What is the Correct Ford OEM size for both front and rear sway bars - 1971 Mustang

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Flywheel

Flywheel

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1971 Mustang Mach 1
I have found a whole bunch of differing information on the internet regarding the actual correct OEM factory size for both front and rear sway bars on a 1971 Mustang. So I thought I would reach out to our forum on this.

I have a 1971 Mustang Fastback that I acquired a few year ago. It has the original 302 engine, and runs great. Despite it having the original 302, I have restored, renovated and painted it to look every bit like a Mach 1. I am now in the process of updating the suspension so it will handle better. ( so it will handle like the 1971 Mustang Fastback - with competition suspension that I bought new in 1971, and drove solidly for 8 years until starting a family ). My current car has a 3/4 inch front sway bar ( that looks original ), with no sway bar in the rear. It's got new shocks, and new rear leaf springs ( From Detroit Eaton ). Original front Springs. I have regular rear shock mounts ( not staggered ).

I'd like to change out the front sway bar, and also add a rear sway bar. Anyone out know the Actual Correct Factory Sway Bar specs?
ps - A Slight chance I may upgrade the engine in the future ( 352 Clev )
 
7/8" front bar came on the 4V cars. Everything else got the 3/4" front bar.

Rear bar was 1/2" on M & Q code, 5/8" on 71 429 & 71/ 72 R-code 351s

I'm running a factory 7/8" front bar with urethane frame bushings and end links, with no rear bar. Pretty happy with how it handles.
 
Flywheel said:
I have found a whole bunch of differing information on the internet regarding the actual correct OEM factory size for both front and rear sway bars on a 1971 Mustang. So I thought I would reach out to our forum on this.

I have a 1971 Mustang Fastback that I acquired a few year ago. It has the original 302 engine, and runs great. Despite it having the original 302, I have restored, renovated and painted it to look every bit like a Mach 1. I am now in the process of updating the suspension so it will handle better. ( so it will handle like the 1971 Mustang Fastback - with competition suspension that I bought new in 1971, and drove solidly for 8 years until starting a family ). My current car has a 3/4 inch front sway bar ( that looks original ), with no sway bar in the rear. It's got new shocks, and new rear leaf springs ( From Detroit Eaton ). Original front Springs. I have regular rear shock mounts ( not staggered ).

I'd like to change out the front sway bar, and also add a rear sway bar. Anyone out know the Actual Correct Factory Sway Bar specs?
ps - A Slight chance I may upgrade the engine in the future ( 352 Clev )
Click to expand...
Here are all the sway bars for 1971 for each body style and option.1971 Mustang front and rear sway bars.jpg
 
Addco make good sway bars and can be bought from NPD etc. As your car did NOT have a rear bar, you'll need the one that clamps to the springs. NPD do not show Addco part numbers, but you can choose either a 1" front matched with a 3/4" rear or if you want to go firmer, a 1 1/18" front with a 7/8" rear.
For better information, go to ADDCO's website. I found them very helpful.
 
I guess it is now time for me to get off my dead tail feathers and measure the diameter of the sway bars on our two 73 Mustangs just to see if there is something else to upgrade. heh heh... Not that I am racing around or anything, those days are long gone by. I just need more projects for these cars so I have something to do in my retirement years.
 
I always thought you should have a little under steer going into a turn and could use torque to transition to neutral or oversteer handling.
I achieved this with the 7/8” front & 1/2” rear on my 71. My 13 MCA did this out of the box.
 
Thanks everyone for the helpful and accurate information.
Based on your input, and other research, I'm thinking of going with a good quality 7/8 inch front and a 1/2 inch rear swaybar, although am not sure how to mount the rear bar.

Although there was no rear swaybar on it when I got it 3 years ago, there is a set of 4 holes on each side of the rear frame rail.
Plus a different set of 2 larger holes on both sides close to the rear of the leaf spring. Attached are some pics.

Do these look familiar to anyone as mounting holes for a rear swaybar? Attached are some pics.
Thanks in advance.
 

