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