NVH oscillating ramps like Rolls Royce and Honda use?
Discussion
I had a visit to the old Rolls factory at Crewe many years ago. They demonstrated a type of ramp that new cars would be placed upon which would then 'bump' the wheels to simulate a variety of road surfaces and road speeds. The same kind of ramp is shown on the Honda TV sponsorship slots between programmes.
Does anyone know where I could get access to one of these rigs to put my own car on it? It has developed an irritating rattle/vibration, but its really impossible to establish where it is coming from (I can't stick my head inside a dashboard at the same time as driving it, believe it or not). I reckon half an hour with one of these special ramps would get the problem solved, but its not the kind of rig that any old garage is likely to have.
Does anyone know where I could get access to one of these rigs to put my own car on it? It has developed an irritating rattle/vibration, but its really impossible to establish where it is coming from (I can't stick my head inside a dashboard at the same time as driving it, believe it or not). I reckon half an hour with one of these special ramps would get the problem solved, but its not the kind of rig that any old garage is likely to have.
TUS 373 said:
I had a visit to the old Rolls factory at Crewe many years ago. They demonstrated a type of ramp that new cars would be placed upon which would then 'bump' the wheels to simulate a variety of road surfaces and road speeds. The same kind of ramp is shown on the Honda TV sponsorship slots between programmes.
Does anyone know where I could get access to one of these rigs to put my own car on it? It has developed an irritating rattle/vibration, but its really impossible to establish where it is coming from (I can't stick my head inside a dashboard at the same time as driving it, believe it or not). I reckon half an hour with one of these special ramps would get the problem solved, but its not the kind of rig that any old garage is likely to have.
You're looking for a 7-post shaker rig. They are very expensive and other than in professional motorsport applications or car development, I'd be surprised if you can find one. I've never heard of a normal roadcar being put on one to search for this sort of problem, as I believe the costs would be prohibitive - they are usually used as a sort of "chassis/suspension dyno" for want of a better term.Does anyone know where I could get access to one of these rigs to put my own car on it? It has developed an irritating rattle/vibration, but its really impossible to establish where it is coming from (I can't stick my head inside a dashboard at the same time as driving it, believe it or not). I reckon half an hour with one of these special ramps would get the problem solved, but its not the kind of rig that any old garage is likely to have.
C
Get friend to drive car along quiet private road you sit in passenger seat to locate the squeak.
If private road can easily climb to the back when you hear the noise if it is not where you first thought. Stopping and restarting means you have to retune ears to find the same noise again.
If private road can easily climb to the back when you hear the noise if it is not where you first thought. Stopping and restarting means you have to retune ears to find the same noise again.
JonnyFive said:
Find a cobbled road.. Guildford has one. Shakes the s
t out of your car 
Exactly, although around by me you would struggle to spot a cobbled road from a pot holed one.t out of your car At least using this approach if the rattle stops and the car still keeps on going you know it wasn't an essential part
Thanks chaps.
I can hear the rattle on a cobbled road right enough. Just can't get to find out where it is other than (possibly) inside the dashboard. Ideally, I could do with reclining the driver seat, laying over the seat upside down, with my head in the foot well whilst the car is on the rig. Even better, get somebody else to do that!
The car is a Lexus RX. The dealership has been very good (as you would hope to expect, Lexus being Lexus). However, I live 30 miles from the dealership, and the roads near them don't seem to show the rattle up when I have been in the passenger seat. It's getting to the stage where they have tried the process of elimination stuff and changed out suspension components, so the next stage would be the dash coming out. I don't really fancy that if it is avoidable. After reading the thread about the 'extended dealer test drive in an Audi A3' today, where it was kept for two weeks, got abused and must have been on an 80 mile round trip carrying the dealerships children to the golf course, I am not that keen on people having it for an 'extended test drive'. On the other hand, the rattle is driving me nuts!
I can hear the rattle on a cobbled road right enough. Just can't get to find out where it is other than (possibly) inside the dashboard. Ideally, I could do with reclining the driver seat, laying over the seat upside down, with my head in the foot well whilst the car is on the rig. Even better, get somebody else to do that!
The car is a Lexus RX. The dealership has been very good (as you would hope to expect, Lexus being Lexus). However, I live 30 miles from the dealership, and the roads near them don't seem to show the rattle up when I have been in the passenger seat. It's getting to the stage where they have tried the process of elimination stuff and changed out suspension components, so the next stage would be the dash coming out. I don't really fancy that if it is avoidable. After reading the thread about the 'extended dealer test drive in an Audi A3' today, where it was kept for two weeks, got abused and must have been on an 80 mile round trip carrying the dealerships children to the golf course, I am not that keen on people having it for an 'extended test drive'. On the other hand, the rattle is driving me nuts!
http://www.lola-group.com/content.asp?ContentId=9&...
Doesn't strike me as a cheap way to find a rattle.....
Doesn't strike me as a cheap way to find a rattle.....
Multimatic have one, i saw it on one of these "follow an LMP car through it's developmment" type programmes and the name stuck because it was the same company that caterham used to develop the inboard pushrod suspension on their CSR cars (not that i'm a car nerd or anything, lol)
ETA: Got it.
http://www.multimatic.com/engineering/4postovervie...
HTH
ETA: Got it.
http://www.multimatic.com/engineering/4postovervie...
HTH
esuuv said:
http://www.lola-group.com/content.asp?ContentId=9&...
Doesn't strike me as a cheap way to find a rattle.....
Funnily enough, one of the people I studied woth, her brother works/worked for Lola in Huntingdon. Like you say, probably very expensive, not to mention a 9 hour round trip.Doesn't strike me as a cheap way to find a rattle.....
Oxford Brookes has one also - I used it for some experimentation as part of my final year project.
The ones used for automotive are typically 4-post rigs, one for each wheel. The 5/6/7 post rigs have additional hydraulic rams to pull the car downwards, to simulate aerodynamic loads - whilst you can happily do this with just the one post, if you want to account for changes in aero balance front-to-back and side-to-side you need three more on top of the wheel posts, hence 7 posts.
For the OP's issue, you could just run a few swept sine inputs from 0.5Hz up to about 50Hz - any higher and the tyre tends to absorb the vibration. It is interesting to see the different bits of a car resonating at different frequencies, especially if you change between heave or pitch modes.
The ones used for automotive are typically 4-post rigs, one for each wheel. The 5/6/7 post rigs have additional hydraulic rams to pull the car downwards, to simulate aerodynamic loads - whilst you can happily do this with just the one post, if you want to account for changes in aero balance front-to-back and side-to-side you need three more on top of the wheel posts, hence 7 posts.
For the OP's issue, you could just run a few swept sine inputs from 0.5Hz up to about 50Hz - any higher and the tyre tends to absorb the vibration. It is interesting to see the different bits of a car resonating at different frequencies, especially if you change between heave or pitch modes.
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