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The rear hole is about 23 1/2" from the end of the rear frame rail. I used an old ADDCO square "U" bolt and reinforcement plate in the 2 existing frame rail holes. I also used stock rubber bushings and Prothane end links. The spring plate bracket was from NPD. See the attached pix.
 

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351c1971 said:
The rear hole is about 23 1/2" from the end of the rear frame rail. I used an old ADDCO square "U" bolt and reinforcement plate in the 2 existing frame rail holes. I also used stock rubber bushings and Prothane end links. The spring plate bracket was from NPD. See the attached pix.
Click to expand...
Very good.
Thanks for the information, and also taking the time to take and post the pictures.
 
351c1971 said:
My H code Mach 1 had the holes in the frame rails for the OEM rear sway bar. Some fabrication was required to mount the 1/2” OEM bar.
Click to expand...
Hi,

Reference the Rear Sway Bar. Attached are 2 pics I took of identical holes that are on each side of my rear frame rail of my 71 Sportsroof. Are these the same holes that you used to mount the rubber bushing bracket for your Rear Sway Bar? Also, can you please advise what type of fabriction you had to do in order to mount your rear sway bar? My car did not come with a rear sway bar, only a front one. I'm considering getting an ADDCO rear swaybar from Nat Parts Depot, but am not certain its the best product out there.
Appreciate any help, thanks,
Tom
 

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From a manufacturing aspect, the holes will be pierced in all the frame rails regardless of final use, but the question is, did they install the weld- nuts as well? On a production line, it would make sense to install weld-nuts in all the rails, but back then, did Ford do that? Logic was not one of Ford's strong points.
 
I prefer the OEM bar, but you will have to cobble up the bushing mounting hardware. I believe the ADDCO kit comes with all needed brackets.

In any case, be sure to mount the rear bar before you do any intended exhaust modifications. It is VERY busy back there.
 
Stanglover said:
From a manufacturing aspect, the holes will be pierced in all the frame rails regardless of final use, but the question is, did they install the weld- nuts as well? On a production line, it would make sense to install weld-nuts in all the rails, but back then, did Ford do that? Logic was not one of Ford's strong points.
Click to expand...
Ford used lag screws (with 1/2' hex heads) to fasten the bushing retainer to the frame. The factory-style ADDCO rear bar uses the same mounting holes in the frame as the factory bar.
 
Last edited:
Flywheel said:
Hi,

Reference the Rear Sway Bar. Attached are 2 pics I took of identical holes that are on each side of my rear frame rail of my 71 Sportsroof. Are these the same holes that you used to mount the rubber bushing bracket for your Rear Sway Bar? Also, can you please advise what type of fabriction you had to do in order to mount your rear sway bar? My car did not come with a rear sway bar, only a front one. I'm considering getting an ADDCO rear swaybar from Nat Parts Depot, but am not certain its the best product out there.
Appreciate any help, thanks,
Tom
Click to expand...
I sent Addco my original rear sway bar from my 72 Q code Mach 1 and they remade them. It’s not perfect, but it fits much better than their first version. With the larger bars on front and rear my car handles much better than the factory ones.
 
jpaz said:
I sent Addco my original rear sway bar from my 72 Q code Mach 1 and they remade them. It’s not perfect, but it fits much better than their first version. With the larger bars on front and rear my car handles much better than the factory ones.
Click to expand...
Sure does. But then we have staggered shocks that the new revised bar is meant for. I don't know about the fit for bars that clamp to the springs on non-staggered shock cars. That's something I've not even seen.
 
Sheriff41 said:
Ford used lag screws (with 1/2' hex heads) to fasten the bushing retainer to the frame. The factory-style ADDCO rear bar uses the same mounting holes in the frame as the factory bar.
Click to expand...
Yes, I'm referring to the nuts inside the rails. Come to think of it, they would be "capture nuts" not weld-nuts (that are spot welded in place. Capture nuts are able to 'float')
 

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