Thread: Whats acceptable amount of backlash

if you aren't firmiliary with this kind of thing I would recomend getting it checked by a rover mechanic or some one who knows rovers and then you will have a reference point for your self as to what is acceptable and what is not, treat it like a learning process most inspections don't cost that much any way,well worth it. In the disco excesive back lash can be in the transfer case as well, this is the case for most all wheel drives.

You need a better understanding of what is going on in different parts of the drive train.

For example: A fair bit of backlash can be detected in the t/case between the front and rear output shafts. The clutch dogs for the selecting high/low range have a lot of backlash to make engaging easier (every 2nd tooth is removed). And the backlash between the gears in the centre diff is added to this. The ratio between the pinions and side gears in the centre diff, multiply the total backlash.

However if the bearings are worn and not preloaded properly, the backlash will be increased.

Originally Posted by Bush65

You need a better understanding of what is going on in different parts of the drive train.

For example: A fair bit of backlash can be detected in the t/case between the front and rear output shafts. The clutch dogs for the selecting high/low range have a lot of backlash to make engaging easier (every 2nd tooth is removed). And the backlash between the gears in the centre diff is added to this. The ratio between the pinions and side gears in the centre diff, multiply the total backlash.

However if the bearings are worn and not preloaded properly, the backlash will be increased.

thats what i am here for.it does make what i call a fair clunk and the diso will jolt slightly when going from drive to reverse and vise versa, it is loud enogh 4 me to think holly **** on my test drive anyway, i have also been reading alot about it on this site, it is acutally quiet when engageing low range. (dont think its been used off road very much if at all) its just when selecting d or r on the auto.

Originally Posted by toey1977

thats what i am here for.it does make what i call a fair clunk and the diso will jolt slightly when going from drive to reverse and vise versa, it is loud enogh 4 me to think holly **** on my test drive anyway, i have also been reading alot about it on this site, it is acutally quiet when engageing low range. (dont think its been used off road very much if at all) its just when selecting d or r on the auto.

LT230's can suffer from worn splines in the input gear/gearbox output shaft due to poor lubrication.

The fix is to use the later input gear with longer splines and cross drilled lube holes. Unfortunately it is expensive to replace the worn mainshaft in manual gearboxes.

This splines can be inspected by removing the circular PTO cover from the rear of the t/case. It may be necessary to pull the input gear to get a good look, but first try jacking up a rear wheel and rock it back and forth with the box in gear as you look for play between the gear and shaft.

If there is what appears to be red rusty gunk in the area of the splines, then you probably have problems - the red stuff is the result of fretting corrosion. With the cross drilled gear, the splines should get plenty of lube and don't suffer from this.

The cross drilled gear is not available for early LT230's and the best that you can do is drill it yourself of have a machine shop do it - not easy because of the hardness of the material.

Otherwise there is a part that fits inside the PTO cover to catch oil and direct it to the splines (I have not had anything to do with this part or even held one in my hand).

If you have a ZF auto, the spud shaft (that the input gear fits on) can be replaced without removing the t/case, but you need the version with long splines to suit the cross drilled input gear.

Good luck.

Some of the clunking may be due to a worn ball joint on the rear suspension - its relatively cheap and easy to replace.

You may be able to eliminate this as a cause by putting the handbrake on firmly (it operates on the rear driveshaft) and then shifting the auto from forward to reverse to see if the clunk reduces - if it does, the ball joint is suspect.

Originally Posted by mark2

Some of the clunking may be due to a worn ball joint on the rear suspension - its relatively cheap and easy to replace.

You may be able to eliminate this as a cause by putting the handbrake on firmly (it operates on the rear driveshaft) and then shifting the auto from forward to reverse to see if the clunk reduces - if it does, the ball joint is suspect.

I have found that using the next grade oil,50/50 85/90-95/140 will remove alot of slop but in the Disco(auto) simply putting your foot on the brake when changing makes a big difference.All this of course will only work if all the things posted above are OK. Pat

Originally Posted by mark2

Some of the clunking may be due to a worn ball joint on the rear suspension - its relatively cheap and easy to replace.

You may be able to eliminate this as a cause by putting the handbrake on firmly (it operates on the rear driveshaft) and then shifting the auto from forward to reverse to see if the clunk reduces - if it does, the ball joint is suspect.

Hi Mark, Just thinking about the defender, Tried what you have mentioned, move a bit from 1st . to reverse with hand brake on. stops a lot of clunk in the back end, am thinking a frame ball maybe?


Cheers Sumo

Originally Posted by sumo

Hi Mark, Just thinking about the defender, Tried what you have mentioned, move a bit from 1st . to reverse with hand brake on. stops a lot of clunk in the back end, am thinking a frame ball maybe?


Cheers Sumo

It would point to it. Its the most likely suspect but others are worn rear drive flanges and trailing arm bushes. Another way to check the balljoint is to look from under the rear of the car at the ball joint while someone in the drivers seat takes up the drivetrain slack with the foot brakes applied firmly but not the handbrake. You're looking for movement at the ball joint. Make sure you dont get run over.....