65 Futura in East TN . . .

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Re: 65 Futura in East TN . . .

Postby Lou's Comet » Mon Apr 15, 2019 8:06 pm

bigdan wrote:Troubleshooting continues . . . . .

Finally took the 65 out to test the new adjustments. The vibration that appears to have originated from the driveshaft is gone, or barely noticeable, but now other issues seem to be arising. I do still have a slight vibe on acceleration, and a fairly steady one at 70-75 mph also.

For the acceleration vibe, plan is to pull the driveshaft and get balance checked, especially since there are no weights on it. I'm debating on motor and tranny mounts as well. Any recommendations on motor mounts - preferably something more rigid than the stock rubber? Trans mount ideas? Currently using a stock 68-69 Bronco mount - hey, it was the right height!

As for the high speed vibe. I'm thinking that could be a rotor or wheel; kind of curious if my trim rings could be throwing it off a bit.

Keep in mind these aren't ridiculous vibrations, but any one of us would notice. Any pointers are welcome -

Thanks for looking -

Dan


I agree with John, Tomb, and mike that the angles should match. And will set mine the same.

Not all pinions are centered with the trans, so you want to check those angles to. Which is hard to explain but if you look at the picture at the end of the page on this link you will get what I am saying. The angles being talked about are the ones from the side view in the picture, the angles from the top view in picture are also important.

http://www.moparts.org/Tech/Archive/axle/8.html
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Re: 65 Futura in East TN . . .

Postby tomb22 » Mon Apr 15, 2019 8:12 pm

I had a garage balance the tires once and ended up with a vibration. Took them someplace else and they found the tires where not balanced very good. After re-balancing them the problem went away. Just a thought.
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Re: 65 Futura in East TN . . .

Postby bigdan » Tue Apr 16, 2019 2:20 am

Lou - it's a centered pinion. I already checked it out :mrgreen: . Angles are correct on the driveline now, so if there is any further issue with the driveshaft it would have to be a balance issue. I thought about doing the old hose clamp check, but I called the driveline shop that built the driveshaft for me and they'll check it no problem, so we'll go ahead and rule that out also.

Tomb, I've been pondering the same thing. Right now I think I'll pull the wheels tonight and do a run out on the rotors first then go from there.

Again, I may be being a little picky, but this car was built for the road, so I'll keep tweaking till I'm happy. It's not bad, but I notice, so we'll keep chasing it.

Thanks for looking -

Dan
Currently diligently patiently trying to complete my 65 Futura long term project. . . . .

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Re: 65 Futura in East TN . . .

Postby Jims65cyclone » Wed Apr 17, 2019 7:24 pm

bigdan wrote:I do still have a slight vibe on acceleration, and a fairly steady one at 70-75 mph also.

As for the high speed vibe. I'm thinking that could be a rotor or wheel; kind of curious if my trim rings could be throwing it off a bit.


The 70-75 mph sounds too fast for it to be a tire balance or roundness issue. That usually shows up around 55-65 mph, depending on the diameter of the tire, but it can also be impacted by the natural frequency of the spring. The 55-65 rule of thumb is for stock springs, which err on the side of comfort rather than performance. If your springs are stiffer (higher rate) or shorter than stock springs, that could affect the speed at which bouncing, or vibration, can occur, so it might be a tire problem even at 75 mph. Do you feel it more through the steering wheel, or through the seat/body of the car? That can point you to a front wheel or rear wheel problem. Roundness can have as much or more of an affect on vibration as balance. Try jacking each wheel up just off the floor, place a reference object (screwdriver handle, etc.) on the floor 1/4" from the tread and rotate the tire while you watch the gap between the tread and reference. Do the same for the inside and outside sidewalls. You should have less than 1/8" variation in the gap around the circumference of the tire. More than that could mean a casing issue with the tire, or bent rim. If it's a tire, I'd expect it to be more of a constant speed vibration than an acceleration vibration. I think the acceleration vibration is still linked somehow to the drive train. Anyway, JMO, and worth every penny you paid for it. :roll:

Jim
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Re: 65 Futura in East TN . . .

Postby bigdan » Thu Apr 18, 2019 2:42 am

Jim -

The 75mph vibe seems to be coming from behind me, if that makes sense. The acceleration vibe seems to be driveline, only under acceleration. Again, these are minimal to the point that 8/10 people wouldn't even notice, but it drives me crazy - and I love figuring stuff like this out.

I pulled the driveshaft yesterday and it's at the shop getting checked, so we'll rule that out. Just in case it's a mount issue, I grabbed a set of Ron Morris motor mounts and a poly trans mount to minimize movement there as well. I'll check tires and rotors this weekend.

This is all just fine tuning, but I'm having fun doing it. And realizing, that at some point, I need a lift!

Thanks for your input, fellas-

Dan
Currently diligently patiently trying to complete my 65 Futura long term project. . . . .

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