Jump to content
SAU Community

Do i need to skim rotors?

-S-
 Share

Recommended Posts

-S- Community Regular

-S-

Posted
Posted

Hi all,

 

Need advise. ..

 

Long story short , do i need to skim my rotors that have been lying on the grass/dirt for more than a year?

 

I've measured the thickness for both front and rear rotors and they have not thin out at all . Not even 1 mm :) obviously they're full of rust and dirt . I've removed the dirt but wondering if i should skim it to remove rust and also balance the rotors before fitting them? (Not even sure if people balance rotors or not)

 

I've attached 1 pic to pretty much show how It was kept under the weather lol...

20161202_180320.jpg

Link to comment
https://www.sau.com.au/forums/topic/469195-do-i-need-to-skim-rotors/
Share on other sites
GTSBoy Grand Master

GTSBoy

Posted
Posted

You can give them a rub with abrasive paper to try to remove a lot of rust.  They will not have changed dimensions in a way that you can measure, so you shouldn't worry about that.  They only real problem with using paper to clean them is that you may make the surfaces not evenly flat whilst doing so.  But you'd have to rub pretty hard in one spot a lot longer than other spots to achieve it.

Oddly enough, it's not the friction surface you need to worry about the most.  If there is thick rust on the hub surface, you need to clean that up.

-S- Community Regular

-S-

Posted
  • Author
Posted
You can give them a rub with abrasive paper to try to remove a lot of rust.  They will not have changed dimensions in a way that you can measure, so you shouldn't worry about that.  They only real problem with using paper to clean them is that you may make the surfaces not evenly flat whilst doing so.  But you'd have to rub pretty hard in one spot a lot longer than other spots to achieve it.

Oddly enough, it's not the friction surface you need to worry about the most.  If there is thick rust on the hub surface, you need to clean that up.

 

Will it be easier if i send it to a workshop to skim it to remove rust? I don't mind saving some money to do it myself though but i need guidance...

 

Reason i ask about skimming rotors is because a friend told me i should get it skimmed & balanced as well... do people even balance rotors? ?? I mean the last thing i need is driving and feeling a lot of vibration/ shake. ..

 

GTSBoy Grand Master

GTSBoy

Posted
Posted

No, rotors do not get balanced.

My position is never get rotors machined unless they absolutely need it.  You lose material and life from them every time you do it.  The only time to do it is if there is a lip than needs to be gotten rid of, or grooves in the surface, or serious warpage.  Although serious warpage should probably prompt replacement.  The other reason people get rotors machined is when they think they have warped rotors but they actually have uneven build up of pad binder material on the rotor faces.  This can also be successfully fixed with abrasive paper.

If your surfaces are nice and flat and you don't have a lip on the outer edge, try paper first.

Lastly, I never get rotors machined off the car.  It's just so easy to get the mobile brake guy to come and do them on the car, whether at home or in a workshop.  So you may as well just clean them up yourself and see how they go before moving onto machining if you need to.  But it is important for you to realise that there are other reasons for you to get braking vibrations also.  It may not necessarily be that the rotors are not good.  So if you do put it all together and run it and find vibration, you'd be well advised to look at the other reasons.  At the least you can put a dial gauge onto the car and spin the rotors to see if they have a lot of runout other wierdness going on, and this can be done better on the actual hub and bearing that they are working on than a lathe anyway.

  • Like 2
V28VX37 Veteran

V28VX37

Posted
Posted
5 hours ago, GTSBoy said:

No, rotors do not get balanced.

...

Well, they do - at the manufacturer. One of the RDA's I installed recently had a nice straight 'slot' cut on the outer rim of the disc at one single spot, whilst the other rotor didn't - I am 99% certain it's to balance it. The pair was less $200 so pretty cheap compared to mucking around with rusted rotors.

Also re machining rotors on hubs, it's a good option but some guys only do plain ones, the one my shop uses wouldn't touch my slotted DBA's on the car.

When re/installing rotors make sure you check run out and oscillation: https://www.sau.com.au/forums/topic/448613-r34-gtt-brake-improvement-without-breaking-the-bank/?do=findComment&comment=7803377

As others have said you definitely want to check the condition of those calipers. Rebuilding them at a workshop will cost a bit (my GTT fronts rebuild was around $400 drive in/drive out), but brakes is one of those things that you need to be pretty confident in what you're doing to DIY.

Also: If that's what your rotors and suspension looks like, what the rest of the underbody like??

dbasteve Enthusiast

dbasteve

Posted
Posted

I guess you've harvested the potatoes already. :369_sweet_potato:

Hi Mate,

Please either re-machine those discs or get new ones (your pads will thank you), rebuild the calipers (seal kit), replace the studs and clean the rust off those hubs and inside the disc hat. You should then have a safe ride.

