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Performance rear end options?

395 Views 12 Replies 7 Participants Last post by  Ls420
Hi All I have a 5.3 Turbo LS swapped 420 sel. I'm looking to see what performance rear end build kits or entire assemblies are available and what they can hold in order to attempt to not have to 8.8 swap the car. If I can't find one then I'll have to chop the floor for ladder bars and install a 8.8. However I'm trying to see if there is anything available bolt in that can support 700 horsepower and 600 or so torque. Let me know! thanks.
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1986 560SEC, 1988 300E, 1991 500SL
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I’m running a Wavetrac LSD centre and hopefully will be making north of 700HP. I’m thinking the weakest link in my drive line is now the axles, time will tell.
 

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I wanna see some photos of the motor swap! Wavetrac is a good option, but as Brento mentions, the halfshafts might become the weakest link overall. They'll hold up for a while, I'm sure, but I'd imagine after prolonged stressing, especially if you're doing aggressive launches, you'll eventually twist them into a pair of twizzlers.
 

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95 SL600
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No sense in trying to make any w126 rear end try to deal with 700hp. There are lots of gear options, although they aren’t very strong differentials and axles. Go to classicjalopy.com for either a 2.82, 3.07 or 3.46 ratio. I believe the gear sets can be interchanged between 123 126 and 107 models and possibly more but not sure in that. Yours appears to be a 2.24 gen 2 rear.
I wouldn’t put too much effort into this. As you will have to make an adapter for the rear yoke, and get a 1 piece driveshaft made to that length. Do yourself a favor and look at the axle stub that goes into the wheel hub and make a decision from there. It’s not robust and neither are the axles.
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1986 560SEC, 1988 300E, 1991 500SL
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If the half shafts do appear to be the weak link there are options to fabricate from 4140 or something similar and I believe the W140 shafts could be made to work which are a larger diameter with some modification/machining. I don't know what the stock propeller shaft can handle but I upgraded mine to the S55 one out of my donor car. If you ditch the flex disc at the differential, you can replace with a universal joint for more strength, but unless you are running another universal joint at the transmission I'd stick with a two-piece shaft instead of single piece. If you retain the rear flex disc which has only 3 bolts I believe this will become the weak link in your driveline.
 

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1987 Mercedes Benz SEL 420 Ls 5.3 turbo swapped
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Discussion Starter · #8 ·
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For those asking foro a picture of it. I bought it originally to use the engine out of it and swap into one of my mustangs. But then saw how far along the build was once I bought it that I decided to finish it and restore the car. Thank you for your comments I'll look into the options you guys provided. Thanks.
 

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1987 Mercedes Benz SEL 420 Ls 5.3 turbo swapped
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Discussion Starter · #10 ·
I bought it setup this way. However i do have a intercooler kit to install on it and it is going to be a e85 car on 20 pounds of boost. Should be good for at least 700 to the wheels. Already have a 4l60 in it that I'll be doing a 4l80 for. Driveshaft side was already figured out by previous owner but I'll definitely be going 8.8 after speaking with bicylindrico. Car is ran on holly terminator x max. As for the radiator. It's a trunk mount setup with 2011 coyote f150 fans and a electric waterpump to push the water from the radiator to the engine. The engine water pump handles the flow in and out and the electric waterpump handles the line flow.
 

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1987 Mercedes Benz SEL 420 Ls 5.3 turbo swapped
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Discussion Starter · #11 ·
Sucks to know there is only a handful of us trying to push the platform into the insane level of power. i've been looking at s600 cars to buy to boost as well and keep the original engine.
 

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Good luck! I've torn up 9.25 inch GM truck axles with a lot less power than that!
 

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1987 Mercedes Benz SEL 420 Ls 5.3 turbo swapped
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Discussion Starter · #13 ·
Good luck! I've torn up 9.25 inch GM truck axles with a lot less power than that!
In my exp doing 8.8 swaps. 35 spline axles and a good center pumpkin will just about take everything you can throw at it if you do the right mods. My 135i bmw is 8.8 swapped pushing 850 and my drag car makes 14xx on kill map with its twin turbo 7.3 and glide. My daily driver mustang makes 600 on a supercharged setup
 
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