[GtoFM]

Are the original specs published anywhere for coil springs? I have not been able to find anything.
Some suppliers list different springs for each year, while others list the same spring for multiple years.
I have a '64 GTO, MT, no A/C. I am starting to reassemble the stock front end, but springs are still in the undecided column.
In '64, did the GTO option get different springs over the LEMANS and TEMPEST?

Thanks for the input.

[John V.]

Yes, definitely the GTO was different from the Tempest and Lemans.

All '64 GTOs regardless of Body Style got the same Rear Springs. They also got the same Front Springs unless A/C was optioned.

If A/C was optioned, different Front Springs were specified and depended further on whether Auto Trans was also optioned or not.

If the HD Springs and Shocks option was ordered, the GTO shocks were different from the base GTO shocks but the Springs were NOT affected.

The Spring choices are identified by p/n and application in the '64 Tempest Inspector's Guide, a factory document.

The GTO Spring rates can be found in the '64 AMA Specs. This used to be included in the PHS packet, don't know if it still is.

My copy isn't real accessible at the moment. But if nobody else steps up to provide that info, I can try to dig my copy out.

I'm not sure what springs were selected in the resto of my '64 GTO convertible. I'm okay with the Front Springs but I believe the car sits way high in the rear, I doubt the Rear Springs are very close to what was used originally.

[John V.]

I was mistaken, the AMA specs did not define the GTO spring rates.

They give the base car specs and also the optional V8 (326 was the optional V8) specs but then simply say that Heavy Duty Springs are optional for all applications which is true for all other A body choices EXCEPT for the GTO which did not offer an optional spring choice. But the Tempest & Lemans HD Spring specs are not defined.

Here is what the AMA specs do show.. Some of the specs may be useful and if nothing else, the GTO spring rates would have exceeded the listed rates.

Front Spring Type: Coil
Material: SAE 9260
Coil Design Ht. & ID: 11.4 x 3.6
Spring Rate: 275 lb/in w/ opt V8
Rate at Wheel: 80 lb/in

Rear Spring Type: Coil
Material: SAE 9260
Coil Design Ht. & ID: 8.52 x 5.50
Spring Rate: 106 lb/in
Rate at Wheel: 96 lb/in

I could have sworn I've seen the '64 GTO spring specs somewhere but I've checked in a few other places and couldn't come up with it. Since there are aprings specs in the AMA Spec document, I may have seen that and assumed that the GTO specific specs were included.

Since the Tempest and Lemans Springs were more variable depending on a number of things, I did not check the Spring Charts but it is possible that the AMA listed specs were only valid for a specific combination.

Regardless, the '64 GTO suspension was considered very "stiff". Not nearly as compliant as a modern car suspension. The sales literature recommended trying out the standard GTO suspension before opting for the even "stiffer" HD Shocks, the only suspension option you could choose.

[PontiacJim1959]

The GTO Restoration Guide shows 3 front springs for '64, Standard, AC/Manual, AC/Automatic. The '65 uses the same Standard, but different for AC/Manual, as well as a different springs for automatic with a Standard, and one for AC.

The HD suspension did not change the springs, it was the addition of the HD Shocks.

I also have the '64 AMA specs, but here is what I show additionally.

Front:
Spring Rate (Lb per in.) 225 and 275 with optional V8
Rate at Wheel (Lb per in.) 66 and 80 with optional V8
Design Load (Lb @ design height) 1380-1430 and 1635-1685 with optional V8

Rear:
Design Load ( Lb @ design height) 715-765


Front Stabilizer - .875 diameter and .938 diameter on the GTO.

My guess with the variations of the design load of the springs is dependent on the standard, A/C Manual, and A/C Automatic. The 1965 AMA Specs are identical to above.

[John V.]

Actually the Design Load spec is the acceptable “range” for a particular Spring.

The Inspector’s Guide notes that the Spring with the High Load Range was to be installed in the LH position. Springs with Low Load Range Were marked so the installer knew which was which. If both were Low or both were High the position was Both (in other words, didn’t matter).

All of this was provided in the Inspector’s Guide.

[GtoFM]

Thanks for the replies! Here is what I have.

According to PHS, no 'H.D. Springs & Shock Absorbers--FRONT & REAR' option selected.

The only specs I found for replacements are from MOOG. MOOG does not produce springs for the '64 GTO. Most likely because the GTO is an option on the LeMans. They do spec springs for the'64 LeMans and Tempest.

Front, Standard:
Spring Rate 297 lbs/in.
Design Load 2025 lbs.

Front, A/C or Wagon:
Spring Rate 315 lbs/in.
Design Load 2174 lbs.

Rate at Wheel spec is not listed. Not sure where they come up with that Design Load weight. Coil size is the same for both, 11.00H x 3.63 ID

So the question is, how much will the extra Spring Rate and Design Load effect the ride height?

