66 230SL Dashpots--are they obtainable?

[dsayars]

My '66 230SL has an old-fashioned carburetor style dashpot that is worn out, no damping. I have not found this dashpot offered anywhere or even mentioned anywhere online, and the only dashpot I've found discussed on this site is vacuum dashpot that seems to have have been installed only on later models. This seems odd, because with a non-working one like mine, the car is barely drivable, stalling, with rpm dropping to near zero when the foot goes off the gas for low speed maneuvers and frequently stalling.  Questions:

1. Does anyone have one of these to sell or know where I can find one?

2. There are only a handful of dashpots of this kind available anymore, for any kind of car. Does anyone know of workable substitute?

Thanks for any information you can offer.

-Dave

[Tomnistuff]

Hi Dave,

I have the same problem with my 67 230SL.  I`ve been searching for quite a while and have found only one that looks exactly like ours and is CAD plated.  I have not bought it because Amazon.com says they ship only inside the US and to APO addresses.  I live in Canada.   If you google "Pierburg Dashpot", you will find it for about $55 US.  

I did find another at Rock Auto (Part No. DP301), but it does not appear to be CAD plated and the threaded stud looks a little short.  I will ask them to measure the full length to see if it will work for me.

I think almost any of them can be adjusted to work on our cars since they only "catch" the closing throttle and close it gently to avoid stalls due to idle speed undershoots caused by high vacuum spikes.  A fuel/air mixture stops burning if the vacuum is too high and the engine will stall before the combustion can recover.  (I don't think you want a lecture on fuel/air mixture combustibility threshold as a function of fuel/air ratio and manifold absolute pressure.  The combustibility threshold is characterized by a complicated 3D surface.)

Good luck and wish me luck here in Canada.

Tom Kizer

[66andBlue]

Measure dimensions "A" and "B" of your old dashpot as described here: http://www.sl113.org/forums/index.php?topic=16057.msg110949#msg110949
and then call carburetor shops (http://www.thecarburetorshop.com/Dashpots.htm) or this ebay seller - http://myworld.ebay.com/a.e.auto/ (search his shop for dashpots) - and ask for a replacement that might fit yours.

[Tomnistuff]

Thanks Alfred for the tips.  Have you noticed all the restrictions they place on the sale of the dashpots?  I know they might negotiate if I knew exactly what I want, but doing it from outside the country is a bit difficult.  That CAD plated one in the photo I attached is for most SAAB 900s and 9000s between 1986 and 1993.  I`m going to run to my local take-it-off-yourself junk yard (one of the biggest recyclers in Canada) and see if I can find one.  Since they`re CAD plated, they should still be in good shape after only 20 years.

Tom Kizer

[dsayars]

Thanks Tom, Alfred-

Tom, I went to the link on the "reference" topic Alfred mentioned and you said there you'd bought one in Februry at autopartsobsolete.com? Since you're still looking, Itake it it didn't work for you?

One thing I notice from the photos on the reference page page is that the dashpots are shorter than mine and the mounting brackets are different. You can see from my picture thatmy mounting bracket is longer and cradle-shaped, with a hole in the rear fror the threaded end and a guide in the front for the nose. This puts the A length at about 2-2/2", B at about 1-1/4. If yours is a 230, it may be the same, though one of those pictured is also identified as a 230.

I've come across the Pierburg, but I've found no indication that it comes in sizes. An attempt at a universal dashpot?

Saw your last post and I'd meantime decided I should hit the junckyards, too. My only fear is that even they won't have anything old enough. Most of the cars old enough to have dashpots are now the steel in new cars.

Out of curiosity. "Dashpot" is usually defined as an oil-filled damper, making a shock-absorber techincally a dashpot. But the round, flat chamber on these suggest sa diaphagm. Do you know what the innards of these are?

-Dave

[badali]

Here is the one on my 1966 230 SL.  It looks different than yours.  My car was built in Oct 1965.  There are wires going to mine.

[stickandrudderman]

Badali,
the device you have is an entirely different device to the one in question although the purposes are similar.

[badali]

stickandrudderman,
Is mine different since I have an automatic transmission?  Or because of when it was built?

