Upgrading w123 with 1st generation w126 brakes - Page 4 - PeachParts Mercedes-Benz Forum

tobybul · #46 03-05-2009, 03:07 PM

How would I know if I'm ordering 1st gen vs 2nd gen calipers?

Chad300tdt · #47 03-05-2009, 03:29 PM

Quote:

Originally Posted by tobybul

How would I know if I'm ordering 1st gen vs 2nd gen calipers?

Any w126 up to and including 1985 is first generation. 1986 and up is second generation.

I ordered calipers for a 1985 300SD for my upgrade.

SurfRodder · #48 04-25-2009, 03:30 AM

Quote:

Originally Posted by winmutt

To do it right you need the sheet metal backing plate from the second gen, this is the only real difference between the first and second gen W126 brakes.

You need the whole spindle... The 2nd gen spindle sticks out further (~1") than the early 126/123 version to accommodate the larger rotor/hub. the backing plate is also different, as stated, as are the calipers and rotor, hub may be the same as early 126, i dunno.
I just pulled all the stuff to do the swap on my car. Im gonna powdercoat all the hard parts and replace all the software prior to the swap. Basically I pulled the spindle from a late 126, took the steering knuckle off another 123 and bolted it to the later spindle(yes, the spindles are nearly identical outside of the longer snout for the larger rotor/hub ass'y).
anyway, i also pulled all the rest of the hardware (LCA, etc.) from a 123 so I could have everything ready to swap out in a day. i picked up the rotors(really good shape, ill have 'em cleaned up locally) and grabbed the calipers while i was at it (part yard core is much nicer than local auto parts core charge)
the rotors are significantly bigger than the 123s and they are also vented. now i just gotta find some bigger rims that i like...

my123ca · #49 04-25-2009, 08:15 PM

Quote:

Originally Posted by winmutt

I am considering also using the booster from the snd gen W126 but haven't gotten there yet.

Have you done this yet? Will the booster from a 2nd gen w126 bolt directly to the w123? They are smaller in diameter. Which mastercylinder will you be using?

tobybul · #50 05-06-2009, 08:16 AM

Installed my 126 brake upgrade yesterday. Used made in Germany Balo rotors and reman ATE calipers.

Everything came together just fine. No need to disassemble the bearing housing after you remove the hub from the 123 rotor. Just transfer everything to the 126 rotor.

Put new hoses. Had to blow out one caliper. It was plugged up with something as it would not bleed.

Only thing I noticed after driving it was the rotor was scraping the inner dust cover. I thnk the dust cover maybe a bit banged up and hitting the rotors. I just ordered new ones from the dealer ($16 ea).

Also, I may have to bleed the lines again. I did not see much fluid coming out of the right-rear brake. Any thoughts on this. I'm using a power bleeder. Also feels mushy.

Oh and another thing I noticed recently about brake pads. They seem overly thick. I had to sand them down to get them in the calipers.

winmutt · #51 05-06-2009, 08:40 AM

Quote:

Originally Posted by my123ca

Have you done this yet? Will the booster from a 2nd gen w126 bolt directly to the w123? They are smaller in diameter. Which mastercylinder will you be using?

Smaller in diameter but longer. There is more volume in there I am pretty sure. Haven't done it yet, when I put ABS on I will use the snd gen one. I would really like to find some r107 4 pots.

#52 05-06-2009, 08:45 AM

Length only matters in how many pumps it has before boost drops off. Plate/diaphram surface area determines power.

tobybul · #53 05-11-2009, 07:48 AM

On the rotor upgrade, I noticed that the Mintex brake pads were quite thick and made the rotors drag and squeel. They were at least 1/2" thick and were quite snug in the calipers.

