Replace Lj10/20 drum brakes with disc brakes – a summary

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dunstan
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Replace Lj10/20 drum brakes with disc brakes – a summary

Post by dunstan » Mon Feb 04, 2013 6:34 pm

I've spent the day reading 9 year's worth of threads on fitting disc brakes to LJ10s and LJ20s. Since so many of the threads are old, it occurred to me that it might be helpful to have an up-to-date thread that summarizes the known options.

As I understand it, they are:

1. Cut down your existing LJ front brake hubs, modify some Samurai SJ413 brake brackets, then combine them with SJ413 brake calipers and rotors, a la Smuz http://www.lj10.com/howto/discbrakes/" onclick="window.open(this.href);return false; and lil beast viewtopic.php?f=18&t=737" onclick="window.open(this.href);return false;

This requires some fabricating. It's reversible and will leave you with all your current LJ hardware, with the exception of the hubs that you cut down.

or...

2. Replace your LJ birfields with SJ410 birfields (viewtopic.php?p=39333#p39333" onclick="window.open(this.href);return false;), replace your LJ knuckles with Samurai SJ413 knuckles, and then use SJ413 brake calipers, brackets, and rotors. The closest illustration of this that I could find is a writeup on Highway-star's LJ80 viewtopic.php?p=48758#p48758" onclick="window.open(this.href);return false;

This doesn't require any fabricating, but SJ410 birfields are hard to find in the US.

I'm sure there are other more dramatic options, but that's all I had for now. Does anyone have anything to add, or see anything incorrect in what I'm saying?

Thanks.
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Re: Replace Lj10/20 drum brakes with disc brakes – a summary

Post by Ruby » Mon Feb 04, 2013 6:54 pm

One of the lj 10/20 pro's will have to confirm but I thought the splined part of the birfs are smaller than the lj80 so the sj410 birf will not work on a lj10/20?
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Re: Replace Lj10/20 drum brakes with disc brakes – a summary

Post by dunstan » Mon Feb 04, 2013 7:13 pm

Oh... maybe the hours and hours of reading left me a little confused on that. I thought it was possible.
This guy seems to have done it: viewtopic.php?f=3&t=4819&p=48672#p48672" onclick="window.open(this.href);return false;
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Re: Replace Lj10/20 drum brakes with disc brakes – a summary

Post by Ruby » Mon Feb 04, 2013 8:43 pm

Ya it does appear to work, guess I'm mistaken.
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Re: Replace Lj10/20 drum brakes with disc brakes – a summary

Post by dunstan » Mon Feb 04, 2013 8:47 pm

Well thanks for checking, anyway. I have such a headache from reading posts for 6 straight hours, I'm sure I've probably got something wrong :)
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Re: Replace Lj10/20 drum brakes with disc brakes – a summary

Post by dunstan » Mon Mar 11, 2013 5:34 pm

Since we seem to have settled on the options for front disc brakes, can anyone summarize the options for rear disc brakes? I see plenty of people have disc brakes all round, but I can't find a single detail of how they done it. Can anyone help?
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Re: Replace Lj10/20 drum brakes with disc brakes – a summary

Post by stevec » Tue Mar 12, 2013 9:12 am

There are kits to convert Samurai's to rear disc brakes, but all involve relocating the e-brake to the driveshaft or t-case. Samurai drum brakes should just about bolt on (I think the bolt pattern is the same?), and gives you a rear-axle e-brake. That would be your best solution.
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Re: Replace Lj10/20 drum brakes with disc brakes – a summary

Post by Ruby » Tue Mar 12, 2013 9:36 am

stevec wrote:Samurai drum brakes should just about bolt on (I think the bolt pattern is the same?), and gives you a rear-axle e-brake. That would be your best solution.
If LJ 10 backing plates are the same as LJ 80's, then it just requires opening up the center hole of the Samurai backing plate to 2" to allow the bearing to pass through.
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Re: Replace Lj10/20 drum brakes with disc brakes – a summary

Post by dunstan » Mon Mar 18, 2013 12:18 pm

Thanks guys. I guess I was just interested in seeming a brief summary of how to fit rear disc brakes. I don't plan on doing it, I was just interested to fill the knowledge gap. But not to worry.
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Re: Replace Lj10/20 drum brakes with disc brakes – a summary

Post by stevec » Mon Mar 02, 2015 1:52 pm

One of my winter projects was to do this swap on my LJ81. The stock brakes are adequate, but were designed for the 1300# LJ10 and LJ20, not the 1700# LJ80/81. Add another 500# of trailer, a couple of people, and camping gear, and my stopping distance got a lot longer.

