Brake rotors

[doctorgonzo]

I did a search, but didn't see an answer. I felt me rear rotor for the first time tonight and it's grooved. Not super deep, but can feel it for sure. I checked the pads and they need replacement, but not metal on metal, so guessing this has existed for a while. It's my understanding local auto brake shop can't turn those because they are stainless. Is that right? I'm going to get a good measurement caliper and see if there enough left to turn this weekend. A little leakage from caliper also. You guys know a good source for re-build parts? It's a 1981 GS1000G.

 

[Shin-Ken 1074]

I don't know what your rotors are made of however, the stock Suzuki rotors on my Kat have been machined and turned out perfect and within run-out spec. Should be someone here who knows where you can have the job done. A genuine caliper kit which includes the piston and seals is the way I have gone with mine, not that expensive either, cheers.

 

[doctorgonzo]

Thanks. I'll call around tomorrow and just ask if they do MC rotors. The kit is about $35 at Babbitts. If anybody knows a better price, let me know.

 

[duaneage]

Post in parts wanted, everybody has a spare or two hanging on their wall somewhere.

 

[srsupertrap]

I did a search, but didn't see an answer. I felt me rear rotor for the first time tonight and it's grooved. Not super deep, but can feel it for sure. I checked the pads and they need replacement, but not metal on metal, so guessing this has existed for a while. It's my understanding local auto brake shop can't turn those because they are stainless. Is that right? I'm going to get a good measurement caliper and see if there enough left to turn this weekend. A little leakage from caliper also. You guys know a good source for re-build parts? It's a 1981 GS1000G.

I had this shop do three GS1000 Brake Rotors for me . . . . excellent workmanship.

http://cgi.ebay.com/ebaymotors/SUZU...020QQitemZ300216468171QQrdZ1QQsspagenameZWDVW

 

[salty_monk]

Yes, stainless & need grinding. It's likely you're not noticing a lot less performance from some slight grooves on the rear though so unless you're feeling flush...!!

The caliper kits are about $17 from Z1 enterprises.

Dan

 

[doctorgonzo]

Yes, stainless & need grinding. It's likely you're not noticing a lot less performance from some slight grooves on the rear though so unless you're feeling flush...!!

The caliper kits are about $17 from Z1 enterprises.

Dan

Yeah, I was just freaking out I think. SHOULD be done, but a caliper kit and fresh pads should do for now. When THESE pads wear out I'll look for a rotor or get this one ground.

 

[posplayr]

srsupertrap

srsupertrap

Any idea how much he took off of your disks? I just went an measured all of my bikes and it seems like i could do some surfacing to my spares bike, but they are all already slotted so I guess i dont need to go there.

The front spec appears to be 0.200 +/0.008 with a service limit of 0.180
and the rear is 0.260 +/- 008 with a service limit at 0.240
My fronts(L/R) and rear are :

81 GS750EX 0.182/0.192 and 0.237 (daily rider)
80 GS750EZ 0.198/0.200 and 0.258 (parts bike)
83 GS1100ED 0.192/0.187 and 0.270 (weekend road bike)

Looks like my plan is to remove the GS750EZ rotors which only have 30K Texas hiway miles and get them turned for my GS1100ED.

Swap the GS1100ED frnt left and rear tor the same on the GS750EX. I'm not too worried about the 750 as I only commute in town on side streets.

I would basically be getting ride of the GS750EX frnt left and rear.

Posplayr

 

[Shin-Ken 1074]

Hi posplayr, not sure if you are asking me about the rotor work or not? Anyway I had them skimmed as there was only light scratches and score marks on the front pair so minimal material was removed. I had the rotors done because I had the fork tubes out to be straightened and rechromed as they were a bit shabby at the 150,000km mark, cheers.

 

[Guest]

A little groove won't hurt anyone. :-D
The pads wear into them in just a few uses, the pads last just as long and I don't think braking power is any less.

 

[duaneage]

Most GS front rotors come in at 4.9 - 5.0 mm. I've seen quite a few pass through my garage and that is the norm. THe one exception was rear that the caliper locked on, that had record album grooves that were very deep.

You can use an orbital sander and 80 grit to put swirl lines on the rotor to help break in the new pads.

 

[posplayr]

Just found this link: Very interesting

Just found this link: Very interesting

Boondocks
Posts: n/a

Quote:
Originally Posted by denydog
May very well be a problem, but I don't think it was the case with my original rotors. They looked clean as a whistle, and the shop checked and found the run out exceeded tolorance....

See The "Warped" Brake Disc and Other Myths of the Braking System for information on why discs are measured and found to have runout and be "warped". The deposits are often not visible. The article concentrates on cast iron discs, but SS discs manifest the same behavior.

