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A-body 73up disk swap, How much does track width change #925645
02/10/11 03:55 PM
02/10/11 03:55 PM
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Lyons, CO
MileHighDart Offline OP
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considering doing the 73 Up BBP disk swap on my dart. But the thing I dont like about it is that it widens the track width.

Does anyone know for sure, How much it will widen the track width ? I thought it was almost 3/4" per side, but I had one guy try to tell me its only about 3/8".
It seems pretty visible to me on the 73 up abodys that the front wheels stick out quite a bit more than the rear.
?????

Re: A-body 73up disk swap, How much does track width change [Re: MileHighDart] #925646
02/10/11 03:56 PM
02/10/11 03:56 PM
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I think it's a half inch per side .

Re: A-body 73up disk swap, How much does track width change [Re: JohnRR] #925647
02/10/11 05:02 PM
02/10/11 05:02 PM
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Eagle, Idaho
Neil Offline
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What other options are out there for large bolt pattern brakes that don't make the track wider?

Viper caliper swap with the drum spindles? Does the large bolt pattern rotor fit on the drum spindle?

I know a guy who put converted a duster to LBP with a kit that involved machined early mustang rotors and some caliper adapters. I can't remember all the details, but I think he was able to keep the stock spindles and track width.

Re: A-body 73up disk swap, How much does track width change [Re: Neil] #925648
02/10/11 05:08 PM
02/10/11 05:08 PM
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I make a kit that converts 5 x 4" bolt pattern (10") drum knuckles to 5 x 4 1/2" disc brakes.

Re: A-body 73up disk swap, How much does track width change [Re: Neil] #925649
02/10/11 05:10 PM
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Quote:

What other options are out there for large bolt pattern brakes that don't make the track wider?

Viper caliper swap with the drum spindles? Does the large bolt pattern rotor fit on the drum spindle?

I know a guy who put converted a duster to LBP with a kit that involved machined early mustang rotors and some caliper adapters. I can't remember all the details, but I think he was able to keep the stock spindles and track width.




Stock KH disc setup with a machined mustang rotor would keep it close , or find a pair of the early race rotors used on the 68 SS A bodies and the earlier road course 64-66 A bodies.

Re: A-body 73up disk swap, How much does track width change [Re: JohnRR] #925650
03/07/11 01:58 AM
03/07/11 01:58 AM
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So Cal, USA
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I'm getting ready to swap '73-76 front discs onto my '67 Barracuda, and I don't want the front wheels hanging out too far. Could a front wheel with less backspacing be used to compensate for the increased track width?

Re: A-body 73up disk swap, How much does track width change [Re: Fab64] #925651
03/07/11 02:05 AM
03/07/11 02:05 AM
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Quote:

I'm getting ready to swap '73-76 front discs onto my '67 Barracuda, and I don't want the front wheels hanging out too far. Could a front wheel with less backspacing be used to compensate for the increased track width?




Wrong way, you want a wheel with more backspace to move the wheel in.

Track
73+ is 59.1
67-72 is 57.4

Re: A-body 73up disk swap, How much does track width change [Re: RobX4406] #925652
03/07/11 10:14 AM
03/07/11 10:14 AM
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In 73 the rear track was narrowed. That might be part of what you're seeing. I put '73+ style bbp discs on my 73 swinger and 225 tires tucked in fine on stock AR toque thrust IIs.
Good luck

Re: A-body 73up disk swap, How much does track width change [Re: radar] #925653
03/07/11 11:05 AM
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Quote:

In 73 the rear track was narrowed. That might be part of what you're seeing. I put '73+ style bbp discs on my 73 swinger and 225 tires tucked in fine on stock AR toque thrust IIs.
Good luck




You won't see what the owners of small bolt pattern 72 down A bodies will because your car was designed to have that track width.

What vehicle came stock with AR torque thrust II's ???

Re: A-body 73up disk swap, How much does track width change [Re: JohnRR] #925654
03/07/11 01:49 PM
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Hard to see in this picture, but my son's Dart has 73-up discs with cut-down C-body axles out back in a stock A-body 8-3/4. The wheels are stock 15x6.5 rallyes. Nothing looks out of place or out of proportion to me.


Re: A-body 73up disk swap, How much does track width change [Re: Jim_Lusk] #925655
03/07/11 01:51 PM
03/07/11 01:51 PM
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In this picture my Barracuda still has the small bolt 7-1/4, but has 73 discs up front. Again, nothing looks out of place or proportion.


Re: A-body 73up disk swap, How much does track width change [Re: Jim_Lusk] #925656
03/07/11 01:53 PM
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Lastly, my old 67 fastback. Small bolt all the way around with K-H discs and an A-body 8-3/4. The wheels are 14x7 slotted mags.


Re: A-body 73up disk swap, How much does track width change [Re: JohnRR] #925657
03/07/11 06:24 PM
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Quote:

Quote:

In 73 the rear track was narrowed. That might be part of what you're seeing. I put '73+ style bbp discs on my 73 swinger and 225 tires tucked in fine on stock AR toque thrust IIs.
Good luck




You won't see what the owners of small bolt pattern 72 down A bodies will because your car was designed to have that track width.

What vehicle came stock with AR torque thrust II's ???




