how do you set/adjust backlash on diff centres?

[SiKiD_01]

i would like to know how to adjust/set the backlash on the diff centres' ring and pinion.

EDIT: for suzuki Vitara '89.

i have a spare diff lying around, so i can practice. are there any special tools i need? gauges? measuring devices? etc.

i can't afford to have the diff guy reset my centre when i take it out. about $100!

if i'm going to need to be taking centres out and putting them back in, i'd rather learn and do it myself.

my original diff shate itself... unknown reason.
this is my second diff, and i sense it is on its way out!

thanks in advance.
i have done a search.

[J Top]

Some vehicle description would be rather helpful
J Top

[RB zook]

suzuki

[SiKiD_01]

sorry. Suzuki Vitara. 1989. rear diff.

[Woop]

This site might be some help to you. Just apply to Zuk instead

http://members.cox.net/cglabe1/Diff/diff.html

Nick

[XterraGuy]

The November issue of Petersen's 4 Wheel and Offroad (USA rag) has a little tip about how a tech improvised a way to measure the backlash in the field using only a vernier caliper rather than the traditional dial indicator. Just fix the pinion so it can't budge, then set one jaw of the caliper against the housing below the ring gear, rotate the gear away from that jaw until it stops, set the other jaw against a tooth on the gear, take a reading, rotate the gear back towards the jaw with the jaw still engaged on the same tooth and take another reading. Subtract the difference, you have your backlash reading!

Pretty spiffy,
Brent

[J Top]

Backlash does not normally increase in a diff with out wear or part failure happening first.
What condition was your oil in,was there metal on your drain plug magnet?
I feel you need some asssistance from a tech-wise friend to check the bearings and gears for wear.
J Top

[SiKiD_01]

when first bought the vitara, it had a lot of free play in the drive line. half inch to one inch rotation on the drive shaft. i drove it like that for a good 4 months or something, and then weird things started to happen. the diff would lock itself up, acting like a locker, good and bad.

i think the oil in the diff was changed before i bought the vitara, as it was clean when i checked, after 4 months, there was metal on the diff plug, and that was it, no milkiness or anything like that, so seals were fine.

i took the diff out, i think its clled the third member or something. the diff housing was still on the car, just the carrier was pulled off. it turned out that the tiny pins that hold the spider gear pins broke/snapped, not holding the big spider gear pins in place, and resulting in elongated holes in the actual centre housing/carrier. so the spider gears could move around a bit, and bind, the reason for the locking. the side gears were also chipped at every other teeth, so it was no good, and beyond repair, as i was told.

now the new diff i got was from a qld wreckers, was complete and ready to bolt in add oil, and drive. now it is doing the same thing as my old diff.
i want to take it out and have a look, and then i might as well buy a locker (not likely) or weld it shut (likely) for good.

i can practice with the old diff for setting backlash and so on, as the old ring and pinion are still good.

sorry, u guys must hate my stories.

thanks anyway

[J Top]

If you are going to weld it and it is only the spiders and pins that are worn you don't need to adjust backlash,just weld the gears together.and then cut a plate of steel to fit on all the gears and weld that to the gears as well to increase weld area and strength.
To adjust backlash you remove the lock tabs from the bearing caps, then you loosen the cap bolts off about a turn,then you rotate the side nuts to increase or decrease backlash as required.The theory is to move both side nuts the same amount,ie, one a half turn in and the other a half turn out to keep your carrier bearing preload the same.When you have the backlash close to what you want,you torque up the cap bolts and recheck it as this can change it.
J Top

[dumbdunce]

The November issue of Petersen's 4 Wheel and Offroad (USA rag) has a little tip about how a tech improvised a way to measure the backlash in the field using only a vernier caliper ...

Because we ALL carry an accurate vernier caliper in the field tool box

I have used that method in the workshop when I can't find the dial gauge but it isn't super accurate.

be aware that changing backlash will change the contact pattern and if you reset your backlash it may be necessary to re-set the pinion height, which usually involves a press, and shims, and much weeping and gnashing of teeth until you've done it a few dozen times. also if your ratio is lower (numerically higher) than about 4.3:1, it is difficult to get a really good oval contact pattern even on new gears, making it a bit hard to tell if it's right or not.

if you're welding it up, pull the carrier out and split the ring gear off, then do all the welding far away from the other bits of the diff. a couple of bits of spatter welded to tooth faces will destroy the gears in a very short time

good luck

Brian