Standalone ASD controller? - PeachParts Mercedes-Benz Forum

fha772 · #1 01-27-2013, 05:13 AM

Hi all,

I've been looking at various ideas to fit a LSD to my W123.
What I was thinking was, is it possible to fit an ASD diff out of a W201, or W124, into my car?
I know I can fit it, and have a very limited LSD, but is it possible to wire in the controller to work the ASD system?

Cheers Frank.

97 SL320 · #2 01-27-2013, 09:27 AM

I'd probably use a manual hydraulic pressure regulator rather than an electronic system. You would have a dial to adjust the amount of limited slip.

fha772 · #3 01-27-2013, 10:22 AM

Thanks, for the idea.

How exactly does the ASD work?
From what I understand, the hydraulics put pressure on the LSD clutch packs, to increase the amount of lock.
Is this right?
So, if I used a pressure regulator I could add as much lock as I'll need.

I don't think I really need 100% lock, just enough to stop the wheel spin, coming out of corners.
I don't need much lock when setting off, as this car is for track use, and hardly ever used for drag runs, so I don't think I'll need loads of lock, but definately more than the unassisted 25-30%, that the ASD has.

Could I use the power steering pump to power it, or would I be better fitting a SLS pump to the camshaft?

97 SL320 · #4 01-27-2013, 01:47 PM

The SLS pump is more for ride height so pressures and volume are likely higher that your needs. It would work but is a lot of effort.

ASD units have a very small 2nd pump inside the power steering pump. Look around the 124performance web site for PS pump repair info.

Since you only need a small volume of fluid to make things happen and holding that pressure to maintains lock up, a hydraulic cylinder used as a plunger might do the trick. ( The rod of the cylinder would be attached to a lever or screw to move it.)

There are some considerations with running the ASD full time. The locking pressure is applied from the outside in. ( axle flanges ) there might be a problem with actuator wear at high speeds. The solution might be as simple as adding a thrust bearing but, I have not gotten a hold of one to inspect.

I want to do this to my 91 300SL that is turning into a track day car.

Supposedly someone makes a spring block to increase the limited slip function. An alternate method would be to add a hardened ship under the clutch pack. This works but needs inspection from time to time and reshimmed to maintain clutch drag. ( A spring block does this automatically )

fha772 · #5 01-27-2013, 04:18 PM

I suppose it is possible to use a brake/clutch master cylinder, with a screw adjustment, to apply a set amount of pressure.

In trying to stop my car doing this out of every slow corner...

97 SL320 · #6 01-27-2013, 06:26 PM

You would have to use a MC with the proper seals as oil will swell standard brake rubber. ( and brake fluid will swell regular rubber which is why auto trans fix in a can smells like brake fluid. ).Too large a rear sway bar will cause the inner tire to lift and spin so take up most of your roll stiffness at the front.

I'm pretty sure the old aluminum bodied screw cap Lockeed MC could be gotten with this type of seal. ( MG Midget type )

Also try some oval track racing places for a remote weight jack. These are hydraulic systems that fit under the suspension springs and are used to change ride height on the go. A pump unit from one of these would work.
Do you have a industrial surplus store in your end of the world? In the US we have places like " Burdens Surplus Center " and many military surplus places. These would be a good source for odd bits. ( though many of the mil surp places just deal with clothes, tents and such. )

whipplem104 · #7 01-27-2013, 11:46 PM

You can just tap the P/S pump. Tee in on the pressure side and run a solenoid. ASD locks up solid though. So if you did want to regulate it you could just put a adjustable pressure regulator on like suggested. Still just tap the P/S line. It will not last very long though if you are racing with it. The clutches will just burn up. These are good for limited use in snowy conditions. They are expensive and a pain to rebuild.