I had a spare LJ80 axle, as well as a spare Samurai axle, so I had everything I needed except the SJ410 birfields. I was able to find a set of two brand new birfields on ebay Australia for about $100 shipped, so I ordered them. (Note: do a search for “SJ410 CV Joint”!)

Like others, the hardest part was separating the birfield from the LJ80 axle shaft. On both, I ended up cutting the cage and removing the ball bearings to get them apart; on one of them I even had to cut the star off the shaft. Other than that, the process went quite smoothly. I went “all in” and replaced the rotors (mine were out of spec), and calipers (this axle had been sitting out, so they were pretty rusted.) I also replaced the tie rod ends, as one of mine was pretty loose. One thing to note is that you will need longer brake lines, similar to what you would need when lifting a stock Samurai. I used Geo Metro lines, but there are others that work too (i.e. Honda). I chose not to upgrade to a Samurai master cylinder, figuring I could do that later if needed. Turns out, it isn’t needed at all.

I finally finished everything up Saturday, and took my LJ81 for a test drive. Before going out, I adjusted the rear brakes as well. I haven’t had the front aligned yet, but got it pretty darn close with a couple of tape measures (one at the front of the wheels and one behind). For this reason, I stayed off the freeway, but it was smooth enough that I felt comfortable getting it up around 55 mph.

Driving impressions: All I can say is “WOW”! I did a couple of “hard brakes” on residential streets with no traffic, to see how quickly it would stop, and braking from 25mph to zero is almost instantaneous. The first time I just about went through the windshield (yes I was wearing my seatbelt!) The fronts lock up well before the pedal gets to the floor. I couldn’t tell if the rears locked up or not, but I expect they would if I hit it hard enough, as I’ve locked them up before. It rolls a bit easier with the hubs unlocked, so I expect I might see a slight improvement in gas mileage as well.

As a side note, my tires are BFG AT’s, LT215/75R15, with about 20 psi in them. If you are running smaller tires (i.e. stock), you’ll lock up even quicker. If you are running bigger tires, it’ll be harder to lock the front brakes, but I think even with 31’s, you shouldn’t have too much trouble.

One final note: I looked at the various axle shafts I had, and confirmed that this swap will also work on an LJ10/20 axle, although I can't imagine needing that much braking ability on my LJ10's!
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Re: Replace Lj10/20 drum brakes with disc brakes – a summary

Post by zukimoo » Wed Mar 04, 2015 5:54 pm

I did the SJ413 front disc brake swap and the SJ413 rear drum swap onto my LJ80 and it worked good. Hardest part was splitting the birfs. I ended up buying four SJ410 fronts for the birfs and got lucky that the first two popped right off. LJ80 birfs gave me a hard time. I could have cut them off but wanted to try to save them just in case it didn't work.
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Re: Replace Lj10/20 drum brakes with disc brakes – a summary

Post by Meatloaf » Thu Mar 05, 2015 8:35 am

stevec wrote:...
Like others, the hardest part was separating the birfield from the LJ80 axle shaft. On both, I ended up cutting the cage and removing the ball bearings to get them apart; on one of them I even had to cut the star off the shaft. ...
Excuse me if I missed something , but don't you need the keep the LJ80 shafts intact to use with the SJ410 Birfs?
How would that one shaft work if you cut the star off of it?

