Rear shock and spring help.

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Edward Schubert
Posts: 110
Joined: September 10th, 2007, 5:06 pm

Rear shock and spring help.

Post by Edward Schubert »

I have a 1984 Zink/Citation with a zero row rear. The orginal shock is 13" eye to eye. The spring is 12" (it takes a gorilla to compress). I have no idea what the shock is nor the spring rating. It keeping with the spirit of FV's I am looking for a simple low cost replacement. How about a dbl. adjustable Pro shock, single adjustable or simply a neutral comp/rebound shock as a place for me to start vs. the high dollar Penske all seem to be using. Also what spring rate should I look for? The 12" deal is a bear to compress...could I go with 10"? Does any of this make sense or do I need to get out the credit card and go for the Penske deal?

If there is anyone in the Va. Tidewater area (Newport News, Williamsburg, Norfolk) area that would like to come by my house (Willamsburg) and give me some advise I would welcome it. I will meet you at an event and do grunt work as a trade off.

Thanks/Ed Schubert

edschubert@noland.com 757-692-1181
Ed Schubert
Zink/Citation 18B
edschubert@live.com
757-692-1181
butchdeer
Posts: 208
Joined: June 24th, 2006, 4:06 pm

Re: Rear shock and spring help.

Post by butchdeer »

We have used a ARS shock for this purpose (non adjutable but revalveable) valved for a zero roll available from SR Racing/ Racecarsupply .com for aproximatly $225.00 with coil over hardware. You can use a 10 inch spring that will be easy to install available in several spring rates for about $60.00 each. There are cheaper shocks but they are not revalvable and most are 50/50 valvings. Call Butch or Jim to discuss your choices at http://www.racecarsupply.com
Butch 859-963-8318 or Jim 859-252-2496
FV since1963
Mad Dog Racing
Posts: 68
Joined: July 18th, 2007, 11:58 am

Re: Rear shock and spring help.

Post by Mad Dog Racing »

Don't know how much I can help, but I'll add an uninformed 2 cents. The 12-inch spring seems long, but I don't know what your rear geometry looks like. The spring should let the adjuster start on the shock threads, otherwise it's usually too long.

There are some older threads about rear end geometry here that sets off my snooze alarm, but might help you. No two people seem to agree on how to set up a rear end, but there are a couple of things to avoid. There are still a few quick cars with a single fixed-rate shock on the back. The single-rate shock is always a compromise, the adjustable shock can be tuned closer to you and from track to track.

My 93 Citation came with a 10-inch, 2 1/4 ID x 150# spring and a 2-way Fox shock. Fox is kind of gone now, so I have a 2-way Penske after breaking the Fox. On the other hand, I have a zero-roll kit for a 70's Zink that has a 10-inch, 2 1/2 ID x 225# spring on a Carrera shock. I took it all off when I converted the car back to z-bar for vintage. That Carrera is a rear shock, not the front shock rate, something like a 3345 or a 3355. Don't know what that interchanges to in another brand.

Butch's reply sounds about right, the new Carreras are 50-50 only.
Ed Womer
Posts: 245
Joined: July 19th, 2006, 8:53 am

Re: Rear shock and spring help.

Post by Ed Womer »

Ed,

Mad Dog is right about this being a boring subject but the one thing you need to find out for anyone to be able to help you is what is called motion ratio. Simply it is for a set amount of wheel movement how much does the shock move. Typically it is done with 1" of wheel movement and how much the shock moves. Unfortunatly you need to remove the spring from the shock and raise the wheel up 1" and measure the change in the shock center distance. On the zero roll system on my cars it is 1" of wheel movement to 1/2" of shock movement.

So with a motion ratio you can see what car that yours is close to so you have a starting point for valving the shock.

Ed
butchdeer
Posts: 208
Joined: June 24th, 2006, 4:06 pm

Re: Rear shock and spring help.

Post by butchdeer »

If you do not know the motion ratio you can post a picture of the Zero Roll kit. I may know what you need if it is one of the roughfly 200 kits we sold for zinks to convert them to zero roll. Others also made conversion kits some were copies of ours and some were different.
Butch
racecarsupply.com
FV since1963
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