OEM BBK: Acura RL 4 piston brake calipers

bendrich

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I have yet to find anyone here on these forums installing Acura RL 4 piston calipers in the front. So, I figured I would make a post about my thought process in going with this option.

I tend to get wordy once I sit in front of a keyboard so here is the TL;DR. 4 piston Acura RL calipers fit on my FK7 Sport with the fastbrakes adapter kit and 12.8" 350Z Brembo rotors. I have confirmed fitment behind the two sets of wheels I have for the car; Evo8 Enkeis (17x8 +38) and Spoon CR93 (17x8.5 +45). They seem to work well so far. However, I have only subjected them to the pad bed in process and some grandpa driving around town. It cost me $375 in hardware.

Honda Civic 10th gen OEM BBK: Acura RL 4 piston brake calipers J squat RL caliper
Please excuse my squat form. Boris would be disappointed.

Now to get wordy.

I began researching brake upgrades for this car after running the full straightaway for the first time at Miller Motorsports Park. It's well known that the original brakes on these Civics really aren't up to the task of multiple laps on a road course, even with race pads and high temp fluid. After one season of HPDE my original calipers were going to need rebuilding or replacing. They were very discolored and the piston boot was reduced to atoms. While a proper performance BBK would almost surely offer the best braking performance, they are very spendy and I do not have any intentions of taking this car back to the track as my CRX project is nearing completion. So I was looking for something to split the difference between refreshing the stock setup and ballin' out on a BBK.

Naturally, the first prospect I considered were FK2/8 Brembos. However, they are still quite expensive and I couldn't find information about how I would actually make them work in regards to mounting the caliper and which rotor to use (re-drill CTR rotors?) I also wanted to retain the use of my 17 inch wheels. I believe Acura TL-S Brembos with appropriate rotors would work - like on Civic 8s and 9s etc - and fit under 17 inch wheels. However, these require some permanent modification to the knuckle and proved difficult to find in the local pick-n-pull yards due to only being on specific TL models. I have read some posts about the Hyundai Genesis Brembos with appropriate rotors fitting, but also requiring 18 inch wheels. Additionally, they are designed to be rear mounted but it doesn't seem like anyone cares about that. The leading and trailing pistons are the same diameter anyway. DC5R Brembos are also designed to be rear mounted AND have staggered piston diameters, which makes them a big no-no for forcing them to work backwards.

Then I came across the RL caliper. These are designed to be front mounted, although they also have equal sized leading and trailing pistons anyway. They are on ALL 2005-12 Acura RL models which makes them very easy to find at the junkyard. The brake master cylinder piston diameter on the FK7 is the same size as the RL, which is especially convenient considering the RL BMC won't bolt up to the FK7 booster. Fastbrakes.com makes an adapter kit, which comes with shiny new bolts and crush washers by the way, to make use of these calipers with 350Z Brembo front rotors. I did not have to trim or bend my dust cover making this an easily reversible modification. The best part is that I'll get to retain the use of my 17 inch wheels.

RL Calipers are HUGE and ridiculously light. They weigh 8 lbs per corner fully loaded. The brackets are super light but the bolts are pretty beefy so let's call it 9.5 lbs mounted to be generous. The brake rotor hub rings are virtually weightless. The 12.8 inch rotor is chunky and comes in at 20.5 lbs. If you're feeling ambitious, you could put together this setup with some fancy two-piece rotors and save some weight. Thanks to 27Won for posting SI brake part weights on his BBK page. This would save 4-5 lbs off the complete front setup, a little less I'd imagine compared to the FK7. The rotating weight is considerably further from the hub but this is the case with all BBKs.

I was able to pick up the pair of calipers from the local junkyard for $40. The adapter kit is $170 shipped. If you're crafty and have the tools, you could probably make this yourself. I ordered new pads, caliper hardware, and rotors from RockAuto for $165 shipped. $375 all in which saves ~$200 compared to the SlickFab Genesis Kit. In that price, I'm not including brake fluid or the SpeedBleeders I installed. I will also admit that the RL calipers aren't performance oriented like the Brembos.

There are some considerations when it comes to frankensteining your own BBK together. An off the shelf kit, such as 27Won, is designed specifically for the car and made to work with the original BMC and ABS module. The factory caliper piston has a surface area of 2561 mm^2. The RL calipers have a combined piston surface area of 5809 mm^2. This is over 100% more piston surface area. Even the 6 piston Wilwood kit doesn't have that much surface area. There are a couple schools of thought on how this goes. One is that you're increasing front bias with all the extra beef up front. The other is that you're increasing rear bias because there will be so much extra pedal travel to fill up the big calipers with fluid, the rear calipers will be very pressurized. My decision was pretty much just to cross my fingers and hope the ABS module would figure it all out for me.

My only hard braking so far has been to bed in the brake pads. I didn't notice anything funny regarding brake bias or pedal travel. I still haven't noticed ANY difference in pedal feel for normal city driving, which I would consider a good thing. The brake line does contact the rotor at full lock. But if you're driving around at full steering lock all the time, there is likely an issue somewhere between the steering wheel and the driver's seat.

