Series disc brake conversion

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aaronledwidge

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Basically i have decided recently to fit some disc brakes to my series. Im not to certain how they will pan out but im most of the way through the process of producing and fitting the kit so i thought i would wack a thread up. Any advice or opinions would be great.

after a bit of reading around the net I found some disks I thought would be suitable from a late 80's Toyota fj there just over 300mm diameter and should have a low enough hat dimension to allow for a flat bracket.

Ihad some girling m16 calipers knocking about so for now will be using theses, there only 2 pot which is a shame and means they have about 15% less piston area than defender calipers. That being said they should be adequate to stop the old series and much better than 10 inch drums.

Once I had the disks and calipers I mocked up the mounting, the series hubs have to be machined flat then the disk mounts on the rear. The stub axle has a 6x114.3 pcd, so I modeled that on cad then measured the offset of the caliper mounts from the centre, I tried 92mm but this is just touching the hub so ill space that out a little.

When I had it all designed I made up a crude bracket out of 12mm ply, this makes the disk a little tight so ill have the brackets laser cut from 10mm steel. The caliper will still have to have some spacers turned down to account for the offset but otherwise look good.

here are a few pics of the first test

IMAG2878 by darransandwich, on Flickr

I mocked it up and all seems to fit pretty well

IMAG2873 by darransandwich, on Flickr


IMAG2877 by darransandwich, on Flickr


IMAG2875 by darransandwich, on Flickr


IMAG2872 by darransandwich, on Flickr


IMAG2871 by darransandwich, on Flickr

I just need to triple check my measurements and get them cut, once that is done its only mounting the disc to the hub which should be simple
 
Once i was happy with my wooden design i had a frend laser cut out the brackets for me

Here is the bracket straight from the laser cutters.

IMAG2881 by darransandwich, on Flickr
Fits nicely in the middle which is a good sign

IMAG2879 by darransandwich, on Flickr
Plenty of clearance for the disc

IMAG2883 by darransandwich, on Flickr
caliper mocked in place.

IMAG2884 by darransandwich, on Flickr

first job as to turn down the series hubs so they could take a disc. The biggest difficulty in this is removing the webs on the back.

Theres a before

IMAG2888 by darransandwich, on Flickr
we opped it in the lathe and checked the runout with a dial gauge, impressively we were looking at about plus or minus 6 thou on the casting.
then turned off the ribs.

IMAG2889 by darransandwich, on Flickr
Once this was done the back of the hub had to be faced off.

IMAG2890 by darransandwich, on Flickr
 
That gave me a pretty good surface to mount the disc so the next job was finding a suitable PCD that would fit both the 6 stud discs and 5 stud hubs.
This was a little trial and error based but we settled on a place that would fit both and drilled the discs out to 5 stud 10mm mounting holes. We then drilledthe hubs to the same pcd and tapped them for an m10 thread.

IMAG2892 by darransandwich, on Flickr

IMAG2891 by darransandwich, on Flickr
 
On Sunday i set about mocking them up on my truck, this is where i realised i dropped a bollock and used 1980+ series hubs which means they wont fit my stub axles, i had 1 spare 80+ front stub but will have to modify a rear one to fit for the other side :annoyed:

Anywhoo i thought i should mock it all up on the truck, the bracket sat on really well

IMAG2895 by darransandwich, on Flickr

Then i wacked on the hub and the caliper. the offset was a little tight which is a shame so ill add a couple of mm to my bracket design but for now i shaved the caliper a little and fitted it all up

IMAG2896 by darransandwich, on Flickr
I have to say im bloody chuffed with how it looks, i just hope there powerful enough

IMAG2898 by darransandwich, on Flickr

Thats where i stand at the moment, im waiting on wheel bearings to arrive from paddocks, need to dig out the other stub axle and cut down and thread lock the disc bolts in place but all is looking good. The basic decision is if they dont feel powerful enough on the front ill put them on the back and make another kit with defender calipers.

Its also worth noting im running a bigger master cylinder as i had twin leading shoe drums, that being said time will tell if its up to the job.
Aaron
 
Last edited:
this is looking pretty interesting, i'll be following this thread :)

only thing i'm a little concerned about is the "spacer" idea to move the caliper away from your mount, this to my way of thinking gives you two possible shear points on each bolt and increased risk of the caliper attempting to "follow" the disc when the pedal is pressed

i'm not an engineer so i may be talking bollocks but i think i'd prefer to build the carriers out of thicker metal and relieve the one side to account for the offset required

anyway keep the thread going with updates/pictures etc' as you progress
 
Thanks for the opinions as for the caliper spacer I have used kits on my old track car with 10mm spacers moving the caliper to no avail so it should be fine, if I have an issue ill turn down a spacer weld it on and mill the blackface down.

As for disco axles I was worried about the caster issues and didn't fancy clocking the axle ends. Plus didn't have any disco axles to hand so it would have meant spending a lot more money than making this kit.

As for insurance time will tell, it's going for an mot before it goes back on the road so I should have an idea of the braking efficiency,
 
Very interesting thread. I am an engineer and did a lot of machining to fit Toyota discs to a series. This was not for my own vehicle so I was not involved with the assembly or testing, however the customer was pleased with the end result. The vehicle in question was an off road trialer and so did not invoke any insurance or other issues. I am happy with well set up standard 11" brakes, the project I was involved in was done to improve braking after submersion and this it achieved.
 
Yeah that's basically my issue, I don't like the brakes after submersion in water or mud and haven't got the time to keep re building them.

Sounds like an interesting project thoughh
 
This is looking very good, thanks for the update on where you are up to.

Not 100% sure you could sell them as kits, but, you could probably offer a service to do the conversions assuming all goes well and insurance is happy.

(most people don't have access to milling equipment / the skill to mill things down! )
 
Thanks mate, thats nice to know. I dont think i would have the time to make up kits, ill see how it all goes, the plan is once this is done to try another set with defender 4 pots and move these to the back of my series.

I think if you wanted to sell kits you would be better off finding a disc like the zeus one with a hat dimension big enough to pass over the whole hub, takes loads of the hassle away i did try and find one like this but have had no luck so far.
 
If you want to sell any form of kit beware. I have stopped making any bike brake parts for other people due to the legal/liability issues. Over the years I must have done a few dozen disc brake conversions for various bikes and never had a problem but not any more.
 
Yeah I looked at Zeus, last I heard it was 800 plus. I had it in my head disco axles would have needed clocking to get the diff angles right. Or isn't that such an issue?

Divie, I know exactly where your coming from liability is an issue although plenty of people do it in the tuning world I don't know what they put in place.
 
Oh right, not bad at all then. I read you needed to weld up and re drill the axle casing to restore the castor. That's not too bad then.
 
The guys I know that do supply brake parts are well established traders, they can afford the liability insurance premiums to cover them. Not an issue for me any more I have retired and just keep a lathe and mill at home workshop for my own work and bits for friends. I still seem to find more work than I find time for !
 
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