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Crack Brake dust boot (replaced)

7K views 35 replies 12 participants last post by  RB_PB 
#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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#10 · (Edited)
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.
 
#11 ·
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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#13 ·
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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#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
 
#15 · (Edited)
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
 
#17 · (Edited)
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?
 
#19 ·
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.


Sent from my Pixel 2 XL using Tapatalk
 
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#20 ·
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....
 
#22 ·
The hardest part is to get the dust boot part that mates with the caliper body out as there is a small metal ring embedded in the rubber. I used a knife & Screwdriver to slowly wiggle it out. To reinsert the new dust boot into the caliper body just required A LOT of pressure. I cheated and use a bar clamp like this


Worked perfect...

The challenge to replace without total disassembly is that there is a small section of hard brake line directly attached to the caliper, so you can't simply unbolt the caliper and wiggle it to get the clamp to compress the seal. It may be possible with something like this
 
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#23 ·
Does anyone know the sizes are of the front and rear caliper pistons / rings and dust seals on the 4C?

I haven't found them specified, didn't see them in this thread, and unfortunately @DrPyro2k 's links up-thread are no longer valid.

The one vendor, Ohio Performance, shows 10 different sized kits but without knowing the size I'm dead in the water.
 
#24 ·
This tread looks like it's the same as a Clio RS3 caliper...


So, maybe this fits??

 
#25 ·
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#26 ·
I was just talking about this to a buddy today who has the same problem on his car (not an alfa). While I have never Trarked mine I do wonder how much of a problem this is on ours, what is the regular life span on these seals, do the new ones have better life expectancy?
 
#28 · (Edited)
I did find Carlson part numbers for these kits (not sure if that is a good brand name or not) but they don't seem to be distributed in Canada (story of my life).
I can get on ebay. - can anyone advise if this is a quality brand, or junk?

Front rebuild kit (not including pistons) is Carlson D1379
Rear rebuild kit (not including pistons) is Carlson D1822

From the ebay photos, one of each of the above appears to be sufficient to do the entire car.
 
#29 ·
For others who might come across this issue in future, Carlson manufacturer’s part numbers are:

Front 15482 (need 2 kits)
Rear 41293 (need 2 kits).

Trying to find a Canadian vendor for these. Rears are on Amazon Canada but I need the fronts more.

Dealership cannot locate them. Alfa Workshop was able to find the product. Seems silly to have to import from the UK or US, but that might just be the way.
 
#30 ·
Another question. Caliper bracket bolt torques.
Manual says:
Rears are M10 x 1.5 x 25. Torque “value” (daNm) is 5.4 division symbol (not slash - my keyboard doesn’t have this) 6.0.
Front bolts areM14 x 2 x 90. Torque “value” (daNm) is 15.2 division symbol 16.8

How do you read that division symbol? Torque to the lower value and then to the higher?
 
#31 · (Edited)
Going back in this thread, I found info from Rock Auto, who carry the seals.
They have a Canadian Dollar site. Yipee!
Several manufacturer options for front and rear.
If anyone else is looking:

Various manufacturers’ part numbers showing here:
Rectangle Font Technology Parallel Screenshot


Raybestos is a name I’m familiar with (also AC Delco), so I’ll probably go with that. Any comments on the brands?
 
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