.

By placing a metal spacer of 5mm in thickness( eventually I used a Biro pen spring cut to length and wound round the cable between the ferrule and the sheath) this appeared to solve the problem. Still keeping to the recommended overall cable adjustment as per workshop manual. To date after several thousand miles the box is performing as required with no shudder. WATCH THIS SPACE!

One of my engineer friends suggests that maybe the ferrule has slipped,or cable stretched, the extra adjustment in the valve body gives initial priority to the Torque Converter, shudder usually means insufficient fluid in the vanes. A cheap quick fix as opposed to Autobox removal and rebuild.

Good post....cables always stretch as the years go by....

It wasn't the cable stetching! After being very careful on acceleration the vibration returned so it had to be something serious or fundamental.

There was indeed starvation to the Torque Converter!!

Off came the ATM sump and low and behold some of the valve body bolts were loose.

As the sump was off I removed the sump filter and removed the valve body. 17 bolts in total differing lengths so draw a sketch to ensure they are replaced correctly.
The cable was kinked slightly through age so a new one was fitted. The cable ferule is applied by the fitter after the cable is in place, there should be 0.8-1.00 mm gap between the ferule and the cable sheath end when the resistance is felt ( crimped with pliers),then the red sheath is pushed home and then the cable is adjusted to give 1mm ferule projection on wide throttle.
Be aware when and if you remove the valve body most of the fluid drains fron the oil pump & torque converter.
I filled up my normal refill amount and got no traction! It needed 2 litres more once the fluid was hot and all gears were selected,

Good info there mate. Many thanks

To date this appears to have solved my "Earthquake on Acceleration".

The adjustment of the Kick-Down cable is critical and a point to note is that IF you adjust the cable to give a gear holding pattern - that is to say you expose more of the ferrule on full throttle another problem (NOT CRITICAL!) occurs.

The 1-3 gears change smoothly and with excellent acceleration then BANG at 40mph the overdrive (4th gear) engages. The result is LOADS of black smoke!!!

As you accelerate on the wide throttle, the Gearbox speed govenor changes automatically at approx 40mph from 3rd, and without the benefit of a Turbo the unburnt fuel lays a black carpet behind!

Got my emissions checked after an Injection Pump rebuild & calibration, timing was spot-on and normal running gives the results that fall well below the MOT spec.

THESE BUSES ARE MARVELS OF ENGINEERING EH??