Chevy disc brake. SOS

[farzadmip]

So I've been struggling to do this junk yard conversion on a 71 d44. I've done the conversion on the 68 and used a larger backing plate that posed no problems. We'll when I fitted it all on the 71 all was well except the stock steel wheels wouldnt fit. So I went back to the junk yard and picked up the heavy duty backing plates that are the full circle ones. Fit inside the wheels no problem. Problem is the rotors are too close to the backing plate to get the back brake pad in. At first I thought it was because I was using the spacer method on original ford spindles. So back to the junk yard for chevy spindles. Bolt it all up and have the same problem. I called horses because theyre always awesome about tech and he informed me they use the 76-77 rotors from a bronco. I told napa 88 ford f150 rotors because I always read to use f150 rotors up to 895 as long as they weren't abs. Could the rotors be the problem? I did use the same rotors on the 68 but they were different backing plates. Any help would be appreciated this thing had been killing me for awhile. I keep moving on to other projects because I'm so frusterated. Ready to say screw it and rebuild the drums...

 

[farzadmip]

Just talked to a guy at napa and he shows 76 bronco rotor as the same as what I have. Does that sound right to you guys?

 

[TOOLMAN]

IIRC, you can use the 1/2 ton 4x4 rotors/hubs from a bunch of years of ford as long as they weren't abs or auto hubs. There may also be one or two weird years you couldn't use the hub/rotor...like '93 or something like that. Looks like the hubs are correct. Did you grind off the little nubby thing on the back of the knuckle? That will definitely give you caliper clearance problems.

 

[farzadmip]

Yeah I did grind the knuckles as well as a little off the calipers. Problem is spacing between the backing plate and the rotor. I can't even get the pad between the 2 without the caliper. I'll see if I can snap a pic

 

[thegreatjustino]

I've used rotors all the way up to '91 on Chevy disc brake conversions. The ones you have should work fine.

 

[farzadmip]

Here's a picture of my problem area. Kind of hard to get the right angle on the phone. If I really shimmeed it I could get the pad behind but it seems way too tight compared to others I've done. Justin have you used these backing plates?

 

[farzadmip]

Forgot the pics lol

 

[ET]

I would think bearings and races would effect spacing between caliper bracket and rotor. Does this happen on both sides and condition on bearings? Just a thought.

Eugene

 

[farzadmip]

Wheel bearings and races are new timkens from graveyard.

 

[TOOLMAN]

Which pads and calipers are you running? They would have to be from the same variety as the backing plates. I used those same plates (with Chebby spindles, calipers, and pads. There are some funky years out there you can't use, but I think the plates are all the same. I'll have to look at mine when I get home.

 

[farzadmip]

I'm not sure what the caliper brackets are off exactly. I too the other ones I had as a point of reference because all that the salvage yards has were mostly off in the back of a pickup bed. Calipers and pads were 76 k5 blazer.

 

[farzadmip]

Parts were from oreilly calipers BHH 18-4045, BHH 18-4046 pads are BB SC52

 

[thegreatjustino]

Here's a picture of my problem area. Kind of hard to get the right angle on the phone. If I really shimmeed it I could get the pad behind but it seems way too tight compared to others I've done. Justin have you used these backing plates?

I have done the chevy conversion three times now. Twice I used the smaller backing plate that just had the sheet metal dust cover and once I've used the heavier duty backing plates. I've never used the spacers, always used the Chevy spindles. I've never had an issue with the pads fitting. However, since the calipers here in CA don't really rust out, I've always re-used the calipers and pads I pulled off the donor truck. So, I'm sure there was some wear on those used pads. I don't know if I'd have the issue you're having with a brand new set of pads.

I see in your pictures, you're just holding the pad up to the rotor. Have you actually tried installing the loaded calipers on the bracket to see what the pads are doing? You clearanced the knuckles enough for the caliper to slide toward the knuckle enough? I know grinding the knuckle too little can play hell with this conversion.

 

[farzadmip]

I think I've reached some sort of progress. I took the 68 apart to compare the spacers since the chevy spindles weren't working. So the one off the 68 was slightly thicker so I tried it and gives me enough clearance. Funny thing is the thinner one worked fine on the 68. Only concern now is that the hub lock nut is only 2/3ds threaded onto the spindle

 

[76Broncofromhell]

I think I've reached some sort of progress. I took the 68 apart to compare the spacers since the chevy spindles weren't working. So the one off the 68 was slightly thicker so I tried it and gives me enough clearance. Funny thing is the thinner one worked fine on the 68. Only concern now is that the hub lock nut is only 2/3ds threaded onto the spindle

Did you re-use the drive hub assembly (the piece that the wheel stud presses into) from the drum brakes with your discs?

If so, that's the problem.

You can use any 76-92 F-150/Bronco 4x4 brake rotor.

 

[bronconut73]

Did you re-use the drive hub assembly (the piece that the wheel stud presses into) from the drum brakes with your discs?

If so, that's the problem.

You can use any 76-92 F-150/Bronco 4x4 brake rotor.

I used my drum hubs.
It worked fine, can't remember too many details as it was 25 years ago....

 

[76Broncofromhell]

I used my drum hubs.
It worked fine, can't remember too many details as it was 25 years ago....

As I recall, the drum hubs have a different spacing that that of the disc hubs.

http://classicbroncos.com/disc_faq.shtml


My knowledge is also a bit old however.

 

[farzadmip]

They are disc hubs. Works been crazy with Sturgis Bike Week so to be continued when I get more time.

 

[72Sport]

See if you have the right backing plates. The correct ones have 37845 stamped on the knuckle side. Looking at the backing plate with the caliper hole straight up the 37845 should be stamped on the center of the flat area between the 3 and 4 o'clock position.

Seat the caliper pistons in the body of the caliper body with a c clamp if you haven't all ready.

For what its worth when doing the Ford conversion with Duff parts they recommend loosing the wheel bearings while trying to install the new pads with new rotors.

 

[farzadmip]

See if you have the right backing plates. The correct ones have 37845 stamped on the knuckle side. Looking at the backing plate with the caliper hole straight up the 37845 should be stamped on the center of the flat area between the 3 and 4 o'clock position.

Seat the caliper pistons in the body of the caliper body with a c clamp if you haven't all ready.

For what its worth when doing the Ford conversion with Duff parts they recommend loosing the wheel bearings while trying to install the new pads with new rotors.

Thank you. I now know that I have the right backing plates I have Monday off and will try it with the bearings loose.