Author Topic: NVH Vibrations  (Read 256 times)

FazerBob

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NVH Vibrations
« on: May 10, 2019, 11:49:59 PM »
Driving on the motorway I get a bad vibration around 65 to 75 MPH. Lifting off the throttle eases things a bit, but going onto half throttle results in a vibration similar to bad wheel balance. Full throttle is rather alarming, with very bad vibration and harshness throughout the car.

The car was fitted with new wheels and Nankang tyres shortly before I bought it around 3 months ago. New rear brake disks and pads were fitted a couple of weeks ago at MoT time and wheels were balanced just last week, when I was told that nothing was needed on the rears as they were perfectly balanced.

When I took the car for MoT I had to slowly move it around the garage forecourt and noticed that at barely walking pace there was a 'cyclic' lumpy effect as if I was driving over a brick etc.

I asked the mechanic to check it out during the test, but he found nothing to explain the fault, but suggested
changing the disks and pads, which he said still had life in them, but as I already had new replacements with the car he thought it worthwhile to change them.

There appears to be no excessive movement in the engine mounts, but of course that may be different at speed. With the rear of the car on axle stands I have spun the wheels, with no roughness or tight spots. Driving the wheels while on the stands showed no faults either.

Any ideas guys?

johnjames

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Re: NVH Vibrations
« Reply #1 on: May 11, 2019, 12:58:29 AM »
Hi can you let us know which Kit you're having trouble with and what the donor is cheers
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FazerBob

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Re: NVH Vibrations
« Reply #2 on: May 11, 2019, 11:22:30 PM »
My car is a 430 Spider, based on a 2001 MR2 Mk3 Roadster.

Matty2Hotty

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Re: NVH Vibrations
« Reply #3 on: May 12, 2019, 08:07:16 PM »
Check the tie rods. There are some small white platic bushings that go in the steering rack.

I would honestly get all 4 tires rebalanced at another shop.

Last could be possible bad axle.
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redhot

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Re: NVH Vibrations
« Reply #4 on: May 12, 2019, 09:10:53 PM »
I'm trying to sort out a similar issue with my 430 Spider on an MR2 roadster. It as the DNA front steering and suspension mod kit.
I've been getting front wheel shake thru to the steering at speeds of 50mph+, last time I felt anything like that was with a kitcar in the 80's (Jago jeep). The wheels have been balanced 3 times in the last year (by each owner), one was the roadforce wheel balance (which simulates road pressure against the tyre on the machine). My original hunch was wheels not balanced. Wheel bearings are fine.

All my bushes and ball joints seem good (only done 500 miles since last MOT). However my car has been sitting on these new looking tyres for 5 years, and not driven, so they will have ovality/flat spots. The more I drive the car now, the less I feel the front shaking, so it could be flat spots.

I'm changing the rubber bushes to Polyurethane, but I doubt its that. A steering damper bolted to the rack with U bolts would help a bit. I'm getting oversteer too, and the steering doesnt centrallise as one would expect, when turning and steering straight.

I wonder if any other DNA 430 Spider owners have similar issue. Must be fixable. Geometry or a design issue is a concern.

Darren

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Re: NVH Vibrations
« Reply #5 on: May 13, 2019, 06:23:55 PM »
The only reason for a shake is that a wheel or hub assembly is not running true. If a tyre is out of shape, balancing will not fix the issue
take a look at the last 10 minutes of this vid
https://www.youtube.com/watch?v=4cx9apL7HhY

If your hub adapter is not faced correctly, this will also introduce a shake, if your adapter is not flat against the hub, this will introduce a shake/vibration. if your discs are not true to the hub this will introduce a shake vibration

Basically what I'm saying is that, it's a process of elimination. You know the wheels are balanced, but are the tyres sitting on the  rim correctly?

I would then look at the hub area, bolt the adapter up securely then trace the edge with a dial Vernier, this should tell you if the mounting face of the wheel is flat and true.

Unfortunately the extra stuff bolted  onto the drive train increases the chance of some vibration, which means tracking down the fault becomes more of a chore.
 
Hopefully some of the 430 owners may be able to shed some sort of light on this issue, my set up is not DNA or Toyota
Darren
Well, I'm into the 11th year of the project, could it be ready for Stoneleigh 2020, doubt it. The longest DNA build ever

360MKbuild

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Re: NVH Vibrations
« Reply #6 on: May 13, 2019, 06:36:16 PM »
Agree more than likely the spacers are not true. The last 4 dna cars in the garage all spacers needed milling to run true.

redhot

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Re: NVH Vibrations
« Reply #7 on: May 13, 2019, 08:18:57 PM »
Agree more than likely the spacers are not true. The last 4 dna cars in the garage all spacers needed milling to run true.

This is good intel, thanks

Furrari

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Re: NVH Vibrations
« Reply #8 on: May 17, 2019, 11:33:32 AM »
I think what I would do is firstly check if the mounting of the wheel is true to the hub.  This should be checked at the balance stage, but this checks it to the wheel centre, not how the wheel is mounted on the car.  Use a giant sticky pin.  Use plasticine to mount it to the body and rotate the wheel.  Check the perimeter of the tyre and the edge of the rim both for diameter run out and for wobble.

Next take the wheel off and check that the face of the hub is parallel to the original hub ( the extender is even thickness) and that the original hub is running true.  Finally check that the extender is concentric with the hub assembly.

If all that lot is correct you can have the whole hub/wheel/tyre assembly balanced on the car but very few places can do that these days.

If all the above doesn’t work ask somebody else for ideas.
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