Issues that come with rear disc brake swaps

[Fenny]

I remember reading stories online about the issues that come with disc swaps such as needing a whole new trail arm etc etc. I'd love to gather the most info possible on this matter since I'm highly considering it on my MB2 (no ABS). If anyone here knows anything about rear antiroll bars I'd love to know more about that too, I tried to check for em but I'm not sure if it's possible to mount one on stock arms without braces of some kind. Thanks in advance!

[SirPaperbag]

The part about needing new trailing arms is 100% correct, as the drum brake ones lack the proper mounting points for a disc brake system.

But you've got to be careful with which arms you choose, as the wrong ones could end up increasing your rear trackwidth and that's gonna end badly for your handling.

 

As our M-chassis have borrowed a lot of suspension components from 5th gen Civics (EG), I'd recommend searching for EG5/EG6/etc. trailing arms, as they should keep everything in spec. I for one got a pair of EG5 arms to go with my non-ABS system.

 

But that's only part of the problem.

 

If you've somehow managed to get yourself the right trailing arms then you still have to find a matching brake proportioning valve (or prop valve) that splits the pressure correctly between front and rear.

Otherwise your rear brakes might either not bite enough, or bite too much and cause the rear to kick out while braking (very dangerous).

This is especially important if you've got something like an MOT or TÜV here in Germany, where your car gets an inspection every X years and they check your brake performance.

 

M-chassis Civics also use an old style of prop valve, which makes it EVEN HARDER to find the correct ones. What you generally want to get is called a "4040" valve, which is just the model number, nothing more (some dumbasses online claimed those valves split 40/40, but where the hell would the remaining 20% go?)

 

I also found a nifty table somewhere on an obscure forum, and I don't know where exactly I got it from, so I sadly can't attribute the original poster, but here it is:

 

 

 

And depending on the caliper sizing, you might even have to upgrade your master cylinder, but that's getting really technical.

So, in short, get the correct trailing arms, a somewhat correct prop valve and maybe upgrade your master cylinder.
If you want to do it properly, it's a whole lot more work than just doing enough for it to work.

 

 

Pro Tip: You can also fine-tune your front/rear balance by using more or less aggressive pads.

 

 

And regarding rear ARBs, you've got a choice between either buying some used EG6 brackets, using aftermarket ones, and reinforcement braces with mounts included.

 

I went with a used EG6 ARB, plus mounting hardware, because I wanted to try out how much difference just that dingy little thing would make (a lot).

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Here are a few pics of it both installed, and some pics of the used mounting hardware. You also need fitting lower control arms with mounting holes for the endlinks.

And I'd recommend buying new endlinks while you're at it. And maybe a few harder rubber bushings on top.

I also had to fabricate some small metal standoffs for the mounting bracket to properly fit to the rear frame (top right picture, the screw just above the yellow marking).

 

This would be the alternative, a rear brace with mounts included:

 

 

But some places also carry aftermarket versions of the OG hardware that I mentioned and shower earlier, so that's an option, as well.

 

All in all, it's a s**t job with tons of little hang-ups, researching, browsing marketplaces and painful installation, but the handling difference is night and day.

[Dave]

On 11/8/2024 at 7:38 AM, Fenny said:

A reply this detailed deserves to be in the FAQ section of this site! It really seems a more difficult job than a cam swap and a tune haha

If I ever manage to stumble upon the main parts for a cheap enough price (Hondas in general were very expensive relative to other cars here in Italy so not many sales...) to justify all the work I'll definitely try. Thanks for all the info! 

Good shout mate, I'll se about getting this added to FAQ. And thank you, cracking info there!

[dr_broon]

33 minutes ago, SirPaperbag said:

The part about needing new trailing arms is 100% correct, as the drum brake ones lack the proper mounting points for a disc brake system.

But you've got to be careful with which arms you choose, as the wrong ones could end up increasing your rear trackwidth and that's gonna end badly for your handling.

 

As our M-chassis have borrowed a lot of suspension components from 5th gen Civics (EG), I'd recommend searching for EG5/EG6/etc. trailing arms, as they should keep everything in spec. I for one got a pair of EG5 arms to go with my non-ABS system.

 

But that's only part of the problem.

 

If you've somehow managed to get yourself the right trailing arms then you still have to find a matching brake proportioning valve (or prop valve) that splits the pressure correctly between front and rear.

Otherwise your rear brakes might either not bite enough, or bite too much and cause the rear to kick out while braking (very dangerous).

This is especially important if you've got something like an MOT or TÜV here in Germany, where your car gets an inspection every X years and they check your brake performance.