Cheers 

Duncan Grand Master

Duncan

Posted
Posted
6 hours ago, dbasteve said:

I guess you've harvested the potatoes already. :369_sweet_potato:

Hi Mate,

Please either re-machine those discs or get new ones (your pads will thank you), rebuild the calipers (seal kit), replace the studs and clean the rust off those hubs and inside the disc hat. You should then have a safe ride.

Cheers 

do what this man says, he knows.  and welcome back to the forums :)

dbasteve Enthusiast

dbasteve

Posted
Posted
10 hours ago, -S- said:

I'm doing all except the studs...

Studs are cheap and easy to replace. Those in the picture look like they have advanced corrosion and aren't safe. 

Assuming you can get some wheel nuts on don't leave it too long.

niZmO_Man Grand Master

niZmO_Man

Posted
Posted

After changing wheel studs three times because of "technicians" who can't put wheels back on my Subaru properly, yes they are cheap to change but quite a crucial part of keeping your car on the road.

https://partsouq.com/en/search/all?q=43222-28B00

-S- Community Regular

-S-

Posted
  • Author
Posted
Studs are cheap and easy to replace. Those in the picture look like they have advanced corrosion and aren't safe. 
Assuming you can get some wheel nuts on don't leave it too long.

I thought u meant the stud of the caliper. Lol. Yeah i guess I'll look into it. .. thanks
dbasteve Enthusiast

dbasteve

Posted
Posted
22 minutes ago, -S- said:


I thought u meant the stud of the caliper. Lol. Yeah i guess I'll look into it. .. thanks

No Worries and good luck.

Give everything a good ol soak in WD40 a day or more before. Take the pads out first. 

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
Go to topic listing


  • Similar Content

  • Latest Posts

    • GTSBoy
      "Cheap" bolt on turbo on RB25DET NEO

      By GTSBoy · Posted

      The HG high flow is excellent, and costs about the $$ you're talking about. But it, and probably every other highflow, uses a diffeent core than the original turo, and the original Hitatchi core is quite long. So, I think it is inevitable that there is likely no such thing as a highflow that just "bolts on" with no other effort required. And the same is likely true for HG's outright replacement "bolt on" turbos (the ATR things). And the same is likely true for anything similar from elsewhere. I have no idea if the cheap Chinese/Taiwanese complete turbos from eBay/Temu/etc are as bolt on as they claim. I mean, they claim the bolt onto the NAs as well as the turbos, and we know that can't be "bolt on". But it wouldn't matter because I'm not buying a $169 4 psi turbo for anything other than a paddock basher.
    • Kapr
      "Cheap" bolt on turbo on RB25DET NEO

      By Kapr · Posted

      Bummer...yeah i "need" something to "ease" up the work and for my driving it would be enough.    Iam counting the tune "without" turbo. I do not mean "cheap" like something from Temu around 200 USD, "Cheap" is something around 1000 USD? 
    • GTSBoy
      Neil's R33 Gts-t Build

      By GTSBoy · Posted

      Starter motors used to use the weight of metal (magnets) to provide torque. Now they use (more) current instead. This. It's completely normal.
    • Duncan
      Neil's R33 Gts-t Build

      By Duncan · Posted

      So thing that had me stumped, but I think is OK....is that when it was up in the air, in neutral I had it running to bleed to coolant while I put the wheels back on. I noticed the rears were turning (slowly) which I'd never seen before 20250928_163512.mp4     Because there had been an issue with clutch slip due to pedal adjustment on the dyno, I assumed there was still and issue so spent some quality time upside down under the dash adjusting the pedal....but no matter what I did the wheels still turned in neutral. Even disconnected the master cylinder to pedal rod and same. In despair, I even removed the clutch slave so there was no chance of any preload causing it.....still happened. So either: 1. Something is not right in the bellhousing, or 2. Its a thing sometimes with cold, thick gearbox oil Internet says it might be 2, I hope so!
    • Duncan
      Neil's R33 Gts-t Build

      By Duncan · Posted

      OK, few more things sorted and it is ready for a shakedown on 10-Oct, with one weird thing. Changed the run in oil and filter for the good stuff. 8l came out, about 8.5 went in with filter so that looks all good. Changed the starter (again), this time for a brand new one, works good. Interesting that the Taaaarks one is shorter than factory but spins harder, I guess electronics have moved on a little in the last 30 years. Will be nice to have a bit of extra space under there. Put the timing cover back on, and noted where the cam gears were set as a record.  Will need to double check the timing but it is pretty close. Also put the coil pack cover and intake snorkel back on. Exhaust Inlet Changed the water out for coolant, bled up nicely. Removed the rear brake pads (well worn factory sumitomo ones!), gave the hardware a good clean and reassembled. I've put bendix XP on the back again because the price is excellent at $150 a set and they worked well on the V37. Front pads have plenty so no issue there
×
×
  • Create New...