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Half leaf on rear springs?
#11
Stanglover,

I may be late to the party here. I have always stressed on this forum to always replace your springs with the factory rated spring rates. This due to the design of the leaf springs is to hold the vehicle up.Sway bars prevent body roll. We all should know this.

[Image: 1971_Springs.jpg]

What Is Rate, Load, and Load Rate?

These are terms that apply to all types of springs: leaf, coil, air, torsion – and they’re commonly misunderstood.

Spring Rate is the amount of weight required to deflect a springs an inch. The lower the rate, the softer the spring.

Load is simply the amount of weight on the spring.

Load Rate is the amount of weight a spring is designed to support at a certain height.

Too many people confuse spring rate and load rate. So a great way to impress your friends is to drop the correct usage in casual conversation.
Source: Detroit Eaton Springs

According to Eaton Detroit Spring, your rate should be 138 Lbs. Do you know what the rate is for the Grabber-Trak springs you picked up on Friday?

Shocks-
The purpose of shock absorbers is to control the release of the springs’ kinetic energy. Or – stated more simply – shocks stop the springs from continuously bouncing up and down.

Take a look at this Tech Guide.

How To Install Underride Traction Bars On Your Vintage Ford Mustang

http://www.mustangandfords.com/how-to/ch...tion-bars/

mustang7173
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#12
Mustang7173, Thanks for your information, much appreciated. I do have the Eaton Detroit Springs listing for the 71 Mach 1.
I'm in process of installing the Grab-A-Trak springs, one almost done, one to go. I'm NOT using the shackles provided as they are half the thickness of the originals, which are still in perfect condition, save for a coat of paint and a need for the new rubbers, so I'm refinishing the plates and shackles before bolting it all up. They will alter the ride height somewhat which is to be expected as the old one will have settled over the years. As for the rate, that is not listed for the Grab-A-Trak's, but they are the only 4.5 leaf listed with standard eye location. Total Control Products list at 180lbs for the 4.5 leaf, but they only have mid-eye or reversed eye, not what I want at all. I believe Grab-A-Trak are Scott Drake, so likely made in Taiwan as most of his stuff is........... shame!!!
My plan is to have the original springs rebuilt at some point and they can always be put back in if this plan does not work as hoped. I don't want any sort of traction bars, but if it means not breaking something, I may have to rethink it later.
I'll post later when I get both side done and tested. For now this is the path I'm on.
Geoff.
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#13
Stanglover,

Sounds good. Look forward to the updated post!

mustang7173
  Reply
#14
So today I got the new 4.5 leaf rear springs in with the help of my neighbor buddy. I decided to reuse the shackles after a clean-up and paint job. These are 1/4" thick steel whereas the Scott Drake ones are half that thickness. I did use the new rubbers of course. I was a little concerned as the locate pins on the new springs looked like they were going to miss the hole in the axle plates, but after checking the measurements, it was obvious the old spring were so sagged out that the axle was actually back about a 1/2". A shove with the boot was all it needed to get them in place. (I'm working on Jack Stands guys, not a hoist!)
Once done and checked, I took it out for a test drive. At this point, I honestly don't know what the spring rate is for these Grab-A-Trak springs, but the ride was awesome compared to before. No more thumping and bumping going over rough roads and the handling seemed pretty damn good too. No wheel hop that I noticed....... Yet!
Downside is the ride height is up about 1.5" and now I literally can't see anything out of the back window on the Mach 1. I'm sure the new springs will settle a bit over time, but I might look at using lowering blocks for the time being. Mid eye springs would have been perfect right now, but given time, they would have settled too low for my taste. Besides, it's hard enough for this "Old Fart" to get in and out now with it at stock height.
Next will be some hard driving to find out if it was really worth the hassle and expense, but as I said, a less bumpy ride is a good thing for sure.
Geoff.
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#15
Which shocks are you using?  I've found the cheap Monroe and Gabriel gas charged units only last about 1-2 years depending on use.  The fronts wear faster than the rears. I really like the plain KYB shocks as they have lasted about 4-5 years now and going  strong.  I've run the Gas-A-Just's before but find them too firm. Especially in cold weather.  I don't care what the advertising says, they are notably firmer when cold and don't adjust for nothing.

