#1  
Old 07-16-2019, 05:49 PM
avman avman is offline
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Arrow Coilover conversion for 65 GTO Quick Performance Ford based 9" and UMI

So last August I had a QP Ford 9" based highly optioned rear axle assembly installed in the 65 GTO. UMI roto joint equipped UCAs and the lift bar LCAs...
Also got the upper control arm mounting point brace.
QP welded regular lower control arm brackets to the powder coated rear axle housing, so they have to remake it.
I also went with new Moog standard height springs and new adjustable drag shocks. Because of the spring perch design of the QP rear axle housing, I had to eliminate the air bags, and I thought that the new springs would result in a level ride height but it looks like a boat in the water, the rear is too low.
I also barely missed the correct measurement in narrowing the rear axle housing so I had to install 1/4" spacers behind the wheels to keep the tires from rubbing on the inside wheel tub.
I figured that if I wanted to switch to coilovers I could just buy a kit, but that is not as easy with an aftermarket rear axle.
So given the ride height problem, I am having the new rear axle housing setup for coilovers from the get go. I am also adding 1/4" in width to both sides, to eliminate the spacers and still hope to have enough axle spline engagement so as to not have to have new axles made.
Both Quick Performance and Global West independently without consulting with each other came to the same conclusion:
Putting the coilovers in front of the rear axle housing, welding an attachment point to the frame by the top of the spring perch, and that way the adjustable lower lift bar brackets will not interact or interfere with the coilover mounts, and unlike the conversion kits that focus the weight of the body being supported by the shock attachment point, the body weight will be supported by the coilovers in the factory location-based the spring perches. (Note: Global West has a solution for that by including a crossmember in their coilover conversion kit, but because of the mounting points on mine being located on the frame by the spring perches, instead of the weaker shock connection area, that isn't required in my case)
Here are a couple of examples of what Quick Performance had recommended, and the picture of the "eyelet" mount in the spring perch for the coilover to mount to is basically what Global West has suggested as well.
What do y'all think and has anyone done or seen this?
Thanks!
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  #2  
Old 07-24-2019, 11:20 AM
avman avman is offline
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Bump hoping for some replies!

  #3  
Old 07-25-2019, 12:44 AM
avman avman is offline
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No one??

  #4  
Old 07-25-2019, 07:23 AM
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Sirrotica Sirrotica is online now
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It's probably fine due to you're keeping the coilover in the same space that the factory designed the spring to be, no deviation from the OEM design means that you probably will have the same characteristics of the OEM design.

If QP has used that design already it's pretty much already proven to work. I wouldn't worry about it functioning properly if it's a proven design.

One question in my mind would be why are you using fixed position coilovers, as opposed to adjustables? Seems it would be preferable to have the adjustable coilovers as opposed to mechanically moving the attachment point for ride height.

If you want an infinitely adjustable suspension I'd keep the air bags without the steel springs. I have air ride in the rear of my dually and love it for comfort and height adjustability, I can also adjust it to what I'm hauling as far as weight requirements. There is no smoother ride. Mine is a 4X4 and I have a plan worked out to air bag the front end too so it rides better and will support the snow plow when it's on the truck.

If you're racing it and want the repeatability of steel springs you're probably on the right track. I have air bags inside of the steel springs on my 05 GTO and have entertained the thoughts of pulling the steel coils out in favor of straight air ride bags. But this car is strictly a street car, and I'd like to improve the ride over the steel coils with air bags inside of the springs.

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  #5  
Old 07-25-2019, 07:05 PM
avman avman is offline
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Thanks for the reply!
Yes, more cruising than racing the 1320, but the tweaked out, maxed out rear suspension is to maximize traction on the drag strip.
The coilovers ARE adjustable, the bottom picture is from QP, and that allowed for height adjustment independent of making changes to the coilover collar position.
My concern was being able to achieve AT LEAST stock ride height, because so many people who convert to coilovers are looking for a lower than stock ride height.
I can't use the air bags that used to hold up the rear end because the QP spring perches (at the rear axle end) don't allow for them. I could go air ride, but I think springs in the coilovers are going to help me get dialed in and keep it that way.
According to Global West, they are going to present their bracketing hardware solution to me soon.
I am encouraged by separate companies coming up with similar solutions independent of each other.
In other words, it's GOT to work.

