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Discussion Starter #1
I've had quite a bit of work done on my 1984 El Camino, a full drive train replacement with LS3, etc. I'm having vibration that begins while driving around 75 MPH and gets fairly substantial at 90, enough that I know better than to go further. The shop has chased the problem and believes it has come down to the wheels and tires. They sent them to a shop that balances rims and tires and I got the car back yesterday. Although I've not attempted 90, I did briefly hit 80 and the vibration remains. The shop is suggesting that the vibration is due to the low profile tires and that I should replace with larger side wall tires in the future.

Do any of you run 45 or lower profile tires on a 78-87 Elko and have a good smooth ride without higher speed vibration like I'm describing?

The tires are Michelin PILOT SPORT SS 235/45ZR17 and have about 1000 miles on them.

All the drive train replacement work is under warranty at this point so I obviously don't want to sit on this problem if its not the wheels and tires.
 

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I've had quite a bit of work done on my 1984 El Camino, a full drive train replacement with LS3, etc. I'm having vibration that begins while driving around 75 MPH and gets fairly substantial at 90, enough that I know better than to go further. The shop has chased the problem and believes it has come down to the wheels and tires. They sent them to a shop that balances rims and tires and I got the car back yesterday. Although I've not attempted 90, I did briefly hit 80 and the vibration remains. The shop is suggesting that the vibration is due to the low profile tires and that I should replace with larger side wall tires in the future.

Do any of you run 45 or lower profile tires on a 78-87 Elko and have a good smooth ride without higher speed vibration like I'm describing?

The tires are Michelin PILOT SPORT SS 235/45ZR17 and have about 1000 miles on them.

All the drive train replacement work is under warranty at this point so I obviously don't want to sit on this problem if its not the wheels and tires.
I'm running 235/45-17's on my 86 with zero vibration issues. Are the tires and wheels new or were they on before the drive train vibration showed up. Regardless, if the wheels are true and the tires are sound and balanced, they shouldn't vibrate any more than a tall profile tire would. You will most likely have a little harsher ride, not a vibration.

Second guess would be maybe a driveshaft not happy with its orientation. You could rotate it 90, 180 or 270 degrees and see if the vibration decreases.
 

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I've had quite a bit of work done on my 1984 El Camino, a full drive train replacement with LS3, etc. I'm having vibration that begins while driving around 75 MPH and gets fairly substantial at 90, enough that I know better than to go further. The shop has chased the problem and believes it has come down to the wheels and tires. They sent them to a shop that balances rims and tires and I got the car back yesterday. Although I've not attempted 90, I did briefly hit 80 and the vibration remains. The shop is suggesting that the vibration is due to the low profile tires and that I should replace with larger side wall tires in the future.

Do any of you run 45 or lower profile tires on a 78-87 Elko and have a good smooth ride without higher speed vibration like I'm describing?

The tires are Michelin PILOT SPORT SS 235/45ZR17 and have about 1000 miles on them.

All the drive train replacement work is under warranty at this point so I obviously don't want to sit on this problem if its not the wheels and tires.
I'm running 235/45-17's on my 86 with zero vibration issues. Are the tires and wheels new or were they on before the drive train vibration showed up. Regardless, if the wheels are true and the tires are sound and balanced, they shouldn't vibrate any more than a tall profile tire would. You will most likely have a little harsher ride, not a vibration.

Second guess would be maybe a driveshaft not happy with its orientation. You could rotate it 90, 180 or 270 degrees and see if the vibration decreases.

some questions come to mind, as WillitsDad pointed out:

1) new tires or existing? did the issue exist before?
2) have those tires been rotated so they are not in the same corner as before?
3) you say "full drive train replacement"? how full? rebalance/replace driveshaft?
4) can you borrow some other wheels/tires temporarily to test it out?
 

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Discussion Starter #4
I purchased the car to perform the drive train swap so didn't have it long. I never took above 75 so don't know if the problem existed previously.

The engine, transmission, rear end were replaced but the drive shaft is the original but was shortened I believe. And balanced. theres very little mechanical left on the car that is original.

