• Mustang Forums
  • 1965 - 1973 Classic Mustangs -General/Talk-
  • Classic Mustang Specific Tech

Flex-A-Form Composite leaf spring install problem

  • Thread starter Thread starter atomicpunk
  • Start date Start date Dec 18, 2005

atomicpunk

Member
May 15, 2005
80
0
6
Rocky Mountains
Dec 18, 2005
#1
  • Dec 18, 2005
  • #1
I finally got around to attempting the install on my Flex-A-Form composite leafs today, despite receiving them several months ago. Disassembly of the first side was a snap - surprisingly. I knew, of course, this meant I was doomed.



Top spring - stock, bottom spring - FaF. I'm attempting to use the Prothane heavy duty shackle kit from Mustang Depot. The gold bolts are from it, the brown one is the stock front.

As you can see, in the FaF, the stock front bolt fits in the rear and the new rear bolt fits in the front. I'd suspect the shackle kit was wrong, except that the stock spring is the opposite - the new shackle bolt fits in the rear, and the front bolt (obviously) fits in the front. The interior diameter of the rear is 1/2" and the front is 3/5".

Am I being retarded here, or did Flex-A-Form reverse the bushings? My first thought was I had the springs backwards, but looking at them, I don't see how that could be the case ?

FaF's limited instructions include 5 DONTs, one of which is "do not remove spring eye bushing"

Any other Flex-A-Form users have any problems?

I'm also hoping the shackle movement is enough to let me fit these springs on, they end up being a bit longer than stock ...

thanks!
 
M

mustangdave

My rearend needs a stud and two nuts.
Founding Member
Feb 26, 2002
2,976
1
56
North Carolina
Dec 18, 2005
#2
  • Dec 18, 2005
  • #2
Both ends of the FaF look the same so just turn it over.
 
1

10secgoal

Active Member
Dec 1, 2003
2,801
3
49
San Diego
Dec 18, 2005
#3
  • Dec 18, 2005
  • #3
You can't turn it over, but can you get it to fit with your old shackle kit ? Don't wuite understand the problem. The front hole is larger.
 

mdjay

Premium Sponsor
Dec 9, 2003
896
0
16
Las Vegas, NV
Dec 18, 2005
#4
  • Dec 18, 2005
  • #4
The Prothane shackles are made around the stock dimensions of the sleeve.

If the sleeve is to small on those FAF springs, either change the sleeve itself, or drill it out.

Also check the diameter of the front eye bolt. If it's smaller, just use the sleeves on the rear in the front!
 

atomicpunk

Member
May 15, 2005
80
0
6
Rocky Mountains
Dec 18, 2005
#5
  • Dec 18, 2005
  • #5
I ended up doing the obvious, despite being recommended against in the instructions - I popped the bushings out and swapped them, fits like a champ.

I'm not sure why they say don't do this, a quick google search found quite a few people removing the urethane bushings from the flex-a-forms and replacing them with aluminum bushings.

Of course, vacillating on this all day meant I only got one side done, so I can't get a test-drive impression yet. These things seem *very* firm - even laterally. My old springs were slopping around all over, so I can't wait to try them out.
 

Tubo(2-bo)

Member
Mar 25, 2004
279
0
16
Ft Walton Beach FL.
Dec 18, 2005
#6
  • Dec 18, 2005
  • #6
What's the difference in spring weight??
Interesting swap, looking foreward to more of your posts.
 

atomicpunk

Member
May 15, 2005
80
0
6
Rocky Mountains
Dec 18, 2005
#7
  • Dec 18, 2005
  • #7
I weighed them, knowing that question pops up a lot:

Stock C7 coded springs: 30 lbs

Flex-A-Forms: 8 lbs
 
G

gsxrken

Member
Sep 12, 2005
206
1
18
Weschester County, NY
Dec 18, 2005
#8
  • Dec 18, 2005
  • #8
Yes, PLEASE post your initial driving impressions when you have them. I would like one more testimonial before I pull the trigger on these. ANd what shock absorber you are using... did FAF recommend a particular shock? Some harsh stiction KYB's could erase your fiberglass benefits.
 
