[70GTO_John]

Hi there,
I'm seeking some advice, I will need to buy front & rear coils for my 70 GTO which I'm restoring. body is presently off at the frame, I will replace the body bushings as well.

Looking to have a correct stance once done, I want the car to be within the stock ride height.
I don't want to end up with 'off road' look.
The coils that I had on the car were incorrect.

Any suggestion would be appreciated.
400, Auto, PS, PB, non-A/C.

[76TA462]

Not sure if it makes sense for you so just 2 cents. On my second gen Firebird I only have coils on the front. After all the pains of height configuration on the front over the decades, I went to coil-overs. Problem solved for me and I am extremely happy with the flexibility. Wish I had coils on the back, but I am staying OEM style so have figured my way around that. The front flexibility made that aspect easier to work with.

[scott70]

Originally Posted by 70GTO_John

Hi there,
I'm seeking some advice, I will need to buy front & rear coils for my 70 GTO which I'm restoring. body is presently off at the frame, I will replace the body bushings as well.

Looking to have a correct stance once done, I want the car to be within the stock ride height.
I don't want to end up with 'off road' look.
The coils that I had on the car were incorrect.

Any suggestion would be appreciated.
400, Auto, PS, PB, non-A/C.

Sorry I don't have any actual aftermarket part numbers but I know what you mean..can't stand seeing these GM A bodies witthe front or the rear 10 miles in the air and they left it like that. Doesn't look good and does nothing for the handling. My 70 gto is still sporting the original coil springs. Maybe find some decent originals?

[59safaricat]

Front Coils Moog 5390 https://www.ebay.com/itm/39410496498...Bk9SR-biydeRYQ


Rear Coils Moog 6319 https://www.ebay.com/itm/33454256663...Bk9SR-Lw9deRYQ

[tjs72lemans]

For my 72 I bought from Ames and they look stock like I wanted.

[gman005]

TJS do you have picture of your 72? I need new rear springs for my 72.

[mrennie]

Some info that may be helpful.

https://drive.google.com/drive/folde...4W?usp=sharing

[tjs72lemans]

Here ya go. Keep in mind, I also put one inch spacers on top, as some say a vert sags when top is lowered. I am glad I did.

[Shiny]

I need to replace the rear springs on my 70 LeMans to drop the height. This thread confuses me, so thought I'd ask for clarification.

First of all, Coil Spring Specialties are highly recommended but exceed my budget.

So I'm targeting off the shelf Moog parts..

My car currently has some unknown "heavy duty" springs but it sits too high for me. Perhaps they were cargo coils or something... I don't remember where I got them but suspect I bought them used off eBay without a clue as to PN ???



mrennie (thanks Michael!) shared some older Moog catalog pages that said these are recommended for a 70 LeMans coupe:

Standard, w/ or w/o AC: 5401
Heavy Duty, w/ or w/o AC: 5413

See Michael's post #7...

OPH provides lots of detail about Y96 Ride & Handling options here, but doesn't translate into Moog replacement PNs:

Link to OPH Info on Suspension Options

Questions:


1. Does Moog's "heavy duty" description for the 5413 equate to the Y96 option mentioned by OPH?

Here's an older Squidward post of a 5413 on a 72?:

Link to Thread



Would it sit the same on a 70? Squidward's rear tires look bigger than what I plan to use - P225/70R14s.. so not sure how that would change the look, but I'd like the top of the tire at or inside the top of the opening without a big gap like I have now.


2. Has anyone put Moog 5401 on their 70? Any photos?

Here's a post with 5401 on a 68. Would it sit the same on a 70?

https://forums.maxperformanceinc.com...24#post6588924



3. Does anyone want to share pics of a 70 with KNOWN Moog 5401 or 5413, preferably relatively recent purchases and 14" tires? I'm also open to other Moog PNs..

Mike

[propuckstopper]

Coil Spring Specialties. They are dead on correct.

[Shiny]

propuckstopper - I did see your recommendation and got a quote. I simply can't justify the custom cost, even if I don't get what I want with off the shelf Moog or aftermarket.

Originally Posted by 59safaricat

Front Coils Moog 5390..

Rear Coils Moog 6319

I chased this PN down and it seems another good candidate that might put the height somewhere between the 5401 and 5413, although the stiffness is a little lower than 5401.

Here's a photo posted by 68WarDog of his car with 6319:



Was posted here: Link to another thread

Anyone else use this on a 70 with 14" wheels and ~26.5" tires?

I also see UMI sells a stock height spring with a rate of 130 lbs/in, which is in between 5401 and 5413. They cost more than Moog, but less than Coil Spring Specialties and are likely to be exactly what they say vs what may be a quality crapshoot with Moog parts.

And I like the model UMI chose for their web page:



I also read several threads about variable rate springs like CC501 but I want to stick with constant rate.

Mike

[67Lemons]

Here’s my car with original springs and a 1” rear spacer sitting on 15’s

[Kenth]

I´m using MOOG 5400 in front and MOOG CC501 in rear. Same springs for about 30 years now.
I have found the MOOG 6319 is softer and sits slightly higher.

[Shiny]

Beautiful cars, thanks for the pics and info! This helps a lot.

