Hey guys,

I have always wanted to do my own alignment, and after having done lots of research I am just about ready to go. I do have a question though.

I know all about the tape measure method to set toe, but I want to give the string method a shot first. For those who have done it this way, where is the center line on a C6? Or do you measure from another area to set up your string?

Froggy does a nice video on You Tube how he does the string method on his C5Z, but he measures right off the hubs to set the string. I thought the rear hub sticks out more than the front one, and if so wouldn't throw your strings off?

Any guidance would be greatly appreciated

 

It does not matter, it is squaring the string to the car. I've never seen this string thing before, really simple & cool. I think the way I would do it is get the front on the ramps like he has done, then with a floor jack lift the rear & get it on the same level.

Did you find how he is doing camber & caster?

 

Bob, BEZ06 just did a thread on DIY alignment. He is the TPMS guru and a racer and all around smart guy...check that one out.

 

He has another video where he does the camber. That is much simpler to do that the toe.

If the rear hub sticks out farther than the front hub, and you measure the same distance from each hub, the string cannot be squared?

 

Sure it can. You just need it to be parallel, the same distance from each front wheel, and the same distance from each rear wheel.

 

What's the point of a string alignment if you're not working off the center of the car? Parallel strings (to each other?) give you no more information than tape measures.

It is likely that both the F and R subframes are not centered on the car which will change your camber settings and hub to string distance.

If you are using a camber kit on a C6 base model you will not be able to have equal camber in the rear unless the subframe is centered as there is no adjustment on the R upper A-arm.

Personally, if you want a really precise alignment you need to get the subframes centered and work out from there. Otherwise, except what's good enough and spend your time driving.

--Dan

 

Parallel strings lets you have the front & rear wheels tracking together, can't do that with a tape measure.

 

Assuming the subframes aren't centered, but the car is symmetrical around the center, couldn't you set the strings equidistant on each side from some known location on the chassis?

You just need 4 points (front and rear, each side) and the strings remain parallel, but I imagine that this would be adequate to set the alignment for most anyone. It should even allow you to center the subframes.

I've been around road racing for awhile, and even at the professional level, I still see strings and camber plates in the paddock more than the portable laser systems. Good enough I guess.

I suspect on a road car with a soft suspension and bushings everywhere that that kind of precision isn't required anyway, with everything moving around under load - and I know I'm not enough driver to tell the difference in 0.01 degrees of anything.

Have you aligned lots of corvettes? And if so - are the subframes frequently misaligned significantly? Just curious.

 

Perhaps, but I think it still depends on what you are using as a reference point. I use a laser to set thrust angles to zero.

Setting the strings parallel is easy enough but if the subframes are still offset I don't see what using strings gains.

It's not that I've aligned that many Corvettes but that I have worked with mine a lot and with friend's cars. I noticed the offset subframes when moving to Pfadt Camber Plates and installing them for others. Having a fixed lower a-arm mount lets you easily see that one side is different from the other.

On the rear of a base C6 there is the fixed upper a-arm mount. The only camber adjustment is on the bottom using the plates. If you need to use different plates from side-to-side the subframe isn't centered.

On the front you can also tell as you use a set size plate on both bolts on the lower a-arm and then set camber/caster using shims on the top a-arm. Again, if the number of shims side-to-side is different for the same camber reading the subframe is not centered. I have seen them off by two notches.

Having the OEM eccentric bolts on the lower a-arms masks any offset (within reason) but does show up when it is not possible to get the same maximum camber setting side-to-side. The factory will also have a different number of washers on the front (and rear for Z06) bolts behind the upper a-arms to aid alignment.

My idea of using strings (without ever have done so) is that the strings are parallel to the centerline of the car and that you are looking at measurements to the hub face or tire that are equal side-to-side. Obviously, front and rear, having different track width, will differ. Diagonal distances would also be the same when measured.

Can't swear to it but that's what I picture. I also freely admit that I am not good enough to feel minor differences in alignment and am not OCD enough to care. Plus, I've seen far too many top racers in autox whip out a tape measure and change their settings to close-enough.

--Dan

 

Do you have a link??

BJK

 

Sure, I just searched his posts for the key word "alignment"


http://forums.corvetteforum.com/c6-t...mine-pics.html

http://forums.corvetteforum.com/auto...r-degrees.html

 

Read that one already, but it has nothing to do with my original post. Froggy was nice enough to answer my question for me, here are his replies to my messages:

FROGGY: "Strings are exact parallel to center line of car. This is done with the Smart Strings (precision) bars. Or another means that you decide on. There are grooves in the bars for the strings to rest in.

This is critical, down to at LEAST 32nd inch if not 64th.

Distance string to hub on each AXLE must be equal. I measure to the ridge of the wheel bearing in front and to the axle stub in back.

Front axle is a little less track then back axle. It should measure this way. Does not matter as you are parallel to CENTERLINE.

So, yes, rear hubs are out a little more, of course this is sort of relative as it depends on what you are measuring to from the string to what?? It matters that it's the same left side vs right. This gives you individual 4 corner toe settings".

ME: "So to summarize, if you measured 4" to the string from the rear stub, and 4" to the string from the front hub edge, then all would be well"?

FROGGY: "Just for example I might measure 3.5 on the rear to the stub and 4.0 on the front to the ridge.

So long as side to side is = no worries.

Then once you are set you start measuring the string to front of rim and string to back of rim, each corner at a time. you adjust one corner at a time".


Thanks again Froggy, that is exactly what I wanted to know

 

That's exactly why I wanted to know where people were measuring center line from.

 

Then mark a spot F & R on the frame (not the subframes) at the centerline. The strings as shown will give toe and camber/caster within the limits of the subframe offset (if any). If the subs are offset it will show up when going for a large camber setting, in that one side will not get close to the amount on the other side, due to the offset. On a street alignment it shouldn't be an issue. But, if you want 2.5-3.0 in F and 1.5-2.0 in R you'll most likely run into this unless they're centered.

Hope it goes smoothly for you.

--Dan

 

Excellent info Dan, many thanks!!!!!!