3.06 ATB Differential - Page 3 - PeachParts Mercedes-Benz Forum

Roncallo · #31 05-15-2019, 07:10 PM

Quote:

Originally Posted by duxthe1

I also cleaned up the ABS sensor bracketry and bolted that to the housing.

Please do elaborate with pictures. How id ABS handled on this car. Is this a 4 channel ABS or 3 channel. Is ABS on the input or output of the diff. Can you post pictures of the brackets.

duxthe1 · #32 05-15-2019, 07:25 PM

This car only has one sensor on the pinion. The previously mentioned bracket is pretty much just a metal shield covering the sensor keeping random road debris from causing havoc.

whipplem104 · #33 05-16-2019, 12:33 AM

The old ABS cars dont care if you change the differential because they changed the tooth count on the pinion. So you just swap a whole differential in and done.

Roncallo · #34 05-16-2019, 06:41 AM

Quote:

Originally Posted by duxthe1

This car only has one sensor on the pinion. The previously mentioned bracket is pretty much just a metal shield covering the sensor keeping random road debris from causing havoc.

So it bolts into the side of the case like the 107 but has an additional shield.

Roncallo · #35 05-16-2019, 06:42 AM

Quote:

Originally Posted by whipplem104

The old ABS cars dont care if you change the differential because they changed the tooth count on the pinion. So you just swap a whole differential in and done.

Those were the days.

duxthe1 · #36 05-16-2019, 07:29 PM

Here's a pic of the cover/bracket. Also a better picture showing the cooling fins on the V8 diff cover.
As requested the diff cover part number 129-351-16-08

duxthe1 · #37 05-24-2019, 06:26 PM

After putting it off for too long, I finally got the diff installed with the V8 subframe. It was a straightforward swap. The only discrepancy was due to the V8 subframe being for dual channel ABS and my car is single channel. This leads to the bracket that routes the ABS sensor's cable not lining up. Nothing a zip tie couldn't fix.

First pic is the V8 part ready to install. Second pic is the job ahead. Its a lot of work to pull a complete subframe. 3rd pic is the undercarriage with the subframe removed. 4th pic is the rear lower ball joints. These were particularly stubborn to press out, even with the special tool. Given the poor shape they were in, it was a must do while everything was apart.

After buttoning everything up I put it up on the alignment rack hoping to just square up the rear toe. Nothing is ever that easy, and a full alignment ensued. The right rear camber was too negative before, and it remains so. I suspect its an artifact of the bodywork in the right rear quarter. I had hoped that the subframe swap would have resolved it. Apparently it will require a spindle. Not a priority since it isn't wearing the tire bad from it.

A quick test drive did reveal a leak and on closer inspection the left stub axle had pulled out enough to clear the seal. After popping it back in it felt solid against the circlip so I went ahead and drove it home. Still ok so I'm not worrying about it but will keep an eye on it. I suspect that during assembly I may have popped it loose. I installed the spindle, links, and spring as an assembly so it was like wresting an octopus. I could have easily pulled the axle enough to compress the clip without realizing it.

The good news is that it's dead quiet at speed. I can already tell the difference in the mounting. The old rear bushings were on their way out and I can feel that its tighter now on hard shifts even though I didn't do any real beating on it yet.

FWIW, I've got a 3.27 ratio diff for sale if anyone wants to make an offer.

duxthe1 · #38 05-29-2019, 11:24 PM

Thought I'd post a pic of the old subframe. Compared to the pic of the V8 subframe above you can see the difference in the rear mounting. Another big difference is that the front cross bar is stamped sheet but on the V8 part it is tubular.

Still haven't beat on it too much yet but it does give me a bit more confidence in full throttle kickdown in hard turns.

duxthe1 · #39 06-17-2019, 08:43 PM

After about 600 miles I've pulled the diff back out. There was a slight hissing sound coming from the left side bearing. Couldn't hear it in the car but with the windows down, driving past a fence or like, I could hear a noise reflected that didn't sit well. Running it up to speed on the lift it was clear the noise was mainly the left side bearing and maybe a little on the right.

So today I swapped it back out for the 3.27 while I get the LSD sorted..... again.

So upon disassembly it looks like the preload was too tight on the side bearings. Upon inspection you can see fine scoring of the race with pitting just starting. Damn! I consistently measured 0.19 to 0.20 mm for case spread and the spec is 0.10 to 0.20 mm. I figured that the tight side of the spec would be ok. I figured wrong. My next move here is to go 0.05mm thicker on both side shims to put the case spread on the low end of the spec while keeping the backlash where its at.

