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  #1  
Old 08-16-2018, 05:53 PM
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Srt8 diff in r129

I'm waiting on pistons for my turbo build, so I started looking at limited slip diff options.

I'm out of town getting ready for Monterrey car week, and can't compare my diff. I've checked out tons of online info and pics and compared, but I think this diff will bolt into my r129, may need to swap my backing plate.

What do you guys think? Any experience?

https://m.ebay.com/itm/2008-Dodge-Charger-SRT-8-OEM-3-06-Rear-Carrier-Differential-Assembly/392072381293?hash=item5b4955c36d:g:ZUYAAOSwdu9aoDpt&_trkparms=gclientid%3DjWn7ftXr41Z4I0IfTNfVKU4qCH4fK2yywX9mozV8E9jLDZ6io-Ny3DZ2sXUU68_x&_trksid=p2489528.m4335.l8656
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  #3  
Old 08-16-2018, 07:13 PM
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I have a complete rear end assembly from a 1999 SL500 for sale on ebay right now. The casings do look similar but not exact. The SL500 gear ratio is 2.65:1 and it 'might' be an LSD as the backing plate has the fins that you typically see on LSD diffs.

Here's a link with pictures should you want to make your own comparisons.

https://www.ebay.com/itm/122834150353?ssPageName=STRK:MESELX:IT&_trksid=p3984.m1555.l2649
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Check out the W114, W115 enthusiast website.
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  #5  
Old 08-16-2018, 08:53 PM
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Quote:
Originally Posted by alabbasi View Post
I have a complete rear end assembly from a 1999 SL500 for sale on ebay right now. The casings do look similar but not exact. The SL500 gear ratio is 2.65:1 and it 'might' be an LSD as the backing plate has the fins that you typically see on LSD diffs.

Here's a link with pictures should you want to make your own comparisons.

https://www.ebay.com/itm/122834150353?ssPageName=STRK:MESELX:IT&_trksid=p3984.m1555.l2649
Fins do not = LSD I " think " MB last used LSD on a 80's era 190 E W201 Sport line or some other racing spec option. There is a hydraulic limited slip diff in the 80's as well ( early 4matic wagons ? ) , it has a 3/16" ish steel line running to each side of the diff.

The R129 never came with LSD, it used ASR ( Acceleration Slip Regulation ) . Also, there were many different diff sizes and axle lengths in the R129 so be sure to do some research to see what you have right now before looking to replace it.
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  #6  
Old 08-17-2018, 12:34 AM
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Looks like it might fit with a back cover change. But fit and work are two different things. If you put it in your transmission will go into limp home mode because of the gear ratio change. And I don't know what it would do to your ESP. You would have to install a two channel speed changer on the input of your transmission control unit or get an aftermarket controller from PCS.
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To see my 129 parts for sale visit:
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  #7  
Old 08-17-2018, 10:10 AM
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The 215mm does not just fit. I am retrofitting one to the w124. It is the same case as the C63 and others of that size/era. It will fit but requires custom rear cover and or custom rear subframe work. I tried about 3-4 different rear covers. Maybe there is one that works but I could not find it.
Unless you are planning on doing a wheelie the 210mm diff is more than up to the task. The axles are the week link and they start breaking around a 1.5ish 60' at the race track.
Any ways I have a thread on here about the setup I am doing.
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  #8  
Old 08-17-2018, 02:30 PM
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No esp on this car, and everything will be stand alone. I'm sure my abs will be out the window too but no big deal on that.

Not to worried about the strength of the current diff, especially with automatic car. But would like to keep to a steel cased diff, aluminum start to spread on high hp srt cars is what I'm reading. But a wheelie would be fun to see in 129. Good to hear they can handle down to 1.5s, I've never gotten under 1.8s in any of my other cars, all sticks.

Main concern is lsd and changing gear ratio. Does the diff fit the space? Does the front single mount line up? This will not be a daily driven car, could the subframe mounts be filled in new holes drilled in subframe for a direct mount, no rubber?

