Old question, new day

[mjlan]

Keep in mind that as you cut coils the spring rate will increase. Probably not a deal breaker but should be pointed out.

Your 302 with I assume an aluminum intake manifold is a lot lighter than a 351C with an iron intake.

 

[70cobrascj]

Keep in mind that as you cut coils the spring rate will increase. Probably not a deal breaker but should be pointed out.

Your 302 with I assume an aluminum intake manifold is a lot lighter than a 351C with an iron intake.

Should order 302 with no A/C springs.

 

[Sheriff41]

I think @RIBS went through this in his build thread, also. See post #287 https://7173mustangs.com/threads/ribs-71-convertible-build-june-21-till.38365/page-15

 

[Steve McMahan]

Wow, 70cobrascj, that looks great. Mine looks like a drag race launch in progress

 

[Stanglover]

Just for the heck of it, I just measured the wheel arch center on my car, which is 14 1/2".
I know the springs are the originals from the paint daubs that were on them. The free height should be 15", mine were within 1/16" so did not get replaced when I redid the front suspension. My car is a 351C 4v with manual trans, no AC. The build sheet shows N-P whatever that means.
It does seem like there is a weight discrepancy causing your problem.
I'm wondering if your spring still have visible paint daubs on them. A gentle cleaning might reveal the paint marks.
Here's mine.

 

[Steve McMahan]

I painted them

 

[Stanglover]

I painted them

I expect most do not thinking about any markings. I probably got lucky with mine.
Oh well, onward and upward.

 

[mjlan]

I forgot to reiterate- somebody pointed out that if you added height above the spring (poly upper spring seat I think) the change in ride height will be greater than the thickness of what was added. This is due to what's called the 'motion ratio' which is ratio of the lengths of the lower control arm and where the spring is acting on that link. So if you added 1/2" above the spring and the spring is halfway along the LCA you've increased ride height by 1"...

 

[AcesArneson]

I agree Aces, but how do I communicate with them the ride height I want? I’m not clear what to tell them. I’ve got a stock OEM spring and the car is way too high. Here is the data I’m using to establish my correct ride height:

View attachment 84925
Either than 11.91 front bumper (mine is over 15”) or the idle arm lower bolt 10.4 (mine is over 14”) seems improbable with my stock spring and engine combo. And I have 15” tires, etc.

Also, I don’t have the wheels and tires I intend to get later. Should I do that first, then establish the height delta I need? And, I have no desire to cut the spring because I know from past experience you typically cut the wrong end, the end that gives you the moment articulation, to translate a smoother ride.

I’m wondering if I have the process out of order.

You could call them and let them what your ride height is, where you want it to go and what additional improvements you plan on making that could change ride height. I am not sure how long you have had your new springs in but they will eventually settle down a bit. It sounds like you have a mismatch somewhere, they shouldn't be out that much but if you got the small block springs. There are different springs the 351C and 302, I know there is a significant weight difference with the Cleveland being (from memory) about 130-150 lbs heavier. Also if your car had A/C and it was removed you have cut another significant weight that needs compensation. Cars with a 351C and A/C use the bigger springs, all other 351W's and lower use the small block springs and even have options for A/C, and non-A/C.

 

[AcesArneson]

So, to muddy the waters more, I’ve got a 5.0/AOD from an 87 TBird with AC. I know it’s lighter than the 351/FMX w/AC, but hard to see that differance equaling almost 3”. If you were me, and I’m aiming for 1” lower than stock would have been, what replacement spring would you buy from Eaton OR how much would you remove from these springs, assuming I cut from the saddle side?

Hey Steve, I would call Eaton and give them the info. They are the best at determining what you need and there will be no guessing involved as long as you know the weight of 5.0/AOD combo which you could get from a T-bird forum. The FMX is one heavy son-of-gun, especially with a 351 as original equipment. If I had to guess I would say you are at least 130 lbs lighter. Do you have a daughter or grand-daughter that could sit on the hood for you to check your ride height while it is loaded?

 

[Steve McMahan]

Thanks for the great suggestions. Yes, I did a Prothane (?) isolator above the stock spring. I measured the spring and its .630ish wire, which points to it being the 7N spring. I’ll know once I remove it to check free length. I’m going to try the cut the spring and see if I like the results, since I can order new ones if I don’t like it. Being FTR allows me the time to ponder, change it, ponder, and change it again.

Plus, I’m still on my salvage yard rollers; I’m still not sure if I should wait until I get the final rims and tires I want before surgery.

 

[RIBS]

I think @RIBS went through this in his build thread, also. See post #287 https://7173mustangs.com/threads/ribs-71-convertible-build-june-21-till.38365/page-15

Yeah mine was in the air forever…I cut one winding off. The ride is not harsh. 2 suggestions..make sure your front assembly is sort of loosely put together, especially LCA to frame mount . This allows some settling. Of course any driving should be careful and slow and short until everything is tight again. However, mine never settled. I double-checked with manufacturer, my car was 95% fully weighted. The only non stock config was new alum intake, and dual exhaust.
also, if you are bold, cut one winding off and reassemble. If you are timid, cut 1/2 the first time.

Also you can buy or rent from West Coast Cougar an excellent internal spring compressor that is safe and easy to use…it replaces the shock, and pulls the spring tight securely and straight.

 

[RIBS]

Here is the car in fully loaded road trip config with spare and a weekend of luggage and food…and a few beauty shots right after I completed the build. Keep in mind a full winding cut tucked my front a small amount, and was the look I was going for…

 

[Steve McMahan]

Nice job RIBS. I’ve got that spring compressor you’re talking about. Since it looks like a few days of rain here in Az Sunday to Tuesday, might be the time to be bold and cut.

Two weeks ago I had the front end alighted for the first time after the rebuild. I had the guy check every bolt to make sure it was right. So, while I don’t like the look now, I might chicken out. I’ve still got tons of small stuff to do. Thanks again for the pics and advice.

 

[AcesArneson]

Here is the car in fully loaded road trip config with spare and a weekend of luggage and food…and a few beauty shots right after I completed the build. Keep in mind a full winding cut tucked my front a small amount, and was the look I was going for…

Did you have to roll the lips on the inner fenders?

 

[RIBS]

Did you have to roll the lips on the inner fenders?

No rolled fenders. 235-15-60 on 7” rims up front, 245-60-15 on 8” rims in back, zero clearance issues. No rubs on full turns.