Improving GM's suspension, 64 Riviera

[CTX-SLPR]

So I've been dinking around with other threads largely because I've been questioning about specific pieces of suspension design. I've decided to come back to my original thread with specifics on how to design the suspension vs. cluttering up thread about general parameters.

Here's what I've decided to work with and have even started buying parts for.
Frame side is unmodified '64 Riviera
Upright side are C5/6 uprights, just reversed side to side since the car is rear steer. I'll probably be making my own steering arms and/or going rod end style depending on which way I need move the pickup point
Sticking to standard height ball joints since the top isn't really an adjustable point with the C5/6 upright and the lower doesn't do much more than chew up ground clearance for the LCA's
Upper control arm will be modeled after the SPC unit by starting with Riviera bushings and cross shaft and welding on tabs for 5/8in swaged steel rods out to a plate that has the tapered hole for the UBJ
Lower control arms will be box section ending in a tapered piece with a weld on screw in LBJ cup if the K727 will work with the C5/6 upright
Wheels will be Land Rover 18x8 or 19x8 since they have almost the same offset as the C5/6 wheels do without the 9.5in width. They also have 5x120mm bolt pattern with 14mm studs that hold the wheels on with a shank and washer type setup. I'm thinking I'll get a machine shop to redrill the C5/6 hubs for the Land Rover studs and move the pattern in to 120mm vs. the 120.67mm of the C5/6.

Side note, I really like doing the modeling for this stuff. Doing the modeling in excel is a bit crude but I've not gotten the hang of the open source version of my prefered programing language (IDL, open source GDL). Anyway back to what I've modeled it as doing.



So far I'm modeled camber curve, caster curve and anti-dive. I'm sure I'll find more things to model along the way (like instant center) but since I'm sticking with GM's frame side points I'm not exactly flexible on a lot of the parameters.
UCA Length: 12.05in
LCA Length: 19.39in
Static Camber: -0.114º
Camber Gain: 0.42+0.13º/in of compression
Static Caster: 7.38º
Caster Gain: 0.62º/in of compression, 1.25º in extension
Anti-dive: Estimated 51% with a 24in high CG and 67% front brake effectiveness, lower if the CG is higher (remember this is an X-frame car so it's essentially channeled over the frame)

Any of this look concerning? I can't really change the anti dive or change the caster gain since they are locked into the frame side of the suspension.
I plan on trying to reuse the stock springs, shocks, and sway bar for a bit to save money. I'll have to shim the bottom spring mounts since I get a 3in drop from the C5/6 uprights due to the spindle to LBJ height differences and I want 1in of that back. I do plan on going to a set of coil overs and a splined swaybar when I've saved up enough and converted the rear axle.

Thoughts?

[CTX-SLPR]

Ray,

If I understand you, you want to push the lower coil over attach point out to the brake reaction rod attachment for more travel. Since I do plan on using a shockwave, I'm not sure how I'd push it out without the bag hitting the spring pocket on the top? I'm not really interested in cutting the frame up for that kind of clearance. Also the arms will be totally fabricated pieces since the lower arm will be 3.75in longer than stock and the uppers 1.625in longer. I was thinking that tubular was going to be the easiest way of making the lower arms but would have to mount the shockwave on the top of it in addition to the strut rod pickup points. The anti-roll bar could be mounted to the side or over the top I would think.

Thanks,

[exwestracer]

Oops, missed the shockwave part for some reason...

Keep in mind, since your arms will be getting longer outboard of the spring, you are increasing the stress on the arm itself. I'd urge you to have another look at cutting that top spring bucket... The further out you can get that lower shock mount, the less bulk you have to build into the arm.

Having said all that, my opinion is that the stock design (hat channel) is about the best there is for handling the load if you keep the spring near the center of the arm. I'd probably taper the beam height from the ends in to the shock mounting location. Something like this maybe...

[CTX-SLPR]

Thanks,

On cutting the spring pocket... many of the same limitations that restrict me to the stock suspension mounts on the frame side drive my reasoning for not trimming the spring pocket. I am trying to do the best I can with the starting point GM has given me, I see the cutting of the spring pocket as a slippery slope to a whole new front stub. While I reallize this would probably be 20x better, it's not in my time or monetary budget.