I considered painting them, but ended up sticking with the raw metal. I told myself I would clean up the calipers, but I got too excited after test fitting them with the wheels and ended up completing the install. I think it looks pretty pretty cool.

Happy Civic driving everyone!

The car is still on stands in these pics so ignore the monster truck height. And the pic of the stock brakes for reference was taken on the opposite side of the car.
Honda Civic 10th gen OEM BBK: Acura RL 4 piston brake calipers stock front brakes Evo8

Honda Civic 10th gen OEM BBK: Acura RL 4 piston brake calipers RL Evo8

Honda Civic 10th gen OEM BBK: Acura RL 4 piston brake calipers RL Spoon
 
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Hondanickx

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Great work! I love the fact these fit in 17" Wheels .Do you think they would also fit the OEM 17"Wheels?How much side clearance do these have?(Between spokes of the wheel and caliper)
And going from other RL swaps with 350z discs they all say there is very minimale clearance Between brake Pads and discs .Because RL discs are 28mm Thick and 350z is 30mm thick.Is this also the case here?

Since the master cylinder is the same size , i don't think there is going to be any problems.The brake bias is still the same only pedal travel could change.
 
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bendrich

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Do you think they would also fit the OEM 17"Wheels?How much side clearance do these have?(Between spokes of the wheel and caliper)
And going from other RL swaps with 350z discs they all say there is very minimale clearance Between brake Pads and discs .Because RL discs are 28mm Thick and 350z is 30mm thick.Is this also the case here?
I would think, heavy emphasis on think, that the OE 17s might fit with a 20mm spacer. I won't be able to get any real measurements until this weekend. However my eyeball ruler would say between 5-10mm of clearance at any point on the caliper, about the same on both sets of wheels. The Evo8 wheels are little more pokey but have thicker spokes. It seems that >=2mm clearance is generally regarded as safe.
I do believe I came across a post of someone hearing about the RL calipers contacting the barrels of certain 17s and getting 18s to be safe. But I also saw posts of them under stock TL and TSX 17s with spacers. The factory RL wheels are 17s as well. There is even adequate clearance between the wheel weights on the barrel of the Spoon wheels and the calipers.

As far as pad clearance goes. I had less pad clearance after installing new race pads in the stock calipers with 21k mile rotors than new RL pads with new Z rotors. They aren't rubbing under no-brake conditions but I guess that could change if it all gets REALLY hot. But I didn't hear or feel that when bedding in the pads.

I also saw posts about pad overhang with these calipers, but I believe that was all related to people running these with smaller rotors, 12.6" and some 11.x", on older Hondas. That is not an issue with this setup.

When I'm able to get out to the car with a ruler/micrometer I'll post with some real numbers.
 

Hondanickx

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On the Acurazine forum some guys did the RL caliper swap and that fitted behind oem 05' TL wheels which are 17x8 Et 45.The oem 10thgen wheels are 17x7 ET45 , so there's a 12.7mm difference in space.
Don't know how much space the TL wheels had but asuming they have at least 2mm of space , a 10mm spacer would be enough with the oem wheels.But this would all depend on the shape of the spokes as wel.

I did some digging myself and found out the Euro/JDM 05-12 Honda Legend uses 'almost' the same calipers only they don't have the " Acura" logo on them.
The legend uses 318mm x 30mm rotors with a total height of 50.2mm and a center diameter of 70.2mm.Which is almost the exact same as the 350Z rotors ( except for the diameter).

I've checked the part numbers of the calipers and they are slightly different
Euro/JDM legend caliper is 45018-SJA-E03 (Right) and 45019-SJA-E03 (left).
The Acura RL caliper is 45018-SJA-A02 (Right) and 45019-SJA-A02 (left).
The difference here might the fact the Legend uses 30mm thick rotors and the RL 28mm rotors.
 
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factionr

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@bendrich Did you use the stock brake line and the supplied fastbrakes banjo and sealing washers for the Rl caliper without any issues?

I’ve been piecing together this setup and thanks for confirming the fitment. I’m hoping these will fit behind Rota Grid 18x9.5 38 offset.
 


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bendrich

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@factionr Yes sir! No issues at all.

9.5 +38 should fit fine, unless they have some super wacky spoke shape behind the face. Don't take my word for it, but that spec is quite a bit more aggressive than both wheels I have.
 

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@bendrich what size was the fk7 BMC?
And your stock brake rotors are 282/262mm right?
The euro spec 10th gen is 293/282mm but use smaller brake Pads.I think the SI prop valve has a better ratio Since those rotors are 312/282mm.
 
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Hondanickx

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I found more info about the calipers:

For people using the oem lines with banjo bolts, be carefull. https://www.tsxclub.com/threads/rl-caliper-upgrade-brake-line-problem.183498/
The mating surface isn't milled flat from factory,because the RL calipers use a piece of hardline with a male inverted flare fitting and not a banjo bolt.
So you could be lucky and the mating surface is flat enough to seal ,but it could also be irregular enough to have leaks which the copper washers don't seal off.
Also there's isn't a tang to prevent the banjo bolt from rotating and could possibly get loose.
If you're using aftermarket stainless lines you could have the lines made with a inverted flare fitting already.

