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-   -   Tire Alignment/Balancing (http://www.clubcobra.com/forums/era-speak-bob-putnam/98269-tire-alignment-balancing.html)

cobra de capell 07-12-2009 03:25 PM
Tire Alignment/Balancing
 
I just put Goodyear Billboards on my ERA - it's #91, so an older one built in the late 1980's.

It's sort of bouncing around a little - possibly either tire alignment or balancing issue - if it needs alignment, what sort of information do I need to provide relating to the people doing the work - the front end is what, in other words? Sorry, I'm complete lost when it comes to fixing anything. Also, the tires were balanced off the car - should they be balanced on the tire for a better result?

One additional item - it's strange, in that there is a slight vibration now when I first drive the car - like the tires are really out of balance, but after a few miles the vibration disappears - is that normal.

Any input will be appreciated.

patrickt 07-12-2009 03:45 PM
Quote:
Originally Posted by cobra de capell (Post 965748)
- if it needs alignment, what sort of information do I need to provide relating to the people doing the work - the front end is what, in other words?
Straight from the manual:

Camber 0 deg. +/- 1/4

Caster 4 1/2 deg. +/- 1/2

Toe-in: 1/16"-1/8" (0.1-0.2 deg/side)

But if your car seemed to track and drive nicely with the old tires then it's probably not an alignment issue.

strictlypersonl 07-12-2009 04:28 PM
Lately it seems that front end people are required to know next to nothing about how to do their job. They punch in a car model and the electronic alignment machine tells them how many shims to add or subtract in the designated place. I'm not even sure whether the alignment machine tells them the actual readout!

The upper control arm mounting is similar to the 1976 Camaro but I haven't yet located the Camaro specs. Once I do, I'll be able to "translate" the alignment shop's instructions to something more appropriate to the ERA.

tcrist 07-12-2009 05:14 PM
CDC,
The Billboards will vibrate/shake for the first couple of miles. That is just a by-product of the Billboards. They kind of flat-spot while setting and then round out after a few miles. That could be what you are feeling.

Terry

FWB 07-12-2009 05:27 PM
the tires themselves could be out of round. jack up one tire just so it clears the ground, just an RCH, spin it watch some stationary point inside the wheel well as you spin.

Stentor 07-12-2009 06:30 PM
Quote:
Originally Posted by cobra de capell (Post 965748)
One additional item - it's strange, in that there is a slight vibration now when I first drive the car - like the tires are really out of balance, but after a few miles the vibration disappears - is that normal.
Any input will be appreciated.
Yep, after sitting for a few days the Billboards will flat spot. After a few miles the shaking and vibration will stop (this is one of the downsides of the tires).

cobra de capell 07-13-2009 09:18 AM
Thanks for all the input - interesting, I was out for a ride Saturday and again on Sunday - the "flat spotting" or "vibration" was way less on Sunday after sitting for a day versus Saturday after sitting for a week - therefore, that's a huge part of the problem - not really a problem - just the way it is.

As for alignment - I'll try to find someone out there that knows what they are doing.

RedBarchetta 07-13-2009 11:03 AM
The contact patch on a bias ply, in motion, will move toward the back of the car (versus the same contact patch on a radial). This is why my caster is now off and the car pulls to the right (didn't have this problem before the Billboards). So moving to BB's necessitates a mandatory re-alignment (IMHO).

-Dean

patrickt 07-13-2009 11:11 AM
Quote:
Originally Posted by RedBarchetta (Post 965932)
The contact patch on a bias ply, in motion, will move toward the back of the car (versus the same contact patch on a radial). This is why my caster is now off and the car pulls to the right (didn't have this problem before the Billboards). So moving to BB's necessitates a mandatory re-alignment (IMHO).
Right, and if you ever peruse the early Camaro forums the standard advice for First Gen Camaros is not to use the factory alignment specs for their car, but rather use the Second Gen specs because of the bias versus radial difference (that's assuming the reader was upgrading to radial tires). I don't see why a Cobra would be any different. It would seem that alignment specs for one type of tire are probably not suitable for the other.

patrickt 07-16-2009 10:02 AM
OK Bob, Translate Away...
 
Quote:
Originally Posted by strictlypersonl (Post 965766)
The upper control arm mounting is similar to the 1976 Camaro but I haven't yet located the Camaro specs. Once I do, I'll be able to "translate" the alignment shop's instructions to something more appropriate to the ERA.

http://www.clubcobra.com/photopost/d...amarospecs.jpg

strictlypersonl 07-16-2009 10:34 AM
Thanks a lot! Now I have more work to do! :rolleyes:


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