Rear Disc Brake Conversion Kit

[midcoma]

Speaking of testing, I'm still looking for a volunteer in the Hampton Rhodes, VA or Eastern NC area for a test vehicle.

Anyone that's willing to meet me at NCCAR for testing and kit install.

Most mods are ok (lift, larger tires, armor, gears, etc.), but must have stock brakes with ABS.

Somebody in this area must want a free kit...

 

[jkeith.w]

That's what I was thinking too. You need some more mechanical advantage than what the factory e-brake lever is designed to provide.

Yes! (and [MENTION=118207]midcoma[/MENTION] has some voodoo that he has shared with me to correct this)

This is due to the drum brake geometry being self energizing. Hence you don't need much force on the e-brake cable to properly activate the drums.

Disks are a differently story. They do require a lot of pressure - that's why power brakes are needed for disks. (older cars like my air-cooled VW with drums on all 4 corners don't even need powered brakes)

I like that you said that, so that I could bring in my day-job experience here.
4-wheel discs were used in older cars for some time before vacuum-assisted brakes, but master cylinder sizing was crucial there. The cars I work with have drum brake parking brakes in the rear disc setups (even back into the 60s), but since the 90s, a lot of European cars used the mustang-style cam activated parking brake with just some targeted lever geometry; so I'd bet this is solvable as well with the right brain thrown at it.

I'm pretty excited about this kit; Fwiw - easy pad changes, self-cleaning, self-adjusting, and no need to break open the hydraulic system to service the rear axle stuff. Win-win-win-win.

Full disclosure: after following [MENTION=53470]Rockdawg84[/MENTION] I was going to get around to working on this eventually, but now I don't need to. (win!)

 

[mtbtim]

I'm pretty excited about this kit; Fwiw - easy pad changes, self-cleaning, self-adjusting, and no need to break open the hydraulic system to service the rear axle stuff. Win-win-win-win.

These are the same pros that [MENTION=118207]midcoma[/MENTION] mentions for the argument to do this mod, but like I said in my response above, how often are you really replacing rear shoes or rear pads? Maybe every 75-100k miles? It obviously depends how you drive for sure but rear brakes don't need servicing all that often.

The drum brakes on our rigs are self-adjusting as well if you use your parking brake like you should and not let the weight of the rig rest on the parking pawl of your automatic transmission. Even the guys who have manual transmissions should use their parking brake because it's a safety back-up.

It's true with a disk brake set-up in the rear that you wouldn't have to disconnect brake lines at the wheel cylinders to remove the axles for a rear axle seal job or maybe you're pulling the 3rd member, but again, how often are guys pulling axles on their rigs? And, if you cap off your brake lines when you disconnect them to pull the axles, you lose minimal brake fluid and the bleeding process is beyond easy.

As for self cleaning, I guess people who do a lot of wheeling in muddy conditions or do lots of water crossings might benefit from this functionality.

I'm looking forward to seeing some hard data on the braking performance so myself and others can make an informed decision on whether this mod is worth doing. I would also like to see what the total cost will be for this mod. It will obviously depend on what calipers, rotors and pads you choose, but I'd like to see somebody other that the OP do this mod, report what they spent on parts and how much time they invested in doing the work. These are all things I would like to know before diving into a mod like this.

 

[CWccw]

Im for one when these are actually for sale. Till then, this is just a talk about the possibility. Seen this kind of thing in many forums before. Just being real...

 

[MattJakobs]

Speaking of testing, I'm still looking for a volunteer in the Hampton Rhodes, VA or Eastern NC area for a test vehicle.

Anyone that's willing to meet me at NCCAR for testing and kit install.

Most mods are ok (lift, larger tires, armor, gears, etc.), but must have stock brakes with ABS.

Somebody in this area must want a free kit...

Well damn, I just moved from this area not too long ago and would've loved to be a test dummy. I'll throw this thread in a few local FB groups and hopefully that'll help you find someone.

As a matter of fact, [MENTION=119443]Twitchstyle13[/MENTION] would probably be in...

