Big Bearing Explorer Disc Brake Conversion thread

[MsMyMny]

I agree with Todd on this one. If you have a 2 3/8” brake space and installed the Explorer kit you would end up with the inside pad leaving 1/8” of the sliding portion showing. Close but doable. It takes forever for the rear pads to wear down anyhow. So far the ones installed on The ABCO rig are wearing evenly.

I have made a set of 1/8” shims (yep I'll try to market them if they work) to put between the rotor and axel flange. My first thought was that it would work if the button on the axel flange stuck out far enough to engage the rotor with the shim in place. The problem is that if the rotor doesn’t engage the button on the axel with the shim in place there is a risk of broken studs and I like to keep my wheels on their respective flanges.

I’ll get the shims installed and see how the rotor REALLY engages

Scott Merrell
ABCO

 

[trailpsycho]

Thanks Scott. Talk to you soon.

 

[taxx]

Thanks Everyone! I will be pulling the trigger on the Explorer kit in the next couple of days, I will post pics and provide more info to this thread as to any issues as I do the install. Thanks to all who have responded thus far and keep any info coming.

Cheers!

John

When you gonna start on this? You gonna be around working in the garage this weekend? I will stop by and drink your beer if so.

 

[trailpsycho]

Probably sunday, maybe friday evening...Saturday we will be cruisin' the river....hopefully, my D44 Yukons and Sup-joints come in today or tomorrow. Will be sourcing the other front end parts at NAPA today and tomorrow....I still need to come up with a spanner wrench. I will call you later. How is yours running?

 

[taxx]

Probably sunday, maybe friday evening...Saturday we will be cruisin' the river....hopefully, my D44 Yukons and Sup-joints come in today or tomorrow. Will be sourcing the other front end parts at NAPA today and tomorrow....I still need to come up with a spanner wrench. I will call you later. How is yours running?

running great just toasted my tranny. going to dayton in the am to pick up a new one for cheap

 

[trailpsycho]

So, that whining sound WAS bad, huh?!

Sorry to hear that. Talk to you soon.

 

[Madgyver]

Scott,
Let us know how the shims work out. I'll be in the market for a set of Explorer discs soon to use on the other 77.

madgyver

 

[MsMyMny]

Madgyver...
I'll keep ya posted on the shims.

Scott
ABCo

 

[thesnake]

shim update?

How did the shims work out?

John

 

[Cactus killer]

BC sells the shims and they also come in their rear disc kit.

 

[trailpsycho]

No, he is speaking of shims that fit inside the rotor (separate from the ones that go on the axle before the retainer plate)...their purpose is to shim-out the rotor to provide the "ideal" 2.5" BS. The stock 76/77 axles (or Yukon aftermarkets) provide a 2 3/8" brake backspacing. The Explorer disc set-up is set up for a 2.5" brake backspace; while the caliper is a 'floating'-style caliper and this 1/8" difference should not be an issue, a 1/8" spacer should put the whole brake assembly into "spec".

As for the spacers, in question--Snake--, they are still on the table in the kitchen...I know, I know...I am hoping to go visit my machinist buddy this week...been very busy at work and planning/executing the 10 yr wedding anniversary trip. Hopefully, I can get some "quality time" with the Bronco soon and get this buttoned-up (with pics, details and such). I WILL report as soon as I get it done...just has not been a priority of late...I know blasphemy. Best

John

 

[thesnake]

Thanks trailpsycho!!! I've got too much computer time on my hands. Blew my back out at work, so I can't do anything at the moment anyway. I'll wait patiently for your update!!! Hopefully I won't get involved in the dreaded workman's comp crap.

snake

 

[trailpsycho]

I want to apologize for taking so long to provide more info/feedback. So, first let me re-cap. Here is what I have a 76 9" BB rear end; its been outfitted with a 31 spline ARB and 4.88 gears to turn 31 spline Yukon chromolly axles. I have purchased the Explorer rear disc conversion from Scott @ AmericanBronco.com. The are a couple of issues with the Explorer conversion, however, that keep it from being a direct bolt on and go upgrade. First itis designed for a brake backspace of 2.5 inches. The 76/77 9Inche with their big bearing bolt patterns have a backspace of 2 3/8", however...1/8"--does that matter, lets see. Another issue is the pattern of spacing of the backing-plate, which is slightly different between the BB and the Explorer...I think these figures were mentioned earlier (but can be found on the American Bronco website)...anyway, we dont have to worry about the bolt pattern of the backing plate, because Scott re-drills these (to the BB pattern) before he sends them out. Another detail, is that a spacer is necessary between the bearing/seal and the retaining plate. I had already had my bearings installed, to remove them, I would have had to have taken the chance of damaging the bearing to remove them, so since the retaining plate is about an 80% contact (see pic), I figured that the spacer could also be similarly >80% contact--wtih the retaining plate holding it in place. So, from the first pics, you can see that I have installed the axles with the spacers and the retaining plates.

 

[trailpsycho]

I dont foresee any issues with the modification of the spacer ring provided in the kit...it seams logical that the retainer plate is a 80% contact surface, so the spacer being the same should be OK. You may ask, well the retainer wont/cant deform, b/c its is boled to the housing, true, the spacer is inside the housing, so it too cant expand and it is held in the axle housing by the retainer plate. So, now you are asking, John, what about the issues...OK, OK...so that brings me to the rotors, their openings are too small for either the factory 28 spline axle hubs (I checked) or the Yukon 31 splines that I will be running...so I had the rotors and the spacers (that I asked Scott to make me to "sovle" the brake BS issue-which I will address) opened up to 2.875 " from I believe about 2.6?? or 2.7??" that they are on the 8.8 axle. They slid right on, Thanks RON! So the next pics are of the rotors on the axle without the spacer. Scott had marked the center spot, before he shipped me the brakes, so I would know where "ideal center" would be for the rotor. You can see that I am just off this mark without the spacer. You can also see how there is a nice fit with the inside edge of the hub and the backing plate...this is relevant to the drum style parking brake...the drum assembly is well within the rotor's hub.

