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Unread 04-18-2013, 08:22 AM   #151
CJ7ROB
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There may not be a clear concise write up yet but people have done the conversion. Not exactly rocket science.. we're talking about disc brakes here. For years people have converted drums to discs on all types of cars and trucks for better stopping power, so its not like this is something new.

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Unread 04-18-2013, 08:36 AM   #152
Matt1981CJ7
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Quote:
Originally Posted by CJ7ROB View Post
There may not be a clear concise write up yet but people have done the conversion. Not exactly rocket science.. we're talking about disc brakes here. For years people have converted drums to discs on all types of cars and trucks for better stopping power, so its not like this is something new.
Fair enough.

But, from what I've read so far on this particular upgrade, many guys have created more problems than they've solved.

I think I'll pass until someone comes up with a definitive procedure.

Matt
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Unread 04-18-2013, 09:13 AM   #153
billybooster2
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I think there are a number of factors as to the EXACT best way this works but there are variables that affect the final outcome and the choices needed;

Manual or power brakes - this affects the proportioning valve that Jeep used and whether to have to remove a piece from it for 'back pressure'

Wheel cylinder volume - the closer the volume match to the caliper volume, the more 'equal' the hydraulic pressure at that end will be.

Brake backing plate cut down - that or remove, save, buy a new bracket from BSRK...it's a trial and error deal with an angle grinder.....just gotta make the caliper fit nit touch the plate

Disc thickness and stud hole size - there are 17mm and 10mm thick discs out there from the Geo Tracker that both work/fit -but the 10mm is what should be 'checked' at purchase. Also, the studs used on some after market one piece axles are thicker than the holes in the rotor. Drill them out one step on the step drill if necessary.

Bracket installation - the beautiful BESRK (and others I guess, but shameless plug) brackets bolt right up to a perfect AMC20 axle. If there are bits of axle tube metal in the way where it joins the flange, these should be removed to ensure a perpendicular fit...not rocket science but a leaning bracket means a leaning caliper, means funky squeezing! If there is a lip or weld or similar on the axle tube a slight grinding of the inner edge of the bracket will allow perfect seating...

Then there's the caliper to disc lining up issue. Quite simply, the (Nissan 300ZX) caliper when bolted directly to the bracket is too close to the inner edge and needs to be shimmed by eye works perfectly using washers, hardened Grade 8 if you like as rusty flaky or aluminum soft things might die over time. The gap is about 1/4 inch. Eyeballing gets it right - you know when it's wrong - you are simply centering the rotor in the caliper or vice versa.

So now the brackets on, the calipers on, the pads are easy and the best part is to come - recognize that that caliper cannot be squeezed back into place with a clamp - it rotates down and in... the parking brake part when used will force the caliper out and then it needs screwing back in.

The original Nissan soft lines that go from the caliper to their hard connector screw directly into the jeep original hard line... just a matter of bend to fit location.

Bleeding these should be done off the vehicle. I personally leave the top most caliper bolt in and rotate the caliper so that the bleed valve is at the top of the caliper, then i keep rotating and little baby beautiful airy bubbles come prancing out at the nipple. It's easy to know they're done, no more air. But closing the valve while it is upright ,bubble free gives great response.

My ORIGINAL set up was a manual brake set up with it's associated hard lines and prop valve. I used junkyard Nissan 300ZX rear calipers, Geotracker rotors that I drilled out a notch for my one piece axles, bolted, spaced, bled and run today. Since doing it I went all in for a hydroboost from a mustang and, again, all i needed was new hard lines from the unit to the prop line as the fittings were different. It made it even better than the old master.

It seems the prop valve is the biggest contender for issues - if you use a manual prop valve, I see no issues... or you can change to a later model 4-disc version and adapt hard lines accordingly.
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Unread 04-18-2013, 09:24 AM   #154
Matt1981CJ7
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Billy, sounds like you have a good handle on the details.

Someone needs to put together an all-inclusive parts list (including part #s), and a clear set of instructions, for this upgrade.

Matt
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Unread 04-18-2013, 09:51 AM   #155
billybooster2
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This gent had an issue with the bracket (no idea why myself as mine works fine) He also installed a new prop valve... he didnt use junkyard parts http://www.jeepforum.com/forum/f8/ju...rsion-1494699/
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Unread 04-18-2013, 11:05 AM   #156
Matt1981CJ7
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Quote:
Originally Posted by billybooster2 View Post
This gent had an issue with the bracket (no idea why myself as mine works fine) He also installed a new prop valve... he didnt use junkyard parts http://www.jeepforum.com/forum/f8/ju...rsion-1494699/
Thanks, that one is a little easier to follow along, but it doesn't sound like the gent is completely happy, yet. He mentions wanting to add a vacuum booster, near the end of the thread, but never updates to say whether that helped.

