Suspension Upgrades - UMI, CPP, GW, etc. - Pontiac GTO Forum
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post #1 of 15 (permalink) Old 02-28-2018, 07:55 AM Thread Starter
 
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Suspension Upgrades - UMI, CPP, GW, etc.

I am looking at upgrading the suspension to coilovers, aftermarket control arms with improved suspension geometry, newer bushings, etc. I am looking for advice / help from folks that have already researched the options.

1. Mark @ SC&C seems to be one of the more highly educated suspension gurus on the Chevy A platform
2. CPP sells a kit, but I don't believe their control arms change the geometry
3. UMI has some nice looking kits - but they are pricey
4. Global West - supposedly their control arms improve suspension geometry as well, but I haven't been able to get any details

One of the big questions I have is : are the control arm upgrades really worth it / needed? Or should I just focus on coilovers and replacing bushings and upgrading sway bars (if needed)?

Then, based upon others research and experience, which companies should I look at / buy ? Thanks

Chris

1965 GTO Convertible 3 speed tri-power drum brakes originally

Current setup:
400 cu in with tri-power
4 speed Muncie
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post #2 of 15 (permalink) Old 02-28-2018, 10:04 AM
 
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I use Spohn and UMI. ( 1968-1972 GM A-Body, Chevelle, Malibu | Suspension & Chassis Parts )

Using stock front suspension arms as I am not auto-crossing. Just Spohn sway bars (front and rear) and Spohn control arms on rear.


Alot of what changes you make depends on how you'll be using your car.
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post #3 of 15 (permalink) Old 02-28-2018, 10:10 AM Thread Starter
 
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Originally Posted by 1968gto421 View Post
I use Spohn and UMI. ( 1968-1972 GM A-Body, Chevelle, Malibu | Suspension & Chassis Parts )

Using stock front suspension arms as I am not auto-crossing. Just Spohn sway bars (front and rear) and Spohn control arms on rear.


Alot of what changes you make depends on how you'll be using your car.
The car is / will be a street car. I like to drive, but given the age and the fact that it is a convertible, I will leave the racing to my shifter kart and other faster cars. That said, the suspension is just too vague and loose for my liking and I would like to tighten everything up a bit. ( I am installing a new steering box with 12.7:1 ratio.) Thanks
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1965 GTO Convertible 3 speed tri-power drum brakes originally

Current setup:
400 cu in with tri-power
4 speed Muncie
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post #4 of 15 (permalink) Old 03-01-2018, 09:50 AM
 
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I went with all CPP parts for my Convertible as well. Price and customer service was great as well as reviews that I looked into. I'm working on the rear coil over/ tubular arms and sway bar now. Looking forward to having a car handle nearly as well as todays car do. Won't be racing either but I live in the mountains and you know how our cars like corners now (NOT)

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post #5 of 15 (permalink) Old 03-01-2018, 02:44 PM Thread Starter
 
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Stich - looks great! I have enjoyed dealing with the folks at CPP in the past with other old classics. I wish I could get confirmation on their control arms and suspension geometry.

1965 GTO Convertible 3 speed tri-power drum brakes originally

Current setup:
400 cu in with tri-power
4 speed Muncie
cij911 is online now  
post #6 of 15 (permalink) Old 03-01-2018, 03:37 PM
 
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This is one of those topics, its best I refrain from commenting on CPP quality. Also have direct experience with the GW tubular arms designed for use with the B body tall spindle conversion, had bump steering issues.... this was on a '69 GTO installation.

last thing, the pic I'm seeing above of the early 8.2 Pontiac rear with sealed axle bearing axles, and looks 295 50's, maybe 315's, will share with both of you, original sealed axle bearing bolt-in axles were not designed for the kinds of side loading forces that wide of tire can put on the prehistoric design sealed ball bearing axle bearings. Coming from my experience supplying cut-off nice used rear 1/4 panels, as well as supplying countless fully checked out new axle bearing installed sealed axle bearing axles... have seen the carnage too many times. Mopar, then Ford & GM went to tapered axle bearing boltin axle rearends for a reason. Today, for the needs of the Ultimate cornering modified vehicles, even large tapered axle bearing retention is frowned upon, & thus one will see very expensive aftermarket rears equippped with full floating axles. Such a full floater isn't needed in the above cases, but such boltin axle sealed axle bearing rears, just asking for trouble.
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post #7 of 15 (permalink) Old 03-01-2018, 05:17 PM
 