 

M-chassis Civics also use an old style of prop valve, which makes it EVEN HARDER to find the correct ones. What you generally want to get is called a "4040" valve, which is just the model number, nothing more (some dumbasses online claimed those valves split 40/40, but where the hell would the remaining 20% go?)

 

I also found a nifty table somewhere on an obscure forum, and I don't know where exactly I got it from, so I sadly can't attribute the original poster, but here it is:

 

 

 

And depending on the caliper sizing, you might even have to upgrade your master cylinder, but that's getting really technical.

So, in short, get the correct trailing arms, a somewhat correct prop valve and maybe upgrade your master cylinder.
If you want to do it properly, it's a whole lot more work than just doing enough for it to work.

 

 

Pro Tip: You can also fine-tune your front/rear balance by using more or less aggressive pads.

 

 

And regarding rear ARBs, you've got a choice between either buying some used EG6 brackets, using aftermarket ones, and reinforcement braces with mounts included.

 

I went with a used EG6 ARB, plus mounting hardware, because I wanted to try out how much difference just that dingy little thing would make (a lot).

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Here are a few pics of it both installed, and some pics of the used mounting hardware. You also need fitting lower control arms with mounting holes for the endlinks.

And I'd recommend buying new endlinks while you're at it. And maybe a few harder rubber bushings on top.

I also had to fabricate some small metal standoffs for the mounting bracket to properly fit to the rear frame (top right picture, the screw just above the yellow marking).

 

This would be the alternative, a rear brace with mounts included:

 

 

But some places also carry aftermarket versions of the OG hardware that I mentioned and shower earlier, so that's an option, as well.

 

All in all, it's a s**t job with tons of little hang-ups, researching, browsing marketplaces and painful installation, but the handling difference is night and day.

Great post there mate

[Fenny]

19 hours ago, SirPaperbag said:

The part about needing new trailing arms is 100% correct, as the drum brake ones lack the proper mounting points for a disc brake system.

But you've got to be careful with which arms you choose, as the wrong ones could end up increasing your rear trackwidth and that's gonna end badly for your handling.

 

As our M-chassis have borrowed a lot of suspension components from 5th gen Civics (EG), I'd recommend searching for EG5/EG6/etc. trailing arms, as they should keep everything in spec. I for one got a pair of EG5 arms to go with my non-ABS system.

 

But that's only part of the problem.

 

If you've somehow managed to get yourself the right trailing arms then you still have to find a matching brake proportioning valve (or prop valve) that splits the pressure correctly between front and rear.

Otherwise your rear brakes might either not bite enough, or bite too much and cause the rear to kick out while braking (very dangerous).

This is especially important if you've got something like an MOT or TÜV here in Germany, where your car gets an inspection every X years and they check your brake performance.

 

M-chassis Civics also use an old style of prop valve, which makes it EVEN HARDER to find the correct ones. What you generally want to get is called a "4040" valve, which is just the model number, nothing more (some dumbasses online claimed those valves split 40/40, but where the hell would the remaining 20% go?)

 

I also found a nifty table somewhere on an obscure forum, and I don't know where exactly I got it from, so I sadly can't attribute the original poster, but here it is:

 

 

 

And depending on the caliper sizing, you might even have to upgrade your master cylinder, but that's getting really technical.

So, in short, get the correct trailing arms, a somewhat correct prop valve and maybe upgrade your master cylinder.
If you want to do it properly, it's a whole lot more work than just doing enough for it to work.

 

 

Pro Tip: You can also fine-tune your front/rear balance by using more or less aggressive pads.

 

 

And regarding rear ARBs, you've got a choice between either buying some used EG6 brackets, using aftermarket ones, and reinforcement braces with mounts included.

 

I went with a used EG6 ARB, plus mounting hardware, because I wanted to try out how much difference just that dingy little thing would make (a lot).

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Here are a few pics of it both installed, and some pics of the used mounting hardware. You also need fitting lower control arms with mounting holes for the endlinks.

And I'd recommend buying new endlinks while you're at it. And maybe a few harder rubber bushings on top.

I also had to fabricate some small metal standoffs for the mounting bracket to properly fit to the rear frame (top right picture, the screw just above the yellow marking).

 

This would be the alternative, a rear brace with mounts included:

 

 

But some places also carry aftermarket versions of the OG hardware that I mentioned and shower earlier, so that's an option, as well.

 

All in all, it's a s**t job with tons of little hang-ups, researching, browsing marketplaces and painful installation, but the handling difference is night and day.