G

gsxrken

Member
Sep 12, 2005
206
1
18
Weschester County, NY
Dec 21, 2005
#9
  • Dec 21, 2005
  • #9
Any updates?
 

70vert

New Member
Dec 31, 2004
722
0
0
Bay Area, CA
Dec 21, 2005
#10
  • Dec 21, 2005
  • #10
(bump)

heh heh, I'm interested too. (bump)

I really want a Griggs rear, but I could live with this and a Watts Link and something to control axle wind-up on accel and decel.
 

atomicpunk

Member
May 15, 2005
80
0
6
Rocky Mountains
Dec 25, 2005
#11
  • Dec 25, 2005
  • #11
Sorry, I didn't get around to driving it until *yesterday* due to work/family scheduling - and even then, I wasn't able to take it for a very long spin.

It seems to me that the rear is more firmly located than before, and the whole car feels more stable/predictable. It also seems less like a truck going over bumps.

It's tough to do any performance driving with a driver's seat with a bent frame. I've got to get off my posterior and order some new seats. I'm also running stock wheels and seriously worn out tires, the other thing I need to take care of.

I *am* running new KYB Gas-A-Justs.
 

Tubo(2-bo)

Member
Mar 25, 2004
279
0
16
Ft Walton Beach FL.
Dec 26, 2005
#12
  • Dec 26, 2005
  • #12
Were these purchased direct from Flex-a-form , or if not who?? As long as I'm asking what is the price in them??
One of the things I've read over the years, concerning glass springs, is a Need(?) to encapsulate them with a sealing coat of some sort. Any information with this??
Thanks for posting, I've had a back burner interest in these for a long time. Its nice to see someone in real life using them.
 

atomicpunk

Member
May 15, 2005
80
0
6
Rocky Mountains
Dec 26, 2005
#13
  • Dec 26, 2005
  • #13
I purchased them directly, $400 shipped. I don't know anything about the requirement to seal them - they are covered in a thick black paint. You can see a few spots where the white material is peeking through in the picture.
 
You must log in or register to reply here.

Similar threads

6
Hey all,I’m putting together a 302 for my 1968 Mustang and wanted to post the combo + some questions to make sure I’m not missing crucial
  • 68_Disgustang
  • Feb 22, 2026
  • 1965 - 1973 Classic Mustangs -General/Talk-
Replies
3
Views
640
1965 - 1973 Classic Mustangs -General/Talk- Feb 28, 2026
Noobz347
New Products From J&M Products - 1979-1998 & 1999-2004 Race/Extreme Duty Rear Lower Control Arms
  • J&M Products
  • Oct 9, 2025
  • Vendor Sponsor Forums
Replies
0
Views
230
Vendor Sponsor Forums Oct 9, 2025
J&M Products
SN95 The Unicorn
  • HANO Motorsports
  • May 18, 2025
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • 2
Replies
21
Views
1K
1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- Aug 15, 2025
HANO Motorsports
For Sale Borg Warner WC T5, Stock Bell Housing, RAM Clutch Set, Double Hump Cross Member, & Pro 5.0 Shifter
  • AeroCoupe
  • Aug 9, 2025
  • Drivetrain Parts
Replies
1
Views
520
Drivetrain Parts Dec 26, 2025
AeroCoupe
3
Eight inches is enough for me...
  • 351MooseStang
  • Nov 27, 2025
  • 1974 - 1978 Mustang II Talk & Tech
Replies
5
Views
495
1974 - 1978 Mustang II Talk & Tech Mar 2, 2026
Bullitt347
Share:
Bluesky Email Share Link
  • Mustang Forums
  • 1965 - 1973 Classic Mustangs -General/Talk-
  • Classic Mustang Specific Tech
Menu
Log in

Register

  • Forums
  • What's new
  • Media
  • Resources
  • Contact
  • Sponsor
X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?

X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?