Disc Brake Conversion / Knuckle Grinding Mod Question

I wanted to start a separate thread for this question in case others have the same issue down the road.

I’m putting disc brakes (the Kaiser Willys kit) on my 1966 D27A front axle. The directions state that I need to grind the fill plug and the knuckle, specifically part of the inside “flange” of the knuckle where the felt seal / metal plates bolt on, to provide clearance for the eventuality of the floating caliper moving inward as pads wear out.

My question is where to grind?

I figure i can clock everything one set of spindle stud bolts “up / forward” from where the KW directions recommend, and not have to grind the plug and the shoulder around the plug, but I’ll lose one seal bolt hole (white area in above picture). If I do this I can design and CNC plasma cut a new thicker piece of backing metal to bridge between two adjacent bolts and make up for the lost one. I don’t think the caliper would hit the frame unless extreme wheeling was done and that’s not my plan.

I wanted to ask those that have gone through this conversion before - how did you “clock” your backing plate and caliper? Love to have some advice before I go grinding tomorrow.

 

did you look into the Brenan metcalf disc brake conversion? no grinding.

Brennan Metcalf
970-764-8729
Info@Brennans-Garage.com

 

So, you're using ford parts.
Brake calipers, loaded for caliper nmounts CB7191
I haven't heard of anyone using ford stuff. I used Chevy backers and calipers on both my D25 and D30. I had to grind a very small amount to get them to clear. Like less than 1/8 of an inch on the side of the caliper and the knuckle. That area looks like quite a lot.

 

@Jeepsterjim I had not seen that - looks like a much better solution. I will look into it.

I bought this kit from Kaiser Willy's - a couple years ago and it's been sitting on the shelf in my garage waiting for me to have time to start into this part of my Jeep. Thus I'm not sure what parts are for OEM for what. The calipers are 18-4046 / 18-4046, which look like new versions of this GM 2.75" caliper.

Here's the picture from their directions showing how much grinding they require - which seems nuts to me as you have to grind the fill plug flush and drill out a new one somewhere else on the knuckle (if you clock the backing plate all the way rearward).


I see that Horespower Industries sells a nearly identical kit to KW but they grind away the part of the caliper that looks like it would interfere with the knuckle (see my red circles).

Could I just mill off some of the material from these calipers?

I wish I had seen Brennan's plates before I bought the KW kit - but I doubt they'd let me return it now that I pressed the hub / rotor together....

 

That is great, thanks! I have some "flush" filler plugs, but to get them down enough to seat properly they hit the sphere inside the knuckle - was thinking I could try some thread tape to make them seal higher up in the hole if I use them? Or mill the tops down a bit so they are truly "flush," or mill down the OEM square ones and and drill/tap for a zerk.

If you had to do this again, would you do what you did (grind the knuckle) or would you try and take just the calipers down?

Edit: Herm's install pictures show the amount of grinding needed better:


Just trying to do some research here - does anyone know what caliper mounting bracket Moses references in the conversion in his book? He says it's a Warn kit but I can't seem to find it - wondering if it might be a stock bracket from a vehicle that Warn drilled for the CJ bolts??? Or was it something Warn engineered and made from scratch?

 

I have a write up on here somewhere. I used Chevy brackets and calipers. Jeep thick rotors and organic pads with longer lug bolts. May need different bearing races and seals.

 

It is a lot to grind. I clocked mine like 17degrees and used 77 k10 calipers.

 

I used the Horsepower kit . About 3 hour install with a perfect fit . Zero grinding .

 

Well thanks for the input everyone.

I decided to use what I have (the Chevy stuff), and machine the calipers for clearance. So far so good, the trial bolt up looks good. The bonus was we got to play on the 1972 Bridgeport!!

I’ll post some better pics when I get it all cleaned up and put together.

 

As Warloch said Warn engineered those brackets. Warn sold all the Full Float and front hub conversion stuff to Randy's Ring and Pinion years ago. They are making some of it and selling it under Yukon brand.

 

Followed up on this with Warn, here’s their reply:


Hello,

These brackets were designed to be used as a caliper mount on a rear axle assembly that had our full float conversion installed then Mr. Ludel would use that on a front end assembly. These brackets went obsolete when we got out of the axle business around 2007.



Thanks,


Todd Wright – Strategic Sales Representative

Warn Industries Inc.|12900 SE Capps Rd.|Clackamas, OR 97015|

 

I wanted to update this thread with a safety PSA. As many of you know by following my build thread, I'm getting pretty close to the end of my project. Yesterday to take a break from cutting carpet, I decided to try and get the spring and felt washer between the brake pedal and the firewall. In doing so, I compressed the brake pedal as far as it would go....and it gave way to the floor, and I heard a loud bursting noise followed by the sound of fluid hitting the floor.

Upon inspection, the brake caliper wall had burst from the pressure, right where we milled it down for clearance around the knuckle. From the looks of it there may have been a pinhole leak for a while.


So - lesson to all you DIYers who thought grinding the calipers instead of the knuckles might work - beware. We thought we left at least 0.125" but obviously we did not. We even removed the plunger and cylinder and measured.

I talked to Dan at Horsepower LLC about how they manage to mill theirs -- and they use new calipers, not remanufactured ones like I presumably got from Kaiser Willys before I bought this kit in 2018.

If you are going to do disc brakes and you don't want to grind your knuckles, I'd say if you are not a machinist go with the Horsepower conversion Kit. Over all I am feeling very lucky that this happened in my garage and not on the road.

 

wowza! thats a scary thought. do you trust the other side that hasnt popped yet??

 

Nope, that's coming off too. At this point I don't really have an easy option other than to buy the Horsepower LLC machined new calipers. It is a hit to the wallet at $220 but better than losing brakes in the woods somewhere. Just wish I had known about them in 2018 and bought their kit instead of the overpriced KW one.

 

or go wirh metcalfs?

 

He uses different brackets so I'd need to buy those too, and take everything apart to get to the brackets.

 

ah, that makes sense.