# Rear Coil Springs



## jtwoods4 (Dec 22, 2011)

Hey Guys, I have the stock rear coil springs on my 69 GTO. When passengers are in the back seet I get some bottoming out. I tried replacing the rear coil springs with stock replacements but I need somrthing stiffer. I do not want to use drag bags, just stiffer springs. Can anyone point me in the right direction for getting a stock ride height spring but a much stiffer spring?


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## Eric Animal (Oct 28, 2007)

Google : Eaton Spring....they will make you anyspring height and rate you want. Eric


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## Pontiacpurebrred (Jun 22, 2011)

You could also try your stock springs with coilover shocks.


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## jtwoods4 (Dec 22, 2011)

Pontiacpurebrred said:


> You could also try your stock springs with coilover shocks.


Not sure what you are talking about.


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## Pontiacpurebrred (Jun 22, 2011)

They are shocks with additional coil springs around the shock housing. 

http://www.globalwest.net/cor-6466s.html

They add nice stability and additional control without compromising ride. (As long as you get an adjustable shock)


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## ALKYGTO (Mar 29, 2010)

Can I ask why you don't want to use "drag bags"? They actually work quite well and are inexpensive.


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## Instg8ter (Sep 28, 2010)

:agree...the drag bags let you level the rear end and adjust the ride just how you want it without being harsh or jacking the back of the car up for under 100.00 and a 30 minute install.


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## jtwoods4 (Dec 22, 2011)

Just installed the drag bags. $84.00


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## jtwoods4 (Dec 22, 2011)

Well I have another problem now. I am getting wheel hop now that I have the drag bags installed. They solved the problem of the rear end bottoming out with passengers. However, if it is just me in the car and I try do a burn out from stopped position I get pretty wheel hop. I only inflated the bags t0 12 psi but I guess this doesnt allow the rear end to flex like it should and causes the geometry to change enough to cause wheel hop. Any idea how to resolve this?


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## BearGFR (Aug 25, 2008)

What's the condition of the rubber bushings in your rear upper/lower control arms? (Assuming you still have stock pieces)

Bear


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## jtwoods4 (Dec 22, 2011)

The bushings are in great condition. The rubber is not cracked or hard and brittle. They look like they're supposed to.


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## ALKYGTO (Mar 29, 2010)

Ugh, one thing leads to another doesn't it? Sorry you're having problems now. Are your stock control arms "boxed" or still the flimsy channel? I have the Southside Machine lower arms and home made boxed uppers. I never had a problem with wheel hop after I boxed my control arms. The rear geometry on these cars is not quite right with the stockers so possibly changing the instant center on your suspension will fix this.


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## jtwoods4 (Dec 22, 2011)

BearGFR said:


> What's the condition of the rubber bushings in your rear upper/lower control arms? (Assuming you still have stock pieces)
> 
> Bear


Does your car bottom out or hit anything if you are loaded down with 2 passengers in the back seat?


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## Instg8ter (Sep 28, 2010)

let a little air out of the bags and try it, see if you can find a happy medium. The 69's sat very low in the back from the factory with skinny 14" 70's on them. the wheel offset is critical when you try to squeeze 245+ 15" on them, can take a little off the inner wheel house lip with a grinder if the tire is just barely touching it when loaded. I know the 66' has a 2" inner lip and flat top wheel wells that make it a balancing act with wide tires.


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## BearGFR (Aug 25, 2008)

jtwoods4 said:


> Does your car bottom out or hit anything if you are loaded down with 2 passengers in the back seat?


Not that I've noticed, but my rear suspension isn't stock either. I've got fully adjustable upper/lower arms with sphereical joints, frame mounted sway bar, mount stiffeners, double adjustable shocks, --- oh and a Moser 9".

I asked about your rubber bushings because that can be a source of the hop. The tires bite, the bushings deflect a little under the force and that changes all the angles a little and lets the housing rotate rearward just a smidge, the tires unload.... lather, rinse, repeat - rapidly.

Bear


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## ALKYGTO (Mar 29, 2010)

^ Same reason I asked about the lower control arms. The unboxed arms deflect in the same manner. Also do you have the brackets that tie the upper and lowers together at the front? I believe only factory 4 speed cars had these and they will keep you from ripping out the rear crossmember. I replaced mine with tubular units but these are neccasary IMO for any decent HP car. In fact, my roll cage is tied into all the suspension attachment points. 

