[z06fun]

So for Stock class Solo2, how does the LSS adjustable ride height play into the rule for after market shocks about having to have a shock that matches the OEM distance from the mounting point to the spring perch so as not allow an altered ride hieght due to the spring perch in a different location from the stock part.

For a car equiped with the LSS, if we were to buy an after market shock that had an adjustable perch, would have to make sure that it matched one of the locations of the OEM LSS shock? I think we do but, how closely? The rule doesnt state how closely, but it would seem reasonable that something within +-2mm would be legal. But if +-2.5mm is ok then you could buy an aftermarket shock with a traditional adjustable perch and place the perch anywhere within the range of the OEM LSS perch, meaning you could corner balance the car.

What do you all think?

 

[elise77]

Ok....When you go to an aftermarket shock you have to match the pearch height....Period..... +/- 2 mm is a ton....However....here is where it gets interesting.

The shop manual will have a tolerance on the location of the pearch as well as the spring tolerance......I am not going to tell you how to do this but you can play with both tolerance for your favor....AND ITS on the up and up...

If you are looking for a locating pearch tolerance.... Standard machinging practice is +/- 0.005 INCHES..... +/- 2 mm is 0.080 +/- People will put you in the shed for that......

Later

 

[z06fun]

Being able to use the spring tolerance to your advantage as far as corner balancing would require you to have lots of OEM springs available right? What I mean is, say you have a spring that is on the short end of the spring length spec, you can't put in a shim to bring it to the long end (or some place in the middle) of the spec can you? Any shim would be considered part of the perch, not the spring right?
Although maybe if you welded a shim to the spring, then maybe it would be part of the spring. Am I catching your drift...
Or maybe it would be easier to take a spring that is at the long end of the length spec and slightly grind the end of it shorter, but still keeping it within the length spec.

Are you allowed to modify a part if it is still in spec after the modification? I would think for changing a spring length you could because *in theory* if you had many different oem springs availble to you they would all be at slighlty different lengths and you could eventually find one that is the exact length you need (assuming it not way out at the ends of the distribution)

 

[Randy Chase]

You can (and some people do) sift through a lot of springs to find the one that works best for you. You can not modify a spring, even if the modification is such that it is still in a factory range.

 

[elise77]

Ok, I am not sure the best way to explain this......

The easy part...sorry you can not modify a stock part...You can not take a tall spring and make it a spec part....that is asking for trouble.....

BUT....You can purchase a dozen springs and pick the 4 that are the shortest....( As long as they are within factory spec) and install the short ones.....

Then Yes, in theory you can use a flat washer on top of a threaded pearch and call it part of the pearch.....if you wanted to ....but the location must be in the stock location. Since Lotus has like 4 locations on the shock....You have 4 choices to locate the pearch.

An example. I had a 350Z....stock rear camber was neg 2.2 per side....IT PUSHED LIKE A TRUCK..... I purchases 10 sets of lower control arms. The shortest ones were almost a full 1/4 in shorter than what I had on the car...Within NISSAN SPEC.... I put them in and my rear camber went to neg -.3.....and my push went away....PLUS I still had adjustment room on the cam bolts...In the original configuration I could only get down to neg 1.5 camber...

I hope that helps.....You are entering a gray area....for every yes you can do that you will get one no you can not.....writing a letter is the proper way to check it out....

 

[John Stimson]

Not all factory service manuals provide dimensional specs and tolerances for parts. My Miata manuals don't include such information. Only the body shop manual has frame dimensions.

Is there any other way to obtain the specs from the manufacturer?

 

[elise77]

Not that I know of....

Sorry

 

[z06fun]

I was thinking the same thing, like I don't recall seeing in any of my shop manuals, a spec for the spring perch location from the mount hole or whatever. I had always assumed you would have to set an aftermarket adjustable spring perch by laying next to the stock part and matching it up if the shop manual didn't have actual dimensions.

Elise 77, thats interesting Nissan quality control you found lol. I never would have though the part to part variations for a control arm would be that much. Interesting indeed. Also interesting that you had to REMOVE neg camber for a stock class car lol.

Thanks for all info, I didn't think you were allowed to modify a spring but just wanted to make sure.

 

[elise77]

Yah, the 350z comes with sooooo much neg camber in the rear and none up front.....

It makes the car from the factory push like a dump truck....Thank GOD it has a motor to rotate the car around the front wheels.

By pulling rear camber out and changing the rear toe the car actually handles really well.....If it only had a real diff. Nissan put that viscous limited slip in it.....280 lb/ft of torque just smoked the inside wheel at will.....If it had a quaife or even a real clutch type....I would still be running it in BS....and I even might have walked away from this 2 1/2 year waiting list that I have been on...

later