Disc Brake swap-A body Rotors

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3yearcuda

3yearcuda

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I have searched many threads for answers to this question. I am in the process of swapping 74 dart front disc's to my 69 Barracuda. I will have when complete, 4.5"x5 bolt pattern on the front and the 4.0"x5 bolt pattern on my rear 8 3/4. My question is, can front rotors be purchased with the 4.0"x5 pattern as i will need rotors soon anyway? I really dont want to change rear axles to 4.5"x5 pattern. Does anyone have any other suggestions to, in the end have the same bolt pattern?
Thanks.
 
Nope , you would need to redrill the rotors for small pattern. You can buy aftermarket axles and drums for your rear end with 5 on 4.5 pattern.
Every time I mention adapters for the rear someone says "Not safe" and I agree they aren't safe for a tire smoker application.
 
I think thats correct. You are going to have to run adaptors or swap out your rear end axles and drums to the 5" on 4.5". I think swaping out the axles is the best way to go. I bought the Yukon's with green bearings and used 1973 backing plates, hardware and drums to get the bigger 10" X 2.5" brakes. The axles are some 20-30% stronger than stock, and the bigger drums will give you better braking at the rear. You can find thes axles on ebay and many rear end suppliers, even Moroso.
 
I am not sure about the availability of the 4" BP rotors that will work for that setup but a few phone calls should give you the answer. I think several people have found themselves with the big/small situation. Switching the rear axles is not that expensive and pretty easy to do. Moser has a set of new relatively inexpensive axles that might be a good option. If you are interested, I may have a set of axles that were filled and redrilled for 4.5"
 
A couple of the aftermarket disk brake conversion kits come with rotors drilled with both bolt patterns. I believe Wilwood is one, not sure about SSBC. This is an option but you will be stuck getting their parts when you need to do a brake job.

Personally I would use the stuff from the 74 Dart and swap the axles and brakes on the rear. I did this swap three years ago on my 68 Barracuda but swapped in an 8.25 axle that already had the big bolt pattern.
 
Ditto to dgc's first paragraph. Since you already have an 8.75" rear, I wouldn't go through the effort to downgrade (in my opinion) to an 8.25. I'd get a pair of big bolt axles from Moser or Yukon and go that route.

If you do decide to pull out the 8.75, send it to me. LOL.
 
Thanks for the feedback. I have spent a ton of time/money on the 8 3/4, so would like to keep it. I could start looking for axles, backing plates, drums, etc. I wouldnt even care about the two different patterns if i can get custom wheels to fit. Someone mentioned universal type rims/wheels? Is anyone using these on thier odd bolt pattern mopars?
 
To the moderator. My apologies for posting this here in "Website Announcements". I meant to place in the technical section.
 
There are small bolt disc setups out there I know a couple of guy's that are running them. As for finding parts not sure how hard. When I was looking at the disc brake up grad on my car, the front calipers were Kellsy-Hayes two piston with the mopar small bolt setup and were about $300 to replace. The big bolt calipers are about $30, though they are single piston.

I think that both Moser and Strange make an A-body 8 3/4 big bolt axel and there may be others out there as well.
 
the SSBC disk brakes come with both 4' and 4.5' bolt hole circles. the funny thing is that they say you can keep your sbp with these brakes yet they come with the 1/2' studs on the lbp already pressed in. but they do come with the 7/16' studs.
 
3yearcuda said:
Thanks for the feedback. I have spent a ton of time/money on the 8 3/4, so would like to keep it. I could start looking for axles, backing plates, drums, etc. I wouldnt even care about the two different patterns if i can get custom wheels to fit. Someone mentioned universal type rims/wheels? Is anyone using these on thier odd bolt pattern mopars?
Click to expand...

I've never seen dual pattern 4" / 4.5" wheels except for front wheel drive cars, which usually have the wrong offset for an A-body. The ones I've seen in the right offset are always 4.5" / 4.75". You might want to email Center Line and see if they're willing to make them in the dual pattern size you want, though - they do machine wheels to order.
 
I played with wheel adapters when I was a teenager, and after a few weeks of dealing with them, I took them off and threw them away. They rob you of an inch of clearance, and don't like to stay tight. There's nothing like driving down the road and having your wheels want to fall off.

The wheel studs on your axle are only 7/16" studs, and by adding the adapters and moving the wheels out farther, it really adds a lot of strain to them. I really don't recommend them. I'd save the $50 and save for the Moser or Yukons. Moser used to sell shortened C Body axles for not a ton of money. I'm not sure if they still do or not.

Cass can set you up with some axles, ready to go, if you'd like.
http://members.aol.com/doctordiff/
I don't know if you get down to Montana very often, but if you did, you could pick them up in person.
 
I totally agree with avoiding the wheel spacers, not that safe, especially if you decide to race your car.

Doctor Diff is a great guy and will set you up. He is a longtime member on the Moparts website and is basically the Mopar head for rear setups including brakes.

Give him a shout and he can fill you in on all the details, re: axle swap.
 
O.K. Thanks for the input. Just saw the SEMA "approved" and thought they might be alright. It isnt the best solution though. I will start looking for some 4.5 side axles here in the near future and stick with stock wheels in the mean time.
 
"SEMA Approved" might just mean they've paid up their membership dues in full. That said, a lot of Corvette guys are running adapters now, but in their case they're deliberately trying to move the wheels out about an inch to deal with putting wheels of the wrong offset on their cars. I haven't seen one of the typical Corvette adapters but they may not be built in quite the same way.
 
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