I've come across some nos Bilsteins, still in their boxes, but maybe a couple decades old. Are they likely to preform as new, or be in need of renewal of rubber parts, etc? Thanks, Paul
Do shock absorbers have a shelf life?
- Thread starter twistinglane
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restart
Well-Known Member
Were they stored upright? That may make a difference.
Just removed rear Standard HD Bilsteins from my coupe. They were installed in 1999 with very low mileage since; my mechanic bench-tested them and they seem to be OK, but I've opted for new shocks anyway...
Will Bilstein rebuild them?
Might be a simple gas recharge if needed since never used.
Might be a simple gas recharge if needed since never used.
'69 2800cs
Well-Known Member
The Bilsteins in my car are probably 25 years old with 100K miles. They still dampen nicely, though surely new ones would be better.
Given the labor to install and the low cost of the shocks, I'd buy brand new.
Given the labor to install and the low cost of the shocks, I'd buy brand new.
restart
Well-Known Member
Ah so....thank you. Good to know. I have been hauling this box of shocks around for years trying to keep it upright. I am going to go kick it over right now!:-?
gwittman
Well-Known Member
That seems to indicate there is no hydraulics in Bilstein shocks. Can you clarify.
For Bilsteins the dampening effect is handled by gas compression vs. the hydraulic fluid displaced in the OEM shock. This is why a different spring is required when changing to Bilsteins because the ride height is affected due to the longer travel and/or compression rate of the Bilstein.
TodB
Well-Known Member
Are there not two varieties, HD which can be used with regular/OEM springs and Sports which require shorter springs? Both have the same dampening specs though some think the Sport are stiffer.
FWIW, I checked around quite a bit and ALL the suppliers I spoke with said the HDs are correct for a stock CS; the Sports are stiffer and don't match up in the databases.
gwittman
Well-Known Member
I am no shock expert but it is my understanding that the nitrogen pressure is on the oil to prevent the oil from aerating while going through the dampening orifices due to velocity and heat. The hydraulic action is still there but is improved with the nitrogen pressure. Yes, Bilsteins do increase ride height a little due to the nitrogen pressure but there are nitrogen pressure shocks that don't effect ride height because they have a different design. The Carrera shocks on my race car are an example of this design.
I did not change springs when I switched to Bilsteins shocks. It did lift the car about 1/2 inch but that was acceptable to me.
I too am no 'shock/strut' expert, but everything I've read about 'gas filled' shocks over the past ~40 years has indicated exactly what gwittman stated.
The dampening of the shock is done via valves and hydraulic fluid. The 'gas' is a dry gas (nitrogen, argon, etc) stored at the top of the assembly to minimize the tendency for the liquid fluid to 'foam' which reduces it's viscosity. Theoretically, the gas pressure maintains the fluid in it's full liquid form (gases are technically considered fluids as well) thus keeping the shock dampening to a more constant level during severe movement of the liquid fluid through the valves. Some drivers like Bilsteins, some like Konis (which are not gas filled, but are adjustable for dampening). I've primarily been in the Koni camp for my BMW's and Porsche 928's (2 of which were track cars) and MB sports cars. I use Bilstein comfort shocks on my MB 560 SEC. Never experienced any noticeable loss of dampening in either brands.
The dampening of the shock is done via valves and hydraulic fluid. The 'gas' is a dry gas (nitrogen, argon, etc) stored at the top of the assembly to minimize the tendency for the liquid fluid to 'foam' which reduces it's viscosity. Theoretically, the gas pressure maintains the fluid in it's full liquid form (gases are technically considered fluids as well) thus keeping the shock dampening to a more constant level during severe movement of the liquid fluid through the valves. Some drivers like Bilsteins, some like Konis (which are not gas filled, but are adjustable for dampening). I've primarily been in the Koni camp for my BMW's and Porsche 928's (2 of which were track cars) and MB sports cars. I use Bilstein comfort shocks on my MB 560 SEC. Never experienced any noticeable loss of dampening in either brands.
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My experience with Bilstein HDs was no increase in ride height.
I'm running Bilstein HDs. The front of my coupe is lowered 7/16ths of an inch via CN springs while running stock springs in the rear.
When I had the HDs installed, there was no increase in ride height.
When I had the HDs installed, there was no increase in ride height.
Isn't the ride height also a function of the damper rings?
You mean spring pads? Yes, and also tired springs vs. new springs.
restart
Well-Known Member
restart,
Aha - those are spring stiffeners. Jack up the car so the helical coils of the springs are spread apart, insert two of these at 180 degrees apart on both sides, then lower the car. The springs will be much stiffer, and the car may be raised slightly. I 'made' things similar to this when I started driving my '88 Porsche 928 with stock springs/shocks on the road race tracks. Really reduced the body roll in corners.
Eventually, replaced springs with stiffer ones and had a set of Koni shocks modified (by Koni) so they could be adjusted externally in about 30 seconds each from full soft to full firm. Used full soft for driving to/from tracks (up to 700 miles each way) and turned to nearly full firm while on the track. That combination along with stiffer sway bars essentially eliminated body roll.
Aha - those are spring stiffeners. Jack up the car so the helical coils of the springs are spread apart, insert two of these at 180 degrees apart on both sides, then lower the car. The springs will be much stiffer, and the car may be raised slightly. I 'made' things similar to this when I started driving my '88 Porsche 928 with stock springs/shocks on the road race tracks. Really reduced the body roll in corners.
Eventually, replaced springs with stiffer ones and had a set of Koni shocks modified (by Koni) so they could be adjusted externally in about 30 seconds each from full soft to full firm. Used full soft for driving to/from tracks (up to 700 miles each way) and turned to nearly full firm while on the track. That combination along with stiffer sway bars essentially eliminated body roll.