Thread: Does fixing driveline slack, fix jerky throttle?

The most common reason for this problem is a dragging handbrake - and it does not have to be dragging much. But transmission slack makes it worse.

John

Thanks John.
It rolls on the slightest gradient, so I don't think its dragging. It would've worn the brake shoes back by now anyway if it had been dragging.

Originally Posted by JDNSW

The most common reason for this problem is a dragging handbrake - and it does not have to be dragging much. But transmission slack makes it worse.

John

I've seen that many times,I've even seen a T/C replacement from the ''flapping'' sound they make on coast when the shoe's rub,the owner and mechanic refused to even back the hand brake off to prove my theory,anyway a wasted few grand. Pat

How does one go about checking if the handbrake is dragging and rectifying it if it is the cause?

Drive a few blocks and then put your hand on the drum - if it blisters, the brake is dragging. Should be slightly cooler than the transfer case.

Dragging can be due to adjustment - easy enough to slacken it off. Chock the front wheels, put both rears on stands, transfer and gearbox in neutral (centre diff unlocked), and turn the prop shaft by hand. Should be able to hear or feel the slightest drag. If you cannot back it off enough to stop any drag and still have a workable handbrake (apply and release brake each time you adjust it), suspect either there is oil in the brake from a leaky seal, or the expander, which is supposed to be able to move with some friction to equalise the shoes, is either rusted in place or free to slop about so that the weight of the mechanism is always resting on the lower shoe. This would be due to incorrect assembly or the spring clip broken.

John

Cool, another thing on my to do list.... Thanks for the info JDNSW, havent tackled this before so all new to me. Gotta do the rear ball joint soon, but any other places that make that goddamn clunking noise that I can fix then I'm all ears.
I think someone (maybe bilbo?) in a previous post on a similar subject said something along the lines of " its all about being one with your car. Some days you are at one and it doesn't clunk. Other days not so good" Bloody true as well. Some days I get very little backlash (well little for my bus) and other days its at almost every gear change and bump.

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Anything that allows either axle to move in response to driving or overrun torque will show up as transmission slack. The most common ones are:-

Ball joint on top of axle - usually a resounding metallic clunk when taking up drive (there is no rubber in this joint).

Rear lower link - usually shows up as steering wander with torque, as it will be different each side.

Front of lower link, either the big nut or the three bolts loose - usually a sharp click when going between drive and overrun.

Front A-frame bushes - muffled clunk on bumps.

Surprisingly, in my experience, problems seem to be unusual on the front axle, perhaps because there are fewer joints with much movement. Most common problem there is panhard rod bushes.

John

Interesting, after my first service, there is a lot more slack in the hand brake, and it seems much smoother to drive, so maybe it was binding.
Mind you a Bas tune also occurred at the same time.
Is not axle flanges fretting out another reason?