Make it handle

[GEARBOXGARAGE]

I've been following this thread for a while and have looked over the posts several times, but I haven't seen much of an answer to a topic that was covered around pages 8, 9, and 10. The topic was about anti-squat and that brought up the theory of swapping or changing the trailing arm mounts to reposition them higher at the crossmember. One member asked what a recommended pinion angle should be, but I seem to have lost the exact location of that post. Robnolimit, you comment that getting the right pinion anlge is free horsepower. Do you have a recommended pinion angle and could you give a little insight on if/how pinion anlge affects handling or perfomrnace?

[wickid demon]

I have a question, how do you calculate your roll center and the best ways to lower it. I know you can lower your motor and gat as much weight down low but can you lower it with A-arm geometry?

[PBFAB.COM]

Originally Posted by wickid demon

I have a question, how do you calculate your roll center and the best ways to lower it. I know you can lower your motor and gat as much weight down low but can you lower it with A-arm geometry?

The roll center is a product of the suspension geometry.... so any changes to it are done my modifying the suspension design.

Lowering the motor will lower your center of gravity.

[wickid demon]

Brain fart I ment center of gravity. I knew the roll center would be effected. Let me try again center of gravity?
Posted via Mobile Device

[jimmydean]

Nate, how about the cantilever setup? What are some of the advantages I will get with that? Will keeping it a longbed hinder the performance? I was considering a mid sized bed, I would rather not go full short since everyone runs short.

I ask here since others might benefit as well from your insight.

[robnolimit]

Originally Posted by GEARBOXGARAGE

I've been following this thread for a while and have looked over the posts several times, but I haven't seen much of an answer to a topic that was covered around pages 8, 9, and 10. The topic was about anti-squat and that brought up the theory of swapping or changing the trailing arm mounts to reposition them higher at the crossmember. One member asked what a recommended pinion angle should be, but I seem to have lost the exact location of that post. Robnolimit, you comment that getting the right pinion anlge is free horsepower. Do you have a recommended pinion angle and could you give a little insight on if/how pinion anlge affects handling or perfomrnace?

Pinion angle is mostly related to the engine/trans. How the pinion angle moves, as the suspension moves, is related to the suspension geometry. Ideally, the Pinion angle should be parallel to the crank angle when the truck is at ride hieght at 60 mph. (it takes some suspension load to run a constant 60) So, if the eng/trans is set in place at 3* up in front, then the pinion should be 3* up in front. Now here's the catch, under load, the axle/suspension will rotate upwards. Trailing arms will go up 1/2 degree, 4-bars = 1 deg, leafs will go 1* to 1 1/2*. So depending on the suspension type, you need to set the pinion slightly lower so that it will rise up under load.

[robnolimit]

Originally Posted by wickid demon

Brain fart I ment center of gravity. I knew the roll center would be effected. Let me try again center of gravity?
Posted via Mobile Device

CG is tough to calculate 100%, but you can get pretty close. You need to weigh the truck, and get the front/rear balance. Once you have that, you can get a close estimate. Lets say the truck has 57% front weight, then the front-to-rear balance point is 57% of the wheelbase. The wheelbase is 114", so the balance point is 65" forward of the rear axle CL. (114" x .57) That gives you the front/rear line. You can do the same for side/side if you want to account for any weight offset there. For the hieght of the CG, in a car, you can use the cam centerline as an average, for a truck, it's cam centerline + 3". If you have four corner scales, there are programs, like from AutoWare, to nail it down. You weigh the truck on level ground, and then lift the scales on one side 10" and weigh it again. enter the weights, wheelbase, front and rear track width, and it will spit out the exact location.

[robnolimit]

Originally Posted by jimmydean

Nate, how about the cantilever setup? What are some of the advantages I will get with that? Will keeping it a longbed hinder the performance? I was considering a mid sized bed, I would rather not go full short since everyone runs short.

I ask here since others might benefit as well from your insight.

I'll let Nate run with the Canti-lever set up on this one. As for wheelbase. shorter is better. Most pure roadcoarse racers follow the rule of WB = track width x 1.5. A C-10 will have a track O.D. of around 68", so 68 x 1.5 = 102" this would be the ultimate road racer C-10, but wouldn't haul much, and lok really goofy. From there, higher speeds = longer WB, lower speeds = shorter WB. Porsche 911 - 67"TW, 104 WB.

[jimmydean]

Thanks for the rule of thumb, Rob. I will play more with wheel base and as the build gets closer, Nate and I will work specifics. I was going with the C4 setup to keep with the theme of the build. But the more I talk to people, the more I am learning just how well this might work out.