Originally Posted by 67Lemons

Here’s my car with original springs and a 1” rear spacer sitting on 15’s

What should I assume for "original spring"? Would it have been closer to the 5401 or 5413?

That looks great to me. To replicate this, a Moog 5401 and a 1" spacer might do it but depends somewhat on tire diameter.

What is the tire diameter? Any idea what you have in the front?

The Moog specs suggest the "heavy duty" 5413 would also raise the car about an inch over stock. I'm squirrelly about this, though, because there's a chance what I have now is a 5413. I will measure the wire diameter today and check to see if it's fixed or variable rate, like a CC507 or something...

Originally Posted by Kenth

I´m using MOOG 5400 in front and MOOG CC501 in rear. Same springs for about 30 years now.
I have found the MOOG 6319 is softer and sits slightly higher.

That looks great too! What diameter are your tires?

I found a receipt that says I installed 5440 in the front. I will look up the differences and see if my front is also jacked up some. I really don't want to swap front again... was not a fun project.

The stiffness goal is difficult for me to guess what I want.

5401 - 128 lb/in.
5413 - 166
As you note, the 6319 is even softer than the 5401, reportedly 119 lb/in.

UMI makes a case for their 130 lb/in in this blurb:

Link to UMI Tech Article - "GM A-Body Spring Height Guide"

For your variable rate CC501, it's probably hard to know the "effective" or "instantaneous" spring rate at installed height but the intent was probably to have it be somewhere in the same range of 128 to 166 but it may also have been "stock" on a wagon that had more weight over the rear. This might actually put it at the low end of that range with your lighter car.

As to the effect of stiffness, I can guess at the "feel" but hard to know without riding in both. I don't want it to feel like a truck but I assume the 166 lb/in was standard in a GTO or with a "Ride & Handling" suspension option like the Y96 OPH mentions. Is this a safe guess?

I like the idea of starting low and using a spacer to increase the height if I don't like it. Thanks for that!


Mike

[Shiny]

Anyone have these specs for the front 5440 PN?

I could not find this PN in the Moog spec docs mrennie shared, but I assume the dimensions are close with the stiffness in between the stock 5372 W/O AC and the 5400 HD.



Here's the Moog Application guide:

[Shiny]

Well.... this explains a little more than a little....

The rear springs currently on my car are NOT variable rate but measure 0.66" wire diameter, which is off the chart for the Moog PNs. No clue what it is, but it is STIFF, which explains why my car looks like I overfilled the air shocks that don't exist.



Here's my list of candidates, all with lower spring rates than what's on there now..



Tires on there now are 205-70R14, about what they will stay...



Can anyone explain these specs better? I understand the dimensions and the spring rates, but not the installed height and loads.

Basically, I'm asking what is the ACTUAL static load on a 70 a-body rear spring? Anyone??

Mike

[Bruce Meyer]

It looks like your calipers are measuring .61 not .66.

[73_Lemans_350]

Originally Posted by Bruce Meyer

It looks like your calipers are measuring .61 not .66.

The "61" you're reading on the dial part gives the thousandths reading. The numbers between the 'jaws' give the tenths reading, so what you're seeing is somewhere around .660 and .661.

[67Lemons]

Originally Posted by Shiny

Beautiful cars, thanks for the pics and info! This helps a lot.



What should I assume for "original spring"? Would it have been closer to the 5401 or 5413?

That looks great to me. To replicate this, a Moog 5401 and a 1" spacer might do it but depends somewhat on tire diameter.

What is the tire diameter? Any idea what you have in the front?

The Moog specs suggest the "heavy duty" 5413 would also raise the car about an inch over stock. I'm squirrelly about this, though, because there's a chance what I have now is a 5413. I will measure the wire diameter today and check to see if it's fixed or variable rate, like a CC507 or something...



That looks great too! What diameter are your tires?

I found a receipt that says I installed 5440 in the front. I will look up the differences and see if my front is also jacked up some. I really don't want to swap front again... was not a fun project.

The stiffness goal is difficult for me to guess what I want.

5401 - 128 lb/in.
5413 - 166
As you note, the 6319 is even softer than the 5401, reportedly 119 lb/in.

UMI makes a case for their 130 lb/in in this blurb:

Link to UMI Tech Article - "GM A-Body Spring Height Guide"

For your variable rate CC501, it's probably hard to know the "effective" or "instantaneous" spring rate at installed height but the intent was probably to have it be somewhere in the same range of 128 to 166 but it may also have been "stock" on a wagon that had more weight over the rear. This might actually put it at the low end of that range with your lighter car.

As to the effect of stiffness, I can guess at the "feel" but hard to know without riding in both. I don't want it to feel like a truck but I assume the 166 lb/in was standard in a GTO or with a "Ride & Handling" suspension option like the Y96 OPH mentions. Is this a safe guess?

I like the idea of starting low and using a spacer to increase the height if I don't like it. Thanks for that!


Mike

As far as I can tell my springs are the originals or they were changed out a long time ago. I’m running 255/60R15 in the rear with 27” diameter and 235/60R15 with 26” diameter. The center of my front wheel well measures 26.5” and the rear is 27.5”

I bought the 1” spacer from Amazon, just a basic aluminum puck for ‘68-‘72 A body’s.

[Shiny]

67Lemons, thanks again!