I had the new rims and tires installed right before the mods were made and the belief was that the vibrations were due to these new tires some how being weathered. I installed the pilots and they and the wheels were laser balanced. The problem remains.

I don't have access to wheels and tires to borrow. Not sure if there's a good source for these.

If I get nowhere I will purchase rims and tires, to prove the issue one way or another.
 

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Discussion Starter #5
Can you kindly confirm that you are certain of no vibration of speeds at least to 90 with the 245s? Your side wall is 4.5 mm wider than mine but close enough.
 

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Don't know about Cali, but here in Texas there are places that rent rims and tires. One of them is called Rent-a-Rim.
If the wheels and tires are round and balanced,
The vibe is likely due to drive line angle or a bad shaft at a high speed like that.
Mine has a vibe from about 90-120, and I know its because of drive line angle. I have quite a bit of negative pinion angle to make it hook.
You can put it on jack stands (under the axle) and let it idle in gear. Watch the drive shaft for any run out and well as the rear wheels.:texas:
 

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I was going to suggest carefully raising the rear end and securing it with jackstands, then run the car up through the gears to see what shakes. Swap tires and try it again. I too bet you'll find it's in the drive shaft, but you might have a bent axle shaft or some other issue.
Patrick
 

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I have a similar issue, and I've been chasing it for a long time. I think for me it's coming down to either the pinion angle ( and I'v adjusted it maybe 50 times), or it may be that the wheels are not centric to the hubs. G-bodies wheels were centered by the center opening in the wheels fitting tightly on the hub, and many aftermarket wheels have different size openings that therefore do not center the wheel.

If it is a very high speed vibration, felt in the seat of the pants, then it is likely driveline related. If it is a slower frequency vibration, it is more likely the wheels. Usually can be felt more in the steering wheel.
 

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Mark
You mentioned "I had the new rims and tires installed right before the mods were made".

Do you still have the previous rim/tire set?
Can you still use a 14 inch stock set on your brakes?
Or do you need a rim larger than 14?
 

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Don't know about Cali, but here in Texas there are places that rent rims and tires. One of them is called Rent-a-Rim
.....
You can put it on jack stands (under the axle) and let it idle in gear. Watch the drive shaft for any run out and well as the rear wheels.:texas:
had not thought of that, wonder what the cost would be for 1 day?

ralph, what about taking the wheels off and watching the axle shaft to see if there is a slight wobble to it? or use a dial meter to see if there is any off-center to it?
 

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My mistake, yours are also 235s. What is your model of tire?
Continental Extreme Contact DW. I'm running 255/45-17 in the rear. Zero vibration with steel "D" slot, (Nascar style) wheels. However, Willits will just barely do 90, LOL.
 

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I would not spin it to speed on stands with no load, open diffs don't like it.

The axle flange would be best checked with a dial indicator, not running. Its to small of a circle to see a wobble unless its real bad.
You can cheap it with a piece of wire fixed to the backing plate with a clamp, keep the wire just off the axle flange and turn it by hand watching the gap between the wire and the flange. This won't tell you how much its bent, just if its bent.
The wheels will be centric to the lugs, which if everything is drilled correctly in fine.
Usually wheel/tire vibes come in earlier, like around 45-60.:texas:
 

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Discussion Starter #17
My current tires are the Michelin PILOT SPORT SS.

The shop is going to rotate the driveshaft connection to the rear end 180 deg--says that's the only option.
 

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Check to make sure the u joint is seated down properly in the rear yoke also.
If you can get it on a drive on rack, have them check the pinion and trans angle. Any more than 3* difference will vibrate.:texas:
 

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Have you recalibrated your speedometer since you went to overdrive and smaller diameter tires with the LS3 swap?
 

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when u had the motor swap done,,you need to ensure the motor sits level,,not exsessive angle down or up,,that will cause issues like u describe,ask me how i know,,i ran -3* pinion angle,,any more it was not happy ,im leaning towards driveshaft myself,if your pinion angle is correct,swap in a spare or get one from a buddy/ pick n pull,,good luck,,be safe.:texas::secret::dontknow:
 
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