After this season ends, I plan on sending my Koni Sports to Truechoice for a rebuild. I was going to have them custom valved and go stiffer in the rear with spring rate (I use 400F/300R springs) but the lot I now run in my region (13 out of 20 or so autocrosses per season) is worse than the one we were evicted from; thus negating my desire for a stiffer shock valving when softer is now the way to go due to the crappy surface.

My question though surrounds the nitrogen gas charging in the shock. I believe it's there for oil temp. stability, yet a lot of stock class cars have it removed making the shock hydraulic only... And considering the soft spring rates most stock class cars have, wouldn't that overwork the shock oil and cause it to overheat?

So is the removal of the gas even beneficial for STS?

Or should I just have the gas charge retained when I get the rebuild?

Anthony "Mario" Crea

 

that my friend is a very tough question...but I will take a stab at it (don't take my opinion as that of an expert, this is just my guess).

In Street Prepared classes where people run really high spring rates the piston in the shock is moving faster (imagine two bouncy *****, one soft, one hard....when you drop them, which one will bounce higher, and keep bouncing?...bad analogy, I know, but it helped me) also with the stiffer springs the piston has less distance to travel and theoritically is only working on a smaller amount of fluid (this all hinges on the ability of the hydraulic oil to dissappate <sp> heat) in stock class where you have to run stock springs that are softer you get more travel outta the piston, and therefore the heat build-up in the fluid is spread out over more area. that's what I think.

again remember that I don't know this as a fact...it's just my guess...it may all be complete BS. I'm sure someone who actually knows will have the answer b/c now I'm curious to find out if my theory is right!

 

I've been told that some stock cars can achieve a slightly lower ride height by running degassed shocks. However, they will need to be rebuilt more frequently. Two guys I know run the same type of car. One is running hydraulic shocks, while the other is on gas-charged shocks. The first car seems to have more bump valving in the shocks, while the second car's gas-charged shocks *seem* to work better over small bumps that don't move the hydraulic-setup's shock pistons as much and allows a little wheel hop. Seems like the difference between a progressive and linear-rate spring. One allows a small degree of squish before stiffening up while the other is stiff all the way through. However, I'm not POSITIVE that this isn't a case where the hydraulic shocks need to have some bump taken out, but it looks like the gas-charged ones have a little more cushion, and may well be a benefit on bumpy lots.

 

This is an interesting topic. I'm going to be sending my stock shocks off to Carerra Custom Engineering to have them gutted and fitted with some Koni Inserts. From what i've found, the Koni Mac strut inserts (8610 and 8611) are twin tube hydraulic shocks, and not high pressure gas-charged monotube. I dont know enough about the differences in shock technology to know which will be better for me. However, i do know that fitting a Koni DA insert on my car will be alot better than what i'm dealing with now. The inserts run about $225/ea, and machine time on the shox will be about $100 for each.

RJ

 

So it's probably best just to retain it. Done. Thanks everyone.

Anthony "Mario" Crea