PDA

View Full Version : 1969 gto ragtop



Shawn01754
04-08-2017, 06:50 PM
Hi Ron, congratulations on your recent win! Love that 69 gto also. Question for you. Ive got a 69 gto convertible, with an aluminum head pontiac with just under 600 hp, its got AC and hide aways (a bit heavy). Ive installed helwig front and rear bars (chasis model). I have 1" drop hotchkis big block springs in the front and 2" hotchkis drop springs in the rear. Ive got CPP-C-5 spindles/ discs & calipers in the front. Also have the hotchkis front upper and lower arms. The rear has umi roto joint lowers and the upper adjustable control arm. Also have the 4 speed braces. Plan on kore 3 rear disc (already have the rotors and calilers)I did all energy suspension hyper flex body mounts. Ive got 255/40/18 michelin suler sports on budnik wheels for the front and 295/35/19 on the rear. Its more of a cruiser, but my question is: should i look at the adjustable front upper control arms? Any recommendations? Any advise is appreciated.

Ron Sutton
04-09-2017, 07:33 AM
Hi Ron, congratulations on your recent win! Love that 69 gto also. Question for you. Ive got a 69 gto convertible, with an aluminum head pontiac with just under 600 hp, its got AC and hide aways (a bit heavy). Ive installed helwig front and rear bars (chasis model). I have 1" drop hotchkis big block springs in the front and 2" hotchkis drop springs in the rear. Ive got CPP-C-5 spindles/ discs & calipers in the front. Also have the hotchkis front upper and lower arms. The rear has umi roto joint lowers and the upper adjustable control arm. Also have the 4 speed braces. Plan on kore 3 rear disc (already have the rotors and calilers)I did all energy suspension hyper flex body mounts. Ive got 255/40/18 michelin suler sports on budnik wheels for the front and 295/35/19 on the rear. Its more of a cruiser, but my question is: should i look at the adjustable front upper control arms? Any recommendations? Any advise is appreciated.

Hey Shawn,

Sounds like you have a good handle on your package. I'm not a fan of the adjustable UCAs, because under hard cornering loads we've seen & measured them flexing, so the geometry moves around. One advantage they have, is it is easier to add caster or camber. I suspect your car's handling would benefit from more caster. But as a Cruiser (your words) you don't need max caster. Hopefully you can get 5° to 6° ... which is fine for a street cruiser. If that's the case, I'd stay with the package you have.

You didn't mention shocks. That is another place you can gain some grip & handling performance. Since you're not Autocrossing or Tracking the car (I'm assuming) ... There's no need for super trick valving like my Track-Star shock valving. But you could benefit from a set of Ridetech single adjustable shocks with their standard valving or my "Street-Star" valving if you want it a little more sporty.

:cheers:

Shawn01754
04-09-2017, 08:59 AM
I was going to ask about shocks. You read my mind. I was looking at viking double adjustable. There for if i wanted to go to coil overs in the future i would have a threaded shock. I do have to say the coils felt really nice down a winding, bumpy road. Drove more like a subaru than a gm old musclecar. The car is in the shop getting full paint so I havent experienced the whole package yet. Shocks I do need. I have some old KYB. Ill check out your street stars. They sound perfect for my ride.
Its almost time to get my 1980 trans am on the progect list. With roughly $3000 budget for susention. Im a bit flexibility to spend a bit more, any suggestion there. Thanks!

Ron Sutton
04-10-2017, 08:51 AM
I was going to ask about shocks. You read my mind. I was looking at viking double adjustable. There for if i wanted to go to coil overs in the future i would have a threaded shock. I do have to say the coils felt really nice down a winding, bumpy road. Drove more like a subaru than a gm old musclecar. The car is in the shop getting full paint so I havent experienced the whole package yet. Shocks I do need. I have some old KYB. Ill check out your street stars. They sound perfect for my ride.
Its almost time to get my 1980 trans am on the progect list. With roughly $3000 budget for susention. Im a bit flexibility to spend a bit more, any suggestion there. Thanks!

Most car guys don't know shocks inside & out. They look at what's popular or brand names they've seen over the years. But the technology gap between shock brands is vast. Brands that I grew up with & loved were once leaders in the field. Today, in my opinion, they are lax because they're selling a zillion shocks to the OEMs & aftermarket ... based on that great brand name recognition. These are quality shocks from quality companies. They'e just using old technology. There are a lot of other common brand shocks ... some new & some old ... some from racing & some not ... that are also quality pieces ... just old technology. First, anything of twin-tube design is going to be slower reacting than a monotube design. I don't even work with any shocks that are not mono tube ... because I know the grip is going to be significantly inferior.

I'll try to share a visual example with you ...
Let's say you, I & a buddy grab a 10' straight edge & go to ANY corner of ANY racetrack in the country. We lay it down & put a light under one side & look at all the low spots, know as undulations in the track surface. In 10' we'll find 4-6 undulations. If we run that corner in your car at 68 mph, the suspension needs to respond 4-6 times in 1/10 of a second ... to keep the tire contact patch on the track. If it was a tight AX course & we were running 34 MPH, the suspension needs to respond 4-6 times in 2/10 of a second ... to keep the tire contact patch on the track. So suspension weight, wheel & tire weight, friction & stiction in the suspension ... and shock & spring response ... all play a role in whether we kept the tire contact patch on the track surface (grip) ... or didn't (loss of grip) ... when turning.

A typical twin tube shock will respond in 25-30 milliseconds. Sounds fast, but it's not. A Monotube ... with the right internal design & piston design ... will respond in 5-6 milliseconds. The other part overlooked is the spring. All spring steels will create similar spring rates, but the responsiveness of the springs are different. Crappy OEM springs ... as well as the springs from most local spring shops, old spring companies & import spring companies use 2000 series spring steel. In the racing world, we consider springs made of cheap 2000 series spring steel as "dead" or "lazy" because they respond so slow. These springs sag easily, deform easily & lose rate easily ... because the quality of the steel is poor. Any of the 4000 series spring steels are twice as good. We see less sag, deformation or rate loss. The response rate is better & therefore grip is better. So is steering response, especially through switchbacks or chicanes. 5000 series spring steel is significantly better than 4000 series spring steel. We rarely see sag, deformation or rate loss ... and they have even faster response & grip with 5000 over 4000. But the best springs are made with 9000 series spring steel. No sag ... ever. No rate loss. No deformation. And the fastest response rate. We've put 9000 series springs on a car that had 4000 springs ... same rate ... and picked up several tenths of lap time. No other changes. Just more grip & a quicker responding car with better springs.

Back to shocks. I only work with 4 brands of shocks these days. ARS (Advanced Racing Suspension), JRI, Penske & Ridetech. Ohlin's are bad ass too. I just don't have as much experience with them. All the trick valving stuff we do with ARS, JRI, Penske & Ridetech/Fox are because these shocks respond in the 5-6 millisecond range. I won't revalve other shocks anymore. Why? Because the valving doesn't matter if the shock is not keeping the tire on the track.

So in conclusion ... I recommend you look at the monotube design shocks, with modern internal designs. Of those brands, Ridetech has the best street performance shock, best warranty & best customer service. Their single adjustable coil over is the best bargain going for $265 each as of this post. We run the Hypercoil springs (4000 series steel) on most street applications & we run Draco springs (9000 series) on all of our AX & track focused cars.

Hope this helps !

Shawn01754
04-10-2017, 02:30 PM
Thanks. Thats great info. Ridetech it is. Helped a lot. I never knew