I tried sanding them down but unless you can sand them evenly or squarely, contact on the rotors can be affected. I replaced the pads with AZ pads

which were at least 1/8" thinner and it worked much better. Plus their are LLT

.

macdoe · #54 08-29-2010, 04:53 PM

Quote:

Originally Posted by SurfRodder

You need the whole spindle... The 2nd gen spindle sticks out further (~1") than the early 126/123 version to accommodate the larger rotor/hub. the backing plate is also different, as stated, as are the calipers and rotor, hub may be the same as early 126, i dunno.
I just pulled all the stuff to do the swap on my car. Im gonna powdercoat all the hard parts and replace all the software prior to the swap. Basically I pulled the spindle from a late 126, took the steering knuckle off another 123 and bolted it to the later spindle(yes, the spindles are nearly identical outside of the longer snout for the larger rotor/hub ass'y).
anyway, i also pulled all the rest of the hardware (LCA, etc.) from a 123 so I could have everything ready to swap out in a day. i picked up the rotors(really good shape, ill have 'em cleaned up locally) and grabbed the calipers while i was at it (part yard core is much nicer than local auto parts core charge)
the rotors are significantly bigger than the 123s and they are also vented. now i just gotta find some bigger rims that i like...

Hello, was wondering if you need to change the whole spindle for the second generation brake swap? or is the only problem the size of wheel needs to be upsized to 15" and backing plate

JHZR2 · #55 12-11-2010, 03:13 PM

Do you buy the hoses for the w123 or the w126 when doing the upgrade?

my123ca · #56 12-12-2010, 08:31 AM

I used W123 hoses. I didnt replace the hoses when i did the upgrade.

winmutt · #57 12-13-2010, 08:13 AM

I had replace my w123 hoses when I got the car and then did the swap later.

macdoe · #58 06-06-2011, 01:03 AM

Hello, On our 1985 300TD we did this second gen. front brake upgrade due to some pulsing in the brake pedal when applying the brakes. The harder you pushed the pedal the worse the pulsing became. I thought the front calipers were sticking or a rotor was warped. This phenomenon started in the winter after making a high speed stop. It was cold that day so I figured that a warped rotor was possible. Good excuse to upgrade...

After doing the upgrade, we thought that our pulsing problems would be solved, but, the pulsing was exactly the same...so... I figured to take the master cylinder off, and found the power brake booster half full of brake fluid. It seems that since the booster is full of fluid that it would be a good time to change the booster as well as the m/c.

I still have the donor car that we got the front brakes from to do the larger brake upgrade and would like to use the booster and m/c from that car, but am not sure if it will work.
Donor car is a 1988 420sel and am planning to swap the booster and m/c onto a 1985 300TD.

Will this work? I did notice that the w126 (88' 420sel) has anti-lock brakes. The 85' 300TD does not have anti-lock brakes.

Maybe in this case the master cylinder from the w126 will not swap over but am still wondering if the power booster will fit. The (w126) newer booster seems longer, since it appears to have dual chambers? I wonder if the steel lines on the 85' 300TD will be a problem or if I could just re-bend them slightly to fit . Wondering who has done this booster swap?
Thanks.

macdoe · #59 06-06-2011, 01:41 PM

With my big brake upgrade, I did not swap out the spindles...my w123 spindles accepted the w126 second gen hubs and rotors with no problems. I did not separate the disc from the hub, but rather just swapped the hubs/discs and bearings right onto the w123 spindle. The length left over to put the spindle nut onto my spindles was the same??? The larger backing plates bolted right on and will interchange from one side to the other. I am not sure what car is being refered to as having a 1" longer spindle but I did not encounter this. I swapped the brakes from a 1988 420 sel onto a 1985 300TD.
One problem I thought we were going to have was when the 15 inch rims were put on and the car lowered it looked like the tie rods were going to rub the inside of the tires just barely. It took actually backing the car out of the garage and hitting a few bumps for the suspension to settle and then the tires had plenty of clearance from the tie rods, or at least what was there for clearance before the swap. I think we have to watch which tires to put onto the front of these cars for that reason.

Anyone have experience in swapping the w126 m/c and power booster onto a w123?

vstech · #60 06-06-2011, 04:56 PM

what rims did you use?
usually the lower tie rod arm hits the wheels on 124 rims... and the hub won't fit behind the mb star....