It was suggested to me by a shop manager to load my FRC when I take it in for a tire alignment.

He said to put 150 lbs of sandbags in the passenger seat, driver seat, and one 50 lb bag in the trunk.

Is this something you guys typically do?

Thanks!

 

ive sat in my cars while they're aligned, but never heard of preloading with specific numbers. i guess it's the same logic though. 95% of my time in my car, im solo, so i just balance it for me. and the wife doesnt weigh so much that she terribly alters the suspension

 

Hey yeah I was kind of curious about that myself. The manager said that the spec from GM told him to load the driver and passenger seat... then he puts another sand bag in the trunk for good measure.

But I was kind of thinking along the lines you were speaking.

 

There's no mention of adding any body loading in the Corvette shop manual section on wheel alignment.

I would ask this manager where he got his "secret spec".

 

I would load it as it would be loaded when you're expecting max handling. In my case, that would be putting weight in the driver's seat to simulate me only in the car. I don't see myself picking up the GF and a couple of bags of concrete mix on my way out of the pits onto the track...

 

I think this more of a personal opinion of this manager really.We have have over the years preloaded several cars whose owners were quite ,let's say hefty,and who drove alone mostly.

 

What's wrong with just saying plain old FAT?

 

LOL.One fella who drove,of all things a Plymouth Horizon,when he sat it the car,the camber changed 4 degrees.Jenny Craig would have run away in fright!

 

That's a good one!

 

They always have me sit in mine at the shop that I go to.

 

Yeah I cannot verify what he said but when I was racing that's how we set em up.

I suppose maybe he assumed the person always carried golf gear, and his wife with him.

 

No secret spec

at least putting your wt in the driver seat is common and the preferred method.

Now dont forget to inflate your tires to the HOT running PSI. Not the cold 32 psi. for the alignment.

Then let the air out and back to the cold psi after the alignment is done

 

Oh interesting... Can you please elaborate?

I know when tires heat up the PSI increases PV = nRT And when I was racing open wheel cars we actually had IR sensors to detect heat of the wheels for such things...

But what's your process for hot cold alignment on the Vette? And what are the hot / cold PSI specs?

 

i just got weird looks @ work lol'ing at this.

 

Cold psi is normally 32 psi. Most ppl dont run to to hard, soo inflate toe 35-36 psi then do the alignment.

Makes a difference

Do my own alignments the old fashion way: String, laser level, triangles, 24" level, and camber plates.

Hoosier cold 22 psi front 20 psi rear HOT 28 psi front, 28 psi rear

ride height difference is almost 3/8" between cold and HOT tire pressures.

takes me all day but will be more accurate then a Hunter.

and if you think about it, you drive your car is what you wan the alignment set too. not the COLD tire pressures.

 

Ah that's bad a$$ lol I'd love to learn more about how you do that...

I used to race open wheel cars.... FSAE if you've ever heard of it. We did all our alignments on our own of course.

On race day we'd level the trailor. Then we'd set the racecar on 4 highly calibrated scales that pivot freely. Lastly we had magnetic levels that attached to fix points on the rim / hub consistently on all tires. And readout of weight distribution from all four tires on a computer screen.

Who ever would be racing the next day would be sitting in the cockpit of the racecar. We'd stay up all night and perfectly align the car. It TOOK FOREVER lol

What kind of levels do you use? We had a simple level with a large magnet on it. The scales were for full size cars like corvettes but cost a bloody fortune. I know they were THOUSANDS of dollars for the set of 4.

I'll be honestest, a few years ago I created a tire pressure sensor rebuild manual. It's been selling on the internet basically making me a couple hundred bucks a year if that.

Well I lost my job as an engineer and I'm currently loosing my house and most all my stuff. Been working very hard for past 2 years to try and find more work but it's difficult to find much of anything.

Now I've decided to focus on the corvette materials. I'm writing more guides as people are starting to come to me with more questions. My next guide will include tire pressure rebuild along with a bunch of stuff related to tire care and replacement.

I actually feel guilty doing research on here as everybody is so helpful. I really want to give back but am going flat broke

 

Whole bunch of DYI for the racer and tech savvy guys

http://www.davidfarmerstuff.com/

From a former SpeedWorld GT racer too

Lots of good parts here too

http://hardbarusa.com/hardbar/index.php?cPath=25

I use the Alignment plates and digital camber gauge

 

I completely understand where you're going with this, but for most of the people here, this is a bit extreme. I highly doubt that the "runflat" tires that many people use, would have that much sidewall deflection between hot and cold tire pressures.

 

I seriously doubt your string and level system is as accurate as a modern laser alignment,which are accurate to a tenth of a degree.But even those are only as good as the tech who is doing the alignment.

 

.....as well as the calibration of the alignment rack.


On the other hand, it makes you wonder how we all survived the past, with a person "observing" a bubble level on a caster camber gauge, or a thin light beam, on a toe-in scale!!