A reply this detailed deserves to be in the FAQ section of this site! It really seems a more difficult job than a cam swap and a tune haha

If I ever manage to stumble upon the main parts for a cheap enough price (Hondas in general were very expensive relative to other cars here in Italy so not many sales...) to justify all the work I'll definitely try. Thanks for all the info! 

[SirPaperbag]

Small update on the whole brake prop valve situation:

 

Apparently, EG6 prop valves could also work, as they don't have ABS and 262/242mm rotors in the front and rear, just like our M-chassis Civics.

 

So, if that's true, you could get a brand new valve for less than $200 from Japan. Part number for these bad boys is 46210-SR3-013

And you should be fine sticking with your original brake master cylinder + booster!

 

But if you've got 242mm discs all around instead you'd need a "1725" valve (46210-1725-XXX) off a Del Sol, not off an EE/ED/EF Civic! (Different f/r rotor sizes)

[dan1]

Amazing reply from SirPaperbag!

 

Just to add ive done this swap on my (non abs) mb2, but also upgraded a few things. My setup is as follows and works sweet:

 

Disc trailing arms off a mc1 aerodeck

MB6 brake booster

MB6 1" master cylinder

Mgzs 180 282mm front calipers (interesting the caliper is the same as from a 97-03 accord, not sure on the carrier)

Mgzs 180 262mm rear calipers

46210-S5A-912 40-40 prop valve

 

 

Regarding the rear arb - the rear brace that SirPaperbag mentions won't fit without modification. DeLaSoul mentions it in his build thread - if I remember correctly the mounting points where the LCAs mount to the chassis are about 8mm narrower on our MBs to EKs

[SAMA8]

Hi, are you sure you need new trailing arms? Upon a short google search, I stumbled upon this.

" You do NOT need the entire trailing arm; ALL 88-00 civics and 90-01 Integras take the same shaped trailing arm. You need only the spindle, which is attached by a 24mm nut, and four T50 torx bolts. Please note that most swap the entire trailing arm because those torx bolts are in there VERY firmly. I have banged the hell out of a hammer and impact and still had them stay. I advise air tools, because even with all my weight and brute force, they may not come out. Brake lines may be stubborn if your car is older and rusty. The brake hard lines can strip easily if you do not use the proper wrench. A brake line wrench is what you need, which is a 10mm box end wrench with a slot cut out so that you can slide it over the hardline. You can use this on the bleeder screw too if you put the bleeder hose over the bleeder valve first so that brake fluid doesn't spill. On an EK chassis civic, the bleeding sequence is right rear, then left front, then left rear, then front right. Don't go in a circle, the EK chassis uses a crossed brake system, so go by this sequence to avoid any cross contamination of air into the lines, otherwise you may be bleeding all day. "

 

Rear disc conversion, keeping the drum trailing arm | Honda D Series Forum

Cheers!

[SirPaperbag]

You are technically right about not needing the whole trailing arms, but good luck with both finding the spindles by themselves in usable condition and taking the old ones off.

Finding parts like that is getting progressively hard as our cars start to turn into oldtimers, and most of these super specific upgrade parts have already been grabbed about a decade ago. We're kinda late to the party in that regard.

 

The spindles are also secured to the trailing arms with extremely strong threadlocker, which oftentimes are pretty old and corroded on top, which makes removing them near impossible without drilling them out.
Stripped a bolt attempting to remove the disc brake ones, even with applying heat and using rust remover beforehand.

 

No chance.

 

So, yes - you technically don't need them, but realistically you will.

Except if you're fine with drilling all of the bolts out and dealing with that headache.

 

And the part about bleeding the brakes is also generally correct. Most cars have their brake systems set up like that so you can still come to a stop if a brake line fails. Otherwise if you combine FR with RR / FL with RL you will only have working brakes on one side of your car, which I don't have to explain why that would be very bad.

[SAMA8]

Okay, so it is possible, but quite difficult in practice. Nonetheless, this is the route I am going to take since the disc trailing arms I have are unfortunately bent. The spindles are in good condition so I will probably bring them to a specialist to be removed and later on installed. 
 

Wish me luck!

Also, what did you do about the handbrake cables; I bought EG ones, however I am not sure if they will fit. 

[SirPaperbag]

I just bought handbrake cables for the MB6/MC2 models. They have rear discs and in the case of the MB6 are the exact same chassis as mine.

 

Haven't attempted the actual swap yet, but I've got all the neccessary parts lying around already and am pretty sure that the MB6 cables are gonna work.

And don't forget that you'll need different brake lines, as well! (Just the flexible part, though)