 

[posplayr]

Disks and Pads what to do....

Disks and Pads what to do....

This makes it sound as if it takes nothing for your rotors to feel warped. This might explain what is going on with my E350 Van under light braking.

See The "Warped" Brake Disc and Other Myths of the Braking System

The driver can feel a 0.0004" deposit or TV on the disc. 0.001" is annoying. More than that becomes a real pain. When deposit are present, by having isolated regions that are proud of the surface and running much hotter than their neighbors, cementite inevitably forms and the local wear characteristics change which results in ever increasing TV and roughness.

I might try this first before shipping all my rotor off to get 0.020" milled off of the and be below the service limit.

You can use an orbital sander and 80 grit to put swirl lines

Recommendations on Pads other than the FERODO Platnum?

Any comments welcome.

Posplayr

 

[posplayr]

Shin-Ken 1074

Shin-Ken 1074

Thanks for the comments, It would be nice to have a fresh surface if I only had to give up 0.005" (0.0025" each side) max which would put be about 25% or the way to a service limit from 0.200" (front).

The orbital sander might work in a pinch and I guess I would try that on the GS750 daily rider. The GS1100ED might deserve a little better.:-s

So how do your disks measure out now?
Did you notice an improvment in smoothness?
What pad you running?

My disks are not bad, I will be stripping it down to bare frame and deciding homw much to do to wheels and brakes. Brakes are a good thing .

Posplayr

 

[p_s]

See The "Warped" Brake Disc and Other Myths of the Braking System for information on why discs are measured and found to have runout and be "warped". The deposits are often not visible. The article concentrates on cast iron discs, but SS discs manifest the same behavior.

Great article. I like these kinds of articles where they justify their advice with sensible physics instead of how many bikes they've raced and other bull.

 

[Shin-Ken 1074]

I'll mic them up and let you know the disc spec. They were smooth to operate before the skim so they were not really in need I just had it done while the front end was apart. Using EBC pads, get around 30,000 km a set, cheers.

 

[Nessism]

The front disc on my 550E was warped or damaged in some way - pulsation could be felt in the brake lever. Tried to measure runout on the bike but there was way too much slop in the system to get a decent reading. Removed the disc and measured it while laying on a surface plate - something like 0.008" deviation (can't remember). The service limit is 0.012" which is completely crazy, the judder would put you on your ear at that point. Wound up buying a used rotor off ebay for $30 shipped and the new/used one measured at 0.002" and is running great. Suzuki's spec is a little wonky so keep this in mind.

Not sure what this has to do the the original question in this thread but thought like sharing.

BTW, thickness variation is a real enemy of discs with wear. You need to measure the thickness all around the disc in multipul places to get a handle on that. And contrary to what the article states, heat warping often leads to high spots on the disc...which then leads to thickness variation as the disc wears (not caused by deposits in many (most) cases.

 

[srsupertrap]

Re: posplayr questions

Re: posplayr questions

Any idea how much he took off of your disks? I just went an measured all of my bikes and it seems like i could do some surfacing to my spares bike, but they are all already slotted so I guess i dont need to go there.

The front spec appears to be 0.200 +/0.008 with a service limit of 0.180
and the rear is 0.260 +/- 008 with a service limit at 0.240
My fronts(L/R) and rear are :

81 GS750EX 0.182/0.192 and 0.237 (daily rider)
80 GS750EZ 0.198/0.200 and 0.258 (parts bike)
83 GS1100ED 0.192/0.187 and 0.270 (weekend road bike)

Looks like my plan is to remove the GS750EZ rotors which only have 30K Texas hiway miles and get them turned for my GS1100ED.

Swap the GS1100ED frnt left and rear tor the same on the GS750EX. I'm not too worried about the 750 as I only commute in town on side streets.

I would basically be getting ride of the GS750EX frnt left and rear.

Posplayr

I cannot recall exactly how much they removed but it was well within the Service limit. I had the rotors shipped to my place of work and I checked the parallelism with a dial indicator and I believe the max reading was .0005" which is quite good.

Inspection terms are often used interchangeably. Flatness is a measurement to itself which is identified with a datum. Parallelism measures another surface relative to the datum. So if you take a brake rotor and place it on the inspection plate and sweep the side facing you (up) with a dial indicator you have measured the parallelism. To measure flatness the rotor would be placed on equally spaced 1-2-3 Inspection Blocks and then swept from the bottom with a dial indicator. I would agree with the previous suggestions the best functional check is to mic your rotor.

Again, this service was an excellent solution for me because my rotors were already cross drilled and I didn't want to toss them.