Thread: oil springs?
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Old 03-16-2019, 10:58 AM   #11
Joe K
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Join Date: Jul 2010
Location: Cow Hampshire
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Default Re: oil springs?

I am reminded of my 1978 Chevrolet Isuzu Pickup. You remember those days, 6' bed, 5 speeds on the floor, no A/C, roll down crank windows. And once you disabled the "air pump" (sprays compressed air at the exhaust valves to cool them and combust any CO gases remaining) 40+ miles per gallon.

The truck was a POS - except for cheap. A rust-bucket in waiting - but more because of the rear bed which was produced in the US and applied here rather than the actual Japanese sourced cab/engine/drivetrain.

In 1979 I'm driving it to South Boston from Cape Cod, up the treacherous Route 3 all the way. A road of MANY potholes at that time. And hammering my spine into the seat-back brace which bent under my 200lbs plus (at that time.)

I resolved I would "improve" the ride - loads of firewood in the back worked well to settle it down - until some South Boston miscreant stole the green hardwood out of the back of the truck. What does one do with a quarter ton of green hardwood in South Boston?

Resolving again to "soften" the ride, I removed the rear leaf springs and dismounted and "cleaned" each spring - reassembling the spring pac with lubricious quantities of Never-Seize - which in those days was oil-based rather than today's water based formulation.

Time came for my next ride - and WHAT A RIDE it was without any weight in the car. The poor little truck was ALL OVER THE ROAD in cartoonish gallops. Other drivers sensed the handling inadequacy of the truck and the (apparent) stupidity of the driver and kept a wide berth. So embarrassing.

I did arrive at my destination in one piece - and was thankful for a post 9 p.m. return to Cape Cod when the commuting traffic had abated.

Some more weight helped - but I clued into the REAL problem which is that a spring/dashpot combination has an "optimal" displacement return resistance. Too much resistance makes the system return slow and uses up time which can allow further displacement - too little resistance makes the system return to center faster - but causes rebound which delays actual return to "center."

For each spring/dashpot/weight combination there is an "optimal damping" condition with quickest return to center and maximum control.

In the case of my truck, I REMOVED the Never-Seize, and replaced the rear shocks with Mom&Pop Monroe replacement shocks. Afterwards, the car was still uncomfortable to take to Boston (what small pickup is not?) but at least I had control of the vehicle along the way.

More weight in a vehicle can "soften" the ride - but at some expense in control and handling. With the weight one delays that "return to center" and potentially causes rebound with the additional weight. For a truck, the return to center position delay caused by weight might not be a bad thing since a truck is "oversprung/over resisted" by design. (i.e. stiff ride) I.e. It's designed to carry a load.

The original Model A design included lubrication as part of the spring design. Hence Ford offering the spring covers as a "useful accessory." But it also requires the correct shocks, set at the correct resistance for the weight of the car and the contents. Ford was fairly advanced in anticipating this design asset and allowing for adjustment.

MANY Model As on the road are "barnyard relics" which haven't had either a shock applied OR lubricated springs since before WWII. In these cases (My 29 CC pickup an example) the resistance of the spring leaves sliding across each other may substitute for the lack of a Houdaille shock unit resistance. Lubricating the spring MAY, and probably will make the ride/control worse.

Joe K
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Last edited by Joe K; 03-16-2019 at 11:10 AM.
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