Brake Disk Diameters?

Bradmph · 01-30-2009, 12:26 PM

Hi,

I own a 1989 MKI MR2 and my left rear brake disk needs to be replaced because of a small scrape on the face of the disk. It makes a little noise as the pads rub over it, plus it has a little tweak to the trueness of the disk which I can feel in a slight pulsating as I come to a stop.
Anyway, I located another MKI in a wrecking yard and grabbed the left rear disk, among many other parts that I always grab for possible issues in the future

.
When I got home, I removed the left rear wheel and held the wrecking yard disk up to mine and was surprised to see that the wrecking yard disk diameter was a bit larger then mine

. This disk did not appear to be an aftermarket update of any kind.
What my question is...did Toyota make changes in the rear disk size in the middle of the production of 1989 MKI MR2's? The wrecking yard listed the MR2 as a 1989 just like mine, though it did have more options like power windows, cruise control, etc. I researched online and it appears that the MKI MR2's came with a 9.4 inch diameter disk. I have looked for rear disk replacements in many Toyota parts web sites and almost everyone I have found are listed as 10.5 inch disk.
WTF is going on here? Will these larger disk work on my car without having to replace the calipers? Sure didn't look like they would. I sure would like to put these slightly larger disk on my car. Now if the wrecking yard happen to make a slight mistake posting the year of this MR2, why would Toyota down sized their rear disk from a prior year.

Any help is appreciated...Thanks

328FTW · 01-31-2009, 07:25 AM

That is strange. In theory the 89 disks should match each other although there are 2 different sizes the larger was standard after 87 I think. There could be a discrepancy in the model between the cars like the one you got the disk off is a SC and yours is an n/a but an 89 should have the larger package anyway. Unless the disk and brakes have been swapped. I have never tried swapping the rotor without changing the calipers so have no idea if that would work.

Too bad you don't live around where I do, I have so many of the damn small ones I can't give them away. Can you have the old disk machined down? I had a my SC set machined because the junkers I was buying were invariably warped from rattleguns in tyreshops, was a big improvement.

Bradmph · 01-31-2009, 01:47 PM

Thanks, Machining down sounds like a good idea but before I do, I am going to take a ride back to the wrecking yard and take some measurements on the parted out MR2. Also check the actual year of production. This wrecking yard is a blessing to be so close and accessible. The prices at this yard have allowed me do so many repairs and fixes to my MR2. For example, replacing my rear spoiler with the third light spoiler from the yard only cost me $13.00. Replacing the entire interior from the original blue to black was a totaled cost of about $50.00, It's like a candy store with every type of candy you can imagine for a nickel. I am in the process now of installing original cruise control parts used from this yard and probably won't pay over $25.00 for it all. Weeee!
I'll take another look at the yard's MR2 more closely and see what the issue may be on the brakes, if I need the calipers to fit the larger brakes then I'll grab them too for $5.00 a piece and rebuild them. I could always just have my old ones shaved as well, but if I need to remove the calipers, I might as well up size them to these larger ones.

328FTW · 02-01-2009, 01:55 AM

You are so lucky to have a good dealer nearby. The one near me wanted $130 for a mkII spoiler + $30 per side molding. I couldn't believe it. I brought one online for $1 in the end 1/130 of what he wanted. What's more the car I was trying to buy it off was at pick a part the day before which had cheap prices so I rushed back the next day with tools so I could get parts and it was in his yard across the road. He paid a grand for it and took it then jacked up the prices. The spoiler was $30 from pick a part complete, 130 from him incomplete. It is actually cheaper to get parts from toyota new than him and he is a f***nut.

efx · 04-17-2009, 04:30 PM

Well, I got an 85 and the manual states about 10mm for thinckness I think it was. Which means that would be 20mm for the thickness, but what do I know. Check your book because the 89 is different from the 85, 86 from what I have been reading...As for the rotors though, you should just get yourself some new ones and be safe if it's that bad.As for the noise, semi metalics were doing that to me so I had to change them. It got pretty annoying so i just changed them.

