Advice on rear Leaf Spring / 71 351C 4V

[EdM]

I went with Shaun's 4 1/2 leaf mid-eyes and his coil over system up front and could not be more pleased.

 

[Stanglover]

I went with Shaun's 4 1/2 leaf mid-eyes and his coil over system up front and could not be more pleased.

  Interesting. Nice shop/garage by the way. Thanks for sharing.

Geoff

 

[Mjordan]

I went with Shaun's 4 1/2 leaf mid-eyes and his coil over system up front and could not be more pleased.

I’m planning for the same leafs, coils, and bilsteins all around. Hoping to eventually get his full setup later on. How’s the ride with them?

 

[Rmach1]

That’s a good looking car Geoff!!

Rmach1

 

[Stanglover]

That’s a good looking car Geoff!!

Rmach1

 The one pictured from EdM is very similar to mine, except mine is not a ram air car. Thanks anyway. Here's a pic of mine.

 Geoff.

 

[Stanglover]

Well guys, time to eat crow!! I have not looked at or even thought about the rear springs since I last posted on why it "appeared" that the axle was out of alignment by nearly 1/8th inch on the right side.

Today, I started to think about what I want to do so as to be ready for Spring and get the axle repainted and back in the car. I have a box full of the spring plates and brake bits. 

EDIT NOTE: I'm rewriting this as dumb-ass here realized I was not putting the spring plate on the correct side of the spring in the pictures. The top side is where the axle plate goes and the hole in it is 9/16" diam. That means that the max amount of inaccuracy would be 1/32". Not much but still to be considered imo.

My apologies to those who already read this screwed up post and wondered " WTF".

At least I did prove that the spring locate pins were not out of position relative to the bushing end eye, BUT the bushings themselves were out relative to the eye by as much as 1/16th inch. However, now I know I screwed up, none of that matters.

I can get the springs re-arced, the guy at the spring shop says he does it all the time. Also I may be able to get better bushings put in to reduce that error, so the GAT's will be ok. Now I also have a Traction-Loc in the diff. spring wrap-up should not be as much of an issue (I hope).

When it's all back together, I will need to take the car in for a 4 wheel alignment. Knowing what I know now, I should be able to center the axle on the mounts pretty damn close before hand. 

I removed the pic as irrelevant now.

 

[Stanglover]

Today I got my springs back from the spring shop after having them de-arched. Unfortunately they went a bit too far with them. I wanted 1-1 1/4" knocked out of them, but ended up at 1 3/4". I guess the guy got a bit carried away with the 100 ton press! At least I can adjust the ride height with longer shackles if need be. I know also that they will be somewhat stiffer now, but I think that was a trade off I knew about. Right now under the current situation, buying new replacements is not an option. Not only with this virus thing, but the Canadian dollar just dropped about 10 cents making anything I buy in the US almost double the US price.

In today's "one minute video" from Eaton Springs, they go into the importance of correct torque force on the U Bolt nuts. I thought I'd post it.

 

[MKSpeedlab]

Just figured I would ask here since there has been a lot of discussion around leafs here. I was looking at replacing the leafs in my 72 along with shocks since one shock is toast and the springs are probably due. I had considered the Dayton springs Rockauto lists(PN:42331) that say they are the improved handling 4 leaf. 1-1/8" pack thickness, 138lb/in, and 650lb load. Has anyone tried these and are they any good, or is there something else I should be looking at. Im also up in Canada so just want to find something good but isnt going to murder me with the exchange rate. 

 

[Stanglover]

Just figured I would ask here since there has been a lot of discussion around leafs here. I was looking at replacing the leafs in my 72 along with shocks since one shock is toast and the springs are probably due. I had considered the Dayton springs Rockauto lists(PN:42331) that say they are the improved handling 4 leaf. 1-1/8" pack thickness, 138lb/in, and 650lb load. Has anyone tried these and are they any good, or is there something else I should be looking at. Im also up in Canada so just want to find something good but isnt going to murder me with the exchange rate. 

