Opinion/Experience with Eaton Leaf Springs!? - Vintage Mustang Forums
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post #1 of 21 (permalink) Old 05-12-2019, 03:05 PM Thread Starter
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Thumbs Up Opinion/Experience with Eaton Leaf Springs!?

Greetings fellow Mustangers...

I've researched this quite a bit on this Forum. I've learned that Eaton is the way to go because of the 5160 steel. NPD Eaton is the most economical place to buy due to the mass shipping. I have visited Eaton's site for comparisons.

I'm curious how many of you who have these on their cars (particularly the 67-69 Coupes) and went with which spring rates? It seems to me the OE is 85 and the next step 114 are the most logical choices. How did those spring rates feel? Expect to very rarely have passengers in the back seat if that matters much.

Current state of springs is that the bushings are very cracked and noisey. If I get in the back seat (all 160 lbs) of me you can feel the drop. Contrast them with an all new front suspesion and they are feeling pretty soft. I do have descent shocks all around with a good return bounce.

L/R is sagging more than any other corner of the car.

Wondering if I go with stock height springs if best practice is to do the 1" raise to level it with the front via the slightly longer shackle, or get that 1" the expensive way by custom ordering via Eaton directly?

Current measurements (front springs seem mostly settled w/engine on them 4 months, driving for 2. About 200-300 miles.

215/60/15 Front @30 psi
225/60/15 Rear @30 psi

My car: 1968 Mustang C-code coupe but now with a 302 of about average 4bbl horsepower. Car does not have factory A/C but had compressor and the inside under mounted dash a/m type unit. Won't get another this year. Maybe next.
L/F - 26-5/8"
R/F - 26-3/4"
LR - 25-1/4"
RR - 26-1/4"

Oh yeah and the seller said the newly installed front springs were supposed to give it a little bit of drop, but it looks pretty average height to me.
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post #2 of 21 (permalink) Old 05-12-2019, 03:26 PM
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Would you be interested in a lightly used set of mid-eye five leaf springs that you could pick up?
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post #3 of 21 (permalink) Old 05-12-2019, 03:31 PM
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I have the 114lb. Eaton leafs on mine and they are fine. But here's the deal; I also have the larger 22gal. fuel tank and plans to load the thing with travel bags and my wife so I may discover an issue here soon with it sitting too low in back and rubbing something. If that happens I may bump to the 138lb. Eaton's and upgrade the shocks to the venerable Bilstein Street valved jobby-doos. I don't care for the idea of longer shackles myself.

'68 302 T5z Custom Conversion.
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post #4 of 21 (permalink) Old 05-12-2019, 07:55 PM Thread Starter
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Grabber, probably not as mid-eye are lowering springs and I am headed the other way. I want to be close to stock height to match with the front. But thanks!

Yeah I've been thinking I'm going to go with the 114 too. I'm still working on getting a wife to throw back there though I do have an original metal trunk top luggage rack in good condition. Normally don't like them but it's part of the car's unique character as you don't see any Coupes with those anymore.

What is this dislike of the extra 1" shackles? Is it looks or technical? At 1" Would you even know if you didn't get under the fuel tank area? I know it's known to put extra strain on the leafs by shifting things around, but I would think it would take more than a 1" lift. No? Such as those 70's trick cars where they jacked the cars way up.

Problem if I order the extra 1" built into the leaf is that there is no going back if it's sitting up too high Wish there was a way to shim these or put in variable seetings in the event that that one side is sitting too low vs the other side, or you want 1/2" 1/4" etc.
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post #5 of 21 (permalink) Old 05-12-2019, 08:50 PM
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Okay, let's see:

Quote:
Originally Posted by jsbenami View Post
I want to be close to stock height to match with the front.
The 114's by Eaton are the original GT spec and iirc they sit about 1/2" lower than the 85lb. base springs. Should be fine for what you want.

What is this dislike of the extra 1" shackles? Is it looks or technical? At 1" Would you even know if you didn't get under the fuel tank area? I know it's known to put extra strain on the leafs by shifting things around, but I would think it would take more than a 1" lift. No? Such as those 70's trick cars where they jacked the cars way up.
Old school cheap way out to stuff more rubber under there and they would necessarily make any car less stable/predictable in turns.

Problem if I order the extra 1" built into the leaf is that there is no going back if it's sitting up too high Wish there was a way to shim these or put in variable settings in the event that that one side is sitting too low vs the other side, or you want 1/2" 1/4" etc.
I believe you would find the GT spec 114's just about perfect. Mike Eaton himself strongly discourages shimming leafs. Something about altering some fulcrum point I gather. Still, people do it all the time and if kept to a minimum change...

