• Hi Guest!
    You can help ensure that British Car Forum (BCF) continues to provide a great place to engage in the British car hobby! If you find BCF a beneficial community, please consider supporting our efforts with a subscription.
    There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Subscribers don't see this gawd-aweful banner
Tips
Tips

Armstrong lever-arm dampeners - clean & replace

Share this page

tosoutherncars

tosoutherncars

Jedi Knight
Offline
Hi all,

Just took delivery of my latest eBay win - a used pair of front Armstrong dampeners. (From stepping on the bumper of my 1500, it looks like one is working, and the other isn't.)

I plan on giving the 'new' set a thorough clean & flush, and then swapping them onto the car (to minimize downtime). Maybe at that point I'll send the current ones to Peter for rebuilding... I guess we'll see how the 'new' ones perform. I thought I'd document the process.

So far... got one shock on the bench. They both look very clean. Arm had resistance both ways, but resistance was not completely even / smooth, and the arm wanted to bind at the limits of travel (at either end). Pulling the cover plate, the shock contained oil, no dried gunk, no strong smell.

Dumped the used oil, and refilled through open 'body' with kerosene. moved arm through range, and clouds of silver sediment came flowing out of the valves / holes. Dump, fill, work arm back & forth, repeat. About 20 times, until no further sediment noted. Throughout, the motion of the arm became more fluid, constant and predictable.

Now I can actually feel the valve working... very slow & gentle efforts can move the lever arm, but shoving it quickly causes it to dampen and stiffen up. Again, that's just with kerosene in it.

Next steps... cut new gasket, reassemble, refill and fit to car. I'll try to remember to post some pictures, and notes on performance.
 
Nice, one to go maybe.
 
Re: Armstrong lever-arm dampeners - clean & replac

tosoutherncars said:
Hi all,
Dumped the used oil, and refilled through open 'body' with kerosene. moved arm through range, and clouds of silver sediment came flowing out of the valves / holes. Dump, fill, work arm back & forth, repeat.
Click to expand...
I wonder where the "clouds of silver sediment" came from. Wear of the internal parts - or?
D
 
Re: Armstrong lever-arm dampeners - clean & replac

Dave Russell said:
I wonder where the "clouds of silver sediment" came from. Wear of the internal parts - or?
D
Click to expand...

There was so much of it, I don't think there'd be any pistons left if it were particulate from bore wear. Here's hoping it was just sediment of some sort.
 
Re: Armstrong lever-arm dampeners - clean & replac

Nope, it is the bores wearing. Just like an engine. The catch you feel at the limit of travel is the ridge at the tops of the bores, like an engine. No issue, though, as the lever should never travel that far if the rebound rubbers are in place. Serious quantities of the zinc particles indicates a loose wristpin is machining a nice groove in the bore (just like an engine). That is noticed when there is no resistance in mid-stroke, as the fluid is bypassing the piston.

I'll have cut-aways and pieces at the Ozarks tech seminar "Shocks and Awe" Or "Care and feeding of your Armstrongs".

Peter c.
 
Re: Armstrong lever-arm dampeners - clean & replac

Very interesting, thanks Peter! Do you overbore and fit larger pistons in such cases? Or is it a case of remove & replace?
 
Re: Armstrong lever-arm dampeners - clean & replac

tosoutherncars said:
Very interesting, thanks Peter! Do you overbore and fit larger pistons in such cases? Or is it a case of remove & replace?
Click to expand...

We usually have enough cores for Spridget fronts that we don't need to repair them. On less readily available "cores" we sleeve the bores to standard with brass sleeves. (ahem....just like an engine;-)

Have a great weekend, and DON'T overfill!. Just to the gasket surface is enough.

Peter
 
Back
Top