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Discussion Starter · #1 · (Edited)
After the last track day, my mechanic found the dust boots of the front calibers were all cracked.



Then I ordered the dust boot from Alfisit, but they don't have the calibers seal, and they don't know the size either. So here is the measurement of the seal incase you went into the same problem as I do.

 

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Excellent information, Alipapa.
Thanks for sharing it.
Do you have the part number for the boot from Andre?

I will add this to the Technical Information database.
 

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Nice find @Alipapa!!! I need to replace the brake seals on the front and have a cross threaded rear brake caliper guide pin. Just not sure about their quality..... I also can't find a way to order from their website. Howerver, armed with those part numbers, you can find most on Amazon or Rockauto.
 

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So, I ordered a "full set" of repair kits for my car (Front & Rear) from RockAuto. Plus guide pins & guide pin boots. It costs about $60. Will report back on the quality once I get them in.

I track my car almost exclusively, so constantly replacing the little rubber boots could get a little annoying. Not sure how long it will take till I do it the first time. So, I have been doing some digging, or at least trying to, about the Brembo brakes that are installed on the car. I can't find much info other than disk size (Front: 305mm x 28mm, Rear: 292mm x 22mm) from the Alfa Romeo Documents. From the pictures that @Alipapa has posted, it appears to be symmetrical pistons roughly 36mm in diameter. I will take more detailed measurements when I rebuild. I'm trying to identify a "race caliper" that I might be able to directly replace the existing caliper without altering the brake bias too much (at least no more "forward" bias).
 
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So, I ordered a "full set" of repair kits for my car (Front & Rear) from RockAuto. Plus guide pins & guide pin boots. It costs about $60. Will report back on the quality once I get them in.

I track my car almost exclusively, so constantly replacing the little rubber boots could get a little annoying. Not sure how long it will take till I do it the first time. So, I have been doing some digging, or at least trying to, about the Brembo brakes that are installed on the car. I can't find much info other than disk size (Front: 305mm x 28mm, Rear: 292mm x 22mm) from the Alfa Romeo Documents. From the pictures that @Alipapa has posted, it appears to be symmetrical pistons roughly 36mm in diameter. I will take more detailed measurements when I rebuild. I'm trying to identify a "race caliper" that I might be able to directly replace the existing caliper without altering the brake bias too much (at least no more "forward" bias).
Has anyone ever tried installing a brake proportioning valve to adjust the front rear bias. While it would be a positive....I suspect the ABS might get confused.
 

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I'm not aware of anyone installing a proportional valve in our cars, at least none that post on this forum. That said, I have been doing some initial thinking exercises and preliminary discussions with my race shop. The basic issue that I see with the braking system is 1) the rubber boots will continue to be a fairly often maintenance item (~1 per year - for my usage) and 2) I would like to see some more rear bias to even out the brake temperatures. IMHO, the reason why the 4C does so well with braking (as compared to other street cars) is that it simply weighs 400 - 1000 lbs lighter not because of a superior braking system.

So, options...
1) Keep same setup, install bias valve only. - I'm exploring this option, just don't know if it will mess the ABS and other stability control systems....
2) Some variation of new equipment - This could be just front race calipers matched to the existing Brembo GT brakes (for rubber boot issue) to full Brembo/AP Racing/Others calipers with bias valve (and Bosch Race ABS if you wanted to go all out).

The new equipment option is really competing with what I want to do long term with the car. Spending $10k on a new system to get that extra amount of performance on a "street" car might not make sense and I'd best spend my $ on a "real" race car. I know I have posted on the forum before about this dilemma about 4C or real race car.
 
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Discussion Starter · #14 ·
I received the package last week and didn't open it just now.

The quality seems alright, the rear repair kit is made in China while the front ones are made in USA.

The material is also differnct between those 2, with the front ones is significallty "softer" and more flexable
 

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I just rebuild my calipers once a year as it keeps the pistons from sticking and that keeps the brake pads wearing evenly.
If along the way the dust boots crack or melt it’s OK.
Rebuild kids are very cheap and the labor is not too much also. I do it at the same time I change my racing brake fluid at the end of the season during the off-season.


Sent from my iPhone using Tapatalk
 

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Do you replace the pistons as well? Can't find where to buy it online

我從使用 Tapatalk 的 SM-G9650 發送

Oh no you don’t replace the pistons when you rebuild them unless they’re pitted and worn out. That’s why the rebuild kits are so cheap, just a few O-rings, snap rings and dust boots. All you do is disassemble, clean and inspect and maybe lightly hone the cylinders. Then you just put it back together with the new parts.

I just had my local race shop order the parts and do it. They are not too hard to find. Alternately you could order them from the dealership. Just need to know the model of the Brembo calipers.
Maybe someone smart on the forum can list the front and rear calipers model numbers?
 

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Just need to know the model of the Brembo calipers.
Maybe someone smart on the forum can list the front and rear calipers model numbers?
This is what I have been trying to determine, so we can find alternative sources or brake alternatives. So far no luck, but not done yet.


It is nice to know that you rebuild it yearly, I was thinking along those lines. Don't care about the dust boot much, as I am mostly track use.


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I got a few minutes to compare some of the rebuild kit for the rears to stock. As I noted before, I had cross treaded one of the sliders so I needed to replace it. The stock and the new part are almost identical, with the new part weighing just a few grams more. This is mostly due to the bolt being 1mm larger socket size. Sliding and fit looks and feels okay.

I didn't replace the Piston boot, as the rears are fine.


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I have completely rebuilt the Brembo fronts and partially rebuilt the rear (due to a caliper not releasing properly). I used the kits that were found above, HOWEVER, I have found a better quality source that also includes high temperature dust seals.

I have found two options, that are essentially identical.

https://www.ohioperformancesolutions.com/product-page/38mm-stoptech-brembo-brake-caliper-individual-pressure-seal-high-temp-dust-boots1

and

RacingBrake High Temperature Dust Boots
RacingBrake Seals

The major advantage of the Silicon is that they withstand higher temperatures than the standard EDPM rubber (300 C vs 150 C). The disadvantage is that Silicon reacts poorly to Brake fluid (aka. falls apart). The Dust seals aren't suppose to be in contact with brake fluid anyways, so it is mainly up to you to keep the area clean when reassembling the calipers.

When I have to rebuild my calipers again, I will be moving to Stainless Steel Pistons and High Temperature Silicon Seals. Perhaps some that will need to rebuild before me (in approximately ~1 year) will give it a try and report back. It may be possible to replace just the dust seal without completely taking the calipers off the car and removing the pistons. I may order a set just to try....


Pardon the cross-post, but I thought the information was important enough to share both places....
 
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