Technically... it's Noise, Vibration and Harmonics. Not that we would be nit picky of coursebertvorgon wrote:Thanks for posting that link up Rob, that is without a doubt the best graphic visual example of what is going on.
I fought driveshaft vibration for years in the early days, then found out about the angularity and phase issue, never looked back after that and ever more so when Andy made me my driveshaft.
Derek, it stands for NOISE, VIBRATION and HARSHNESS...
Basically embodies our 510s as we stiffen things up and get rid of factory sound deadening.
NVH Issues
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Re: NVH Issues
- bertvorgon
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Re: NVH Issues
Not to be picky..but I got this from the Web...
https://en.wikipedia.org/wiki/Noise,_vi ... _harshness
http://www.frost.com/sublib/display-mar ... d=35405241
http://www.ricardo.com/en-GB/What-we-do ... hness-NVH/
far be it for me to argue with the Pro's....heh heh....
https://en.wikipedia.org/wiki/Noise,_vi ... _harshness
http://www.frost.com/sublib/display-mar ... d=35405241
http://www.ricardo.com/en-GB/What-we-do ... hness-NVH/
far be it for me to argue with the Pro's....heh heh....
"Racing makes heroin addiction look like a vague wish for something salty" - Peter Egan
Keith Law
1973 2 Door Slalom/hill climb/road race / canyon carver /Giant Killer 510
1971 Vintage 13' BOLER trailer
Keith Law
1973 2 Door Slalom/hill climb/road race / canyon carver /Giant Killer 510
1971 Vintage 13' BOLER trailer
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- Location: Coquitlam
Re: NVH Issues
With gear noise and rotational noises, it's often referred to as Harmonics. Shall we agree that it can be called either? Merry Christmas.
Vehicle Gearbox Noise and Vibration: Measurement, Signal Analysis, Signal ...
By Jiri Tuma
https://books.google.ca/books?id=xy_qAg ... cs&f=false
Handbook of Noise and Vibration Control
By Malcolm J. Crocker:
https://books.google.ca/books?id=46Nvrv ... cs&f=false
Fundamentals of Noise and Vibration Analysis for Engineers
By M. P. Norton, D. G. Karczub:
https://books.google.ca/books?id=jDeRCS ... cs&f=false
Vehicle Gearbox Noise and Vibration: Measurement, Signal Analysis, Signal ...
By Jiri Tuma
https://books.google.ca/books?id=xy_qAg ... cs&f=false
Handbook of Noise and Vibration Control
By Malcolm J. Crocker:
https://books.google.ca/books?id=46Nvrv ... cs&f=false
Fundamentals of Noise and Vibration Analysis for Engineers
By M. P. Norton, D. G. Karczub:
https://books.google.ca/books?id=jDeRCS ... cs&f=false
- TheHeretic
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Re: NVH Issues
Quick update here and hopefully the advice from the experts. So after a lot of work sound deadening the car I was able to take it out for a drive. While quieter for sure, the issue I am dealing with is still there. Basically something happened when the STI differential and coilovers went in. I'm thinking that it is the angle of the driveline (shaft) at this point but I would love your opinions.
So the vibration is mostly there when accelerating from light to full throttle but is the strongest at 5Krpm+. Exhaust rubbing has been eliminated after getting that checked out. I can be accelerating lightly and once the clutch is pushed in while accelerating, the rpms go up (duh) but the vibration goes away immediately.
Not sure what else I can do to "test" other things it could be. Gotta be between the tranny and diff, right?
So the vibration is mostly there when accelerating from light to full throttle but is the strongest at 5Krpm+. Exhaust rubbing has been eliminated after getting that checked out. I can be accelerating lightly and once the clutch is pushed in while accelerating, the rpms go up (duh) but the vibration goes away immediately.
Not sure what else I can do to "test" other things it could be. Gotta be between the tranny and diff, right?
Carpe Diem!
Ryan
Ryan
Re: NVH Issues
when swapping my diff back in the fall I noticed a lot of play and slop and only the rust lines / paint lines helped in getting the diff back in the right place.
I would loosen the four mounting bolts and the mustache bar, give it a wiggle, tighten it back up and see what happens.
I would loosen the four mounting bolts and the mustache bar, give it a wiggle, tighten it back up and see what happens.
two_68_510s wrote:I guess our donkeys are quicker then your sled dogs!
- SteveEdmonton
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Re: NVH Issues
I chased vibration & noise for ages and finally found that the bolts holding the factory tranny mount to my 71B 5-speed were coming into contact with the crossmember (Experimental Engineering) when load came on and the driveline rotated ever so slightly on its axis. Bolts with a shorter head took care of the problem in short order.
Prior to this, though, I had replaced motor-mounts, tightened every nut & bolt in sight, separated brake & fuel lines so they couldn't touch anything-- you name it, I tried it. Of course nothing made any real difference until finally-- finally!-- I figured out what the actual problem was.
It'll be like this for you too. But hopefully you'll find the right thing sooner rather than later.
Prior to this, though, I had replaced motor-mounts, tightened every nut & bolt in sight, separated brake & fuel lines so they couldn't touch anything-- you name it, I tried it. Of course nothing made any real difference until finally-- finally!-- I figured out what the actual problem was.
