driveline backlash

The question is: why did you start looking in the first place? What inspired this examination? If it was a clunk each time you change gears or go from coast to drive, it may be nothing to do with the transmission components but rather the rear suspension. In particular the A frame ball joint on the rear axle housing and all the other bushes in the rear end. Makes a huge difference when they are all movement free!
Red Rocket.

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Originally Posted by mike 90 RR

Backlash

This is my understanding of diffs (at the risk of being flamed via others .. So correct me if I am wrong)
Based on a "open center" type only (RRC)

Your diff could be perfectly fine ...... Just old with too many k's on it
The face of the teeth of the Crown & pinion have just worn down = play
The face of the teeth of the Spider gears have just worn down = play

This puts more space between the edges of the corresponding teeth where they join (Crown tooth to pinion tooth)

Also the center Hemisphere could have some wear in it's pin joint

To adjust the lash is not (most probably) the answer, as you set the crown "Center to pinion" ..... If the diff "whines" ... Then it needs to be checked and have the crown & pinion re-adjusted ... As it needs to run face to face (of teeth) "centered" .... The amount of backlash is governed by this visual setting

So in short /// If the diff doesn't whine (no gear noise) ... answer is NO .. Backlash setting is fine

If you wish to remove more backlash ... then the answer may lay in the purchase of "All new gears" for the diff = $$$$

Hope it make sense


Mike

:)

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Dont want to hijack this, but some might be able to give me a Pauline Hansen on this.

Is there an explanation on why my rear propshaft moves 5 degrees and my front moves 30+ degrees yet?????
Mike has seen this. Move between D and R, the front shaft rotates more than the rear by a long way!!
I am assuming this is diff related, however there is no noise or whine coming from the front at all.

:confused::confused:

Mines the same. Pat

backlash is about 60% from the center diff my 200tdi fender had 280 000 ks and the backlash was really bad it was a pain in the **** .i fitted a part time conversion kit in it and it eliminated 80% of back lash so that has to say some thing

due to the windup of the center diff tending to let the slack turn up in the front shaft as opposed to the rear....

But it does sound a little off to me...

You shouldn't get wind up in the center diff until it is locked, the center diff is used on constant 4wheel drives to prevent wind up.:D

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Originally Posted by lambrover

You shouldn't get wind up in the center diff until it is locked, the center diff is used on constant 4wheel drives to prevent wind up.:D

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My classic is a '93 so has BW transfer with viscous.
The centre diff is always locked. The rear output shaft slips directly onto the CD which is installed inside the lower chain sprocket.The viscous slides onto the other side of the CD and the yoke for the front propshaft slides onto the other side of the viscous, which then splits the torque output 50/50 front and rear. With the BW transfer, if you take either driveshaft off, you still have drive to the remaining shaft.
In a normal transfer, you need to manually or electrically lock the CD or you will get no drive anywhere.
So if there is any excess lash in either diff, your propshaft would still take it up until it loads.
Mine however seems a little excessive.
I just answered my own question.... i think....... ;)

with a normal transfer case there is no center diff, but there has to be a selection be it manual or electronic which actuatates a selector within the transfer to engage 4x4, transfer case' with the center diff just allows for different speeds traveled by the front and rear wheels which is needed on hard surfaces.

Quote:

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Originally Posted by lambrover

with a normal transfer case there is no center diff, but there has to be a selection be it manual or electronic which actuatates a selector within the transfer to engage 4x4, transfer case' with the center diff just allows for different speeds traveled by the front and rear wheels which is needed on hard surfaces.

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Ummmmm... if there is no centre diff in a normal transfer case, then why is the lock referred to as a "Centre Diff Lock"???? :eek::eek:

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Originally Posted by LOVEMYRANGIE

Ummmmm... if there is no centre diff in a normal transfer case, then why is the lock referred to as a "Centre Diff Lock"???? :eek::eek:

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Because you are probably not familiar with a "normal" transfer case - a "normal" transfer case refers to the ones in a Series Landrover, older Jeep, older Landcruiser, Hilux etc that are selectable four wheel drive - they do not have a lock referred to as a "centre diff lock".

But getting back to the original question. You have to be careful what you are looking at when measuring driveline backlash. For example, if you chock the wheels and measure the free rotation of the drive shaft at the transfer case, with the handbrake off (in Defender for example), you will measure at the rear, the free play in the rear diff (mostly end play on the differential gears, not on the C&P), and free play on the splines at each end of each axle plus any on the pinion yoke and U-Joints. At the front you are measuring in addition to this, the free play in the spline on the inner end of each CV joint and the free play on the CV joint as well. All of these add up, in the case of the free play on the axles and diff, multiplied by the diff ratio.

But if we measure the free play by chocking one wheel front and back and jack up the other front wheel front and back and turn the wheel with the handbrake on to measure the free play, then for the rear drive we are measuring free play in the parts mentioned above (but without the diff ratio multiplier) and in the rear the same but with free play in the transfer case added. This will mostly be end play on the gears in the centre diff - you can see just how much this is by locking the centre diff and measuring again.

If, instead of using the handbrake, you put it in gear, and turn one front or back wheel while keeping the back or front respectively stationary, then the free play will be closer the same front and back, as the centre diff play will appear on both. This is closer to the driving situation.

Gets confusing
John