Another note is there is TSB released from Honda for the Honda Legend calipers (which are the same ones as the acura RL)
https://h-tune.co.uk/club/threads/legend-front-brake-caliper-pad-retainer-broken.9974/live
Front brake caliper pad retainers found to be broken at time of brake service.
It is suspected that dirt trapped between the brake pad retainer and caliper body caused the retainer's pad contact surface to lift, and repeated load at the time of braking led to fatigue failure of the pad retainer.

A Service kit part number 45023-SJA-305 is provided to repair affected vehicles which is now available at Honda dealers. During front brake pad inspection, if the brake pad retainer is found to be broken (A), remove the front brake caliper and replace the brake pad retainers in accordance with the following procedure, using the service kit parts.

I have not found any issues online about this for the Acura RL calipers so far.

The Honda Legend uses a 318x30mm front rotor and 304x10mm rear rotor and it has a Advics 7/8" BMC.
The Honda Civic SI uses a 312x25mm front rotor and 282 x8mm rear rotor and it has a Nissin 3/4" BMC
The Honda Civic Type R (FK8) uses a 350x 32mm front rotor and 304x11mm rear rotor and has a 15/16" BMC.
 
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swanarg

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I'll be putting this same kit on my FK7 in the next couple weeks. Just waiting on parts to come in :D
 

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There is a monoblock caliper that is even cheaper and easier to find that is very similar to the rl caliper.Fastbrakes is working on a adaptor kit... ;-)
 


swanarg

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@bendrich what size was the fk7 BMC?
And your stock brake rotors are 282/262mm right?
The euro spec 10th gen is 293/282mm but use smaller brake Pads.I think the SI prop valve has a better ratio Since those rotors are 312/282mm.
Do you know if the US spec can use that 282 rotor without modification? or does the Euro spec have a different rear set up to accommodate? I'm looking to upgrade my rear rotor to a larger size but don't see anyone making brackets for them except RAGE Performance out of Singapore and they wont sell the bracket by it self. They want you to buy the kit which is too expensive.
 

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Do you think they would also fit the OEM 17"Wheels?
I thought original wheels specs on the Sport Hatch were 18x8 +50 just like the Si?

@bendrich Do you still have your OE 18" wheels? Can you confirm these calipers fit the stock 18s with high positive offset? I drive my car 90% of the time with my factory Si wheels and only throw on my 17x8 +45 wheels to and from the track.

I have been thinking about upgrading pads to improve braking performance, but not really looking to increase brake dust and possibly noise. This seems like a great way not only to improve braking performance, but also keep my lightweight 17" wheel combo all for relatively low cost.

Thank you for doing the research and providing this information to the community.
 

Hondanickx

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Afaik the Sport hatch uses 17x8 and the regular sedan and hatch uses 17x7 Or 16" .Only the SI has 18" wheels .

I was wrong about the US brake size .The USA models use 282mm front and 280 in the rear.They use akebono brakes in the front and ATE brakes in the rear.The front brake pads are larger then the Euro spec .

The euro spec cars use 293mm front and 280mm rear .They have the same rear brakes but use different front brakes.(ATE) .

For anyone who wants to use the Acura RL caliper , you can also use the Lexus LS430 Calipers.
These are also Advics 43mm calipers (same pistons and seals) also Radial mounted But these are Monoblock and they have a locating pin for the banjo bolt which the RL caliper does not have.
They are also found cheap on ebay (cheaper then RL calipers) and brake pads are easly found.After asking about a adapter kit Fastbrakes got interested and he and I bought a caliper for fitment purpose.I no longer have interest in the calipers cause i mainly use my car for daily driving and will be going for a different brake setup.
Fastbrakes said the dowel pins on the LS430 calipers need to be removed or milled of a little to make the adapter kit work .
The Lexus LS460 caliper is even bigger but has the same pistons .

Honda Civic 10th gen OEM BBK: Acura RL 4 piston brake calipers 2002-2006 lexus LS 430 caliper 315 x30 mm disc ,50.3mm height


Honda Civic 10th gen OEM BBK: Acura RL 4 piston brake calipers IMG_0117
 
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bendrich

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@JO3L @Hondanickx

My sport hatch came with the 18x8. I never tried to fit them over the RL calipers. But they definitely wouldn't fit. I sold them after.

That's cool the Lexus caliper is monoblock. But all the calipers are the same price at the junkyard, and surely WAY cheaper than eBay. Any confirmed wheel fitment with the Lexus caliper?
 

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You're right the sport hatch in the USA comes with 18x8 Wheels.In Europe they come with 17x8 Wheels.
The calipers are around $130 for the pair on eBay and fastbrakes bought a used caliper for $50 from the local junkjard.
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