I plan to call Ames for the brand and specs of their springs. I haven't tried Eaton Detroit Spring for info, but I read they are very tight lipped about specs. Also have seen some bad reviews.

[propuckstopper]

Originally Posted by GtoFM

Thanks for the replies! Here is what I have.

According to PHS, no 'H.D. Springs & Shock Absorbers--FRONT & REAR' option selected.

The only specs I found for replacements are from MOOG. MOOG does not produce springs for the '64 GTO. Most likely because the GTO is an option on the LeMans. They do spec springs for the'64 LeMans and Tempest.

Front, Standard:
Spring Rate 297 lbs/in.
Design Load 2025 lbs.

Front, A/C or Wagon:
Spring Rate 315 lbs/in.
Design Load 2174 lbs.

Rate at Wheel spec is not listed. Not sure where they come up with that Design Load weight. Coil size is the same for both, 11.00H x 3.63 ID

So the question is, how much will the extra Spring Rate and Design Load effect the ride height?

I plan to call Ames for the brand and specs of their springs. I haven't tried Eaton Detroit Spring for info, but I read they are very tight lipped about specs. Also have seen some bad reviews.

Call Coil Spring Specialties. Nothing but great success with them on both cars.

[GtoFM]

Thanks, I just closed the CSS site. Definitely will give them a call.

[John V.]

Years ago the "common wisdom" for a '64 GTO restoration was to specify the Convertible Rear Springs because they were supposedly taller.

Not sure who was the common supplier in those days. But it was comical to me because ALL '64 GTOs were built with the same p/n 9776201, Code PN rear springs.

These were the highest rear spring rate Springs installed in any '64 Pontiac A body with the exception of the Extra High Rate Springs used for the Special Police option, p/n 9779274, Code PX.

The GTO rear springs were "stiffer" than the standard Police & Taxi option rear springs, p/n 9776056, Code PL.

The Code PL springs were used for ALL non-GTO applications, except for the 2035 and 2135 Station Wagons, when the Sales Code 621 Heavy Duty Springs & Shocks option was ordered.

As mentioned in my earlier post, a GTO ordered with the HD Springs & Shocks option did get the same larger dia. piston Delco shocks (std. was 1", I believe the HD were 1.25") as all others with this option.

But this option did NOT change the GTO Springs front or rear.

The 2035 and 2135 Station Wagons with HD Springs & Shocks got rear springs p/n 9776057, Code PM.

The same HD rear springs were specified for each application when either the Light Duty or Medium Duty Trailering option was ordered.

Again, the Trailering option did NOT change the GTO rear springs.

The A/C option did not change the rear springs for any '64 application.

The Tempest & Tempest Custom Sports Coupe (2027 & 2127) and the Lemans Sports Coupe & Hardtop Coupe (2227 & 2237) standard rear spring was p/n 9776457, Code PU.

The Tempest & Tempest Custom Station Wagon (2035 & 2135) rear spring was p/n 9776458, Code PV.

All the above were irrespective of the engine, 6 cyl. or V8.

According to the AMA Specs, the Spring Rate for the Code PV springs was 150 lb./in.

The Code PU springs presumably were 106 lb./in. according to the AMA specs.

But this is uncertain because the Tempest 4 dr. Sedan 2069, the Tempest Custom 4 dr. Sedan 2169 & Convertible 2167, and the Lemans 4 dr. Sedan 2269 specified a different rear spring.

According to the Inspector's Guide, the 2167 & 2267 Convertibles got rear spring p/n 9773998, Code PC with the 6 cyl or V8.

The 2069 and 2169 got the Code PC spring with the 6 cyl but the Code PU with the V8.

Note that the non-GTO 2227 & 2237 Lemans Coupes were specified with the Code PU rear springs but the non-GTO 2267 Lemans Convertible got the Code PC rear springs.

It is conceivable that this was the reason why the old recommendation was to use the Convertible Rear Springs for a GTO resto. Still made no sense since the GTO Code PN Rear Springs were the factory choice regardless of GTO Body Style.

The Front Spring choices are even more complicated.

But same as with the Rear Springs, the standard GTO Front Springs were unique to the GTO, not shared with the other A bodies.

The standard GTO Front Springs were p/n 384543, Code SR.

The Special Police option Front Springs were the Extra High Rate p/n 387038, Code SZ used with the 6 cyl or V8.

The GTO Front Springs were the Code SR with or without the HD Springs & Shocks option and with or without either of the two Trailering options.

The only GTO Front Spring exception was when A/C was optioned.

In this case, with Man Trans, the Front Springs were p/n 384544, Code SS.

Presumably, these springs were higher rate than the Code SR springs, owing to the added weight of A/C.

