A-body 73up disk swap, How much does track width change

Posted By: MileHighDart

A-body 73up disk swap, How much does track width change - 02/10/11 07:55 PM

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.
?????

Posted By: JohnRR

Re: A-body 73up disk swap, How much does track width change - 02/10/11 07:56 PM

I think it's a half inch per side .

Posted By: Neil

Re: A-body 73up disk swap, How much does track width change - 02/10/11 09:02 PM

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.

Posted By: DoctorDiff

Re: A-body 73up disk swap, How much does track width change - 02/10/11 09:08 PM

I make a kit that converts 5 x 4" bolt pattern (10") drum knuckles to 5 x 4 1/2" disc brakes.

Posted By: JohnRR

Re: A-body 73up disk swap, How much does track width change - 02/10/11 09:10 PM

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.

Posted By: Fab64

Re: A-body 73up disk swap, How much does track width change - 03/07/11 05:58 AM

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?

Posted By: RobX4406

Re: A-body 73up disk swap, How much does track width change - 03/07/11 06:05 AM

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

Posted By: radar

Re: A-body 73up disk swap, How much does track width change - 03/07/11 02:14 PM

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

Posted By: JohnRR

Re: A-body 73up disk swap, How much does track width change - 03/07/11 03:05 PM

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 ???

Posted By: Jim_Lusk

Re: A-body 73up disk swap, How much does track width change - 03/07/11 05:49 PM

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.

Posted By: Jim_Lusk

Re: A-body 73up disk swap, How much does track width change - 03/07/11 05:51 PM

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.

Posted By: Jim_Lusk

Re: A-body 73up disk swap, How much does track width change - 03/07/11 05:53 PM

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.

Posted By: radar

Re: A-body 73up disk swap, How much does track width change - 03/07/11 10:24 PM

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.

Posted By: JohnRR

Re: A-body 73up disk swap, How much does track width change - 03/07/11 10:54 PM

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 ?

Posted By: Fab64

Re: A-body 73up disk swap, How much does track width change - 03/08/11 02:32 AM

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

Posted By: Neil

Re: A-body 73up disk swap, How much does track width change - 03/08/11 02:53 AM

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.

Posted By: Dartslantsix

Re: A-body 73up disk swap, How much does track width change - 03/08/11 03:40 AM

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.

Posted By: radar

Re: A-body 73up disk swap, How much does track width change - 03/08/11 03:52 AM

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

Posted By: Jim_Lusk

Re: A-body 73up disk swap, How much does track width change - 03/08/11 05:15 AM

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.

Posted By: Jim_Lusk

Re: A-body 73up disk swap, How much does track width change - 03/08/11 05:16 AM

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.

Posted By: Dartslantsix

Re: A-body 73up disk swap, How much does track width change - 03/08/11 06:37 AM

Quote:

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

I just leafed through Tom Condran's book. He states that all A-Body lower control arms are the same length. If what you're saying about the K-frames is true, does the extra width come from the knuckles?

Maybe I've misunderstood something.

Posted By: Jim_Lusk

Re: A-body 73up disk swap, How much does track width change - 03/08/11 07:36 AM

Quote:

Quote:

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

I just leafed through Tom Condran's book. He states that all A-Body lower control arms are the same length. If what you're saying about the K-frames is true, does the extra width come from the knuckles?

Maybe I've misunderstood something.

The extra width comes from the location of the rotor on the spindle.

Posted By: Dartslantsix

Re: A-body 73up disk swap, How much does track width change - 03/09/11 01:18 AM

Thanks for the clarification.

Posted By: Mopar_Country

Re: A-body 73up disk swap, How much does track width change - 03/09/11 01:42 AM

Quote:

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

My car is a 74 and there is a noticeable difference from front to rear track when standing behind it. I kinda wondered why myself.

Posted By: Rick_Ehrenberg

Re: A-body 73up disk swap, How much does track width change - 03/10/11 05:46 AM

Some trivia...

> When the "bulged 1/4 panel" A-body came out in 1970 (Duster), the engineers wanted a wider axle housing. Bean counters quashed it. Everybody commented on how "lost" the rubber looked on 1970 Dusters (rear).

> Then, in 1973, when the 4.5" BC / slider brakes (wider track setup) came out, the Duster / Dart Sport looked so silly (stock) with front wheelhouses looking "full" and the rears "empty", that there was actually a TSB telling service managers that this visual effect was normal. Which it was.

Comments above, re: basic body dimensions and suspension components unchanged 1967-'73, are 100% correct.

Rick

Posted By: JohnRR

Re: A-body 73up disk swap, How much does track width change - 03/10/11 05:51 AM

Quote:

Some trivia...

> When the "bulged 1/4 panel" A-body came out in 1970 (Duster), the engineers wanted a wider axle housing. Bean counters quashed it. Everybody commented on how "lost" the rubber looked on 1970 Dusters (rear).