Mike
__________________________________
Black 1985 GT
Yellow 1973 Mustang Mach 1
Black 2012 5.0 GT, 6-speed, Brembo brakes, 3.73's
Wimbledon White 1966 F-100 Shortbed Styleside, 390ci, Tremec 3550, FiTech EFI
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#16
(07-18-2017, 07:23 PM)MeZapU Wrote: Which shocks are you using?  I've found the cheap Monroe and Gabriel gas charged units only last about 1-2 years depending on use.  The fronts wear faster than the rears. I really like the plain KYB shocks as they have lasted about 4-5 years now and going  strong.  I've run the Gas-A-Just's before but find them too firm. Especially in cold weather.  I don't care what the advertising says, they are notably firmer when cold and don't adjust for nothing.

 I forgot to mention that. I am using KYB Gas-A-Just front and back. I put these in last year when I did my front end rebuild. I put in 1 1/8" front anti-sway bar with a 1" in the back. Those shocks are firm for sure and I don't notice any 'adjusting' going on, but I don't run when cold either if I can avoid it. I think I could have used a 7/8" bar in the back as the 1" is a bit stiff. That said, I can get around corners quite well without scaring the sh*t out of me.
Thanks for asking.
Geoff.
  Reply
#17
(07-19-2017, 07:50 AM)Stanglover Wrote:
(07-18-2017, 07:23 PM)MeZapU Wrote: Which shocks are you using?  I've found the cheap Monroe and Gabriel gas charged units only last about 1-2 years depending on use.  The fronts wear faster than the rears. I really like the plain KYB shocks as they have lasted about 4-5 years now and going  strong.  I've run the Gas-A-Just's before but find them too firm. Especially in cold weather.  I don't care what the advertising says, they are notably firmer when cold and don't adjust for nothing.

 I forgot to mention that. I am using KYB Gas-A-Just front and back. I put these in last year when I did my front end rebuild. I put in 1 1/8" front anti-sway bar with a 1" in the back. Those shocks are firm for sure and I don't notice any 'adjusting' going on, but I don't run when cold either if I can avoid it. I think I could have used a 7/8" bar in the back as the 1" is a bit stiff. That said, I can get around corners quite well without scaring the sh*t out of me.
Thanks for asking.
Geoff.
I am curious if you have an update regarding how the car drives with the 4.5" rear springs. Has the ride height settled? Can you tell me the current ride height from the ground to the rear bottom of the rocker? Also, let me know your tire size. Thank you.

        [Image: 20160929_171923_edit2_small.jpg]

1971 M-Code Mach 1 w/Ram Air, 408 stroker, 285/291 0.558" roller cam, Blue Thunder intake, TKO600, Hooker headers with electric cut-offs, FiTech EFI w/ RobBMC PowerSurge pump
4-wheel disc brakes
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#18
(11-26-2018, 11:58 AM)tony-muscle Wrote:
(07-19-2017, 07:50 AM)Stanglover Wrote:
(07-18-2017, 07:23 PM)MeZapU Wrote: Which shocks are you using?  I've found the cheap Monroe and Gabriel gas charged units only last about 1-2 years depending on use.  The fronts wear faster than the rears. I really like the plain KYB shocks as they have lasted about 4-5 years now and going  strong.  I've run the Gas-A-Just's before but find them too firm. Especially in cold weather.  I don't care what the advertising says, they are notably firmer when cold and don't adjust for nothing.

 I forgot to mention that. I am using KYB Gas-A-Just front and back. I put these in last year when I did my front end rebuild. I put in 1 1/8" front anti-sway bar with a 1" in the back. Those shocks are firm for sure and I don't notice any 'adjusting' going on, but I don't run when cold either if I can avoid it. I think I could have used a 7/8" bar in the back as the 1" is a bit stiff. That said, I can get around corners quite well without scaring the sh*t out of me.
Thanks for asking.
Geoff.
I am curious if you have an update regarding how the car drives with the 4.5" rear springs. Has the ride height settled? Can you tell me the current ride height from the ground to the rear bottom of the rocker? Also, let me know your tire size. Thank you.
 Tony, further to the PM, I'll put this on here as well.
 The ride height has settled a bit, maybe 1/2". From ground to center wheel arch is 26 3/16", tires are worn 245-60-R14's, New tires next spring will put it up a bit, but then it'll be the same at the front. I do have 1" lowering blocks in with no ill effects to handling. Also I have a 1" anti-sway bar. If I were to do it again, I'd probably go for Eaton Springs ones.
Pretty much everything else is within the thread.
Geoff.

I learn something new every day!
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