Author Topic: Rear Disc Brakes  (Read 2306 times)

Offline 7212Mopar

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Rear Disc Brakes
« on: January 23, 2017 - 03:50:25 PM »
I am looking into converting my rear drum brakes to the 11.7" Dr. Diff rear disc brake setup. I see a number of members had already done this. I want to know if I need to change the wheel studs at the axle for this conversion or if I can keep them. They are all in good shape.
1973 Challenger Rallye, AT with 1971 340
2012 Challenger SRT8 392 YJ,  6 spd




Offline burdar

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Re: Rear Disc Brakes
« Reply #1 on: January 23, 2017 - 04:07:35 PM »
If you go to Dr Diff's website and look at his axles, you'll see that he has two options for press-in lug studs...one for drum brakes and one for disc brakes.  The disc brake studs are longer since the rotors are thicker then the drums.  I can take a look at my axles tonight if you want.  I can measure how much of the stud is sticking out past the rotor if that helps.

Offline 7212Mopar

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Re: Rear Disc Brakes
« Reply #2 on: January 23, 2017 - 04:18:51 PM »
 The longer studs at the website are screw in. The ones I have now are pressed in. I do see Dr Diff has option for customer to buy the studs when ordering the brake kit. Just want to make sure I order the right thing. I appreciate you checking.
1973 Challenger Rallye, AT with 1971 340
2012 Challenger SRT8 392 YJ,  6 spd

Offline burdar

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Re: Rear Disc Brakes
« Reply #3 on: January 23, 2017 - 04:23:53 PM »
There are 4 lug stud options.  Two press in and two screw in.  He doesn't list the length of the press in studs but the disc studs are longer due to the rotors mounting flange thickness.

Offline burdar

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Re: Rear Disc Brakes
« Reply #4 on: January 23, 2017 - 07:02:51 PM »
I have a pair of E-body/C-body axles here. The studs stick out past the axle flange 1 1/8".  I measured my Dart studs and they stick out past the rotor 1 1/4".  If the rotor is 1/4" thick, that makes the disc brake studs 3/8" longer.

Offline 7212Mopar

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Re: Rear Disc Brakes
« Reply #5 on: January 23, 2017 - 10:41:42 PM »
Thanks for checking.
1973 Challenger Rallye, AT with 1971 340
2012 Challenger SRT8 392 YJ,  6 spd

Offline 7212Mopar

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Re: Rear Disc Brakes
« Reply #6 on: February 01, 2017 - 12:30:37 AM »
Factory rear drum brake wheel studs left. Rear disc brake wheel studs from Dr. Diff right
1973 Challenger Rallye, AT with 1971 340
2012 Challenger SRT8 392 YJ,  6 spd

Offline Mopar Mitch

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Re: Rear Disc Brakes
« Reply #7 on: February 01, 2017 - 11:57:32 PM »
Do you know if those longer studs are needed on the DrDiff 10.75 rear disc setup, as well?
Autocross/road racers go in deeper... and come out harder!

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Offline burdar

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Re: Rear Disc Brakes
« Reply #8 on: February 02, 2017 - 09:43:19 AM »
I assume so.  Rotors are a lot thicker then drums.

Offline 7212Mopar

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Re: Rear Disc Brakes
« Reply #9 on: February 02, 2017 - 11:02:25 AM »
I agree. It has the same lug stud option on Dr Diff website.
1973 Challenger Rallye, AT with 1971 340
2012 Challenger SRT8 392 YJ,  6 spd

Offline Mopar Mitch

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Re: Rear Disc Brakes
« Reply #10 on: February 03, 2017 - 06:04:30 PM »
By swapping to rear discs (such as DrDiff's options), will it widen the track... as per the extra thickness difference of the rotor vs the thickness of the drum?.... ultimately pushing the wheel out towards the fenders?
Autocross/road racers go in deeper... and come out harder!

See  MOPAR ACTION MAGAZINE, AUGUST 2006 ISSUE for featured article and details on my autocross T/A.

Offline 7212Mopar

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Re: Rear Disc Brakes
« Reply #11 on: February 03, 2017 - 06:28:07 PM »
I would think so, just like wheel spacer. Probably not by much.
1973 Challenger Rallye, AT with 1971 340
2012 Challenger SRT8 392 YJ,  6 spd

Offline shawge

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Re: Rear Disc Brakes
« Reply #12 on: February 03, 2017 - 06:41:39 PM »
IIRC, the Dr Diff brakes pushes the track out +3/16" per side
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Offline 72bluNblu

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Re: Rear Disc Brakes
« Reply #13 on: February 04, 2017 - 02:36:54 AM »
IIRC, the Dr Diff brakes pushes the track out +3/16" per side

That was the info he gave me the last time I asked about his rear disk kits, increases the track by about 3/16" per side.