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| | | | Joined: Jan 2013 Posts: 1,384 Shop Shark | | Shop Shark Joined: Jan 2013 Posts: 1,384 | New head gasket in and engine running fine again. Could never find any reason for the failure so I'll write it off as a defective gasket.
Did a little timing work and think it's on the sweet spot .
So back to the final highway test runs. Pulls hills good, a little loss of speed on the long ones, but will run 65+ around 2500 rpms.
Now the tire vibration shows up badly. set air pressure up to 75 all around, no difference. After taking the rear duals off and running on 4 wheels, I swapped the tires around and found both fronts were the problem. Not a shimmy but a hop up and down balance problem.
Truck has 4 "Double Coin" 8.50R20 drive tires on the back and 2 "Double Star" steering tires on the front.
All were spin balanced when they were purchased. With the rears on all 4 corners, no problem at top end.
1 of the fronts has almost no weight on it (the bad one) and the other has 18 ounces (!!) on it.
Taking them back to the shop tomorrow.
Last edited by Jim Sears; 05/25/2016 2:08 AM.
| | | | | Joined: Mar 2016 Posts: 170 'Bolter | | 'Bolter Joined: Mar 2016 Posts: 170 | 18 ounces ???!!! Good grief! If one tire was that bad, it'd be hard to believe the other needed hardly anything. I wonder if they just screwed up the balance? Have you checked for run-out at the rim? | | | | | Joined: May 2005 Posts: 8,878 . | | . Joined: May 2005 Posts: 8,878 | Are they low quality tires? Where are they made? | | | | | Joined: Jan 2013 Posts: 1,384 Shop Shark | | Shop Shark Joined: Jan 2013 Posts: 1,384 | The rims were all checked and run true.
They are made in china like almost all the 20" radials I've found.
And yes, it could be a quality issue. Apparently Double Coin and Double Star are made by 2 different companies. Not that there is any price difference in any of them.
Very little choice in 8.50 size.
| | | | | Joined: Jan 2013 Posts: 1,384 Shop Shark | | Shop Shark Joined: Jan 2013 Posts: 1,384 | It was the tires.BTW, 8.25R20 not 8.50.
Took them back to the balancer. On the machine, the one with 0 weight, said it needed 0 weight.but before it had even finished spinning the manager and I looked at each other and said "It's not round".
Both of them had serious flat spots. BTW, the one with 18 oz said it had 4 oz too much.
The place that sold them didn't seem suprised. They don't sell Double Star any more.
Finding me replacements. waiting for the call.
Several dealers sell the Double Coin for drive tires and trailers and have few problems. | | | | | Joined: Jun 2011 Posts: 5,096 Crusing in the Passing Lane | | Crusing in the Passing Lane Joined: Jun 2011 Posts: 5,096 | What is the date code on the tires, this century?
Ed
Last edited by EdPruss; 05/26/2016 3:45 AM.
'37 GMC T-18 w/ DD 4-53T, RTO-610, 6231 aux., '95 GMC running gear, full disc brakes, power steering, 22.5 wheels and tires.
'47 GMC 1 ton w/ 302, NP-540, 4wd, full width Blazer front axle.
'54 GMC 630 w/ 503 gasser, 5 speed, ex fire truck, shortened WB 4', install 8' bed.
'55 GMC 370 w/270, 420 4 speed, grain, dump bed truck from ND. Works OK.
| | | | | Joined: Jan 2013 Posts: 1,384 Shop Shark | | Shop Shark Joined: Jan 2013 Posts: 1,384 | Haven't looked, but there is nothing growing on them.
Seriously, no more mucking around. I found a supplier that can get them from Sumitomo. put a premium tire on and be done with it. | | |
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