  #6  
Old 10-14-2019, 07:30 PM
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Ok. Cruisin the Coast 2019 is in the rear view mirror...That's the only vacation my wife and I take every year, and this year we drove back and forth each day vs staying there. Now I can move forward with new parts and plans for my wife's GTO and my Roadrunner.
I had a 3.54 ring and pinion gearset in my 440 Roadrunner from the factory, and with a similar (slightly shorter overall) diameter 17" wheel and tire combination as the 17" wheels and tires on the GTO, which got 3.80 gears in the Quick Performance Ford based 9" rear axle assembly, I used to turn 3,500 RPMs at about 72 mph, so I know the 421 in the goat must be turning around 3,800 at the same speed...With my .70 5th gear in the 5 speed I installed in the Roadrunner, and the 4.10 ring and pinion gearset I swapped in at the same time, I dropped 750 RPMs to 2,750, and launches and 2nd gear are a lot more fun.
So we bought a TKO 5 speed system for the GTO and I selected the .64 5th gear to minimize the RPMs in 5th. I also got the 2.87, 1.89, 1.28, 1.00 1st-4th gears. I think that the 3.27 1st gear would have been too steep, and the mathematical formula that they use for optimal launch performance placed the combination of the 3.80 and 2.87 (vs 3.27) right in the sweet spot for performance. Even though I installed a new street/strip clutch disc and pressure plate 3 years ago when we had the engine rebuilt and performance enhanced, since I needed a new clutch disc, I decided to go with the pressure plate they recommended as well. I added the White Lightning shift tension adjustable shift module. Also added a Lokar shift lever she wanted. Total w/free shipping came to $3,900 and that includes a new driveshaft once I have the measurements. This includes transmission case modifications for fitment.
I will have confidence that I won't have to worry about breaking the transmission with the new power the 421 is putting out since the rebuild, and I am going to send the 3 Rochester 2bbl carbs to Dick Boneske finally to have him mod them to get the most of of the upgrades to the 421. Since the rebuild of the 421, and All American Carburetors only did a stock "restoration" of the carbs (great job, but not what we really needed) we are leaving A LOT of power untapped. Better shifting and less wear and tear on the relatively new 421 are bennies as well.
I also got an exact fit Vintage Air AC system and a CVF Wraptor serpentine belt system for the GTO and the Roadrunner. Both cars will have Dakota Digital dash gauges, and I got a Hydramax hydraulic throwout bearing for the Roadrunner, and I am getting the HitMaster launch control system to go along with that. If that combo works as well as I expect, according to a number of reviews, I will likely do the same for the GTO.
I got Cold Case radiators for both cars, I needed a radiator anyway, and this way they are ready to keep the engines cool even with the new AC systems and the sweltering heat and humidity in the deep South.
I have to wrap up with Global West and get that new replacement rear axle housing from Quick Performance, and the coilover conversion parts lined up so we can get the rear of the car raised to make it level.
Between now and next October, that is a LOT of upgrades, but they will add to the reliability, performance, longevity, and enjoyment we get from our cars.
I will post up what we wind up with regarding the rear axle coilover conversion setup.
Thanks for the replies. I'm still open for comments and suggestions regarding the coilover setup on the GTO.

  #7  
Old 10-15-2019, 09:43 PM
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Sounds like you got everything you and I talked about ironed out. I’m still plugging away but seem to be making decent progress.

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  #8  
Old 11-06-2019, 06:40 PM
avman avman is offline
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So Global West has "fabbed up some parts" for me that is going to allow me to change over from the factory geometry/design of separate shocks and springs to COILOVERS that will mount to the rear axle at the bottom and the SPRING PERCH area of the frame at the top. This doesn't require the cross bar that Global West usually includes in their coilover conversion system, which is designed to reinforce the SHOCK mount area so as to not pound out the shock mounts. As far as I can ascertain, the parts they made for me and the manner of installation will put the coilovers in front of the rear axle housing rather than behind it. That is how they USED TO design their coilover conversion kit, but I think they switched over to the crossbar w/shock mount location because that is easier, more of a bolt in versus WELD IN setup.
Since this is the LAST layout design of the rear suspension for our GTO, I am absolutely fine with the associated parts being welded in. Actually I prefer that at this point. I feel sorry for those who attempt to support the weight of the body by the shock mounts, using basically every OTHER MANUFACTURER'S conversion kit. It makes A LOT more sense to use something like the setup they have blessed me with (I still have to pay for it, I just feel like it is something special they made for me) where the coilovers use attachment points that are designed from Pontiac to support the weight of the body to begin with.
Pictures of the parts to follow!
I'm pretty excited now!

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