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Originally Posted by Pinion head View Post
This is one of those topics, its best I refrain from commenting on CPP quality. Also have direct experience with the GW tubular arms designed for use with the B body tall spindle conversion, had bump steering issues.... this was on a '69 GTO installation.

last thing, the pic I'm seeing above of the early 8.2 Pontiac rear with sealed axle bearing axles, and looks 295 50's, maybe 315's, will share with both of you, original sealed axle bearing bolt-in axles were not designed for the kinds of side loading forces that wide of tire can put on the prehistoric design sealed ball bearing axle bearings. Coming from my experience supplying cut-off nice used rear 1/4 panels, as well as supplying countless fully checked out new axle bearing installed sealed axle bearing axles... have seen the carnage too many times. Mopar, then Ford & GM went to tapered axle bearing boltin axle rearends for a reason. Today, for the needs of the Ultimate cornering modified vehicles, even large tapered axle bearing retention is frowned upon, & thus one will see very expensive aftermarket rears equippped with full floating axles. Such a full floater isn't needed in the above cases, but such boltin axle sealed axle bearing rears, just asking for trouble.
Thanks Pinion Head, I always value your opinion. The wheels and tires in the picture are strictly "rollers" but I will be putting on something like them, I'm sure. It just so happens that in my case, (low budget build) I already know that the rear end is my "weak link" as I'm running a fairly pumped up 455 with a 4 sp and will have to baby it until I can swap it out for a Ford 9" that I'm saving for.
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post #8 of 15 (permalink) Old 03-02-2018, 08:16 AM Thread Starter
 
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Originally Posted by stich View Post
Thanks Pinion Head, I always value your opinion. The wheels and tires in the picture are strictly "rollers" but I will be putting on something like them, I'm sure. It just so happens that in my case, (low budget build) I already know that the rear end is my "weak link" as I'm running a fairly pumped up 455 with a 4 sp and will have to baby it until I can swap it out for a Ford 9" that I'm saving for.
Stich - I thought the Pontiac rear-end could take plenty of abuse ?

Pinion Head - Can you elaborate on the bearing issue and how to modify ? My plan was to run a 10" wheel in the back (18x10) and am curious if I am missing something. (I believe you are suggesting going with a 12 bolt BOP rear or 9" Ford rear ?) Somehow I did not put 2 and 2 together....the 10 bolt on the GTO is an 8.2" which can be a weak link. I really don't want to put a Ford rear end on the car, what do all the purists do 12 bolt with a narrowed rear ? Thanks

Chris

1965 GTO Convertible 3 speed tri-power drum brakes originally

Current setup:
400 cu in with tri-power
4 speed Muncie

Last edited by cij911; 03-02-2018 at 09:26 AM.
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post #9 of 15 (permalink) Old 03-02-2018, 06:54 PM
 
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Originally Posted by cij911 View Post
Stich - I thought the Pontiac rear-end could take plenty of abuse ?

Pinion Head - Can you elaborate on the bearing issue and how to modify ? My plan was to run a 10" wheel in the back (18x10) and am curious if I am missing something. (I believe you are suggesting going with a 12 bolt BOP rear or 9" Ford rear ?) Somehow I did not put 2 and 2 together....the 10 bolt on the GTO is an 8.2" which can be a weak link. I really don't want to put a Ford rear end on the car, what do all the purists do 12 bolt with a narrowed rear ? Thanks

Chris
If you do a search using the red "SEARCH" feature on this forum and type in 8.5" rear end, you should get a lot of hits. This has been covered in depth and at length by Pinion head and he will tell you to go with the later 8.5" Pontiac rear.
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post #10 of 15 (permalink) Old 03-02-2018, 08:00 PM Thread Starter
 
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Originally Posted by PontiacJim View Post
If you do a search using the red "SEARCH" feature on this forum and type in 8.5" rear end, you should get a lot of hits. This has been covered in depth and at length by Pinion head and he will tell you to go with the later 8.5" Pontiac rear.
Believe it or not, with forum searches one is better off going outside and using google and then being re-directed back to the site / thread. I tried several of iterations of 8.5 rear end on here and nothing.
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1965 GTO Convertible 3 speed tri-power drum brakes originally

Current setup:
400 cu in with tri-power
4 speed Muncie
cij911 is online now  
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