I also don't care for his e-brake setup hanging under the axle. Perhaps mounting the calipers in the 10 o'clock position makes a cleaner install. Dunno.

Earlier, someone mentioned possible clearance issues with this mod and narrow-track axles. Has that been confirmed, either way, yet?

Matt
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Unread 04-18-2013, 11:11 AM   #157
82JeepCJ7
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Matt, I'm gathering parts to do this swap using the Maxima calipers and Geo disc. I am going to play with clocking the calipers before I build mounting brackets.
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Unread 04-18-2013, 11:14 AM   #158
Matt1981CJ7
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82,

I look forward to seeing what you come up with.

Matt
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Unread 04-18-2013, 03:40 PM   #159
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Hey 82,

I'm playing the Devil's advocate for the moment....

Doesn't it concern you that this mod uses discs that were designed to stop a vehicle that only weighs 2300 lbs? I'm pretty sure most of our CJs weigh at least 1000 lbs more than that, no?

Are the dinky GEO discs the only ones that fit in a stock 15" rim, or is there some other limiting factor?

Matt
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Unread 04-18-2013, 03:54 PM   #160
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I thought curb weight of a CJ7 was about 2700 pounds.
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Unread 04-18-2013, 04:20 PM   #161
Matt1981CJ7
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Quote:
Originally Posted by waterdowg View Post
I thought curb weight of a CJ7 was about 2700 pounds.
My reference material shows a mid-'80s CJ7 with a 4.2L and a hardtop had an estimated curb weight of 3090 lbs, gross weight 4149 lbs.

Add to that a heavy winch, bumpers, larger tires, perhaps larger axles and a full roll cage, and I bet you're pushing closer 4000 lbs curb weight.

Matt
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Unread 04-18-2013, 04:53 PM   #162
hmantractors
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Brakes

MATT, I INSTALLED MY VACUUM BOOSTER I HAD FROM A 1980 CJ7. ALSO INSTALLED A DISC-DISC MASTER CYLINDER FROM A 1968 CORVETTE THIS PAST WEEKEND. NOW I HAVE BRAKES I AM HAPPY WITH. STOPS IN HALF THE DISTANCE AS BEFORE. WHEN BLOWING THE LINES OUT FROM THE MASTER TO THE PROP VALVE, THE 3/16" LINE TO THE FRONTS BLEW OUT FINE. THE INTERESTING THING IN MY CASE WAS WHEN I BLEW OUT THE 1/4" LINE TO TAKE THESE TO THE PART STORE TO GET LONGER LINES WAS THERE SEEMED TO BE A RESTRICTION OF SOME TYPE. PROBLEM IS I COULD NOT FIND THE STUFF. DID NOT SEE WHERE IT WENT. BUT I DO KNOW I WAS GETTING FLUID TO THE BACK. COULD HAVE BEEN THE CAUSE OF MY HARD PEDAL. WILL NEVER KNOW. YOU CAN CLOCK THE WHEEL CYLINDERS TO THE FRONT OF THE AXLE, BUT I THINK IT IS HARDER TO TRY TO RUN THE E-BRAKE CABLES. AS MENTIONED I AM ON THE STREET OR DIRT-GRAVEL ROADS. NO OFF ROADING SO RUNNING THE CABLE UNDER THE AXLE WORKS GREAT FOR ME. I HAVE DRIVEN THE JEEP A WEEK NOW. AS THE PADS ARE BEDDING INTO THE ROTORS BRAKING IS GETTING BETTER AND BETTER. HOPE YOUR PROJECT GOES WELL. I DID LIST PART NUMBERS FOR WHAT I USED. CHEERS
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Unread 04-18-2013, 04:57 PM   #163
hmantractors
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Master cylinder

TITAN, I GOT THE POWER ONE.
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Unread 04-18-2013, 05:01 PM   #164
waterdowg
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Quote:
Originally Posted by hmantractors View Post
TITAN, I GOT THE POWER ONE.
Thanks I was hoping someone would use the manual MC and post results since it is closer to bore size to the nissan and CJ MC.
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Unread 04-18-2013, 05:03 PM   #165
waterdowg
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Quote:
Originally Posted by Matt1981CJ7 View Post

My reference material shows a mid-'80s CJ7 with a 4.2L and a hardtop had an estimated curb weight of 3090 lbs, gross weight 4149 lbs.

Add to that a heavy winch, bumpers, larger tires, perhaps larger axles and a full roll cage, and I bet you're pushing closer 4000 lbs curb weight. I was thinking weight of a stock base Jeep.

Matt
I'll agree a curb weight with the hardtop will be around that.
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