Thanks guys

Bonus saleen mustang carnage pics, rear end and axle giving out way before 1.5s lol
Attached Thumbnails
Srt8 diff in r129-img_5165.jpg   Srt8 diff in r129-img_5166.jpg   Srt8 diff in r129-imag0212.jpg  
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  #9  
Old 08-17-2018, 03:29 PM
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Quote:
Originally Posted by Justin300sl View Post
No esp on this car, and everything will be stand alone. I'm sure my abs will be out the window too but no big deal on that.
We need to get some definitions straight.

ABS ( Antilock Braking System ) modulates brakes in responce to a wheel being locked under braking.

ASR ( Acceleration Slip Regulation ) modulates throttle then applies a rear brake if a REAR wheel continues to spin at a rate higher than the front wheels.

ESP ( Electronic Stability Program ) is a system that applies any of the 4 brakes in an effort to prevent the car from flying off the road in a corner. ESP isn't very common on the R129 as it was an option on some cars, it was however , standard on the 600SL / SL600

Each system has elements of the one before it, all use the ABS pump / valving system / computer.

ABS

ABS + ASR

ABS + ASR + ESP

If you have a black switch with a chained snow tire ( in the hazard switch area ) , you have ASR.


Quote:
Originally Posted by Justin300sl View Post
Not to worried about the strength of the current diff, especially with automatic car. But would like to keep to a steel cased diff, aluminum start to spread on high hp srt cars is what I'm reading. But a wheelie would be fun to see in 129. Good to hear they can handle down to 1.5s, I've never gotten under 1.8s in any of my other cars, all sticks.

Main concern is lsd and changing gear ratio. Does the diff fit the space? Does the front single mount line up? This will not be a daily driven car, could the subframe mounts be filled in new holes drilled in subframe for a direct mount, no rubber?
I'd be real tempted to use a Ford 8.8 IRS center from a Lincoln / T bird / Explorer Sport Trac. Most have a steel case but the Explorer uses an aluminum case.

DSS makes plug on / CV bolt on flanges for the 8.8 as well as custom axles.

The R129 has painfully small wheel side splines. I looked at a larger( W140? ) upright / hub bearing / spline but the pickup points are completely different and there isn't enough material to grind the hub for the small R129 bearing and the upright doesn't have enough material to use a larger bearing.

For what you want to do, I'd be even more tempted just to use a complete IRS subframe from a Ford or go to straight axle.
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  #10  
Old 08-17-2018, 09:56 PM
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Like I said. I have a thread on here on details on rear end upgrades for these. I go over all of this.
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  #11  
Old 08-17-2018, 11:04 PM
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I looked at some ford units, they do look very similar. Solid axle and tubs may come eventually lol

Sorry whipple, I kept reading the qualfie thread and didn't see the driveline upgrade thread.

Now that I've read it.......... wow you are the man. The work you've done is incredible. I hope to be able to follow that exactly.

What car did that diff come from? Is that the diff your putting the qualfie in? I'm hoping to use an 09 and later for the factory lsd. It's a popular swap to put in the older srt non lsd cars so I suspect the casing should be similar in dimensions, but the axles are different on the 09+ 226mm diff.

Quote:
Originally Posted by whipplem104 View Post
No it is the 215 diff from a srt-8 charger or challenger, 300c. It is basically the same as a Mercedes diff from a w209 w204 large diff. c63 c55, etc. They are just a lot cheaper to get and this one has 3.06 gears in it already. I need the inside flanges for the differential. But I will probably get these when I get the axles customized. I am then going to get a one piece driveshaft when I put this all in. CV joint in the front and rear. I have not decided if I am going to get carbon fiber or chrome moly.
The cool thing is it looks like you could use the w140 axles with the standard w129 case that is in the car stock. Just have your flanges drilled and broached for the larger stubs. I just want more options when I am done and not to do it twice. And I know nothing will break ever.

