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Running car on ramp at full droop.

jl-c

Well-known member
Joined
22 Jul 2013
Messages
518
As title, I want to run the car with rear wheels off at full droop so I can see if there is any run out on the rear discs. Is this possible without doing any damage? Other option is to revolve them by hand using a dial gauge, but that means I have to buy one!
Guess this could be a deMort question :D ?
 
I would be using a dial gauge ..

You can run up a car on the ramp but it may well get upset .. rear wheels spinning but not fronts ( unless a C4 ) .. car might want to activate abs .

you will struggle to measure .. well see a movement that would indicate a disc fault as well .

It can be done .. but the benefits and if it will help .. hmm .. not so sure there .

Rule of thumb ..

Front discs " warped " brake pedal will move under braking .. you feel it going up and down and the steering will shake .

Rear discs and just the pedal will go up and down .

It's only slightly and normally worse when hot .. ie you hold the brake / acc pedal for a bit to get some heat in them .. DON'T go mad here though .

First check .. and i talk from experience here .. make sure the wheel bolts are tight .. they give the same fault as a " warped " brake disc .. just a lot more dangerous !!!

btw .. any obvious pad rust marks on the discs .. ie where the pad was wet and left overnight so it rusts to the discs are often a sign that there is a high spot and will cause judder .

Also a second test without equipment ( i'm thinking as i'm typing here :D ) wheel off and jacked up .. turn the disc by hand .. any time it binds / sticks in a certain place would also indicate a high spot .. high being out of true .
 
thank you deMort, as usual good thought out advice. It is a C2S and wheel bolts torqued correctly, thanks for the thought though!
 
lets just say i had a lucky escape with a car .. brake vibration got worse on a r/t .. something didn't feel right so i cut it short and headed back to the garage ..

Rear wheels were not done up .. worrying for me and the customer !

Try what i suggested .. you don't always need expensive equipment .. some things like a rust deposit and a pedal judder are kinda obvious as to what the fault is :)
 

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