Rear Axle Backlash

[George Des]

Can anyone explain exactly how the backlash is checked on the rear axle. Understand how it is adjusted with the shims but how is the backlash checked if the axle has to be at least partially assembled with the left side axle tube in place as far as I can tell from the description I've read. If this is correct, how does one set up the dial indicator on the ring gear--

George Des

[ja17]

Hello Gearge,

I guess we need a little bit more information. Normally, backlash (slop) in a used differential is a result of wear. It is caused by wear on the rack and pinion gears themselves or casting wear where the gears are pinned in the yoke assembly.

If you are installing a different or new set of gears in your diff., you must deal with the factory lash specs to make everything is set up properly.

[George Des]

Joe-will be using the same gears-simply replacing the bearings--2 pinion bearings and 2 carrier bearings, crush sleeve and seals.



George Des

[JimVillers]

George ... You will need to do a complete setup.  Read the section in the manual and look at this web page.  
http://www.pirate4x4.com/articles/tech/billavista/Gear_Setup
You may also NEED a set of special tools to set pre-load on the the carrier bearings.  It is an interesting job but needs to be done accurately.  I replaced the gears in my 190SL and they survived a cross country trip.

[George Des]

Jim--I looked over your post on the 190Sl site and noted that you were changing out the gear set on your rebuild. What I'm doing is switching out the 2 pinon bearings, crush sleeve, two side bearings and seals only. I'll be using the entire original ring gear set-up and pinion.  When I disassembled the components, I found one shim between the rear pinion bearing cone and the pinion gear and one between the left axle housing and the left bearing cup. Understand how the pinion shim is used to adjust pinion depth and the other to adjust ring gear backlash. Do you think that the tolerances on the new bearings would be that far out of range from the older ones that different size shims would be needed to obtain the correct pinion depth and backlash. Also, the blue book is not clear on the pupsoe of the slotted ring on the right side of the pumpkin housing--is this used to adjust the pre-load on the two carrier bearings. I see where it says to set at about 25 ft-lbs torque--but as I read it that is the torque on the ring not the ring gear turning torque.

Geoirge Des

[wbain]

Jim, I read the info on the DANA 60 completely but since our swing axle rear ends has an enclosed differential with no rear cover, do you have to continually unbolt, inspect and bolt the left side axle off to check the mesh pattern? I've got the Ponton 180/190 etc CD that has the procedures, but I'm still miffed.

Does anyone have a set of pics that can be posted?

[George Des]

Warren--this is one of my questions as well. I'm just replacing the bearings on my rebuild and plan to try using the exact same size shims on the pinion and left axle. Hopefully, these will give the correct contact pattern but who knows. Like you, the only way I can see to check is by pulling the left axle tube off again. The manual I have says the slotted ring on the right axle should be tightened to 25 ft-lbs to give the correct carrier bearing pre-load.  Is this consistent with what you've got? Also not quite clear on how to set up a dial indicator o read the backlash on the ring gear once evrything is closed up. The differntial cases that open from the back appear to be a piece of cake compared to our design as far as accesibility goes

George

[George Des]

Jim/Joe--do you have the torque settings for the large slotted ring on the right axle side. One of my texts shows about 25 ft-lbs once the left axle side is re-attached. Any other torque values you have would also help. I had another text with many of these values in it, but can't put my hands on it. Also, still trying to figure out how to set up the dial indicator to read the ring gear backlash. Do you do this through one of the lubricant filler holes? I can't see any other way.

George Des

[JimVillers]

George .... I am not sure that I understand all of your questions but I'll try.


I assume that the carrier taper bearing adjustment nut is the nut you are asking about (the picture is from a 190SL manual; I assume that yours is the same).  This is the image of the right hand nut.  It requires a special tool to tighten.  Tightening this nut puts pre-load on the bearings.  4mkg or 25 ft/lb will set the correct pre-load.  By adjusting the carrier bearing adjustment nuts on both sides, you can move the ring gear in or out to adjust the backlash.  After getting the desired backlash, torque one adjustment nut and recheck the backlash.

The correct backlash is so that you can just fee the backlash (or gap between the gears) by turning the pinion.

If you need the special wrenches, the 190SL Group will be selling them in a few days (email me, 190SLJim@cox.net, and I'll notify you as soon as I receive them for my stock).

[George Des]

Jim--thanks this clarifies things. What I've now determined is that there is a significant difference between the 190SL rear axle and the 113 in that the left side carrier bearing is not adjustable with a slotted ring. It uses various thickness shims on this side and a large slotted ring on the right side exactly like that on the 190sl. Thus, the only two variables to play with on the 113 are the pinion shim and the left side axle shim. Once these are properly selected, it looks like the carrier pre=load is set by torquing the right side ring to the 25 ft-lbs as you mentioned. I'm using the original pinion and ring gear set-up. I've now switched out all the bearings and races on my set-up-this includes the two pinion bearings and races and the two side carrier bearings. I've re-used the shims. I've done a ring gear mesh check and everything looks good. I'll now disassemble again, put in a new crush sleeve and check the backlash using the "click" method use describe.

George Des

[JimVillers]

George ... It sounds like you have the correct shims and understand the process.  There is no "click" (sound), only the feel of a slight gap (the pinion is not under pressure by the ring gear).

[George Des]

Jim--I read over your notes on the 190SL site noting how you locked the left axle and used the right axle sliding sleeve assembly to rotate the ring carrier. I tried this with my set and when I rotated the sliding sleeve slightly, I feel a small "gap" before the pinion turns--is this what you describe as the backlash? Thx

George

[JimVillers]

George .... Correct.  Backlash is the gap that allows the pinion to rotate without rotating the ring gear.