:?
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Re: Replace Lj10/20 drum brakes with disc brakes – a summary

Post by stevec » Thu Mar 05, 2015 10:08 am

The "star" is actually part of the birfield, not the main (inner) axle shaft. There is a circlip that holds this star in place on the shaft, and the ball bearings fit between the points of the star. Thus, once the star is removed, you can just pull the circlip off, put a new one on, and pop the SJ410 birfield into place.

I bought new SJ410 birfields off ebay Australia, so I only had to separate the LJ80 axles to use the main shaft. Good thing - separating those axles was the longest part of the process! I had a spare LJ80 axle and a spare Samurai axle, so I was able to do most of the work in the garage without touching anything on my LJ81.
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Re: Replace Lj10/20 drum brakes with disc brakes – a summary

Post by Meatloaf » Fri Mar 06, 2015 1:08 pm

Doh!! I DID miss something !! The circlip is shown plain as day in my LJ80 service manual (Pg 209: Figs 17-2, 17-3, 17-4).
The "star" is called the "inner race" in the manual ( for those who care ).
Next time I'll open my manual before I open my mouth .. err keyboard :oops:
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Re: Replace Lj10/20 drum brakes with disc brakes – a summary

Post by stevec » Mon Mar 09, 2015 9:44 am

Yeah, I guess it is technically the inner race for those ball bearings, but it doesn't look like what you expect an inner race to look like, so I call it the "star". :D
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Re: Replace Lj10/20 drum brakes with disc brakes – a summary

Post by 1x1_Speed_Craig » Sat Nov 17, 2018 12:49 pm

Replying to this original (but old) thread to help with future searches...

After getting input from an axle guru friend who used to own his own off-road shop (with custom axle building as their specialty), I'd like to add a potential 3rd option relating to the original post.

I've decided to run Samurai knuckles/brakes on my LJ20, but also want to gain the benefit of using the Samurai lock-outs. That eliminates Option 1. Option 2 sounds great on paper, the unicorn-like obscurity relating to the disc-equipped SJ410 birfields (even internationally on eBay) eliminates Option 2 for most.

When talking with my friend about custom axle shaft options and axle shaft/birfield limitations due to the tiny LJ20 knuckle balls, he suggested building a hybrid axle using Samurai knuckle balls on the LJ20 axle housing. This would allow me to keep the original axle width and low stock axle gearing, but allow the use of readily-available Samurai birfield joints. I'll have to use shortened/resplined Samurai inner shafts (2 shortened "long side" shafts, that is), or have custom inner shafts made. Benefits with this set-up include the use of OEM or aftermarket front hub lock-outs, making a front locker (Lock Right 1520) feasible for a street-driven vehicle (and better fuel economy, if you're worried about that). It'll decrease wear & tear on your rare LJ10/LJ20 differential parts. Custom inner shafts also opens the option to run 26-spline shafts in the front for stronger-than-stock front axle shafts.

Thoughts?
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Re: Replace Lj10/20 drum brakes with disc brakes – a summary

Post by DieLJ » Sun Nov 18, 2018 1:58 pm

Craig, :D Welcome to the modification underground! You are keeping with Suzuki parts, so your exploits remain near the surface and are able to be openly discussed in polite conversation.....but think of the strength, spares availability and aftermarket upgrade options of Jeep, Chevrolet, Ford etc.-------The dark side awaits.......
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Re: Replace Lj10/20 drum brakes with disc brakes – a summary

Post by DieLJ » Sun Nov 18, 2018 2:27 pm

Also, instead of shorting the long side of the Samurai axle, using to short side axles should put you just over 52 inches (based on my half assed calculations). Not overly wide and should tuck under the LJ with the right rims. Other short not custom axles are the Dana 44's out of postal jeeps, some tractors and trenchers used narrow 44's and narrow 60's. Most of the heavy equipment axles are 30 spline (both ends), which would have created a problem with the lockouts---But now there is a 30 spline lockout hub conversion for the Warn 20990 lockout hub........".yes, modify the precious.....precious....modify the precious....."-[youtube]https://www.youtube.com/watch?v=1cff8QzjDNc[/youtube]
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