My '73 swinger came with small bolt pattern 7.25" rear and 10" drum brakes on all four corners. The front wheels came with small bolt pattern too. When I got the car it had dodge stock 14" steel wheels with hubcaps. The rear track was noticeably narrower than the front. This is on a 1973 Dodge Dart Swinger with 198cid /6 motor and 904 transmission.

I swapped the stock UCAs and spindles for '73 up a-body style single piston brakes. At the same time I installed a hot rodded 225 engine and a ford 7.5" rear with a custom driveshaft to get big bolt pattern and installed American Racing Torque Thrust II wheels- 17"x7" with STOCK AR backspace, not custom backspace.

That's what I meant by stock.

The 225 tires tuck in fine front and back.


Re: A-body 73up disk swap, How much does track width change [Re: radar] #925658
03/07/11 06:54 PM
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Quote:

Quote:

Quote:

In 73 the rear track was narrowed. That might be part of what you're seeing. I put '73+ style bbp discs on my 73 swinger and 225 tires tucked in fine on stock AR toque thrust IIs.
Good luck




You won't see what the owners of small bolt pattern 72 down A bodies will because your car was designed to have that track width.

What vehicle came stock with AR torque thrust II's ???




My '73 swinger came with small bolt pattern 7.25" rear and 10" drum brakes on all four corners. The front wheels came with small bolt pattern too. When I got the car it had dodge stock 14" steel wheels with hubcaps. The rear track was noticeably narrower than the front. This is on a 1973 Dodge Dart Swinger with 198cid /6 motor and 904 transmission.

I swapped the stock UCAs and spindles for '73 up a-body style single piston brakes. At the same time I installed a hot rodded 225 engine and a ford 7.5" rear with a custom driveshaft to get big bolt pattern and installed American Racing Torque Thrust II wheels- 17"x7" with STOCK AR backspace, not custom backspace.

That's what I meant by stock.

The 225 tires tuck in fine front and back.






Where did you read that in 1973 the rear track was narrowed ?

Re: A-body 73up disk swap, How much does track width change [Re: JohnRR] #925659
03/07/11 10:32 PM
03/07/11 10:32 PM
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Actually, I have not personally noticed the extra width up front, and I was surprised when I read it here. That's why I decided to ask about it.

I just looked on-line, and found the following track widths:

1967 Barracuda - front 57.4, rear 55.6
1975 Dart - front 59.1, rear 55.6

This matches what RobX4406 said, above. Assuming this is correct, the rear track did not change, but the front track on the 73-76's is wider by .85" on each side (that's just under 7/8", which is .875").

Jim, all three of your cars look fine to me. Are they each running the same width wheels in front and back?

Sources:

1967 Barracuda

1975 Dart

Re: A-body 73up disk swap, How much does track width change [Re: Jim_Lusk] #925660
03/07/11 10:53 PM
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Neil Offline
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Quote:

Hard to see in this picture, but my son's Dart has 73-up discs with cut-down C-body axles out back in a stock A-body 8-3/4. The wheels are stock 15x6.5 rallyes. Nothing looks out of place or out of proportion to me.






Can you recall what size tires are on the front of that vert? I have a set of 15x6.5 rallye wheels and was thinking a 215-65-15 would be about as big as one could go with the 73 and up discs on the front of a 67-72 dart.

Re: A-body 73up disk swap, How much does track width change [Re: Neil] #925661
03/07/11 11:40 PM
03/07/11 11:40 PM
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Guys...
I don't think swapping on the disk brakes widens the track at all. The '73 and up K-frame is what was widened. If you are keeping your stock k-frame and lower arms, you will not see a change in track width.
All you need to swap on the suspension side is the knuckles and upper arms.

Re: A-body 73up disk swap, How much does track width change [Re: JohnRR] #925662
03/07/11 11:52 PM
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Jeez you got me there!

I remember when I first got my swinger I thought it was weird how the back wheels tucked in more than the fronts. I thought I read that it was narrowed that year for handling or something. '73 was a year for a lot of changes, some of which I was wishing my car had (big bolt pattern, disc brakes standard)

I went back and read the axle specs and nowhere says anything about narrowed track in '73...

I'm not afraid to admit I'm wrong- sorry 'bout that!


rdr


Re: A-body 73up disk swap, How much does track width change [Re: Dartslantsix] #925663
03/08/11 01:15 AM
03/08/11 01:15 AM
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Quote:

Guys...
I don't think swapping on the disk brakes widens the track at all. The '73 and up K-frame is what was widened. If you are keeping your stock k-frame and lower arms, you will not see a change in track width.
All you need to swap on the suspension side is the knuckles and upper arms.




Wrong. The k-member dimensions are exactly the same from 67-76.

Re: A-body 73up disk swap, How much does track width change [Re: Neil] #925664
03/08/11 01:16 AM
03/08/11 01:16 AM
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Quote:

Quote:

Hard to see in this picture, but my son's Dart has 73-up discs with cut-down C-body axles out back in a stock A-body 8-3/4. The wheels are stock 15x6.5 rallyes. Nothing looks out of place or out of proportion to me.






Can you recall what size tires are on the front of that vert? I have a set of 15x6.5 rallye wheels and was thinking a 215-65-15 would be about as big as one could go with the 73 and up discs on the front of a 67-72 dart.




The tires on the Dart are 235-60-15 on the rear and 215-60-15 on the front. The other two cars have the same size tires front and rear.

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