John tarantula Posted January 28, 2012 Share Posted January 28, 2012 Have some shiney new DBA's and 2500's to change over next weekend but wondering about checking the runout when fitting. Does everyone check this or do most just make sure all is flat and clean and put the new discs on? Have never checked on previous cars when doing discs but have read about it here a bit more. Obviously in an ideal world I can see why it's worth checking but if most people don't then I'm not going to fork out for another gauge to check it. cheers! Quote Link to comment Share on other sites More sharing options...
mc Posted January 28, 2012 Share Posted January 28, 2012 if you didn't want to buy a clock then you could just clamp a bit of metal close to the disc surface to use as a finger and check it visually? Quote Link to comment Share on other sites More sharing options...
stubzie83 Posted January 28, 2012 Share Posted January 28, 2012 I would measure the run out as the tolerances are very small. For the front discs the maximum allowable is 0.05mm and for the rears 0.07mm. This is not possible to determine visually without a dial gauge. I replaced my discs with DBA 4600's recently and found that the hub has to be very clean or the runout will be excessive. Without measuring the runout I wouldn't have known how much to clean the hubs. Took several cleaning attempts on one hub as the old discs left a lot of crap behind and there was a lot of old copper grease everywhere. I used a brass wire brush attachment on a drill and some brake cleaner to remove all of the crud on the surface. I was then able to get the runout on both discs down to 0.03mm. With the DBA slotted discs you have to measure the runout on the very edge of the disc otherwise the dial gauge goes down the slots. Quote Link to comment Share on other sites More sharing options...
stubzie83 Posted January 28, 2012 Share Posted January 28, 2012 There are also some videos on how to install a DBA disc from DBA themselves. Details cleaning and runout measurements. They are on this page: http://www.dba.com.au/tech-articles-2/ Quote Link to comment Share on other sites More sharing options...
John tarantula Posted January 28, 2012 Author Share Posted January 28, 2012 will have a look at the videos as well. Quote Link to comment Share on other sites More sharing options...
John tarantula Posted January 30, 2012 Author Share Posted January 30, 2012 for the sake of £22 just ordered a dial indicator gauge and arm so can do it properly! Quote Link to comment Share on other sites More sharing options...
jables Posted February 3, 2012 Share Posted February 3, 2012 I'm about to install some front DBA's for the first time and noticed that very few tutorial videos mention checking the runout. Would a good garage go to the trouble of checking this or just install the discs and then check for any brake judder? Quote Link to comment Share on other sites More sharing options...
John tarantula Posted February 17, 2012 Author Share Posted February 17, 2012 for under £25 i just bought a dial indicator gauge and arm off Ebay to check it properly. Check the runout on just the hub once old discs are off and before fitting the new discs, if that's off then the hub has issues, if not then check it on the new discs once theyre on. if out of limits a use a combination of cleaning the hub / disc / rotating the discs til it's within acceptable limits.... that's my plan for tommorow! I think if you just put them on and wait for judder you can ruin them so better to get them on straight in the first place. Quote Link to comment Share on other sites More sharing options...
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