I would have set it a little looser if I had shims in the range needed to do it. My selection stepped from 1.65 to 1.8mm At this point it looks like I'll have to get a thicker shim and have it ground to 1.7mm. The right side shim will have to go from 1.05 to 1.1, which I recall was available in my selection. This is assuming that the replacement bearings install to the same dimensions these last ones did. One odd thing I noted was that the wear path between the left and right sides were in different spots in the races. Given that, I'm gonna have to check and re-check everything again on the next assembly. Nothing will be assumed. I'm specifically not looking for a charming 3rd try.

duxthe1 · #40 06-27-2019, 08:56 PM

I received and installed the new set of side bearings. Measured the setup again and it was still pretty much spot on. No change from installing the new bearings. A revelation did occur during measuring though. The screw in tip of the dial indicator was missing. It screws in to the indicator and was nowhere to be found. I have a sneaking suspicion it came out during my last measurements and caused the trouble with the first set of bearings.

I had previously misspoke about the case spread spec. It is 0.15 to 0.20 mm, where I had previously thought the lower limit was 0.10 mm. My setup measured 0.18-0.19 mm which is about perfect. When ordering my bearings I also ordered a 1.70 mm side shim and was astounded that one came in today. I swapped it for the 1.65 on the left side, which puts the spread a bit under spec and adds a couple hundredths mm backlash. Also ok as backlash was at the tight side of spec.

I hung the diff this evening and ran it a few miles on the lift. The noise is still present, though to a lesser degree, and seemed to diminish a little after a few miles. Gonna have to keep an eye on it. If it doesn't get any worse, I can live with it. If it breaks in and diminishes more, so much the better. I'm gonna sample the oil after a few hundred miles. If its still clean, then I'm calling it good.

97 SL320 · #41 06-28-2019, 06:38 AM

Quote:

Originally Posted by duxthe1

The screw in tip of the dial indicator was missing. It screws in to the indicator and was nowhere to be found. I have a sneaking suspicion it came out during my last measurements and caused the trouble with the first set of bearings.

The missing tip shouldn't be a problem,the ball end is there more or less to protect the surface that is being measured , prevent the indicator plunger from wearing , allow for extensions to be added. A square plunger end " could " affect measurements if off angle to the measured surface but for what you are doing I'd expect the indicator to have more internal error.

Quote:

Originally Posted by duxthe1

I hung the diff this evening and ran it a few miles on the lift. The noise is still present, though to a lesser degree, and seemed to diminish a little after a few miles. Gonna have to keep an eye on it. If it doesn't get any worse, I can live with it.

After the change out, the ring and pinion are going to be running in a slightly different orientation / using areas previously not in contact so it may take some time to wear off high spots

duxthe1 · #42 06-28-2019, 08:25 PM

Quote:

Originally Posted by 97 SL320

The missing tip shouldn't be a problem

The problem with the missing tip isn't measurement error. I think it may have been eaten by the diff.

The first time I dropped the oil out the diff it was quite grey. A couple hundred miles later when I finally pulled the diff back out, that oil came out as clean as it went in.

97 SL320 · #43 06-29-2019, 07:51 AM

Is this a clutch type diff and if so, are the clutches bare steel or coated with something? If coated, perhaps the gray was the initial break in.

The indicator tip's ball is going to be carbide or similar and the housing mild steel. I'm not expecting it to cause a problem even though I would not knowingly drop it in the diff.

If in the diff, it isn't going to be ground to nothing. At minimum it would be laying at the bottom or dented from one go round the gears. At max the housing would be hammered flat ( like engine bearings that have pounded to flakes ) and the carbide ball denting the ring and pinion.

duxthe1 · #44 06-29-2019, 11:26 PM

Not clutch, its a torsen.

Roncallo · #45 06-30-2019, 09:25 PM

I cant see how an indicator tip could get into the bearings at least not in the race. It could get in the gear mesh but that would be obvious score on a gear tooth. Its possible its wedged in somewhere where its just rubbing some rotating member.

When you go to change the shims, remove the carrier completely and drag a coat hanger under the pinion. If I recall there is a drain back passage in the bottom of the diff. Also it you have a speed sensor pull that out and have a look.