The Code SS springs also were unique to the GTO.

With A/C and Auto Trans , the GTO got Front Springs p/n 384752, Code ST.

Presumably, these springs were higher rate than the Code SR or Code SS springs, owing to the added weight of A/C and Auto Trans.

The Code ST springs DID have other usage in the A Body line-up.

They were the HD Front Springs specified when the Sales Code 621 HD Springs & Shocks option was optioned for all non-GTO A Bodies, also used with V8 and both Trailering Options, and also used for the Taxi with V8 and Police with V8. For the non-GTO, the Trans was not a factor.

If the ST springs were stiffer than the SR, it would seem very strange that the GTO did not get them when the HD Springs & Shocks were optioned yet the non-GTO did get them with this option.

A Spring expert might understand the reasoning better but it remains conceivable that the Code SR Front Springs were the stiffest choice PMD had.

[theamcguy]

John V. any info on the 1965 GTO front and rear springs. Thank you

[John V.]

Yes I do.

First, some insight into the part numbering used in that era when each GM was a semi-autonomous car company.

The parts themselves could be used across the Divs so that it was not uncommon to see a mix of Divisional p/ns on each Division's cars.

Pontiac engineering p/ns starting some time around 1963 will look like 977xxxx and ratchet up thru 979xxxx by the late '60s when they went to a different part numbering sequence.

Olds engineering p/ns look like 3xxxxx, always 6 digit.

Chevy engineering p/ns look like 3xxxxxx, always 7 digit.

Buick engineering p/ns look like 1xxxxxx, always 7 digit.

I mention this because you will see that many of the Spring p/ns I listed in the earlier post are Olds p/ns.

This proves to be a useful thing. Turns out the Olds Spring Chart provides design specs for the Rear Springs and they used many if not all of the same springs on the F-85 as Pontiac used on the Tempests (including GTO).

The '65 GTO used the SAME Rear Springs as the '64.

These were p/n 9776201, Code PN.

The Olds Rear Spring Chart is p/n 9773805, in other words, it was actually created by Pontiac Engineering. And all of the Rear Springs listed are Pontiac engineering p/ns so looks like PMD Engineering was given the responsibility of designing the Rear Springs for Olds and Pontiac and likely for Buick and maybe Chevy too.

There was a modest revision from '64 to '65. Thru most of '64, 2 Black Bars under the Letter Code denoted a Spring at the low end of the Load Range. Looks like around May '64, the identification was revised so that now a Black Circle around the letter code denoted a Spring at the low end of the Load Range.

From the Olds Chart:

p/n 9776201, Code PN Rear Springs used for ALL '64 & '65 GTOs regardless of engine, transmission, trailering option, or any other option had the following specs.

ID of Spring - 5.50
Thickness of coil bar - 0.540
Ht. of relaxed Spring - 13.85
Load Range - Low 600-625
Load Range - High 625-650
Ht. "G" of Spring within Load Fixture when subject to specified Load - 8.52

The verbiage on the Chart is very hard to read so the following are my best interpretation of additional dimensions.

Ht. "H" - 4.52. Measured from the top of spring. On the drawing the Identification tape is shown as if that is what is being dimensioned (as an aside, the tape in Production is stated to be Orange Tape, but Yellow Tape with Black Part No. "may be used" for Service).

Note says, "DIMENSION H DENOTES HEIGHT OF SPRING AT CL WHEN SUSPENSION IS AT METAL TO METAL POSITION. MUST CLOSE TO THE DIMENSION WITHOUT TAKING PERMANENT SET."

E - 122

Note says, "RATE PER INCH +/- 3% (might be 5, not sure) WHEN CHECKED 1.00 ABOVE TO 1.00 BELOW HEIGHT G."

N - 4.40

Note says, "N = APPROX. NO. OF ACTIVE COILS - PITCH MUST BE UNIFORM WITHIN .050" I am not sure of the .050, very hard to read. I would guess this is a standard tolerance for Spring manufacturing.

There are numerous other notes pertaining to the manufacturing of the spring, coating (oiling or optional paint), testing procedure, etc.

This is a lot to digest so I'll stop here. I will come back and post comparative specs for the Extra High Rate PX and the non-GTO HD PL Springs to see if anything makes sense.

I will cover the GTO Front Springs too but unfortunately, I don't see comparable specs in the Olds literature for the Front Springs so might not be able to add much other than to confirm what was used for the '65 GTO.

Later.

[John V.]

Refer to my earlier post for Rear Spring usage by application.

Follows are the specs for a selection of springs so that you can compare to the specs for the '64/'65 GTO rear spring specs.

I did some research and learned that the Spring Rate (value "E" on the Chart, the dimension is lb/in) is a measure of how soft or firm the Spring is. The higher the value E, the more weight needed to deflect the spring 1", so the stiffer it is, all else being equal.

