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Brennan’s Disc Brake Conversion - Question

53Flattie

53Flattie

Member
Joined
Sep 23, 2002
I’m getting ready to convert the front of my ‘70 CJ5 to discs via Brennan’s brackets and the Sidekick/Tracker calipers, rotors, and mounts. I’ll be using the recommended Honda Accord brake hoses, but they are metric. So I have two options for connecting the hoses to the hard lines at the frame - cut and re-flare the hard line with a new metric fitting, or get a standard-to-metric adaptor.

I would prefer to do the latter because the tight bends just inboard of the hard line fittings might not give me enough room to re-flare.

My question - does anyone know what adaptor I would need? I assume the hard line is 3/8, but I have no idea what the Honda Accord fitting would be. (It hasn’t arrived yet) I would really like to have all the parts on hand to complete the job at one time. I HATE stopping and waiting for parts…
 
53Flattie said:
I’m getting ready to convert the front of my ‘70 CJ5 to discs via Brennan’s brackets and the Sidekick/Tracker calipers, rotors, and mounts. I’ll be using the recommended Honda Accord brake hoses, but they are metric. So I have two options for connecting the hoses to the hard lines at the frame - cut and re-flare the hard line with a new metric fitting, or get a standard-to-metric adaptor.

I would prefer to do the latter because the tight bends just inboard of the hard line fittings might not give me enough room to re-flare.

My question - does anyone know what adaptor I would need? I assume the hard line is 3/8, but I have no idea what the Honda Accord fitting would be. (It hasn’t arrived yet) I would really like to have all the parts on hand to complete the job at one time. I HATE stopping and waiting for parts…
Click to expand...

The factory hard line is going to be 3/16" not 3/8. The hard line fitting will be a inverted flair with 3/8 in.-24 thread. What thread size is the accord hose? My guess is 10mm or 12mm. Here is a link for adapters if you need a 10mm fitting

 
One additional question, for anyone who has done this conversion - did you have to make any modifications to your master cylinder?
I have a newer dual-res MC. I’ve read that I *might* need to remove the residual pressure valve from the front circuit, but I haven’t found anything definitive…
 
53Flattie said:
One additional question, for anyone who has done this conversion - did you have to make any modifications to your master cylinder?
I have a newer dual-res MC. I’ve read that I *might* need to remove the residual pressure valve from the front circuit, but I haven’t found anything definitive…
Click to expand...
Depends on what your MC is designed for. If it has two equal size fluid reservoirs then its a drum/drum mc and needs 2 lb pressure valves installed. If the reservoir closest to the firewall is larger then its a disk/drum or disk/disk MC.
 
Which MC do you have, not all of them have the check valves in them. If by “newer”, you mean the under floor dual MC Jeep used from ‘67(I think) to ‘71 then it has the check valves under the big “nuts” on the side the brake lines go into. These are easy to remove, but be sure to only remove the one you will use for the disk circuit. The drums use a 10 lb valve and you will want a 2 lb valve for disks with the MC mounted under the floor. You can not get a 2 lb valve that directly replaces what you removed from the MC. Leave MC with no valve in the disk port and use an inline 2 lb valve, most folks get a Willwood, they are readily available from many sources. Many people recommend using the rear chamber of the MC for the disks and the front for drums. I don’t know that it matters on an MC designed for drum/drum but thought I’d throw that out there.
Tim
 
skipilot said:
Which MC do you have, not all of them have the check valves in them. If by “newer”, you mean the under floor dual MC Jeep used from ‘67(I think) to ‘71 then it has the check valves under the big “nuts” on the side the brake lines go into. These are easy to remove, but be sure to only remove the one you will use for the disk circuit. The drums use a 10 lb valve and you will want a 2 lb valve for disks with the MC mounted under the floor. You can not get a 2 lb valve that directly replaces what you removed from the MC. Leave MC with no valve in the disk port and use an inline 2 lb valve, most folks get a Willwood, they are readily available from many sources. Many people recommend using the rear chamber of the MC for the disks and the front for drums. I don’t know that it matters on an MC designed for drum/drum but thought I’d throw that out there.
Tim
Click to expand...
The wilwood ones I used had NPT fittings not flares and I thought it was a bit substandard for a brake system

I’m sure lots of people use them, I did, before I used all “modern” stuff.
 
Thanks guys. I have a drum/drum MC, so I’ll pull the RPV from the port for the discs, and install a 2lb RVP.

Currently, the rear chamber of the MC is plumbed to the rear brakes. I would really like to know if I should change that around to have the rear chamber plumbed to the front discs…

Also, any knowledge if the distribution block ahead of the MC has any type of RVP in it, or is it truly just a distribution block?
 

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53Flattie said:
Thanks guys. I have a drum/drum MC, so I’ll pull the RPV from the port for the discs, and install a 2lb RVP.

Currently, the rear chamber of the MC is plumbed to the rear brakes. I would really like to know if I should change that around to have the rear chamber plumbed to the front discs…

Also, any knowledge if the distribution block ahead of the MC has any type of RVP in it, or is it truly just a distribution block?
Click to expand...
I would recommend getting a proper disk/drum MC. Im pretty sure that disk calipers need more fluid than drum cylinders do because disk/drum masters have double the capacity on the disk side than the drum.
 
Sometimes it is best to only change one thing at a time. Install the discs and bleed them. Try them. I have run Brennan's kit now with single pot, dual pot, drum/drum and disc/drum master cylinders. I have also added discs to the rear and found very little if any improvement in rear discs over virtually any working and adjusted drum rears. The front disc conversion seems to simply work with just about any setup you throw at them. The smaller calipers dont seem to need as much fluid. Everyone seems to over think braking systems to the point of paralysis by analysis. That being said, always use caution testing each and every brake change you make. These are much easier to get balance then original Jeep or GM type calipers. There are a few brake sizing calculators on the internet if you truly want to dive down that rabbit hole.
 
Daryl said:
Sometimes it is best to only change one thing at a time. Install the discs and bleed them. Try them. I have run Brennan's kit now with single pot, dual pot, drum/drum and disc/drum master cylinders. I have also added discs to the rear and found very little if any improvement in rear discs over virtually any working and adjusted drum rears. The front disc conversion seems to simply work with just about any setup you throw at them. The smaller calipers dont seem to need as much fluid. Everyone seems to over think braking systems to the point of paralysis by analysis. That being said, always use caution testing each and every brake change you make. These are much easier to get balance then original Jeep or GM type calipers. There are a few brake sizing calculators on the internet if you truly want to dive down that rabbit hole.
Click to expand...
This is great to hear, and great points.

When you were using the drum/drum MC, did you pull the RVP from the front circuit of the MC?
 
I have used Brake Hoses Unlimited, on both my Jeeps and my 64 Ranchero.

Nick does great work and is fast.

He knows his chit!
 
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