With this Covid 19 crap still going strong in the US and the border still closed (thankfully) I would definitely look toward Eaton Detroit Springs springs, but unfortunately I can't go over to Detroit to pick up a pair. I am planning on replacing those crappy Scott Drake Grab-a-track springs I had de-arched for Eaton 4 leaf 153lb.  BOSS springs. The reason is the g.a.t's have started to bend in reverse. I can get them through this year as I'm not driving as much, no shows etc, but I will need to replace then next year for sure. Most aftermarket one I found are listed as US made from 5160 steel, but are in fact Scott Drake and I'm NOT very impressed with the quality of their products. I have not checked out those Dayton springs, but I will as yes, the US dollar and shipping are killing us right now. I'll get back to you on this soon.

Geoff.

 

[MKSpeedlab]

Sounds good and thanks. I will also look into the eaton springs and see what I would be looking at. Just trying to find good options before I make a decision, and the Dayton ones seem like a good price and shipping isnt completely horrible. 

 

[Hemikiller]

I haven't used this company, but I have used this part# spring, it's what's in my car now, bought them from Mustangs Unlimited about 6 years ago. Back before all the tech info in catalogs disappeared, these were the 429CJ replacement spring. 

https://www.generalspringkc.com/product_p/42-547.htm

 

[Stanglover]

I haven't used this company, but I have used this part# spring, it's what's in my car now, bought them from Mustangs Unlimited about 6 years ago. Back before all the tech info in catalogs disappeared, these were the 429CJ replacement spring. 

https://www.generalspringkc.com/product_p/42-547.htm

Definitely worth checking out the General Springs website. However, my feeling is they are a bit on the soft side @135lbs spring rate.

 

[MKSpeedlab]

Talked with the guys at Eaton Detroit springs, but with the exchange rate they are out of my budget without even worrying about shipping. Although it did sound good since they mentioned being able to do the upgraded 153lbs at stock ride height which is what I want. I miss when the dollar was almost on par, that was a good time to be buying car parts. 

 

[Stanglover]

I agree, the friggin exchange rate is raping us. Shipping isn't any better. I was doing a bit of research into Dayton springs. They go under www.Daytonparts.com. I read up on their history and like many companies, have gone through many hands. They seem to specialize in truck springs, but as the springs we need are listed on RockAuto, they make car springs too. I could not find any specifics other than what is listed on R/A. There are several spring manufactures throughout the US, but I'd love to know who actually makes the springs that Scott Drake brand. I'm sure with the complexity of spring making, S/D don't make their own. If I knew that, I would avoid that company, but that's just my opinion.

The General Springs website is worth checking out and ask questions on who, what and where, i.e. do they make them or just market springs. I have not yet been looking to them myself or really studied the website. Something for the to-do list.

For me, Eaton is basically local. If the border were fully open, I could just drive over and pick them up, but that ain't happening any time soon. I wait!

 

[MKSpeedlab]

Well I checked with a local spring shop, and it sounds like they carry the dayton springs as well, and the price would be better with not having to deal with shipping, plus they have 2 in stock. Im heavily leaning towards the dayton springs for price and them being local. With exchange the eatons are similar price, but the shipping is basically the price of a 3rd spring. So I think I will end up getting them, and see how they do. 

 

[Stanglover]

Well I checked with a local spring shop, and it sounds like they carry the dayton springs as well, and the price would be better with not having to deal with shipping, plus they have 2 in stock. Im heavily leaning towards the dayton springs for price and them being local. With exchange the eatons are similar price, but the shipping is basically the price of a 3rd spring. So I think I will end up getting them, and see how they do. 

