# 69 GTO Rear coil sparring comparability options?



## Molten (Mar 20, 2015)

Hi
Do any of you guys know wha other rear coil springs (including modern) may be compatable with the GTO?
Living in the UK, I am looking to see what parts are or could be equivalent (more readily available over here) to rated rear coils on the Gto.

Do you know of any online resource that shows compatable alternatives (classic or modern)?

Thanks
Scott


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## ALKYGTO (Mar 29, 2010)

Hey Scott, what are you looking to do with the car? Maybe consider an air bag or "drag bag" that goes inside the spring. I run them in the stock spring on my car and you can basically adjust the spring rate with the air pressure. They are not like air shocks because air shocks support the weight of the car putting extra stress on your rear cross member.

http://www.summitracing.com/search?...SortOrder=Ascending&keyword=airlift air bag]

If you are running all stock rear suspension you might want to consider the rear frame braces if you don't have them (most automatic cars didn't) also. 

If you want a higher rate spring usually a convertible spring or a station wagon springs are "higher rate" but they also jack up the back of the car, sometimes too much.


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## Molten (Mar 20, 2015)

Sorry. What I want is to know if there are any standard springs (other vehicle) that could be used instead of standard Gto rear springs?
Ie what (if any) modern springs would be equivalent to load spec of the original
Rear springs and may be more readily obtainable in UK as shipping fees from US is frightening?

But how do the 'air shocks' you mention work?

Cheers
Scott


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## 1968gto421 (Mar 28, 2014)

Hey Scott,
The air shocks were a big trend in the 1970's when guys would raise the rear of their car to run wide tires that protruded from the wheel wells (to avoid rubbing on the fender lip). Air shocks are still available today. The ones that were popular in the '70's were Gabriel Hi-Jackers. The shocks had plastic/nylon tubing (much like the tubing that comes with aftermarket mechanical oil pressure gauges) that mounted to each air shock and generally ran to a tee fitting that connected to an air valve (much like that for a tire) usually mounted in the trunk, but not always. Some guys would use them for drag racing to enhance traction by using a separate air valve for each shock and varying pressures. The more effective way was to use airbags as ALKYGTO mentioned. Also, as ALKYGTO mentioned, air shocks put the weight of the car's rear half onto the shock mounts and the parts the mounts attached to (not good). If your rear springs are sagging, I would use the airbags to level it out. Other than a Hollander manual, I don't know of any sources for spring interchange. Eaton Detroit Spring is the largest Co. I know of dealing with springs for older cars. You might want to contact them as they would have extensive resources on this topic. EATON Detroit Spring - The leading manufacturer of leaf and coil springs for the street rod and restoration industries


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## 1968gto421 (Mar 28, 2014)

Scott,
Another thought would be to check into rear springs for Chevelles (including SS396), Olds Cutlass and 442, Buick Gran Sports/Skylark/Special as these were all GM A-bodies like the LeMans/GTO. The A-bodies equipped with the larger engines and the two-door body should have comparable springs to your '69. Hope all this is of some help also!


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## jbrenner (Apr 15, 2013)

I've got a 66 and originally replaced front and rear suspension with all new stock shocks and springs. Moog springs and middle of the road shocks. I then went the air bag route in the test springs as well. After much wrestling and back and forth in regards to ride height and ride quality, I ended up tearing it all out and replacing it all with QA1 adjustable coilover shocks all the way around. Hind sight being 20/20 I wish I had gone the coilover route from day one. They give you complete adjustability in ride height, I like mine a little higher in the rear, and also ride quality with the valving adjustment knob on the base of each coilover. At the end of it all the coilovers have transformed her into driving like a modern car and replaced the "pillowy" floating ride you get in these old cars, especially on the highway, with essentially a modern suspension. At 70 mph on the highway I now get the slight drop and rebound you do with a modern car when going over bumps, whereas previously the car would float and rock front to back as you get with old school springs and shocks. Granted there are higher dollar springs and shocks out there that solve that problem too, to some degree. But they don't allow for the ride height and ride quality adjustability that the coilovers do. So basically for slightly under $1,000 I've got a much more responsive ride that I can adjust down at the turn of a knob to achieve as soft a ride as I like, or turn up for a more stiff ride, with the additional benefit of being able to raise and lower the front and back end to wherever I like it. Which additionally helps level out the "lean" to one side or the other that these old cars can have too. My two cents, hope it helps.


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## ALKYGTO (Mar 29, 2010)

^ so what if any reinforcements did you add to the rear shock mounts? Did you run a separate crossmember to mount them?

Also Scott....Station wagon springs are another option if you want to "jack" the rear of your car up as they are a heavier rate and a longer spring.


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## jbrenner (Apr 15, 2013)

No separate cross member or anything like that. The QA1's come with their own heavy duty bracketry that allow you to bolt everything right up. In the case of my 66 the upper side of the coilovers bolt through the included heavy gauge brackets using the existing holes where the stock shocks would bolt in. On the bottom side the coilover bolts in where the stock shock bolt would be as well, again through the use of a supplied heavy gauge bracket. All direct bolt in, no cutting, no welding, no nothing. I also have a 69 Buick Skykark N I made the same conversion with just as good results. In the case of the Buick you are required to do some minor drilling of an additional hole on both rear sides for added support. But again, no cutting or welding involved. In both cases installation easily achieved within an afternoon, especially with a buddy helping fetching you tools and beer...mainly beer though...haha.


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## ALKYGTO (Mar 29, 2010)

Can you post some pictures?


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## jbrenner (Apr 15, 2013)

Sure, if I can figure out how to do that.


