Jamie,
I'm also towing a sailboat ('74 Catalina 22)- I highly recommend one as
it's cheap and very well made. It only weighs about 2200lbs, but the
trailer and gear bring it to about 3500. I'm currently towing it with a
beat up '87 Volvo 740 turbo wagon that tows it very well, but I think
the W124 would be more comfortable and fuel efficient. I am also curious
also about the Mercedes' ability to pull up a ramp. The Volvo has been
able to pull the boat up even the steepest of ramps without issues. It
has an automatic with 2.45:1 1st gear, and a 3.73:1 rear axle with an
Eaton G80 locker- and the engine makes 187 ft*lb (253 Nm) of torque at
2900 rpm. Does anyone have the gear ratio and torque specs for the W124?
Is it available with a locking or limited slip rear differential? I
would assume if it has just as low or lower gears, a locker or LSD, and
as much torque then climbing the ramp shouldn't be an issue.
I am mostly worried about the transmission or brakes in the W124 burning
up going over mountains.
For pulling up a ramp, I think one could calculate reasonably well the
steepest ramp you could pull a given boat up given (1) the torque of the
engine at the stall speed of the torque converter, (2) the ratio of 1st
gear times the rear differential, (3) the tire outside diameter, and (4)
the combined weight of the entire rig. It's #1 that I expect to be
hardest to find...
Searching online, I found that my Volvo has a 2700rpm stall speed torque
converter and makes about 175 ft*lb of torque at this rpm - or about
1599 ft*lb at the rear axle. With a 12.5in tire radius, this is about
1535 lbs of forward thrust. Fully loaded will all of my gear, the car
and boat probably weigh 7,000lbs.
So:
Force = weight * sin(ramp angle)
ramp angle = arcsin(force/weight) = 0.22 radians = 12.61 degrees
So in theory I can probably pull up a 12.61 degree ramp. According to
BoatUS, most ramps are designed for a 6:1 slope (arctan(1/6)=9.46
degrees), so I have a good extra margin of ability, although without a
locking diff traction would probably come into play first. If someone
can help me find those same numbers for the W124 300TD, I will redo the
calculation for it.
Tyler
Jaime Kopchinski wrote:
Hi Tyler,John gives excellent information... I just installed a factory-like
euro hitch on my 95 E320 wagon, with rated 2100kg load. Thats 4600lbs! I'm
still searching for my towable toy (a sailboat), but I'm looking at for
3500lbs as my maximum. Its quite a bit of weight. In preparation for
towing that weight, I've already gone over my brakes (ended up replacing
just about everything) and changing my trans fluid and filter. My cooling
system is in good shape, with a recent radiator. My only concern is the
car's ability to pull the boat and trailer up a launch ramp.
With some preventative maintenance, common sense, and good trailer brakes, I
think you'll be fine.
Jaime
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