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i recently restored my '76 tr6, had the allignment professionally done and replace the out-of-round tires with new koker 185 r15s ... but i'm still receiving pretty heavy vibrations at highway speeds .. any input as to how to correct this would be much appretiated
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Vibration around 60
- Thread starter Philboy
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Alan_Myers
Luke Skywalker
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Hi,
There are several possibilities.
You mention heavy vibrations, but where do you mostly feel the vibration? In the steering wheel? In the shift lever? Etc.?
The easiest thing to check is that the tire pressures are correct. Some cars are very sensitive to too low or too high pressures, or significant differences from one side to the other.
Next, also check that the tires and wheels are balanced properly. Even if freshly installed and balanced, there might have been an error or wheel weights might have fallen off. If you just had the tires installed/balanced, you might go back to the installed and have them re-checked. They can check the wheels, too, for any out of round or bent rim.
You mention new tires and I've had "bad" tires on cars before, that just seemed to always have a vibration that couldn't be corrected with balancing. Best way to eliminate this as a possiblity, and incorrect balancing/bent wheels/etc., would be to temporarily swap out with a set of wheels and tires that are known to be good. Maybe off a friend's TR6... if that were possible.
Another possibility is the drive shaft. Do you know if it's been balanced recently? It should be done, particularly after U-joint replacement.
Another possibility if the drive shaft was removed, is that the U-joints are out of phase, not correctly aligned with each other. This especially might happen if the spllined sliding member were seperated and not put back together correctly. I think most TR drive shafts have two arrows engraved - one on the front section, one on the rear drive shaft section - that need to be matched up.
The rear axles can get out of balance, too, I suspect. But I'm not sure about this, so hopefully someone with more TR6 experience will jump in here.
Other things that can cause vibration are the flywheel, clutch and crankshaft, if one or more is out of balance. These are usually rpm-related, though, showing up at the same rpm, no matter what the car's speed. For that reason, from your description, I lean more toward driveshaft, axle or tire/wheel problems.
Hope this helps!
Alan Myers
San Jose, Calif.
'62 TR4 CT17602L
There are several possibilities.
You mention heavy vibrations, but where do you mostly feel the vibration? In the steering wheel? In the shift lever? Etc.?
The easiest thing to check is that the tire pressures are correct. Some cars are very sensitive to too low or too high pressures, or significant differences from one side to the other.
Next, also check that the tires and wheels are balanced properly. Even if freshly installed and balanced, there might have been an error or wheel weights might have fallen off. If you just had the tires installed/balanced, you might go back to the installed and have them re-checked. They can check the wheels, too, for any out of round or bent rim.
You mention new tires and I've had "bad" tires on cars before, that just seemed to always have a vibration that couldn't be corrected with balancing. Best way to eliminate this as a possiblity, and incorrect balancing/bent wheels/etc., would be to temporarily swap out with a set of wheels and tires that are known to be good. Maybe off a friend's TR6... if that were possible.
Another possibility is the drive shaft. Do you know if it's been balanced recently? It should be done, particularly after U-joint replacement.
Another possibility if the drive shaft was removed, is that the U-joints are out of phase, not correctly aligned with each other. This especially might happen if the spllined sliding member were seperated and not put back together correctly. I think most TR drive shafts have two arrows engraved - one on the front section, one on the rear drive shaft section - that need to be matched up.
The rear axles can get out of balance, too, I suspect. But I'm not sure about this, so hopefully someone with more TR6 experience will jump in here.
Other things that can cause vibration are the flywheel, clutch and crankshaft, if one or more is out of balance. These are usually rpm-related, though, showing up at the same rpm, no matter what the car's speed. For that reason, from your description, I lean more toward driveshaft, axle or tire/wheel problems.
Hope this helps!
Alan Myers
San Jose, Calif.
'62 TR4 CT17602L
Paul Johnson
Jedi Warrior
Offline
You could also have run out on the wheels. Run out is best pictured as wobble. With wheels up, simply slowly turn them with some method of measuring variation as it goes around. Should be practically nil.
John_Mc
Jedi Knight
Offline
FWIW: I had a similar problem where the vibration, coming from behind me, occurred at about 60-75 range. Slower, and it was not evident and faster it smoothed out as well. This was after I had some differential work done and turned out to be, as Alan mentioned, U joint related.
[ QUOTE ]
and turned out to be, as Alan mentioned, U joint related.
[/ QUOTE ]
Can I ask how you were able to determine the source of the problem. My newly restored TR4A has the same thing, and I would like to get to the root of the problem (and all the other shake down issues I have on the car for that matter).
and turned out to be, as Alan mentioned, U joint related.
[/ QUOTE ]
Can I ask how you were able to determine the source of the problem. My newly restored TR4A has the same thing, and I would like to get to the root of the problem (and all the other shake down issues I have on the car for that matter).
John_Mc
Jedi Knight
Offline
I had just spent a lot of money having the mechanic work on the differential and the clutch, and this developed AFTER that, so I took it back to him knowing it had to be related to something just done, and he diagnosed the problem (although first he blamed it on a bent rim, which, when replaced, changed nothing but the amount of money left in my checking account). So I couldn't tell you the way to pinpoint if it is a U joint or not. I'm still learning... In this case I could feel that the vibration seemed to be coming from behind me and was speed related.
Paul Johnson
Jedi Warrior
Offline
[quote
Can I ask how you were able to determine the source of the problem. My newly restored TR4A has the same thing, and I would like to get to the root of the problem (and all the other shake down issues I have on the car for that matter).
[/ QUOTE ]
You can get a reed tachometer (from a lawnmower supply store) and place it somewhere that it will vibrate while driving. The reeds will indicate the vibration frequency. Then do some thinking. Does it match the frequency of the crank, the cam, the wheels, the prop shaft? This will really narrow the isolation process for you.
Can I ask how you were able to determine the source of the problem. My newly restored TR4A has the same thing, and I would like to get to the root of the problem (and all the other shake down issues I have on the car for that matter).
[/ QUOTE ]
You can get a reed tachometer (from a lawnmower supply store) and place it somewhere that it will vibrate while driving. The reeds will indicate the vibration frequency. Then do some thinking. Does it match the frequency of the crank, the cam, the wheels, the prop shaft? This will really narrow the isolation process for you.
Paul,
Now that is an idea afte my own heart. I love it. reminds me of the time I was in a Dash8 aircraft the first flight after a new prop blade was installed and the mechanic had a computer attached to a connector on the airframe that apparently then gave him all sorts of readings from which they could determing the fine tuning of ballance (I think that was what I remember).
I am going to have to give this idea of yous a try.
Now that is an idea afte my own heart. I love it. reminds me of the time I was in a Dash8 aircraft the first flight after a new prop blade was installed and the mechanic had a computer attached to a connector on the airframe that apparently then gave him all sorts of readings from which they could determing the fine tuning of ballance (I think that was what I remember).
I am going to have to give this idea of yous a try.
Did you replace the front wheel bearings and seals? When I did and then followed the Bently maunual (torque to 10lbs & back off 1 flat) I had the same thing. It turned out the wheel had play on the stub axle. Either the felt seal was compressing or the bearings seating--I don't know. I re-tightened and the vibration went away.