I get vibration in the body of the car at around 50 mph and up. It's not terrible and I live with it. My dad suggest wheels might need to be rebalanced. I am thinking it might be the driveshaft? Those have weights on them too do they not? The shifter isn't vibrating like crazy. All opinions welcome. And thank you gentlemen.
You might want to try removing, then rotating, the driveshaft to a different position. The shop manual describes the procedure for this and proper orientation.
Vibrations at only 50 and above is a classic sign of a problem with wheel balancing, so I would agree with your dad and try that 1st. When you have them rebalance the wheels tell them to also do a run out test or just look for any signs of one or more tires being out of round. This happened to my 70 Cougar a couple of years ago and it was a small lump in one tire that pretty quickly evolved to a bigger lump and vibration starting at much lower speed due to a belt in the tire starting to let loose.
An old trick for driveshafts is to install a hose clamp. You then rotate the hose clamp and determine if it reduces your vibration. It's not perfect but a relatively simple approach to narrow things down.
Check the balance of each wheel first. Some (shops) will pull off all the weights and balance, I prefer to spin and see if in-fact they come-up showing an imbalance, how much and where.
I'm with the above on the wheel balance but if you want to check the tires having an internal fault, just run up the pressures on all four to 50 lb. and drive it at or above 50 mph on a smooth stretch of road. If the vibration goes away, drop the pressure to normal on one tire at a time and run it back up to 50 mph each time. When the vibration re-appears, that's the faulty tire. If you want to get the driveshaft checked, it's a pretty quick, inexpensive and simple process. Be sure to mark the orientation on the yokes at both ends so you'll be able to put it back as it was. Take the driveshaft to your local driveline shop. They'll mount it up, spin it and check the balance, usually while you wait.
Check wheel balance first. Best way to see any runnout problems is to get it on a lift and have someone run the car at speed of issue . Any wheel, tire, or driveshaft issues will be evident at that point . Dont overlook the motor and trans mounts.
Wow all great suggestions gentlemen. I will get her in when everything clears and we're back up and running again. I need new tires anyway. Mine are going on 8 years old. Old is never good when it comes to tires even if there is little tread wear. I will inflate the tires to 50 psi first and see. That's an easy one to try.
Go with a road force balance. It will tell you everything you need to know about the tires.
Dave
Quote from: GT350DAVE on April 08, 2020, 02:55:45 PM
Go with a road force balance. It will tell you everything you need to know about the tires.
Dave
Dave , never heard this term, can you explain? How is this done?
Thanks
A Road Force Balancing machine is a machine that does just that. It is designed to balance the tire while duplicating the force the tire would see while on the car. We have several shops in our area that have these machines. I know not every shop has one because they aren't cheap.
Dave
Not Dave, but this link might help...
https://www.discounttire.com/learn/road-force-balancing
or this
https://www.motorweek.org/features/goss_garage/road_force_balancing
All GM dealers are required to have a Hunter Road Force Elite due to truck vibration problems. Here is some info plus a locator to find a tire store near you that has one:
https://www.hunter.com/wheel-balancers/road-force-elite
It is not only is a balancer but a diagnostic tool that analyzes & identifies the problem in a wheel & tire assembly.
And yes I am a Hunter sales rep lol, but I personally saw the difference it makes over standard balancing long before I became a rep!
Quote from: mikeh on April 09, 2020, 07:25:20 PM
All GM dealers are required to have a Hunter Road Force Elite due to truck vibration problems. Here is some info plus a locator to find a tire store near you that has one:
https://www.hunter.com/wheel-balancers/road-force-elite
It is not only is a balancer but a diagnostic tool that analyzes & identifies the problem in a wheel & tire assembly.
And yes I am a Hunter sales rep lol, but I personally saw the difference it makes over standard balancing long before I became a rep!
They are awesome. My 37 x 13.50 Truck tires get this every set. Sure helps when it detects a heavy spot or out of round tire so you can reject it on the spot without logging any miles on it.
The Hunter Road Force Balancer has saved me a lot of frustration and money over the years. We have 993 Porsches and they're very sensitive to imbalance. The Hunter equipment can diagnose tire and wheel problems and give the operator instructions to correct them if at all possible. Sometimes, it's just a matter of rotating the tire on the wheel to achieve better balance.
I had a similar experience on my GT350. At around 80mph at both Sears & Thunderhill. Tried rebalancing as I thought the Houisers were losing too much rubber....sticky tires. Still same vibration. Had the drive shaft rebalanced and changed u joints, still there. Went to an aluminum drive shaft, still there. While adjusting the webers using a chassis Dyno, the shop owner experienced the same vibration. The final solution was that the angle of the rear end...the housing...needed to be reshimed as it a shade off. That was the solution for me. Just a possibility for your situation!
I will take that into consideration. Thank you for the tip. My plan was to check out the tires today by overinflating them to 50 psi and trying to reproduce the vibration at speed.. I was totally lazy and didn't get out of bed till 3 in the afternoon. Very uncharacteristic of me. Then we got rain. So I'll try tomorrow with the 50 pound tire inflation first. But your idea is an important lead and thank you.
One thing that I have found is that some individual tires are more sensitive to tire pressure.
Too much is bad. Tires will go "out of round" and/or won't stay flat across the tread.
It usually shows right out of the box on new tires when you try and spin balance them.
70mph vibration is usually the signature of an out of round tire/ Dealers here will tell you "it's illegal" to balance a tire for an "illegal speed".
You need a race tire guy to work this out for you but I'd say you have a bad tire in the bunch?