Higher rated stock spring

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71fordramair

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71 mach i 351c/4spd converted to 429. 71 mustang vert. 250 6,aod,3.0 ratio
71 vert with 302, new springs with 1 1/4 coil cut off. Need more spring rate to prevent bottoming, 351 or 429 spings, which one for street car?
 
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1 1/4 cut is a lot. Contact Eaton Detroit spring and tell them what you want to achieve and they will get you what you need. Chuck
 

Hemikiller

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Yes, that's a huge amount to remove from a spring.

I used Moog 8534 on the front of my 71, which is the 351C non-AC competition suspension spring rated at 428 lbs/in. It sat a bit high with the 302 (alum intake & water pump, headers, small radiator), but it just right now with the 351C. The issue is that they're discontinued now, due to more part number consolidation by the mfr. However, NPD carries them under the McQuay Norris brand.


This is with the 302, the 351C closed up the gap at the front wheel arch.

1664201369151.png
 

71fordramair

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71 mach i 351c/4spd converted to 429. 71 mustang vert. 250 6,aod,3.0 ratio
From spindle to top of flair I am 12 inches in the front and 13 1/2 inches in the rear. This measurement rules out tire size.
 

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71fordramair

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71 mach i 351c/4spd converted to 429. 71 mustang vert. 250 6,aod,3.0 ratio
Yes, that's a huge amount to remove from a spring.

I used Moog 8534 on the front of my 71, which is the 351C non-AC competition suspension spring rated at 428 lbs/in. It sat a bit high with the 302 (alum intake & water pump, headers, small radiator), but it just right now with the 351C. The issue is that they're discontinued now, due to more part number consolidation by the mfr. However, NPD carries them under the McQuay Norris brand.


This is with the 302, the 351C closed up the gap at the front wheel arch.

View attachment 67857
Thanks for that part number, I’ll order soon. Would you have a spindle to flair measurement so I know if I have to cut them. Thanks
 
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You can buy 1" lowering springs from Eaton. Eaton will give you springs made in the US with US spring steel. Moog could be made anywhere these days with no knowing what grade steel was used. However, if Moog publish where their springs are made and the grade of spring steel, then check them out by all means. The type and grade of steel is very important, and a fact lost on many. Price isn't everything.
EDIT, I just looked at Hemikiller's post and the NPD link. I didn't see where it states a manufacturer. Who the heck is McQuay Norris anyway?
 
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71fordramair

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71 mach i 351c/4spd converted to 429. 71 mustang vert. 250 6,aod,3.0 ratio
You can buy 1" lowering springs from Eaton. Eaton will give you springs made in the US with US spring steel. Moog could be made anywhere these days with no knowing what grade steel was used. However, if Moog publish where their springs are made and the grade of spring steel, then check them out by all means. The type and grade of steel is very important, and a fact lost on many. Price isn't everything.
EDIT, I just looked at Hemikiller's post and the NPD link. I didn't see where it states a manufacturer. Who the heck is McQuay Norris anyway?
McKay Noris they put their name on auto parts, I use some rod & main bearings in my Cleveland and they didn’t hold up very long under 12.8 to 1 compression!
 

Hemikiller

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My front spindle center to underside of the wheel arch is 14"

In the modern sense, McQuay Norris is a mostly a brand, much like TRW. They sold everything from suspension and steering parts, to internal engine components. They've been owned by Eaton/Dana Corp, Federal Mogul, and currently Mann & Hummel - maker of the Wix filter. I've used plenty of their products in the past without issue, and have never found fault with their quality. My 71 has some suspension parts from them, and other vehicles I've owned did as well. The main bearings in my 351C were NOS McQuay Norris, which were actually made by "DAB" - Detroit Automotive Bearing - an OE Ford supplier.
 
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McKay Noris they put their name on auto parts, I use some rod & main bearings in my Cleveland and they didn’t hold up very long under 12.8 to 1 compression!
Hmm, sounds like junk made in.................
But then reading Hemikiller's reply, maybe not all that bad after all. I have just not heard that name before.
 

71fordramair

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71 mach i 351c/4spd converted to 429. 71 mustang vert. 250 6,aod,3.0 ratio
My front spindle center to underside of the wheel arch is 14"

In the modern sense, McQuay Norris is a mostly a brand, much like TRW. They sold everything from suspension and steering parts, to internal engine components. They've been owned by Eaton/Dana Corp, Federal Mogul, and currently Mann & Hummel - maker of the Wix filter. I've used plenty of their products in the past without issue, and have never found fault with their quality. My 71 has some suspension parts from them, and other vehicles I've owned did as well. The main bearings in my 351C were NOS McQuay Norris, which were actually made by "DAB" - Detroit Automotive Bearing - an OE Ford supplier.
Thanks for your spindle to flare measurement. Would a 1” lowering spring have a progressive rate you think? I guess if I get the nod springs I’ll measure down 1” and make a cut should be close for 1st try
 

71fordramair

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71 mach i 351c/4spd converted to 429. 71 mustang vert. 250 6,aod,3.0 ratio
Thanks for your spindle to flare measurement. Would a 1” lowering spring have a progressive rate you think? I guess if I get the nod springs I’ll measure down 1” and make a cut should be close for 1st try
NPD
 

JPWally

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To continue on this topic, I would like to reach out to members to kindly ask if they could measure the approximate distance between the upper A-arm and the bumper stop on their cars(stock or modified). I have also trimmed a bit off my aftermarket coil springs and now I am wondering if I have proper suspension travel. I failed to measure this distance before I made the modification and I am simply using a 5 foot lever on the rocker panel to help me with the stance adjustment. My car is a 1973 with the 351C/C6/AC. Thank you in advance!
 

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Hemikiller

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Thanks for your spindle to flare measurement. Would a 1” lowering spring have a progressive rate you think? I guess if I get the npd springs I’ll measure down 1” and make a cut should be close for 1st try

Factory springs are fixed rate, and trimming the spring will increase the rate. Trimming 1" off the free length does not equal a 1" drop in ride height. Eaton Spring has a good article on the matter, and the formulae to get you there.

 

71fordramair

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71 mach i 351c/4spd converted to 429. 71 mustang vert. 250 6,aod,3.0 ratio
Factory springs are fixed rate, and trimming the spring will increase the rate. Trimming 1" off the free length does not equal a 1" drop in ride height. Eaton Spring has a good article on the matter, and the formulae to get you there.

Whenever I wanted to lower the car a certain amount I would just measured down that far on the spring overall length with the tape measure and cut. usually on the money. After taking one and a half coils out the front end bottoms out and is really springy, even with stiff shocks. It feels as if I have lowered the rate.
 
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