W123 ABS Swap - PeachParts Mercedes-Benz Forum

disqo · #1 03-18-2017, 03:29 PM

Yes, it is possible! My first ‘85 300TD was a Euro model with ABS but it was ate up with rust. Eventually I replaced it with a federal model ‘85 300 TD and swapped over all of the Euro parts that I could from the original car. I saved the wiring harness and all the ABS related parts from the original car and finally got around to doing the big swap to have a ABS on my present car. It wasn't too unpleasant and the result seems great although I have not had the chance yet to actually test out the ABS function. If you ever want to do this please be aware that you will need a complete donor car to be sure that you have all of the parts and that I did swap the entire wiring harness from the original car from front to back over to my present car. This allowed for me to use the ABS and manual climate control as well as the euro fog lights and door switch. I still have a bit of tidying to do under the hood but I am very pleased overall.

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disqo · #2 03-18-2017, 03:30 PM

Original Car

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disqo · #3 03-18-2017, 03:32 PM

Mocking Things Up

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disqo · #4 03-18-2017, 03:33 PM

Installed

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greazzer · #5 03-18-2017, 03:35 PM

When you did the swap, were there mounting holes, or slots for the mounting hardware and fasteners in the receiving car? Or, did you have to drill, et cet.?

Assuming you have the donor, side-by-side, and nothing breaks or gets lost, how long is the swap? EG, is this a leisurely one-day event or a steady weekend ordeal?

disqo · #6 03-18-2017, 03:39 PM

The ABS pump sits on a little tower and there are four bolts that mount the tower to the car. The upper two bolts that mount higher on the inner fender already have the holes there. The lower two bolts I did have to drill through the body of the car. I did a bunch of rust proofing work when I drilled the holes so that I won't have problems like the original car did. Definitely at least a weekend long ordeal. I spent about a week of evenings working on it. Pulling the old brake lines and replacing them with the ABS brake lines is tedious it does require some fiddling. I also wanted to be extra careful to clean out any contaminants in the original brake lines and spent a pretty good bit of time bleeding the lines and pump with a pressure bleeder.

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greazzer · #7 03-18-2017, 05:25 PM

Very nice work indeed !

ROLLGUY · #8 03-19-2017, 11:08 AM

Did you replace the ENTIRE wire harness? If so, that alone could take days. Practically the entire interior including dash has to be removed. I have removed several wire harnesses, but never replaced one.

disqo · #9 03-19-2017, 11:23 AM

Sorry, I should have been more clear. I replaced the entire wire harness a few years ago knowing that eventually I would want ABS and I wanted the manual climate control. It essentially required removing the entire interior and the entire original harness from the headlights to the taillights. That process probably also took me about a week of work. I took lots of pictures when I removed the original harness so that I knew where all of the wires routed. I am sure it is possible to separate the wires for just the ABS, but they are bundled with everything else from the factory and it would require cutting all of the sheathing for the harness to separate just that system. The ABS from the factory does require one additional hole through the firewall on the driver's side which I drilled through when I did the harness. Since doing the harness a few years ago the ABS specific wiring has just been hanging out in the engine bay waiting for me to install the pump. Installing the pump and the hard brake lines is what I spent about a week of evenings doing.

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ROLLGUY · #10 03-19-2017, 11:41 AM

Quote:

Originally Posted by disqo

Sorry, I should have been more clear. I replaced the entire wire harness a few years ago knowing that eventually I would want ABS and I wanted the manual climate control. It essentially required removing the entire interior and the entire original harness from the headlights to the taillights. That process probably also took me about a week of work. I took lots of pictures when I removed the original harness so that I knew where all of the wires routed. I am sure it is possible to separate the wires for just the ABS, but they are bundled with everything else from the factory and it would require cutting all of the sheathing for the harness to separate just that system. The ABS from the factory does require one additional hole through the firewall on the driver's side which I drilled through when I did the harness. Since doing the harness a few years ago the ABS specific wiring has just been hanging out in the engine bay waiting for me to install the pump. Installing the pump and the hard brake lines is what I spent about a week of evenings doing.

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I imagine just installing the ABS wiring would would be just as hard as replacing the complete harness. There is also a wire going back to the diff (needs to have the ABS diff to work), so removing the interior is a must either way. You did the right thing by removing the interior. That is a big job, and most folks would not attempt it. Thumbs up to you!

disqo · #11 03-19-2017, 11:49 AM

It did also require swapping the diff so that I would have the ABS sensor and I did the big brake upgrade from a later W126 complete with the spindles, rotors, and ABS sensors.

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greazzer · #12 03-19-2017, 12:05 PM

So, for ABS, this is actually a major operation: removal of entire interior is necessary plus a W126 differential as well as brakes ... plus finding a donor car. Double thumbs-up to you for doing this !!!!!!!