It'll be like this for you too. But hopefully you'll find the right thing sooner rather than later.
'71 4-door
'74 MGB-GT
'04 Miata
'74 MGB-GT
'04 Miata
Re: NVH Issues
yup the freshly plated stock bolts on the dogleg touched my ee member too
two_68_510s wrote:I guess our donkeys are quicker then your sled dogs!
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Re: NVH Issues
Could very well be pinion angle. A small amount of mismatch can cause a substantial amount of vibration. You may have to shim your diff and the transmission to get the angles correct.
Even with IRS, there will be some upwards rotation of the pinion nose when accelerating. Poly bushings will reduce the amount of rotation, but there will always be some, unless solid metal bushings are used.
The following pictures illustrate the correlation of tranny, driveshaft, and pinion nose angles. When under high load. At rest, the ideal angle is slightly downward on the pinion shaft. The diff nose will then rotate upwards under load an align to a zero degree angle.
Even with IRS, there will be some upwards rotation of the pinion nose when accelerating. Poly bushings will reduce the amount of rotation, but there will always be some, unless solid metal bushings are used.
The following pictures illustrate the correlation of tranny, driveshaft, and pinion nose angles. When under high load. At rest, the ideal angle is slightly downward on the pinion shaft. The diff nose will then rotate upwards under load an align to a zero degree angle.
Re: NVH Issues
This is something i am interested in as I am pretty sure the driveshaft angle is wrong on all of my cars. How does one take the proper measurements to check the angle the engine and differential are mounted at? I can level the driveshaft to the body, or to the rear crossmember, but there is nowhere flat on the differential itself or on the gearbox itself to ensure they are mounted flat in the car, anyone have any suggestions or do I need to buy special tools?TheHeretic wrote:I might be missing it but is there a topic or link to a more in-depth discussion around driveshaft angularity? Don't know if right now is the best time to mess with it but definitely will want to address it when I put in the KA24 transmission. Also what is everyone using to measure the u-joints angle? Was going to just download an app to the phone and use it...
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Re: NVH Issues
Place driveshaft in a position so two of the universal bearing cups are 90 degs. Take a socket that fits on the cup and place it and your phone with angle finder on it and measure at trans and diff. I have a digital angle finder with a magnetic and non magnetic base that works great.
"Lastnight the wife said oh boy when your dead you can't take nothing with you but your soul oh "Think"
- John Lennon
- John Lennon
- funwithmonkeys
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Re: NVH Issues
Thank you for that. I have been wondering if there was an easy way to do it and that looks like it.Three B's Racing wrote:Place driveshaft in a position so two of the universal bearing cups are 90 degs. Take a socket that fits on the cup and place it and your phone with angle finder on it and measure at trans and diff. I have a digital angle finder with a magnetic and non magnetic base that works great.
If no one from the future comes back to stop you from doing it then how bad of a decision can it really be?
Re: NVH Issues
I want to borrow some tools from work to do it. Pruftechnik Ultra Cardan Shaft Alignmentfunwithmonkeys wrote:I have been wondering if there was an easy way to do it and that looks like it.
'72 2 door KA project | S14 Silvia RB25DET | S14 RB26DETT (sold) | '90 Audi 90Q20V (sold)
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Re: NVH Issues
Awesome and did you notice what they said? " Shaft offset to help with universals lubrication" because if the shaft is in perfect alignment of it's mating universals they don't properly lubricate themselves. I've alway been told the universals/driveshaft must have some angularity to them for proper lubrication of the universals.JordanTr wrote:I want to borrow some tools from work to do it. Pruftechnik Ultra Cardan Shaft Alignmentfunwithmonkeys wrote:I have been wondering if there was an easy way to do it and that looks like it.
"Lastnight the wife said oh boy when your dead you can't take nothing with you but your soul oh "Think"
- John Lennon
- John Lennon
Re: NVH Issues
Good catch Lou.
I think that point is confusing for a lot of people since oftentimes people measure the angle of the cardan shaft compared to the angle of the input/output shaft. This is an angle but if both angles are equal then the overall alignment is zeroed out.
If you look at OEM Nissan stuff, the diff pinion is offset from the center of the tunnel for just that reason--to allow for parallel misalignment to keep the u joints happy.
I think that point is confusing for a lot of people since oftentimes people measure the angle of the cardan shaft compared to the angle of the input/output shaft. This is an angle but if both angles are equal then the overall alignment is zeroed out.
If you look at OEM Nissan stuff, the diff pinion is offset from the center of the tunnel for just that reason--to allow for parallel misalignment to keep the u joints happy.
'72 2 door KA project | S14 Silvia RB25DET | S14 RB26DETT (sold) | '90 Audi 90Q20V (sold)
- funwithmonkeys
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Re: NVH Issues
I just measured mine and I have 2.4 and 4.5. After a bunch of fiddling I got it down to 2.7 and 4.0. My car is not level so a difference of 1.9 Down to 1.3. To get it any closer I would need to lower the front of my motor. My trans is really close to the tunnel and my CV's are getting really close to my exhaust. Looks like I will will just have to live with it.
If no one from the future comes back to stop you from doing it then how bad of a decision can it really be?