I have throught about using conventional coilovers (the steel spring ones) instead of the shockwaves as both a cost savings and as a method of angling the attach point out farther due to the smaller diameter of the unit. Putting a plate in the top of the spring pocket and drilling some holes for locating bolts to keep it from rotating around the central shock bolt point, which would be the main load bearing point, and offset the upper mount as far inboard as possible and the lower mounting point as far outboard as possible to keep things in clearance in full bump.

I think the alternative is to use as long of a shockwave as possible in the stock location and drop it through the arm and gusset around U section where it's missing the upper boxing plate.

[exwestracer]

It's really the distance from the ball joint that is the critical factor, IMO. I'd recommend doing whatever you "can" to get it further out on the lower arm. Personally I think coils are a better choice...

[CTX-SLPR]

Again, mostly lurking and thinking. It looks like I'll have to cut the frame for air ride, though the ridetech instructions only show the need to trim the lip off. If I have to do any cutting at all I might as well do something more productive with it. Now the frame is fully boxed pretty much except for where the bumper brackets bolt on at each end. However it's an X-frame so I have nothing under the door sills. That might be an improvement for a later date however. If I cut the majority of the outer wall of the spring pocket off, will I adversely effect the frame strength? I'll have to get some measurements from Ridetech to see if I can still fit a shockwave in there but I might be limited to steel coils and have to figure out a ride height that will work on the street or maybe enough shock travel to raise the ride height for the street.

How hard is it to build an upright/spindle? It would be nice if I could design out the "drop" in the C5/6 upright so I could run the suspension with flat lower arms while keeping the overall height. I have a mill that I'm learning to use and a MIG so fabrication is not beyond my ability though I'd probably leave final welding to a pro since I'm not that confident in my skills.

[exwestracer]

http://www.colemanracing.com/Spindle...-5--P4710.aspx

These will pretty much do what ever you need them to. You set the ride height by the relative location of the ball joints to the snout. (You may have to build your own ball joint mounts to get the exact drop you are looking for, but it's a great start...)

[CTX-SLPR]

http://www.colemanracing.com/Spindle...-5--P4710.aspx

These will pretty much do what ever you need them to. You set the ride height by the relative location of the ball joints to the snout. (You may have to build your own ball joint mounts to get the exact drop you are looking for, but it's a great start...)

Good stuff though I have no experience with this stuff so what are the bearings associated with the 5x5in hubs and am I restriced to the brake parts from Coleman as well?

Thanks,

[exwestracer]

Good stuff though I have no experience with this stuff so what are the bearings associated with the 5x5in hubs and am I restriced to the brake parts from Coleman as well?

Thanks,

Probably Chevy Impala, but I'd ask. They don't use anything too oddball. (the ones pictured are Wide 5 3/4 ton Ford pickup snouts) Everything bolts on to that spindle, so you can adapt whatever brake system you want to use. Coleman has brackets for GM and common aftermarket calipers, but the rotors are likely smaller than you'd want on a PT car. They build everything to fit in a 15" wheel.

[CTX-SLPR]

Probably Chevy Impala, but I'd ask. They don't use anything too oddball. (the ones pictured are Wide 5 3/4 ton Ford pickup snouts) Everything bolts on to that spindle, so you can adapt whatever brake system you want to use. Coleman has brackets for GM and common aftermarket calipers, but the rotors are likely smaller than you'd want on a PT car. They build everything to fit in a 15" wheel.

Looks like they use the same bearings as stock on the Riviera according to this post: http://www.lateral-g.net/forums/show...6&postcount=44. A BR5/3 combo vs. the later BR6/3 combo found on the 77+ B-body. That works well for not having to change over my rear axle bolt pattern and I already have a set of '68 Wildcat drum brake hubs that I planned on using to mount discs before I started on the idea of redesigning the front suspension. I think you just gave me a gold mine Ray!

Now do you think cutting the entire wall out of the spring pocket will hurt the frame rigidity?

Anything ever happen on that '63 you were trying to look at?

[exwestracer]

If the Riv is anything like every other GM front clip I've ever worked on, no. What we typically do is add in a doubling plate around the inside of the old spring pocket. That area should be shaped like a truncated cone, with the top being the actual upper perch. If you can form a piece of 12ga steel to fit up in there and weld it around the bottom and top, it will likely be stronger than it was before.

Never heard back from the guy who supposedly had a line on the 2 Rivs....oh well.