 

[toddz69]

I dont foresee any issues with the modification of the spacer ring provided in the kit...it seams logical that the retainer plate is a 80% contact surface, so the spacer being the same should be OK. You may ask, well the retainer wont/cant deform, b/c its is boled to the housing, true, the spacer is inside the housing, so it too cant expand and it is held in the axle housing by the retainer plate. So, now you are asking, John, what about the issues...OK, OK...so that brings me to the rotors, their openings are too small for either the factory 28 spline axle hubs (I checked) or the Yukon 31 splines that I will be running...so I had the rotors and the spacers (that I asked Scott to make me to "sovle" the brake BS issue-which I will address) opened up to 2.875 " from I believe about 2.6?? or 2.7??" that they are on the 8.8 axle. They slid right on, Thanks RON! So the next pics are of the rotors on the axle without the spacer. Scott had marked the center spot, before he shipped me the brakes, so I would know where "ideal center" would be for the rotor. You can see that I am just off this mark without the spacer. You can also see how there is a nice fit with the inside edge of the hub and the backing plate...this is relevant to the drum style parking brake...the drum assembly is well within the rotor's hub.

Are those regular aftermarket 31 spline axles? Or are the flanges turned down to fit inside the Explorer rotors? I can't remember if the stock flanges are larger dia. than the i.d. of the Explorer rotor hats or not?

Todd Z.

 

[trailpsycho]

The next photos show the spacer on the hub, then the rotor installed, calipers, etc. As you can see, there greater distance between the rotor and retaining plate is evident by the mark on the ring, which is now in line wiht the rotor nicely. However, what this also does is leave the drum portion of the rotor much closer to the edge of the drum. Is this bad? I am not sure, but I think I like the idea of the drum being as close to the center fo the rotor as possible-so one strike against the spacer. You can also see with the spacer that the rotor sits on the hub, but cannot be seated fully. Could this also pose a problem? I realize that the lug nuts and rim will sandwhich the rotor to the hub, so this shouldnt be an issue...however, when considering both of the two above issues together, I think the spacer starts looking like not as good a thing. As can be seen from the pics with and without the spacer (above and below), the caliper is of the "floating" style, so its really not affected by either of these issues.

So, whats the final impression: the spacer on the axle between the bearing/seal and the axle retaining plate is necesssary. However, when considering the brake backspacing, an extra 1/8" spacer to bring the 2 3/8" backspacing to 2.5" brake backspace is not necessary. It is also necessary to either machine the axle hubs to meet the tolerances of the rotors or AS I DID, have the rotors opened up to 2.875" or slightly greater (2.88" for instance) so that they fit onto the axle's register (hub).

In my opinion, this is basically a bolt on conversion. I see no reason to do any other modifications. I will not have it on the road for a few more months (heck, the whole truck is still but a large number of parts)... but this should be something that can be done on most "driving vehicles" in about the time it takes to do a set of brakes...maybe a bit longer if you decide to go ahead and remove the axle bearings to put the full spacer ring in its proper position. If you decide to cut the spolid spacer, like I did; do so at your own discretion and peril, I bear no responsibility for a modification you make to a conversion that differs from how the conversion was designed (the conversion calls for the spacer should be installed onto the axle with the bearings removed; then reinstall the bearings--preferably new ones).

If anyone has any feedback, information to add, disagreements with my findings, contradictions, etc; please, post up. I am trying to get the best info up here, available for others who are also considering this conversion. I can also try to clarify, if I have mispoken, type-o-ed, or anything else. Any questions would be appreciated.

Good luck. Happy braking!

John

 

[trailpsycho]

Yes, Todd they are regular yukon 31 spline axles; the same diameter as the stock 28 spline. I had a machnist buddy turn/open the rotor up to 2.875", so that they would fit onto the register.

John

 

[thesnake]

John,

Thank You for all your efforts and the report. You have made this much easier for alot of us!!!

Thank You Again!!!

John

 

[krunchytaco]

I just installed the FMS Explorer kit myself and was wondering what master cylender you guy's are running with 4 wheel discs ? ( no power assist)

 

[trailpsycho]

Cant speak for the master cylinder as I am still undecided to go with the power booster I already have or with a hydroboost unit. Most people have recommended the hydroboost, but I have driven a few imports that had them and if you were going under 10 mph and looked at the brakes, you might be in the windshield.

As far as the conversion, here is one of the other pieces I meant to add to my write-up above. I still need to figure how how I will actuate my e-brake, but here is a brief thread where the Lokar PN for connecting stock e-brake lines to the disc/drum assembly are given. Also if you need to replace your e-brake lines, the Jeg's PN for a line-assembly (assuming with the same adapter--should call first); I figure since its designed for the Explorer kit, it should have the piece to connect with the drum assembly. I still need to work this out...but dont wait on me, the axle isnt even near the frame yet....soon. http://classicbroncos.com/forums/showthread.php?t=81704&highlight=Rear+disc+brake+cable

Best

John