Can I use the large w140 axles with the clk BS wheel hub? Then just do a wavetrac or qualfie and gears on my stock r129 diff? How much lower (numerically)could I go with my case that has 3.69? Can I get to the low 3s

I'm sure this has all been covered but it's so much to take in
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  #12  
Old 08-18-2018, 12:07 AM
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Quote:
Originally Posted by whipplem104

The cool thing is it looks like you could use the w140 axles with the standard w129 case that is in the car stock. Just have your flanges drilled and broached for the larger stubs. I just want more options when I am done and not to do it twice. And I know nothing will break ever.
Quote:
Originally Posted by Justin300sl View Post
Can I use the large w140 axles with the clk BS wheel hub? Then just do a wavetrac or qualfie and gears on my stock r129 diff?
A while back I looked at using the W140 ( large bearing / spline ) rear hub turning it down to fit in a R129 / W210 / W202 bearing. I'd be really uncomfortable with how little material will be left.

At high loads, the hubs internal spline will try to expand, this could expand the bearing's inner race causing the bearing to fail.

With so little material where the flange transitions to the bearing, the hub could break off leaving the spline and nut still intact.

Attached are some bearing sizes.
Attached Thumbnails
Srt8 diff in r129-rear_84_45_39.jpg   Srt8 diff in r129-rear_85_45_41.jpg   Srt8 diff in r129-rear_88_49_46.jpg  
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  #13  
Old 08-18-2018, 12:22 AM
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I just noticed something. . .

The large S class bearing ( 41235000 ) was supposedly used in some 98 - 03 E320 ( I'm guessing wagons W210 )

The small bearing ( 41290005E ) was used on some 94 - 03 E320 W124 / W210 probably just sedans.

With all of this there may be a possibility of a large spline / large bearing upright that will fit a R129. car-part.com does not show a direct interchange but that could be from a brake shield or caliper mounting.
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  #14  
Old 08-18-2018, 12:44 AM
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The problem with using off the shelf axles is the length. It just so happened the c63 axles were close enough form my application and that I was also widening the rear track a bit. I have spacers on my wheels and then with the wider rear end setup I can take the spacers off.
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  #15  
Old 08-18-2018, 12:56 AM
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Quote:
Originally Posted by whipplem104 View Post
I ordered and received a CLK63 BS rear wheel flange. I was going to have some others modified but could not find a good donor. Drilling and broaching the originals was very expensive although not a lot more than the BS ones. The good news is that it is a direct replacement for the w124 flange into the bearing and offsets are the same etc. Just 27 spline. So that also means that the BS axles should work or at least all the comparable parts. I have not gotten an axle length measurement although I am working on getting a set. C63 axles may work also. The lenth is right but the stub into the flange is a little different.
Also I have the differential mounted in the standard w124 subframe instead of the v8 one. Alignment on the one mount is perfect just a little clearance needed to push the diff back a little. Will end up make a new mount once the other rear one is done.
You could probably find a rear cover that works if you tried hard enough. Or just modify the rear cover to fit the subframe. Just some time to make new mounts not very much money so I will work with what I have got.
I will post some picks once I have the diff mounts done.
Quote:
Originally Posted by whipplem104 View Post
I finally got around to pressing in the wheel bearings and flanges and sliding it together for the 1st time with all the parts. Everything fits and the axles are perfect. So all that is left is welding up the subframe for the mounts and bracing and then the driveshaft. I will wait till next spring for the driveshaft and the install because I am saving for my diesel project but I do not think there will be any problems with this at all. So in conclusion the clk63 BS wheel flanges{note the bolts are the larger 14mm instead of the 12mm} and stock bearing with a little machine work on the spindles to clear for the C63 axles are what is needed. The differential fits in the stock front mount location and one of the rear mounts is lined up properly but has to be clearanced and the other has to be made. I am going to box up the subframe after the mounts are welded in.
I did this on the standard subframe not the v8 ones. I am going to reinforce some other areas in the subframe also to make sure that I do not twist or break it. I have a 2800 stall converter for the 722.6 coming so I should be able to launch pretty hard. If not I will go bigger on the stall eventually.

The 140 axle fits 129 diff, but 27 spline on wheel side.
The CLK BS 27 spline hub fits stock 124 wheel bearing.

But are the 27 spline 140 and 27 spline CLK BS the same size? And is the 140 axle the same length as 124 axle?

If so, the best combo to me looks like:
210 mm 129 diff case
Wavetrac or qualfie
140 axles
CLK BS flanges
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