Sounds like a plan, man! Yes, shipping on heavy stuff is a killer. I take it you're getting the  "improved handling" 1 1/8 pack height @ 138 lbs? That would equal the stock Mach 1 spring. Check the free arch is the same or slightly higher to you existing springs. I think it should be around 5"-5.5". Any more and the ass end will sit too high for my liking.  For shocks, I went with KYB Gas-A-Just  and find them quite okay. IF your car has stagger shocks i.e. competition suspension, another big improvement I did was to add a 1" anti-sway bar. I went with the Addco, BUT a member, jpaz, has been in contact with them because the frame width mount area is incorrect. Addco are looking a changing that, but no word yet. Just don't knowingly buy S/D sway bars. Hope this helps, let me/us know how it goes, good luck,

 

[MKSpeedlab]

Ya Ill be getting the "improved handling" springs that they have. From the local shop they are a decent price, and they have all the bits for them. They also mentioned that Dayton actually makes the springs for a bunch of OEM's and also some aftermarket companies who just rebrand them. I ordered a set of the GT shackles as well since they are supposed to be nice for installation. The guys at Eaton spring said to avoid the KYB's, but I had been looking at them, or trying to decide if I break the bank a little and just go with the non-adjustable QA1's. I would definately like to upgrade both the front and rear sway bars, but I think that will have to wait a little bit for the bank account to recover. And by staggered shocks do you mean one in front of the axle and one behind? If so then ya thats what my 72 has. Im excited to get the rear suspension fixed back up and to see how it will ride with it. 

 

[Stanglover]

Ya Ill be getting the "improved handling" springs that they have. From the local shop they are a decent price, and they have all the bits for them. They also mentioned that Dayton actually makes the springs for a bunch of OEM's and also some aftermarket companies who just rebrand them. I ordered a set of the GT shackles as well since they are supposed to be nice for installation. The guys at Eaton spring said to avoid the KYB's, but I had been looking at them, or trying to decide if I break the bank a little and just go with the non-adjustable QA1's. I would definately like to upgrade both the front and rear sway bars, but I think that will have to wait a little bit for the bank account to recover. And by staggered shocks do you mean one in front of the axle and one behind? If so then ya thats what my 72 has. Im excited to get the rear suspension fixed back up and to see how it will ride with it. 

It seems you have a good source locally. I think you'll be ok with those, but time will tell. As for Eaton  saying NOT to use KYB's,  I don't know why. I have no issues with mine, but also right now, I am not using Eaton springs, so I'll look into that later.

So, just curious. I don't recall if you fully described your car or put up a pic. If you have staggered shocks, then I presume it is a Mach 1, "Q" code or "H" code, (4V or 2V), what's your first 5 digits of your VIN?

Here's a pic of my mustang rear end ( I had to be careful there!) This is on  a 71 Mach 1, M code 4V, 4 speed. If there is anything you are unfamiliar with about your car, just ask and someone will be happy to clarify.

 

[MKSpeedlab]

Ya mine is a 72 Mach 1 Q code, I put my Marti report up and you can see more info on the car in my build thread. I only wish my exhaust had been run as nicely as yours when the shop did it 15 years ago. The drivers side pipe came down too soon and has been banging on the shock, so Im actually heading to the exhaust shop right away to pick it up since I got them to fix the pipe to give proper clearance for the shock. So you like how it handles and everything with the KYB's? Do you have the Gas-a-just's? Those are what I had initially been thinking, and if they are a handling improvement then I will likely get them. Dont mind the surface rust, as I have been working on the different projects underneath I have been cleaning it up lol.

 

[Stanglover]

Ya mine is a 72 Mach 1 Q code, I put my Marti report up and you can see more info on the car in my build thread. I only wish my exhaust had been run as nicely as yours when the shop did it 15 years ago. The drivers side pipe came down too soon and has been banging on the shock, so Im actually heading to the exhaust shop right away to pick it up since I got them to fix the pipe to give proper clearance for the shock. So you like how it handles and everything with the KYB's? Do you have the Gas-a-just's? Those are what I had initially been thinking, and if they are a handling improvement then I will likely get them. Dont mind the surface rust, as I have been working on the different projects underneath I have been cleaning it up lol.

Hi, Yes mine are gas-a just shocks. With the heavy anti-sway bar, I can slam this thing around corners and there is not much bounce or roll if any. 

Could I have bought better shocks? yes of course, but on a "senior's pension" (you probably know what I mean here in Canada), I bought what was acceptable. Mine by the way looks a bit better now the axle has been painted, just not sure where I stored the pics!!