> Then, in 1973, when the 4.5" BC / slider brakes (wider track setup) came out, the Duster / Dart Sport looked so silly (stock) with front wheelhouses looking "full" and the rears "empty", that there was actually a TSB telling service managers that this visual effect was normal. Which it was.

Comments above, re: basic body dimensions and suspension components unchanged 1967-'73, are 100% correct.

Rick

Sounds like a 68-70 B body rear would be right at home under one ?

Posted By: OzHemi

Re: A-body 73up disk swap, How much does track width change - 03/10/11 05:58 AM

Quote:

Quote:

Some trivia...

> When the "bulged 1/4 panel" A-body came out in 1970 (Duster), the engineers wanted a wider axle housing. Bean counters quashed it. Everybody commented on how "lost" the rubber looked on 1970 Dusters (rear).

> Then, in 1973, when the 4.5" BC / slider brakes (wider track setup) came out, the Duster / Dart Sport looked so silly (stock) with front wheelhouses looking "full" and the rears "empty", that there was actually a TSB telling service managers that this visual effect was normal. Which it was.

Comments above, re: basic body dimensions and suspension components unchanged 1967-'73, are 100% correct.

Rick

Sounds like a 68-70 B body rear would be right at home under one ?

Not that they are really available around here, but the later (VH-onwards) Aussie diff was a tad wider than the earlier ones. I don't have the specs off the top of my head, but I would say about a 1/2" or abit more per side.

My last VG (now 68hemiB's) had a later diff in it, and a factory steel wheel just made the tire about rub the 1/4 panel...
Since the later cars were rounded compared to the earlier cars (sort of like what happened here) they actually did go with a wider diff there though.

Attached picture 6521875-020(2).JPG

Posted By: JohnRR

Re: A-body 73up disk swap, How much does track width change - 03/10/11 06:09 AM

Quote:

Quote:

Quote:

Some trivia...

> When the "bulged 1/4 panel" A-body came out in 1970 (Duster), the engineers wanted a wider axle housing. Bean counters quashed it. Everybody commented on how "lost" the rubber looked on 1970 Dusters (rear).

> Then, in 1973, when the 4.5" BC / slider brakes (wider track setup) came out, the Duster / Dart Sport looked so silly (stock) with front wheelhouses looking "full" and the rears "empty", that there was actually a TSB telling service managers that this visual effect was normal. Which it was.

Comments above, re: basic body dimensions and suspension components unchanged 1967-'73, are 100% correct.

Rick

Sounds like a 68-70 B body rear would be right at home under one ?

Not that they are really available around here, but the later (VH-onwards) Aussie diff was a tad wider than the earlier ones. I don't have the specs off the top of my head, but I would say about a 1/2" or abit more per side.

My last VG (now 68hemiB's) had a later diff in it, and a factory steel wheel just made the tire about rub the 1/4 panel...
Since the later cars were rounded compared to the earlier cars (sort of like what happened here) they actually did go with a wider diff there though.

Jeff that car is not the bulged 1/4 A body Ebooger speaks of , they would be duster , demon , dart sport , the car in the pic is the same as the 67-69 A bodies

Posted By: OzHemi

Re: A-body 73up disk swap, How much does track width change - 03/10/11 06:12 AM

I know John...the diff is from a later car I am saying...(which were more bulged like the US ones you mentioned)

Just saying if one of our later cars had the same diff width like the Oz cars had later on...it would have been wider to match the front track.

Posted By: John_Kunkel

Re: A-body 73up disk swap, How much does track width change - 03/10/11 08:45 PM

Quote:

Track
73+ is 59.1
67-72 is 57.4

Wheel track is dependent on wheel width/offset.

From my own measurements the '73-'76 disc setup on a '62-'72 B body puts the wheel mounting surface 5/16" out on each side (5/8" wider total)

Posted By: G-Money1320

Re: A-body 73up disk swap, How much does track width change - 03/11/11 12:38 AM

On my 69 dart I run 15x6.5 rallye wheels on the rear with 245/60x15 tires and 14x7 rallye wheels on the front with 235/60 14 tires. I have the later 74/75A disc swap on my car with an 8 3/4 rearend. I dont notice the track difference and that is mostly due to the smaller rim/tire on front but it still looks good

By the way "milehigh" your Dart looks really good with those wheels on it

Posted By: 70HemiGTX

Re: A-body 73up disk swap, How much does track width change - 03/11/11 12:20 PM

I noticed it on my 68 Dart. I put a 73 set-up on the front with 15" x 3 1/2" Weld ProStars that were centered on the wheel spacing. My tires rubbed my fenderwell headers. I bought a set of 15" x either 5" or 6" ProStars with a deeper back space and have better clearance. They still rub, but not near as much. I can turn my steering wheel stop to stop now. Before I couldn't.