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## jbrenner (Apr 15, 2013)

First picture is how it bolts through at the top using the existing upper shock mount holes. Second picture is lower mount using existing holes for lower shock mount. As you can see shock body is threaded allowing for height adjustment and the spring seat has a locking nut beneath it to lock it in place once you're happy with where it is. Second picture also shows valving adjustment knob, black knob just below the threaded shock body, that adjusts the shock rebound. There are 18 "clicks" or positions to choose from, the lower the number the softer the ride. Have mine set at 4 "clicks" on the adjustment knob on all 4 coilovers and she rides spectacular. Nice and soft and smooth but also responsive, as I mentioned before just like a modern car. The ride quality really is amazing, in my opinion anyone. An no, I'm not employed by them...haha. Strictly personal experience.


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## chuckha62 (Apr 5, 2010)

Wait... It uses the existing upper shock mount with no reinforcement? The shock mounts were never intended to support the weight and suspension loads of the car. I hope you're planning on reinforcing that VERY soon!


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## ALKYGTO (Mar 29, 2010)

^ Agreed! 

JBrenner, thats what I was trying to tell OP in my original answer about air shocks,* the upper shock mount is not strong enough to support the weight of the car*. You need to consider installing a weld in cross member to mount those coil over shocks. Yikes! :eek2:


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## jbrenner (Apr 15, 2013)

Valid points in theory I guess, except that the upper part of the spring is not resting on the frame of the car. The shock itself is all that is attached there and obviously absorbs impact adjusting up and down as the shock is designed to do as the car rides down the road going through its normal course of movement. If it were a rigid connection there with no dampening or absorption then would definitely be an issue. Have had them on the car for about 2 years now with very regular driving and there's no problem with them whatsoever. Smooth sailing for sure.


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## chuckha62 (Apr 5, 2010)

The point is NOT the spring resting point. The shock is engineered to support the spring. The upper shock mount was NOT engineered to support the entire weight of the car and all the associated dynamic loads. To say nothing about the two tiny bolts which you are relying on to keep things in check. 2 years or not, it's a suspension that will fail.


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## jbrenner (Apr 15, 2013)

Again, all valid points on the surface. I believe the shock mounting points are a heavier gauge construction than being given credit for. More importantly, to me anyway, these are engineered and manufactured by Spohn Performance. They've been in the game for some time and engineer many chasis, steering and suspension components that are regarded as top quality within the industry. Undoubtedly much engineering and testing goes into their products and I feel good with that. Many miles later she continues to drive 100 times better than she did with the stock setup.


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## chuckha62 (Apr 5, 2010)

jbrenner said:


> Again, all valid points on the surface. I believe the shock mounting points are a heavier gauge construction than being given credit for. More importantly, to me anyway, these are engineered and manufactured by Spohn Performance. They've been in the game for some time and engineer many chasis, steering and suspension components that are regarded as top quality within the industry. Undoubtedly much engineering and testing goes into their products and I feel good with that. Many miles later she continues to drive 100 times better than she did with the stock setup.


So, there is a reinforcement that we can't see on the upper mount? If so, then you're good to go. I totally agree that the valving and spring rate/ride height adjustments are going to be beneficial over the stock, 50 year old technology. 

It's just that from the picture of your upper mount, I can't see any difference from what GM produced and what GM produced was not designed to work in the manner which the picture seems to show.

If it's not reinforced (and after visiting Spohn's website, I don't think it is), I would suggest something like this from Chassisworks: https://www.cachassisworks.com/p-1494-varishock-coil-over-shocks-and-mounts-package.aspx



Edit: added Chassisworks link


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## jbrenner (Apr 15, 2013)

Thanks for the link. So I'm confused as to what the cross member accomplishes, other than connecting both coilovers at the top. Is the crossmember welded into the framing of the car? Is it bolted in? Also mentions it as optional. In reference to mine, the upper mount is a very heavy gauge "extreme duty CNC machined t-bar" as they describe it. And the bolts included are a heavy gauge grade 8 replacement for the stock bolts. All in all, yes, it's a simple setup...as intended form the looks of it. And again, have had them on the car now for quite awhile and they ride like a dream. Smooth. Quiet. Responsive.


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## chuckha62 (Apr 5, 2010)

That particular one welds in and is intended to be the structural member necessary to become the top part of the suspension. 

If your Spohn system is reinforced and provides a solid upper shock/suspension mount, you should be good to go. As with so many things, there's many ways to skin this cat.


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## jbrenner (Apr 15, 2013)

Yes, the spohn system is definitely heavy gauge and while simple, definitely seems to be more than adequate for the purpose. That and I'm one to subscribe to it it isn't broke, don't fix it. Considering how well it continues to drive and respond all this time later certainly not motivated to try and make any changes. For the hell of it I emailed spohn to lose this question to them. Naturally they're going to defend their design and product, their response being that the stock upper shock mount locations are of a heavier gauge construction than one might think and that required testing was performed and dyno tested to ensure quality in design, performance and function. Goes without saying you can't just throw something like this out into the market place without adequate design and testing, for consumer safety reasons alone.


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## Molten (Mar 20, 2015)

1968gto421 said:


> Scott,
> Another thought would be to check into rear springs for Chevelles (including SS396), Olds Cutlass and 442, Buick Gran Sports/Skylark/Special as these were all GM A-bodies like the LeMans/GTO. The A-bodies equipped with the larger engines and the two-door body should have comparable springs to your '69. Hope all this is of some help also!


Hi Guys
Sorry I ain't been on here since posting been busy repairing a bodged up trunk floor that someone had bonded in instead of welding.
I am going down the stock route with a his car and ended up buying mood springs and keyboard gas a just shocks.
Front control arm are BMB tubular kit.
The motor that I got with this car is a 71 Pontiac 455, and I am not sure if the stock front moogs (5386) are right for the 455. 

Will these bo ok?
Thanks
Scott


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