'68 302 T5z Custom Conversion.
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post #6 of 21 (permalink) Old 05-12-2019, 10:42 PM
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I have Eaton springs on two of my cars, and highly recommend them. I would also 2nd 4ocious in that the GT spring is probably what you want based on your description. Additionally, NPD does a great job stocking them, however there are so many different spring rates etc. that I would highly recommend calling Eaton to ask for their part number for the exact application you are after. They are very helpful, then once you get their SKU number for the spring you want, just give it to NPD and they will cross it with their part number. That's what I did, and both companies made it dirt simple.
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post #7 of 21 (permalink) Old 05-12-2019, 11:00 PM Thread Starter
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So here's my order basically...did I miss anything? Yes I am going with 114 GT Spec. I'm still young enough I can get pretty squirrely...but old enough not to wreck or endanger others

They are out of stock on the Eaton Shackles and it's a fortune to order directly from Eaton. Hopefully the Scott Drake China plant still makes bolts and hardware the right way.

I'll definitely call NPD tomorrow since this is a FAT order....not sure if I need the 9/16" shackle bolts or the 1/2". I am not a concourse freak but I do sometimes like how some of them have the coatings that kept these puppers strong and clean. My 68 still has a bit of paint on it's original rear end and many of the bolt's aren't even really rusty very much. (California car till 2000).
Attached Images
File Type: jpg NPD Springd.jpg (126.3 KB, 14 views)
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post #8 of 21 (permalink) Old 05-12-2019, 11:01 PM
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The GT spring rate is good. The 85 lb. (stock) are probably also good, but a little looser/bouncier.

Whatever you do, don't go with the 138 lb.! I had a pair of those (from Eaton) and they were terribly jarring. Every time I went over a tiny speed bump it felt like someone had removed the rear suspension and replaced it with 2x4s. They're terrible. Probably good if you're doing autocross, but awful for normal use.
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post #9 of 21 (permalink) Old 05-13-2019, 12:13 AM Thread Starter
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Haha...yeah that doesn't sound fun driving around on 2x4's. Now I have the full range of experience on spring rates. I try not to go too far outside of the specs especially on chassis stuff.

Nice fastback! Great name. Maybe mine can be Spare Parts Patty since I took ownership with her in a gazillion pieces.
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post #10 of 21 (permalink) Old 05-13-2019, 06:29 AM
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Back in 2004 when I was restoring my 67 GT, I ordered directly from Eaton.
Each set of springs is selected for the exact config of your car, meaning body style, options so to help determine body weight.
It's been many years now, ~ 15 yrs and with 15" wheels car still sits nice. Happy.

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post #11 of 21 (permalink) Old 05-13-2019, 08:59 AM
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Quote:
Originally Posted by Kelly_H View Post
The GT spring rate is good. The 85 lb. (stock) are probably also good, but a little looser/bouncier.

Whatever you do, don't go with the 138 lb.! I had a pair of those (from Eaton) and they were terribly jarring. Every time I went over a tiny speed bump it felt like someone had removed the rear suspension and replaced it with 2x4s. They're terrible. Probably good if you're doing autocross, but awful for normal use.
Thanks for the feedback on them. Im in need of doing something with my springs. Either rebuilding my stock with a half leaf, the 114 pound or the mid eye 138. I was thinking the 138 pound would be too much.

Tom

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post #12 of 21 (permalink) Old 05-13-2019, 09:41 AM
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i went with the stock OEM setup from NPD

very happy with them

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post #13 of 21 (permalink) Old 05-13-2019, 01:25 PM
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for my 66 GT clone I went with mid eyes from a canadian mustang outfit but that was years ago- not sure if they were around?
Did not have any problems
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post #14 of 21 (permalink) Old 05-13-2019, 01:48 PM
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I went with the "GT" spring rates for both front and rear. It's been several years now, very happy with how the car rides/handles. I went with all the stock parameters (standard eye location, etc).


If you go with Eaton, see this thread for the rear. Apparently the little axle nub is too damn small, so you need to install a larger one. My originals broke trying to remove them so just buy new ones when you order the springs. Clamp the springs on each side before loosening/removing it, then just install the new one and tighten it down.

https://forums.vintage-mustang.com/vintage-mustang-forum/951257-1965-8-axle-rebuild-help-2.html



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Last edited by 65 Pony; 05-13-2019 at 01:51 PM.
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post #15 of 21 (permalink) Old 05-13-2019, 04:49 PM Thread Starter
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I spoke to two NPD guys who seemed very knowledgeable on Eatons one guy on this forum from NPD even says he knows the....never mentioned this. Never saw that part on the site.

What are these nub things called?

Also, don't the NPD Eaton springs come already bound together with their spring camps that you have in the photo? or are you referring to the u-bolt clamps.

Ok...Ok so I think I found what these things are. They are called centering bolts.

There are 3 types (of course) listed for all the years. I'm going to guess the biggest one is the one you had discrepancy with.

NPD:

#354712-SBK
#354712-SB
#354712-SA

Last edited by jsbenami; 05-13-2019 at 05:14 PM.
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