> I am a little confused about Alcoas and balancing. I have been told that they do need to be balanced and I have
> been told that they do not. What is the correct routine?
>
> Vic Marks
> Vancouver, BC
> 75 transmode
Vic: I purchased the Alcoa rims last year and had help from a race shop in getting everything balanced. I can't
tell you how to do yours, but I will tell you what I learned from these guys that make a living building and
racing cars.
First off, I found that race enthusiasts are real picky about balancing EVERYTHING ! Components are balanced
separately, and then together. So when I brought in the aluminium rims, the shop ran 3 of the 6 on their machine,
they found all 3 were in perfect balance, so accepted the others as being such also. (I realize that a
statistician would say that's not enough data points...but hey, that was the decision...!) My new 16"
Bridgestone E's were then put on all the rims and each balanced perfectly as a unit.
However, no such luck with the discs and drums! All were checked separately and were all badly out of balance.
It took some grinding and drilling to get these right. Of course all this work is for naught if the alignment is
not also checked...which in this case was, with and without the wheels installed on the coach. (But that is a
whole other subject!)
Anyway, I can only assume that these racing guys don't sweat all this small stuff for nothing...afterall, on the
track, it's money in the bank for them. (All this work was done in the name of our friendship -free- so this shop
had no incentive to do anything non-productive).
I wish I could offer some definitive before/after data, but can't. I can only say that my logic tells me the
truer all the wheels and components run, the smoother the ride, and the longer the component life, ie bearings,
shocks, bushings, etc. I also know that my before picture was not pretty: riding on steel radial rims, with
16.5" radial tires, typically balanced and aligned, pressured to manufacturers recommendation, felt like driving
on a gravel road that never ended. With the 4 bag system, balanced/aligned Alcoa rims w/Bridgestone
LT225/75R16-E's pressured to manufacturers recommendation ........I get a ride akin to a magic carpet!
Which of the improvements was most responsible for that, I can't say.....but I suspect not any one of them
alone. As a package though, they have produced marvelous results. And I can safely state that while the driver
may be unbalanced sometimes, the coach runs true!
BTW, I am told any shop that has the equipment to balance a shaft can also balance other components, ie discs and
drums etc. The only difficulty is in finding the arbors to hold these GMC parts on the machine. I had to have a
machinist manufacture these specialized parts to use on the shops' balancing machine.
Tom Henderson
78 Birchaven 23'
http://gmc76.tripod.com
> been told that they do not. What is the correct routine?
>
> Vic Marks
> Vancouver, BC
> 75 transmode
Vic: I purchased the Alcoa rims last year and had help from a race shop in getting everything balanced. I can't
tell you how to do yours, but I will tell you what I learned from these guys that make a living building and
racing cars.
First off, I found that race enthusiasts are real picky about balancing EVERYTHING ! Components are balanced
separately, and then together. So when I brought in the aluminium rims, the shop ran 3 of the 6 on their machine,
they found all 3 were in perfect balance, so accepted the others as being such also. (I realize that a
statistician would say that's not enough data points...but hey, that was the decision...!) My new 16"
Bridgestone E's were then put on all the rims and each balanced perfectly as a unit.
However, no such luck with the discs and drums! All were checked separately and were all badly out of balance.
It took some grinding and drilling to get these right. Of course all this work is for naught if the alignment is
not also checked...which in this case was, with and without the wheels installed on the coach. (But that is a
whole other subject!)
Anyway, I can only assume that these racing guys don't sweat all this small stuff for nothing...afterall, on the
track, it's money in the bank for them. (All this work was done in the name of our friendship -free- so this shop
had no incentive to do anything non-productive).
I wish I could offer some definitive before/after data, but can't. I can only say that my logic tells me the
truer all the wheels and components run, the smoother the ride, and the longer the component life, ie bearings,
shocks, bushings, etc. I also know that my before picture was not pretty: riding on steel radial rims, with
16.5" radial tires, typically balanced and aligned, pressured to manufacturers recommendation, felt like driving
on a gravel road that never ended. With the 4 bag system, balanced/aligned Alcoa rims w/Bridgestone
LT225/75R16-E's pressured to manufacturers recommendation ........I get a ride akin to a magic carpet!
Which of the improvements was most responsible for that, I can't say.....but I suspect not any one of them
alone. As a package though, they have produced marvelous results. And I can safely state that while the driver
may be unbalanced sometimes, the coach runs true!
BTW, I am told any shop that has the equipment to balance a shaft can also balance other components, ie discs and
drums etc. The only difficulty is in finding the arbors to hold these GMC parts on the machine. I had to have a
machinist manufacture these specialized parts to use on the shops' balancing machine.
Tom Henderson
78 Birchaven 23'
http://gmc76.tripod.com
