Static & Dynamic Wheel Balancing

Bruce Allert · 02-14-2003, 09:54 PM

"Attaboy" to Rex at Americas Tire Shop!!!
Just wanted to say "it is truly amazing" that when your 914 drives down the road with no vibrations it is an experience to behold! I say this because today was the first time in my 2 years of ownership that "Punkin" didn't vibrate, shimmy or shake in any way.
A few months ago I put on 2 new Nitto 205/50/15's on the rear
(the front were pretty good). The car vibrated a bit at 55 but 60 wasn't bad so I lived with it. And if the road surface varied it softend the vibration a bit... oh well.
Today I put on 2 new Nittos so I now have 4 nice tires all around. Took off down the road and when reaching 45 the steering wheel all but vibrated outta my hands. Needless to say I had to go back to the shop.
The guy that did the initial tire change & balancing of all 4 left a lot to be desired. (His theme song prolly was "I don't want to set the World on Fire!") I backed the car into the parking space so all he'd have to do was start it and drive forward. What does he do??? puts it in reverse... then, can't find 1st so it's 2nd all the way into the bay

I knew then I'd be back especially when he said "What kind of car is that??? it's weird!"

When I came back Rex (Asst. Mgr) came right out (cuz "he knew" something was up). He explained the difference between the 2 types of balancing, corrected what the other guy did which was completely wrong for the 914 and I was on my way.
Yes, I lost an hour by returning but I learned something about our cars and, hopefully, it won't happen again (to me)!
bruce

Zeke · 07:37 AM

What can I say? Used to be that poeple at a tire shop were competent. Some were outstanding. I've learned a tremendous amount from the guys over the years. It's truly a shame that I now have to tell them how to do their job. (It didn't hurt that I worked at a tire shop on Saturdays during college days).

The last time I was in a tire shop I went in for a flat repair on a domestic. Car had very nice factory alloys. The mechanic (that's too generous) somehow got the socket wedged on the lug nut. Then he proceededs to loosen it with a hammer and a pry bar. Ruined a $600 rim. So when I get my replcement, the first time I washed my car the thing sliced my hand open. It was a copy and had sharp edges. I had no trouble washing the originals.

The time before that, at another tire shop (I'm running out of tire shops) I go to have new shoes for a 356 that I owned at the time. The first thing I asked the manger ( a brother of a friend of mine) is if he has a VW hub cap removal tool. Oh yes, he says. I go back and three out of four no longer available hub caps are ruined. He denies the damage. I take them off and show him the fresh marks on the inside in the brake dust. The dents they made came through to the surface chrome. What could I do? No amount of money would replace them. You can't find them. I walked away.

I'm soon to buy my own tire changing equipment (manual).

maf 914 · 02-15-2003, 08:12 AM

I cringe when tire time comes around. The boys at the Firestone center which is within convenient walking distance of my office have stripped about a dozen lug nuts and studs on my Nissan pickup over the years. Then they put cheap after market replacement lug nuts on which are not even the same wrench size. Torqued to about a thousand foot pounds. The last time I bought a set of new tires one of the tires went flat the next day when a new valve stem failed as I was driving to the beach. I found a place to pull off on a gravel access road and proceeded to change to the space saver spare. The lug nuts were on so tight I thought I was going to acquire a hernia! On the third nut the Nissan lug wrench head sheared off! SOB! Luckily I had my tool box with a Craftsman breaker bar and some sockets which did the trick. On top of that I had to deal with the PIA pickup tire lowering mechanism under the truck bed! It was only about 90 degrees and 90% humidity so I was really cool about the whole thing. The Firestone manager said "We're sorry, sir"! What morons.

I always take my 914 wheels and tires off the car and take them to another shop for service. Even then I fear for my alloy wheels. So far no real damage to them.

Mike

Plays with cars · Plays with cars's Garage

Hi Bruce, which way is correct for the 914? Static or Dynamic? I've been chasing the same vibration on my 914 for a couple of years and I know that it's related to wheel balancing. I've taken it to a couple of different places for rebalancing, but haven't been able to shake it (pun intended). About the only thing that changes is the severity of the vibration, but it's always there at 55-60mph.

Bruce Allert · 02-15-2003, 10:58 AM

Hey Mark.
Actually I was a little off in saying the other guy did the wrong kind of balancing for the 914. He just did it wrong... period.
Either way will work if it is done properly. Static balancing is ALL 4 tires must be in balance along 2 axes. To be in Static balance, weight must be evenly distributed around the axis of rotation on the lip of the wheel
To be in dynamic balance the center line of the weight must coincide with the centerline of the wheel with the weights placed on the inside or back side toward the center of the wheel.
I will scan an image which shows this as soon as my scanner is up. A reputable tire store manager should be able to do this. It only took me 2 years to find a reputable one!!!
bruce

Bruce Allert · 02-15-2003, 11:48 AM

Here's the example of weight placement. Top picture is Static and bottom is Dynamic
A: shows the improper balance
B: shows result
C: shows proper balance placement

econopa · 02-15-2003, 02:07 PM

This afternoon i replaced the rear wheels following some body work. I noticed some " slop " on the four bolt system. I attempted to center the wheel, but how good can it be? With some "play", the wheel must be off-perfect center. Should this be a concern?

Zeke · 02-15-2003, 05:11 PM

Quote:

Originally posted by econopa
This afternoon i replaced the rear wheels following some body work. I noticed some " slop " on the four bolt system. I attempted to center the wheel, but how good can it be? With some "play", the wheel must be off-perfect center. Should this be a concern?

I was gonna mention something about out-of-round before this popped up. Yeh, that would be a concern for me.

First, check all tires for running true, even after you just got new ones and they are balanced. After having the deluxe balance job (including trueing), I ran some Potenzas on a 911 over 40K w/o ever even rotating them. Of course the alignment was spot on. They wore square to the road until they were slicks.

Plays with cars · Plays with cars's Garage

Thanks Bruce. I was hoping you had found the holy grail of tire balancing for 914s. I'd have been hard pressed to find a shop that stilll had static balancing equipment, but I was willing to try if you'd found that to be effective. Guess I'll keep shopping for an exceptional tire shop.

Bruce Allert · 02-16-2003, 11:38 AM

Mark, I see you have a Gran Sport. I had a 65 Special Gran Sport with the 401 and 2 speed auto. What a fast car. Beat many a 327 Malibu's doin' green light block racing. Held the title for the longest burn out too!!! My Dad couldn't figure out why he was replacing tire so often

So, where were you in the PNW? I have many a relatives in the Akron Ohio area. They used to build Monster trucks.
bruce

Zeke · 02-16-2003, 12:21 PM

Quote:

Originally posted by Plays with cars
Thanks Bruce. I was hoping you had found the holy grail of tire balancing for 914s. I'd have been hard pressed to find a shop that stilll had static balancing equipment, but I was willing to try if you'd found that to be effective. Guess I'll keep shopping for an exceptional tire shop.

I'm not being sarcastic when I say get a tire that is not out-of-round and put it on the computer balancer and it's a done deal. If you still have a vibration, check your half axles and other drive line components. There doesn't need to be a holy grail.