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What spring rates is everyone running?

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Well, I figured it out. I'm going to run 175lb. in front and 200lb. out back. Oh, yes I do have ST sway bars, poly bushings, and (soon to come) coilovers icon_biggrin.gif . Now I have to read about strut sectioning, and find out what Tokico shocks I have to buy, by that I mean for which car the shocks are intended for. Thanks everyone for all the replies. icon_smile.gif

 

!M!

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On 1/10/2002 at 6:42 AM, jeromio said:

I'm the odd man out with "soft" springs - 150/175. I marvel at those running stiffer springs. This is with an L28, but I believe my LS1 will weigh slightly less.

 

My car is crazy, punishing stiff. No track for me yet. Handles great IMO, but I do wish it wasn't so rough over expansion joints, etc.

 

For real. I'm at 225/280 on my coilovers. It is miserable on the street over bumps. 280z with L28ET.  It would handle great on smooth track, but over potholes/bumps, I feel like I actually lose out on handling because it bounces me to the other side of the road.

Edited by AlbatrossCafe

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78 280z. Bought the TTT setup and had 250 front , 300 rear on konis. Felt too soft, swapped to 300 up front. It is slightly stiff but feels much better than the 250s. 250s are way too light for the rear. The shocks are probably around 2/3 compressed at ride height. Just bought 350s, haven't installed them to know if they are going to be too stiff, but at 1620 rear weight with me, spare, full tank, etc. it should be around 1/3 compressed at ride height. 

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On 1/11/2002 at 12:28 AM, Guest Rick Johnson said:

Regarding the comment about the suspension being stiff on square edges orr expansion joints.

 

I use 165 # front and 190# rear spring rates. I have a 1" front bar and a 3/4" rear bar. The secret to a plush ride on square edges is to have compliance (or a spring of some sort) in series with the shock absorber or strut in our case. They call this tailored damping. It allows the shocks to be stiff enough to control roll etc. but provides some cushion from the initial shock of contacting the square edge on the road. In practice this compliance comes from rubber control arm bushings and strut mounts. The rubber acts as the spring in series with the shock.

 

The most critical axis for isolation from smaller square edge road disturbances is horizontal in the rearward direction. This allows the wheels to move rearward immediately while the strut gets around to allowing the wheel to travel upwards. On our 240z's, the two most critical locations for horizontal rearward isolation are the tension rod mounts to the frame and the forward rear control arm mounts. Typically people put hard urethane or even worse, nylon, in these locations. Converting back to the rubber in these two locations will make a big difference in ride comfort. ( I actually shimmed the rubber tension rod bushings to preload them which minimized tension rod movement.) It was still a huge improvement over the nylon pieces I had there.

 

I can imagine that the hard core racers are laughing at these lower spring rates and talk of road imput isolation, but if you value your ride comfort like I do, these turned out to be reasonable compromises.

 

I was running 4k (224#) springs front and 5k (280#) rear. I just bought 3k (168#) to put on the front and move my 4k to the rear. I thought the stiffness was springs.

 

I had no idea a concept like you mentioned with the tension rods even existed. If the softer spring rates don't fix my harsh ride over expansion joints, I'll definitely give your idea a shot next. Thanks.

 

btw yes I know I am replying to a 16 year-old post lol

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3 hours ago, AlbatrossCafe said:

 

I was running 4k (224#) springs front and 5k (280#) rear. I just bought 3k (168#) to put on the front and move my 4k to the rear. I thought the stiffness was springs.

 

I had no idea a concept like you mentioned with the tension rods even existed. If the softer spring rates don't fix my harsh ride over expansion joints, I'll definitely give your idea a shot next. Thanks.

 

btw yes I know I am replying to a 16 year-old post lol

 

Ride comfort is a systemic attribute, it's not just springs or bushings or...

 

Spring rates set ride frequency which sets the amount of force, thus acceleration (F=ma), your body will see from road inputs. These accelerations are tuned via dampers and isolators. This is mostly reflected in how "stiff" the car feels when hitting bumps and dips in the road. Then there's the matter of impact harshness from road imperfections. This is more of a noise and resonance issue. This is dealt with via something called compliance. The bushings responsible for controlling the amount of longitudinal compliance were already mentioned in the post you found. This is all assuming you're not running out of travel on your suspension.

 

Fixing harshness is going to involve making sure you have soft compliance bushings and top mounts. If you're running coilovers with a solid top mount (ball joint), that's not helping.

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16 minutes ago, Leon said:

Fixing harshness is going to involve making sure you have soft compliance bushings and top mounts. If you're running coilovers with a solid top mount (ball joint), that's not helping.

Yep... coilovers with hard top plate (no more pillow mount), poly bushings, and nylon at the tension rod lol. I have everything going against me. Makes more sense now, at least.

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Also for what it's worth, you'd be amazed how "smooth" a well performing suspension can be. Stiff might feel sporty, but remember that the goal is to maintain contact over the road surface, not skip over it. Also don't forget that spring rates are acting as a force between two points. Required spring rate to reach max travel target is subject to weight of wheel package as well as chassis weight. Then there's also suspension geometey which is a huge reason some chassis run wildly different rates. A 400# spring on a 240sx might feel soft but absolutely brutal on a s30.

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4 hours ago, HuD 91gt said:

A little off topic, but in regards to the post above.

 

What is everyone opinion of this setup thezstore sells.  Tension control cup system. It was one of the first

items I did to my suspension and I’ve always found my car to be very stiff.

 

http://www.thezstore.com/page/TZS/PROD/classic20j/23-4190

 

 

Leave the T/C rod bushings stock rubber.  The T/C  rod can snap under load with hard bushings such as aluminum or polyurethane. There are pictures on Hybridz.

 

All of my suspension bushings are polyurethane except for the rubber T/C bushings. Ride is razer sharp, but not harsh

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