[jacovdw]

Brad,

Yours is different because of the automatic transmission and not because of when it was built.
It is only the manual transmission cars that has the dashpot, as depicted in photos posted earlier on this thread.

[Tomnistuff]

Tom, I went to the link on the "reference" topic Alfred mentioned and you said there you'd bought one in Februry at autopartsobsolete.com? Since you're still looking, Itake it it didn't work for you?
-Dave

Dave, here is my story on the one I bought from autopartsobsolete.com.  Before buying it, I emailed them and asked if the one in the photo is the exact one they are selling and not just a representation.  The answer was, and I cut and pasted their words for accuracy, "the same exact one you see in the photo is the same one you will get thanks bob."  I bought it.  It wasn`t.  It also had a tear in the rubber dust cover.  Shipping was too much to send it back, so I just stuck it on the shelf and started trying again.  BEWARE!  Seldom are the photos used really taken of the part that is being sold by anybody, especially those on Ebay.  It`s too much work for them to use individual photos and they know that shipping is expensive, so we are unlikely to send it back.  In addition, I`m outside the country and have little recourse.  As the ancient Romans used to say, "caveat emptor."  It`s also why I prefer buying local if possible.

When I go to the junk yard, I`ll have my old one in my pocket to compare to.

Note that the Pierburg one is for many 86 to 93 SAAB 900s and 9000s.

Tom Kizer

[Tomnistuff]

I was really getting frustrated over such a simple part.
U.S. parts places that had the right dashpot wouldn`t ship to Canada.
Only one Canadian place had something that would work, after I did some heavy duty photograph scaling and calculating to verify that it could be adjusted to fit.  Their price was $22 plus 15% taxes, but their shipping was $35.  I refuse to be ripped off.  I like getting a deal, not paying more than double.
The junk yard was a bust.  Two hours looking and nothing.
Today, I went to a NAPA parts place.  They spent 30 minutes trying to help me but to no avail.  They did, however, suggest an obscure but local carburetor rebuild shop and gave me the address.  The guy at the shop disassembled a new, out of the box 1970s Dodge 318 cu. in. Carter BBD Carburetor (they don`t have much demand for them) and sold me the CAD plated one in the photo for $10 (cash, no taxes).  He`s made a friend for life.  I adjusted the nuts on the new dashpot and my old dashpot, and verified that the new one can be adjusted to work properly.  He has made a friend for life.

As far as I can tell, it is the same as Rock Auto part no. DP301, which fits 1973 - 79 Dodge/Plymouth 318 225 BBD 2 bbl.  That's also the one that had expensive shipping.  I don't know if Rock Auto's is CAD plated.

At least I accomplished a couple of things today.

Tom Kizer

[stickandrudderman]

Yours is different because of the automatic transmission and not because of when it was built.

I'm not entirely sure that is correct but would be interested to see some data.
I have a customer with a 1966 250SE (M129) with auto trans that has the diaphragm installed instead of the idle solenoid.

[Tomnistuff]

When I was in the U.S. auto industry during the years of dashpots and idle solenoids (we called them throttle kickers), the idle solenoids were usually needed to avoid an idle speed sag or even a stall when the automatic transmission was engaged from neutral or park.  The load of the torque converter on a cold engine, resulting in an idle sag and an increase in manifold pressure (loss of vacuum) resulted in condensation in the cold intake manifold, and a consequent "leaning" of the fuel/air mixture and an immediate stall.  The idle solenoid (throttle kicker) kicked the throttle open just a little to compensate for the torque converter load and kept the idle relatively the same.  A "sloppy" or high slip torque converter sometimes didn't need the idle solenoid because the engagement shock on the engine was less than with a tight (low slip) torque converter.

The dashpot served a different purpose in that it prevented high vacuum incombustibility stalls on quick closed throttles, and a few years later, the resulting high hydrocarbon emissions that came with high vacuum decelerations.  The dashpot will still work for that purpose on an auto transmission, but it will do nothing to aid transmission engagement (or even air conditioning engagement) stalls.  There were even a few idle solenoids that had a dashpot stuck on the end of them.  They performed both functions.

Isn't this fun now?  It wasn't at the time.  

Tom Kizer