 

[Twitchstyle13]

[MENTION=118207]midcoma[/MENTION] check your messages

 

[weekendclimber]

I'm looking forward to seeing some hard data on the braking performance so myself and others can make an informed decision on whether this mod is worth doing. I would also like to see what the total cost will be for this mod. It will obviously depend on what calipers, rotors and pads you choose, but I'd like to see somebody other that the OP do this mod, report what they spent on parts and how much time they invested in doing the work. These are all things I would like to know before diving into a mod like this.

I'm not sure about scientific, but I'm going to video some stops at speed and distances it takes to come to a stop before and after with a video of the install of these. Easily several months out, but hopefully this will help someone in the future. Any suggestions to data points to gather?

I'm thinking outside temperature, road conditions, and then try different speeds to start a stop from, and distance from start of braking to full stop.

 

[phattyduck]

If the OEM rear brakes can lock up the rear axle, different brakes are unlikely to improve objective performance (meaning stopping distance, assuming ABS is doing its job).

Subjectively (and objectively in other ways than stopping distance), performance can be improved. Pedal feel would be another place that would be helped by discs. I've never liked the non-linear feel of drum brakes. Heat dissipation would be another factor not talked about here yet - the brakes should be less likely to fade on long downhills, etc.

-Charlie

 

[mtbtim]

If the OEM rear brakes can lock up the rear axle, different brakes are unlikely to improve objective performance (meaning stopping distance, assuming ABS is doing its job).

Subjectively (and objectively in other ways than stopping distance), performance can be improved. Pedal feel would be another place that would be helped by discs. I've never liked the non-linear feel of drum brakes. Heat dissipation would be another factor not talked about here yet - the brakes should be less likely to fade on long downhills, etc.

-Charlie

Hey Charlie, I guess it does make sense that heat dissipation is better with rotors compared to drums. One thing that I have always employed though is Engine Braking. If you are riding your brakes down a steep grade, you haven't selected the proper gear. A lot of people don't know that they can use their automatic transmission just like a manual and switch to a lower gear to raise the engine rpms and slow the vehicle. When going down a grade, I first switch off Overdrive. If that doesn't slow me down enough, I switch to 2nd. If I'm on a gnarly steep grade, I'll even switch to Low if I'm not going to be impeding traffic behind me. It's never good to ride your brakes because you will overheat them and experience brake fade which is scary. Not employing engine braking is the primary reason people overheat their stock brakes and then get uneven brake pad deposits on their rotors making people think they "warped" their rotors. My 98 has the Tundra Brake Upgrade because it's been heavily modified with lots of extra weight but my 2000 is pretty much stock and I have the stock brakes on it. I get zero brake shuddering because I never overheat my brakes.

 

[2TH4IST]

They way I see it are as follows:
Better pedal feel
Better heat dissipation
Easier service
Better water/snow/mud shedding
Less wear items (springs, pins, levers etc.)
Newer technology
Maybe a little less weight
No need to bust open brake system

And I just don't like drum brakes. Never have and never will. I'm excited for these.

 

[Grgg1978]

Man every time someone makes something for these 4runners. Please put me on the list for a whole kit including ebrake

 

[mtbtim]

I'm not sure about scientific, but I'm going to video some stops at speed and distances it takes to come to a stop before and after with a video of the install of these. Easily several months out, but hopefully this will help someone in the future. Any suggestions to data points to gather?

I'm thinking outside temperature, road conditions, and then try different speeds to start a stop from, and distance from start of braking to full stop.

I think that's scientific enough. You're using the same rig and you can do your best to match the conditions by doing it at the same location before and after. I think if you find a good area to do the test you should use it for both tests so you can get a more accurate comparison using the same road surface. The temp of the tires would probably make a difference because warmer tires are stickier. So, you might not get an accurate comparison and throw the test results off if the ambient temps are way different between your two tests like one in the winter and one during the summer. You would also have to check the tire pressure and keep that the same and definitely not change tires between tests. My two cents.

