golfgtdude
Passed Driver's Ed
- Location
- Merseyside, UK
Hi All,
Thought I would share some of my experiences of recent regarding changing some discs/pads on my MK7 Golf.
I've done this procedure plenty of times in the past without an issue (on other types of cars) but on this occasion, after about 5000miles I started to experience judder felt through my chassis and the pedal. I also noticed pad silhouette marks on all my discs which were odd.
A local workshop said I had a stuck caliper causing a 'warped disc' but after further investigation my root cause was quite different. There is no such thing as a warped disc, its more likely disc thickness variation (DTV) caused by runout.
The problem with my car was in fact at the front, I purchased a DTI gauge from a popular internet retailer to test all my discs. Both of my front discs were out of manufacturers tolerance in terms of runout. Simply changing both discs for new ones would resolve the issue in the short term for for reasons below it would return as you read below...
I contacted the dealer who sold me the parts and they sent out their 'brake specialist' to have a look.
The specialist took my brakes apart and notified me that the hubs had traces of surface rust still present and these surfaces must be completely back to shiny steel before fitting any new brake disc (don't angle grind them as he told me one customer did as this changes the profile of the hub and potentially makes the issue worse!). I did clean this up with a wire brush when I originally installed them asI didn't think it would be that sensitive. Apparently 1 micron of dirt is all it takes to set the disc out of true and over time this can/will lead to DTV. The chap cleaned up my hubs, then checked them with a DTI gauge after fitting fresh brake discs, all were bang on within tolerance.. in fact no visible runout at all.
Fingers crossed my brakes will be ok now (they were on their original discs up to 45k).
The specialist was not able to explain the pad silhouette marks but said it could be a sign that they had been overheated or jammed on hard a few times. I do wonder sometimes if the auto braking feature of this car is worse than good since it can have a tendency to slam on if it thinks i'm on a collision course when its just a randomly parked car on the side of a road. Maybe I'll disable this function till the brakes had been fully run in to avoid this from occurring.
For some experiences folks on here this is probably teaching those to suck eggs but I believe some workshops out there may not go to these lengths when installing new discs... worrying for sure but useful to know for home DIY'ers.
Thought I would share some of my experiences of recent regarding changing some discs/pads on my MK7 Golf.
I've done this procedure plenty of times in the past without an issue (on other types of cars) but on this occasion, after about 5000miles I started to experience judder felt through my chassis and the pedal. I also noticed pad silhouette marks on all my discs which were odd.
A local workshop said I had a stuck caliper causing a 'warped disc' but after further investigation my root cause was quite different. There is no such thing as a warped disc, its more likely disc thickness variation (DTV) caused by runout.
The problem with my car was in fact at the front, I purchased a DTI gauge from a popular internet retailer to test all my discs. Both of my front discs were out of manufacturers tolerance in terms of runout. Simply changing both discs for new ones would resolve the issue in the short term for for reasons below it would return as you read below...
I contacted the dealer who sold me the parts and they sent out their 'brake specialist' to have a look.
The specialist took my brakes apart and notified me that the hubs had traces of surface rust still present and these surfaces must be completely back to shiny steel before fitting any new brake disc (don't angle grind them as he told me one customer did as this changes the profile of the hub and potentially makes the issue worse!). I did clean this up with a wire brush when I originally installed them asI didn't think it would be that sensitive. Apparently 1 micron of dirt is all it takes to set the disc out of true and over time this can/will lead to DTV. The chap cleaned up my hubs, then checked them with a DTI gauge after fitting fresh brake discs, all were bang on within tolerance.. in fact no visible runout at all.
Fingers crossed my brakes will be ok now (they were on their original discs up to 45k).
The specialist was not able to explain the pad silhouette marks but said it could be a sign that they had been overheated or jammed on hard a few times. I do wonder sometimes if the auto braking feature of this car is worse than good since it can have a tendency to slam on if it thinks i'm on a collision course when its just a randomly parked car on the side of a road. Maybe I'll disable this function till the brakes had been fully run in to avoid this from occurring.
For some experiences folks on here this is probably teaching those to suck eggs but I believe some workshops out there may not go to these lengths when installing new discs... worrying for sure but useful to know for home DIY'ers.
