I've read on this site numerous posts saying we rockcrawlers don't need remote reseviors on our 2" coilovers b/c we aren't spending enough time at speed to heat them up and require a remote res.

Well, I was all set to just order up some 14" and 16" travel 2" emulsions so I figured I'd call around and get some input from a few manufacturers.

Only got a chance to talk to King......

Here's what they had to say about reseviors:

You don't need reseviors to keep the shock cool on a rockcrawler. You need them on a long travel shock (like a 14") b/c without them, the shock has a huge air pocket in the cylinder to allow the piston to displace the fluid. The problem then is that there is insufficient oil in the shock. What the resevior really does is allow the air pocket to be stored in the res. (figuratively speaking) and then the shock can hold more oil in the cylinder.

Admittedly, I'm no genius; nor am I an expert on coilovers but this doesn't make sense to me.

My thought is that if I'm running a 14" C/O with 5.5" of up travel and 8.5" of downtravel (40/60) than you don't need a huge air pocket since the most the shaft will ever travel into the cylinder is 5.5".

Do any of you have opinions on this or can explain it better?

Thanks in advance.
Sean

Oops.....just found a flaw in my logic. If I have 5.5" of uptravel there's already 8.5" of piston inside the cylinder that is displacing fluid.

So, I guess my question is: Does King make a valid point?

Do I need a resevior?

Thanks,
Sean

Here's a simple explination, say you extend the shaft of the shock and fill the shock with oil. The shock will not compress because there is no where for the oil to go, it is hydraulic locked. If you underfill the shock by the volume of the shaft, the area x the stroke, the shock will then compress, but now you have an air pocket in the shock, this is an emulsion shock. To have the shock perform the best you want to seperate the air from the oil inside the shock, you do this by using a dividing piston, one side is open to the shock body and shock oil and the other side has air/nitrogen. As the shock compresses the dividing piston moves as the shaft displaces oil in the shock body, it moves the dividing piston an amount in proportion to the dividing piston area and shaft area. You can either put the dividing piston in the top of the shock like Bilstein or edelbrocks or you can put it in a remote reservoir. The advantage of a remote reservoir is you can have a shorter shock because the space taken up by the divider piston is in the reservoir, not in the shock body. Having a remote reservoir will give you more oil volume and more heat capacity, but not that much and not enough that you need it on a rock crawler. If you dont want a reservoir, fox and sway a way only have emulsion shocks, bilstein has dividing pistions in the shock body and I'm not sure King sells them without reservoirs.

Goat,
Thank you SO much for that very clear explanation. Sounds like the best thing for me is probably just a regular emulsion.

Thanks again. I really appreciate the help.

Take care,
Sean