Basically your car is trying to put all that HP to the ground. The drag bags have limited (appropriately) the deflection in the springs limiting front end lift and rear end sag. Now the hard parts of the suspension are expected to do thier job and the factory geometry in not good in these cars.

Go to http://www.****millerracing.com/ and do a little reading. You'll want your car to do what the car on his homepage is!


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## ALKYGTO (Mar 29, 2010)

BearGFR said:


> Not that I've noticed, but my rear suspension isn't stock either. I've got fully adjustable upper/lower arms with sphereical joints, frame mounted sway bar, mount stiffeners, double adjustable shocks, --- oh and a Moser 9".
> Bear


Pics of suspension setup Bear? Esp the rear swaybar setup. Is this something you bought or cooked up yourself?


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## Pontiacpurebrred (Jun 22, 2011)

ALKYGTO said:


> Pics of suspension setup Bear? Esp the rear swaybar setup. Is this something you bought or cooked up yourself?


I second this ... Bear what's going on under your rearend?  :rofl:

I will be updating mine and I respect your build greatly so hoping to learn something here.


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## Eric Animal (Oct 28, 2007)

Were you getting wheel hop BEFORE you installed the Dragbags? What else did you change when you added them? Eric


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## BearGFR (Aug 25, 2008)

You respect my rearend? I'm not sure how comfortable I am with this conversation....  

No custom fabrication, it's all aftermarket parts. Most of which came from Spohn Engineering. I even bought the Moser 9" through them.

Axle: Moser 9", high spline count alloy axles, Wavetrac diff, 3.50:1 gears
Upper/lower control arms: Spohn chromoly, adjustable, Delsphere bushings (polyurethane bushings on the housing end of the uppers)
Sway bar: Spohn "Pro Touring"
Shocks: Strange Engineering, double adjustable
Mount Stiffeners: UMI Performance
Brakes: Wilwood Dynalite Pro 4-piston w/internal drum parking brakes
Springs: Factory (fresh)

Moser 9" - Nodular iron center section, 1350 U-joints









Mounted - View of upper control arms and shocks (no sway bar yet)









View of lower control arms (still no sway bar)









The big advantage of these upper and lower control arms is that the joints in them allow the axle to move both up and down, and "rotate" (like in same directions the driveshaft turns) with absolutely no binding anywhere, yet they keep it positively located front to back, side to side, and also in the same rotational direction as the axles turn with much more rigidity than the stock bushings do. Definitely far better than the stock setup.

Brakes









Sway bar - end links mount to frame crossmember and are independently adjustable









Drive shaft loop from Ram Air Restorations









Control arm mount stiffeners from UMI









Close up of sway bar link - adjustability allows preloading one side to help make the car launch straight.









Hope this helps - thanks for asking 

Bear


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## ppurfield001 (Jan 21, 2008)

jtwoods4 said:


> Hey Guys, I have the stock rear coil springs on my 69 GTO. When passengers are in the back seet I get some bottoming out. I tried replacing the rear coil springs with stock replacements but I need somrthing stiffer. I do not want to use drag bags, just stiffer springs. Can anyone point me in the right direction for getting a stock ride height spring but a much stiffer spring?



I got coil-overs and love them. I think you will too. Good luck with whatever you decide.


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## Eric Animal (Oct 28, 2007)

If any of you H-mos wants to check out a sweet rear end, here is mine.....:rofl:arty:...................seriously though, wheel hop, the arch enemy of the burnout, can be caused by many things, :::worn suspension parts, tires, too stiff, PINION ANGLE, chasis flex, suspension flex, shocks, springs...........SO, what did you do, besides adding drag bags??????? Eric :cheers


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## jtwoods4 (Dec 22, 2011)

Man you guys have some nice rear ends.... lol. When I completely deflated the drag bags everything works fine and I get no wheel hop. So I have just decided to use the drag bags when I have 2 full size adults in the backseat. This keeps any of the aftermarket exhaust components from bottoming out or the axle from bottoming out in the transmission tunnel.

Sent from my HTC Vision using AutoGuide.Com Free App


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## ALKYGTO (Mar 29, 2010)

I would consider hardwiring a small air pump into the car hooked to the dragbags so you don't have to fill them from your shop air compressor.


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