01-30-2009, 12:26 PM	#1 (permalink)
Bradmph Driver Join Date: Mar 2008 Location: Spokane, WA Posts: 5 Thanks: 0 Thanked 0 Times in 0 Posts iTrader Rating: (0/0% )	Brake Disk Diameters? Hi, I own a 1989 MKI MR2 and my left rear brake disk needs to be replaced because of a small scrape on the face of the disk. It makes a little noise as the pads rub over it, plus it has a little tweak to the trueness of the disk which I can feel in a slight pulsating as I come to a stop. Anyway, I located another MKI in a wrecking yard and grabbed the left rear disk, among many other parts that I always grab for possible issues in the future . When I got home, I removed the left rear wheel and held the wrecking yard disk up to mine and was surprised to see that the wrecking yard disk diameter was a bit larger then mine . This disk did not appear to be an aftermarket update of any kind. What my question is...did Toyota make changes in the rear disk size in the middle of the production of 1989 MKI MR2's? The wrecking yard listed the MR2 as a 1989 just like mine, though it did have more options like power windows, cruise control, etc. I researched online and it appears that the MKI MR2's came with a 9.4 inch diameter disk. I have looked for rear disk replacements in many Toyota parts web sites and almost everyone I have found are listed as 10.5 inch disk. WTF is going on here? Will these larger disk work on my car without having to replace the calipers? Sure didn't look like they would. I sure would like to put these slightly larger disk on my car. Now if the wrecking yard happen to make a slight mistake posting the year of this MR2, why would Toyota down sized their rear disk from a prior year. Any help is appreciated...Thanks

04-17-2009, 04:30 PM	#5 (permalink)
efx Cage Fighter Join Date: Apr 2009 Location: Los Angeles, CA Posts: 179 Thanks: 0 Thanked 4 Times in 4 Posts iTrader Rating: (1/100% )	10 inches? Well, I got an 85 and the manual states about 10mm for thinckness I think it was. Which means that would be 20mm for the thickness, but what do I know. Check your book because the 89 is different from the 85, 86 from what I have been reading...As for the rotors though, you should just get yourself some new ones and be safe if it's that bad.As for the noise, semi metalics were doing that to me so I had to change them. It got pretty annoying so i just changed them.

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01-31-2009, 07:25 AM	#2 (permalink)
328FTW Can you say grippy? Join Date: Aug 2008 Location: New Zealand Posts: 1,513 Thanks: 12 Thanked 99 Times in 83 Posts My Google Map iTrader Rating: (0/0% )	That is strange. In theory the 89 disks should match each other although there are 2 different sizes the larger was standard after 87 I think. There could be a discrepancy in the model between the cars like the one you got the disk off is a SC and yours is an n/a but an 89 should have the larger package anyway. Unless the disk and brakes have been swapped. I have never tried swapping the rotor without changing the calipers so have no idea if that would work. Too bad you don't live around where I do, I have so many of the damn small ones I can't give them away. Can you have the old disk machined down? I had a my SC set machined because the junkers I was buying were invariably warped from rattleguns in tyreshops, was a big improvement.

01-31-2009, 01:47 PM	#3 (permalink)
Bradmph Driver Join Date: Mar 2008 Location: Spokane, WA Posts: 5 Thanks: 0 Thanked 0 Times in 0 Posts iTrader Rating: (0/0% )	Thanks, Machining down sounds like a good idea but before I do, I am going to take a ride back to the wrecking yard and take some measurements on the parted out MR2. Also check the actual year of production. This wrecking yard is a blessing to be so close and accessible. The prices at this yard have allowed me do so many repairs and fixes to my MR2. For example, replacing my rear spoiler with the third light spoiler from the yard only cost me $13.00. Replacing the entire interior from the original blue to black was a totaled cost of about $50.00, It's like a candy store with every type of candy you can imagine for a nickel. I am in the process now of installing original cruise control parts used from this yard and probably won't pay over $25.00 for it all. Weeee! I'll take another look at the yard's MR2 more closely and see what the issue may be on the brakes, if I need the calipers to fit the larger brakes then I'll grab them too for $5.00 a piece and rebuild them. I could always just have my old ones shaved as well, but if I need to remove the calipers, I might as well up size them to these larger ones.

02-01-2009, 01:55 AM	#4 (permalink)
328FTW Can you say grippy? Join Date: Aug 2008 Location: New Zealand Posts: 1,513 Thanks: 12 Thanked 99 Times in 83 Posts My Google Map iTrader Rating: (0/0% )	You are so lucky to have a good dealer nearby. The one near me wanted $130 for a mkII spoiler + $30 per side molding. I couldn't believe it. I brought one online for $1 in the end 1/130 of what he wanted. What's more the car I was trying to buy it off was at pick a part the day before which had cheap prices so I rushed back the next day with tools so I could get parts and it was in his yard across the road. He paid a grand for it and took it then jacked up the prices. The spoiler was $30 from pick a part complete, 130 from him incomplete. It is actually cheaper to get parts from toyota new than him and he is a f***nut.