108 rear suspension compensator: what is it? - PeachParts Mercedes-Benz Forum

locry · #1 10-23-2005, 06:01 AM

i have a 68 250s w a 615 engine, manual tranny, this is my first vintage mercedes. I have no idea how the rear suspension works, what is the compensator for? and did 108s come with disc or drum brakes?
thanks! can't wait to restore this beauty.

Mark DiSilvestro · #2 10-23-2005, 09:55 AM

Congratulations on finding a stick-shift version.
That would've been my choice.

The hydropneumatic compensating spring was fitted to the W108 and other cars that used the swing-axle rear suspension. It replaced the mechanical compensating coil-spring originally fitted above the differential on the Fintail cars. The hydropneumatic compensating spring is gas-pressurised and I believe it's supposed to provide a degree of auto-level contol when the car is heavily loaded.
Unfortunately, after about 10 years or so, the gas leaks out, usually causing the rear end to sag and new ones are priced at around the $1000+ range, though some claim to have found bargain-priced replacements on eBay.
I prefer to replace them with a $250 compensating coil-spring kit and trade the supposed auto-level feature for improved long-term reliability.

Your 250S should have 4-wheel disc brakes, with small drum brakes fitted inside the rear brake discs to provide for the emergency brake.

Happy Motoring, Mark

#3 10-23-2005, 02:11 PM

It should also have a Six Cylinder Carb, engine 127 I believe not a 615 which is a 4 banger Diesel .

djd · #4 10-23-2005, 09:50 PM

Welcome - I have a '67 250S, gas/automatic. They're nice cars.

locry · #5 10-24-2005, 09:53 AM

yup, it HAD a 6 cylinder i believe, but that was swapped out with a 615 diesel with a manual tranny. Cool huh?

Mark, my 108 has the coil spring already, i think my model came with it as standard equipment. Anyway, i would still want to know how everything is connected. And how it actually compensates for load. Right now the car has too much positive(?) camber, the top of the wheels looking from the rear are pointing outwards \ /. how and where do i adjust that?

anybody have pics of the rear underside?

thanks again guys.

Mark DiSilvestro · #6 10-24-2005, 04:47 PM

Everything I've seen and read indicates that all W108 cars came with the hydropneumatic compensator. Yours could have been converted to the spring type many years ago, as I doubt the original hydro-compensator would have lasted this long. The spring type doesn't adjust for load. As I understand it, the spring simply compensates for having softer springs, under normal load.
As to adjusting for too much positive camber in the rear suspension, it sounds like you're riding too high. Normally, there are/were rubber pads on both the rear springs and the compensater spring which are/were availible in different thicknesses to compensate for ride hight and loadng applications. Perhaps when the original hydro-compensator failed and the rear sagged, someone changed something in the rear springs to jack it up. I recently replaced the bad hydro-compenstor on a '66 250S and had to remove some aftermarket booster wedges that someone jammed in the rear springs. Now it sits level with normal camber.

Happy Motoring, Mark

locry · #7 10-25-2005, 01:42 AM

ok, that sounds simple enough. i'm guessing there aren't any concentric bushings to adjust huh? just the spring spacers to zero in on perfect camber?

again many thanks, i really want to revive this car.