 

[MattJakobs]

Hey Charlie, I guess it does make sense that heat dissipation is better with rotors compared to drums. One thing that I have always employed though is Engine Braking. If you are riding your brakes down a steep grade, you haven't selected the proper gear. A lot of people don't know that they can use their automatic transmission just like a manual and switch to a lower gear to raise the engine rpms and slow the vehicle. When going down a grade, I first switch off Overdrive. If that doesn't slow me down enough, I switch to 2nd. If I'm on a gnarly steep grade, I'll even switch to Low if I'm not going to be impeding traffic behind me. It's never good to ride your brakes because you will overheat them and experience brake fade which is scary. Not employing engine braking is the primary reason people overheat their stock brakes and then get uneven brake pad deposits on their rotors making people think they "warped" their rotors. My 98 has the Tundra Brake Upgrade because it's been heavily modified with lots of extra weight but my 2000 is pretty much stock and I have the stock brakes on it. I get zero brake shuddering because I never overheat my brakes.

I'm the same as far as engine braking goes. I have no problem popping my automatic transmission down to 2nd on long and/or lengthy descents. But there are parts of this country where engine braking is illegal. These areas are few and far in between, but there still are some out there.

 

[phattyduck]

Hey Charlie, I guess it does make sense that heat dissipation is better with rotors compared to drums. One thing that I have always employed though is Engine Braking. If you are riding your brakes down a steep grade, you haven't selected the proper gear.

For the most part I agree. Even with engine braking I have run into issues on some mountain roads though. (of course, that was with the small brakes and 31.6" tires... I'm in the middle of the Tundra brake upgrade as I type this)

Brake bias might be a concern offroad when you are going too slow (<5mph, I think?) for ABS to activate. Any thoughts on that?

-Charlie

 

[weekendclimber]

I'm the same as far as engine braking goes. I have no problem popping my automatic transmission down to 2nd on long and/or lengthy descents. But there are parts of this country where engine braking is illegal. These areas are few and far in between, but there still are some out there.

Aren't they mainly restricting compression braking? Like on big rigs when they do this it's loud? (I honestly didn't know doing this in a passenger vehicle was prohibited)

 

[spartacus]

Aren't they mainly restricting compression braking? Like on big rigs when they do this it's loud? (I honestly didn't know doing this in a passenger vehicle was prohibited)

you are correct no Jake brake. I drive the i70 corridor and use the 2nd gear a lot to not let my brakes overheat.

 

[theesotericone]

For the most part I agree. Even with engine braking I have run into issues on some mountain roads though. (of course, that was with the small brakes and 31.6" tires... I'm in the middle of the Tundra brake upgrade as I type this)

Brake bias might be a concern offroad when you are going too slow (<5mph, I think?) for ABS to activate. Any thoughts on that?

-Charlie

I don't know where you got the ABS and 5 MPH figure from. I can tell you, for certain, that the ABS locks up going 1 MPH on steep descents. I thought about ripping it out all together it annoys me that much. Since going to 35's it's much less noticeable but still there.

When I get the time to do this I'll most likely just remove the ABS. Brake bias will be controlled with a manual proportioning valve. Then some line locks. Then a t-case brake as well as the parking brake. There's times wheeling in the steep when I need my rig to not move and having all that should make it happen. lol

 

[2TH4IST]

I have to agree with abs works at any speed above 0mph. Was on a nasty wallow flexed to the stock max really creeping (in a bone stock runner) skidded a tire and off I went and abs kicking in, that was one hell of a ride I didn't want to take and I wasn't insured by survival (lol). Was not fun one bit. I'll be putting in a on-off switch for the abs when off roading asap.

 

[theesotericone]

I have to agree with abs works at any speed above 0mph. Was on a nasty wallow flexed to the stock max really creeping (in a bone stock runner) skidded a tire and off I went and abs kicking in, that was one hell of a ride I didn't want to take and I wasn't insured by survival (lol). Was not fun one bit. I'll be putting in a on-off switch for the abs when off roading asap.

Been there and it sucks. Hijacking the abs fuse wire to a SPST switch is actually a great idea. I might have to do that instead of ripping it out. I like simple.

 

[midcoma]

Doing some parking brake research and found this interesting thread. Looks like these calipers don't lock up Mustang wheels while moving either.

Parking brake discussion - StangNet