The Load Range is the lbs. the spring can carry when deflected to a prescribed ht. In the case of these rear springs, the Load Range is established at "G" ht., 8.52 in all cases.

p/n 9773998, Code PC

ID of Spring - 5.50
Thickness of coil bar - 0.530
Ht. of relaxed Spring - 14.89
Load Range - Low 675-700
Load Range - High 700-725
Ht. "G" of Spring within Load Fixture when subject to specified Load - 8.52

Ht. "H" - 4.52
E - 106
N - 4.73

p/n 9776457, Code PU

ID of Spring - 5.50
Thickness of coil bar - 0.530
Ht. of relaxed Spring - 14.89
Load Range - Low 625-650
Load Range - High 650-675
Ht. "G" of Spring within Load Fixture when subject to specified Load - 8.52

Ht. "H" - 4.52
E - 106
N - 4.72

p/n 9779274, Code PX

ID of Spring - 5.50
Thickness of coil bar - 0.590
Ht. of relaxed Spring - 13.44
Load Range - Low 785-810
Load Range - High 810-835
Ht. "G" of Spring within Load Fixture when subject to specified Load - 8.52

Ht. "H" - 4.52
E - 170
N - 4.40

p/n 9776056, Code PL

ID of Spring - 5.50
Thickness of coil bar - 0.570
Ht. of relaxed Spring - 14.62
Load Range - Low 830-855
Load Range - High 855-880
Ht. "G" of Spring within Load Fixture when subject to specified Load - 8.52

Ht. "H" - 4.52
E - 144
N - 4.56


Looking at the values, the PN GTO Springs (122 lb/in) are stiffer than the PC or PU springs (both 106 lb/in) but not nearly as stiff as the PL (144 lb/in) or the PX (170 lb/in).

PMD must have had their reasons but seems that the GTO rear springs were not as stiff as the HD Springs used when optioned on any other Pontiac A body.

I suspect the ht. of the relaxed spring probably affected the spring firmness too so perhaps the GTO spring still was stiffer than the PL and maybe the PX would have been way too stiff for "normal" driving.

I'm not real clear what to make of the Load Range, no other spring on the Chart has a lower Load Range than the GTO PN rear springs.

[John V.]

The '65 GTO used the same Front Springs as the '64, standard was the Olds p/n 384543, Code SR except with A/C.

With A/C, the Man Trans GTO got the Olds p/n 384544, Code SS and with A/C & Auto Trans, the GTO used Olds p/n 384752, Code ST.

The Olds F-85 had applications for all 3 of these Front Spring choices but I could not find a Front Spring design specification chart in the Olds literature for '65 or '66.

Judging from the '64 AMA Specs, I would guess the ID would have been 3.6 and the Ht. "G" would have been 11.4. Same for all except the station wagon going by the rear spring specs.

I would also guess that the Spring Rate would have exceeded the Spring Rate of the standard V8 Front Spring which was 275 lb/in.

The relaxed ht. is not given in the AMA Specs.

The Moog p/n 5234 Springs that you found specs for might be close in design to the original p/n 381940, Code SK and p/n 382820, Code SM Front Springs used on many of the V8 non-GTO A Body applications except that the Moog Load spec seems way higher than the Load Range in the AMA Specs (1635-1685 lbs).

The stiffer Moog p/n 5256 Springs that you found specs for might be close to the original p/n 384752, Code ST Front Springs used with the HD Springs & Shocks option used on a non-GTO, but again The Moog Load spec seems way higher than what I would guess.

Without factory specs, I have no idea whether they are similar to the GTO Code SR Front Springs. But based on the very low Load Range for the GTO Rear Springs, unless the Front springs are very different, the GTO Front Springs might be lower in Load Range vs. the Load Range given in the AMA Specs for the V8 Load Range.

Depending on the look, stiffness, and ride ht. you'd like, you might be able to pick something out on Page 15 of this Moog Spec catalog.

https://www.blueovaltrucks.com/tech/...rings_Spec.pdf

You'd want to consult an expert but I think you want to stay close to the 3.6 ID.

That's the best I got. Researching this, it occurs to me that the Springs sold as "correct" for my '64 GTO are probably way different than the factory originals and likely why I think the rear of the car sits way too high.

[Kenth]

Originally Posted by John V.

Depending on the look, stiffness, and ride ht. you'd like, you might be able to pick something out on Page 15 of this Moog Spec catalog.

https://www.blueovaltrucks.com/tech/...rings_Spec.pdf

Seems like MOOG got it wrong in your link describing the coil end style, they mixed up SQ and TG style in the pictures.
I am using the #5244 in my 1966 GTO and it is an open end style spring, tangential, shown as a square end coil.
At least they got it right in the 2002 paper catalog F2926.