11.75 Disc Brake Upgrade problem!

[sac2dude]

I'm attempting this upgrade on my '70 Challenger conv.   I pulled the spindles off of a '75 Dart, checked the measurements, and indeed the lineup with those given in the mopar action article http://www.moparaction.com/tech/archive/disc-main.html.

I pulled the caliper adapters off of a '79 Newport.  No issues, they bolt on well and measure fine.

Went to Kragen, bought a pair of 11.75 rotors (specifying the same '79 Newport) and a set of inner/outer bearings for the '75 Dart, along with inner hub seals.

Result: Bearings fit on spindles fine.  Outer bearing fits in the 11.75 rotor, but the inner bearing and hub seal are too small, and fall into the rotor.

I don't get what the problem could be!

Any ideas?

Thanks!

[72bluNblu]

and a set of inner/outer bearings for the '75 Dart, along with inner hub seals.

This is your problem right here. You need inner bearings and seals for that '79 Newport (or any other car with the 11.75 rotors stock). The spindle diameter is the same for '75 or '79. In fact, its the same from at least '73 to '81 (its probably a much longer run than that). So the internal bearing diameter is the same for the '75 parts and the '79. But as you've discovered, the external bearing diameter is different on the inner bearing, this is because the 11.75" rotors have a larger internal diameter on the inside part of the hub.

I would also check to make sure the outer bearings have the same dimensions as those for the '79, just to make sure there isn't a thickness variation. Wouldn't be any fun to find out that you can't line the hole in the spindle up with the castle nut because the outer bearing is too wide/narrow.

I have a set of 11.75 rotors on my car, the install thread is here http://www.cuda-challenger.com/cc/index.php?topic=56565.0. Although I didn't list anything about which bearings I used. On page 3 there's a list of all the 11.75" rotor cars, any of them should work when giving a reference for the bearings.

[aris_unlimited]

I've been interested in doing a rear disc brake conversion on my 'cuda. Just curious will the 11.75" rotors still allow the use of stock size wheels (15's)?

[Katfish]

Here's the parts list I used for the conversion

raybestos w/pad RC4103/4 $36.00
78 charger (slider)

outer bearing BR2 $6.00
78 charger

wearever rotor YH141132 $52.00
78 charger

dorfman banjo bolt 13938 $5.00

inner wheel bearing BR17 $8.00
77 charger

inner seal 19500 $2.00
77 charger

raybestos hose 4536755 $15.00
76 duster

[HP2]

I've been interested in doing a rear disc brake conversion on my 'cuda. Just curious will the 11.75" rotors still allow the use of stock size wheels (15's)?

15" yes. 14", no.

[mopar12372]

more information please  thankyou!

[sac2dude]

Thanks for the replies!

So, the bottom line is that if my spindle measures the 1 3/8" diameter, then the '79 Newport bearings oughto work just fine.

But I tried 'em.  Yes, they fit the races on the rotors... but they're LOOSE on the spindle!   AAARRGGGHHH!!!

I've measured the spindle repeatedly... same number:  1 3/8

I'm gong to have to make another trip to Kragen to return these.  Perhaps there were differences that year?  I have no idea what to ask for.   

[cudazappa]

You may have the wrong bearings.  P/N might be correct, but wrong bearing inside.  BTDT.  Or made wrong. BTDT, too.

73-89 A/B/E/F/J/M/R (*whew*) disc spindles all use the same inner and outer bearings.  I've done the big rotor swap myself on a couple of rides, I've re-used bearings from the 10.87" setup to the 11.75".

Kragen's part number for the inner bearing is SA17 or A17 (two choices, prices), and outer wheel bearing SA2 or A2 (same deal, two different MFRs)

[sac2dude]

Okay, just returned from Kragen.  Apparently I DO have the right bearings:  BR17 and BR2

But the parts guy thinks they got me the wrong rotors.  The part# looked incorrect to him (7034), so they have some 7038's coming in.  I have no idea what the difference is, but so long as everything ultimately fits... I'm happy.

[cudazappa]

off of Kragens website, the disc should be Wagner #BD60474 

The numbers they are giving you are the Raybestos #s.  7034 is for a C-body newport.  (pre-79, might've gotten the wrong year).    7038 is the 11.75" B/R rotor! 

[ChallengerHK]

You may have the wrong bearings.  P/N might be correct, but wrong bearing inside.  BTDT. 

I had this happen the last time I replaced front bearings: right part number, wrong part.