I am not looking to race hardcore. But I will take it out and see what it can do against my buddies at some local events when its done next year.

[PBFAB.COM]

Originally Posted by jimmydean

Nate, how about the cantilever setup? What are some of the advantages I will get with that? Will keeping it a longbed hinder the performance? I was considering a mid sized bed, I would rather not go full short since everyone runs short.

I ask here since others might benefit as well from your insight.

Rob... I still feel a little stange posting replies in your thread, and appreciate the fact that you have told me several time it doesn't matter... as long as it helps the cause! I just try to be as respectful as I can, and don't want to take away from all the time and energy you have spent sharing your knowledge with members of this forum.

Jimmy... there are a handful advantages to the rocker arm set-up, other than it just looking cool.... here are a couple that come to mind right off the bat.

- It can help in packaging the components when space is at a premium.

- It can allow you to change the rocker ratio and have infinite adjustment in spring rate. You can do all sorts of things by tweaking and changing the rocker arms and their geometry.

[jimmydean]

The rocker ratio was my first thought, and I saw a post from Josh who had it on his custom frame (pic above). I am so giddy with anticipation.

Adding the adjistability of the select ride shockwaves make for some added refinement as well. I will play with wheelbase numbers and weight tonight.

[robnolimit]

Right you are Nate. The ratio is the big advantage. if you use a 4" stroke shockwave, and build a 1.5 ratio rocker arm, you would have 6 of travel available. Also, the 7000 series shockwave will yield appx. 350 lb/in spring rate at 75 psi. On the rocker arm with a 1.5 ratio it will net out at appx. 233 lb/in, which is right in the range you want.

Nate, one expert sharing his knowledge may be seen as opinionated. A group of experts sharing the same same knowedge will set the standards and help shape the future.

[GEARBOXGARAGE]

I see Hotchkis now has 2" front lowering springs, but at a 1500 lb/in rate. This seems kind of high compared to what has been mentioned previously in this thread..... Any thoughts?

[robnolimit]

This goes right to your "set up theory", or plan. you only get to choose one, no mixing to get good results. - 1)soft spring/big bar/low RC. -or- 2) stiff spring/soft bar/high RC. Now somewhere in the middle is med spring/med bar/med RC, but lets choose option 1 or 2. O.E. C-10 geometry nets a pretty high RC, as it should, it's truck after all. So it sort of forces you over to option 2. I have to say that for me, 1500 lbs seams stiff, but, depending on the shock and swaybar, it could work. Remember, if you drive it everyday, and it's not a dedicated weekender, you need to be comfortable in it too.

[GEARBOXGARAGE]

Rob - Yeah, it's more of a weekender and plan on hitting the local track occasionally. I would be matching up the rest of Hotchkis front end components and a custom coilover set-up out back using QA1 shocks all around. I don't mind giving up some ride quality for added performance. I noticed you used the MOOG bick block springs and just cut a coil off. Have you been satisfied with that result?

[robnolimit]

I am really happy with them, it yields appx 1200 lb spring rate, smooth and good handling. For a dual purpose driving, adjustable shocks can be a big help.

[gringoloco]

Originally Posted by gringoloco

Rob, any info on installed dimensions on those f8000s? Can't seem to find them online...
Posted via Mobile Device

Anything on this? Looked everywhere I know to look and can't find info on these. Wondering if installed height would work in factory position on trailing arms...
Posted via Mobile Device

[71shortwide]

awesome thread! Rob and nate and everyone else thank you for your i have learned alot about handling! I just cant make up my mind on my 57 truck or my 82 chevy!

[robnolimit]

hmm, the 9000 bags are 4.5" closed, 12" oper, spec ride height at 9" - 9.5". Oops, '7000' series, (1000 to 1200 lb cap.) they are 4" closed, 13" open, and 8" to 9" RH

[Jonboy]

Originally Posted by robnolimit

I am really happy with them, it yields appx 1200 lb spring rate, smooth and good handling. For a dual purpose driving, adjustable shocks can be a big help.

Do you happen to have a part # for these?

[Matt R]

Originally Posted by robnolimit

Yes, the taller ball joints will add some camber gain. Sounds like a good plan. You can drill and thread the end of the bar, but remember it's tempered. You can also cut about 1" off of the end of the bar and weld a tab up on the end. The piviting link is a good idea.

So does this apply to the stock sway bar? I guess I was under
The impression your not supposed to weld sway bars or springs.
If it is ok that would be an easy way to make a bar adjustable.
Or stiffen it up if needed.
Posted via Mobile Device

[GEARBOXGARAGE]

Originally Posted by robnolimit

Spring rates for stock style C-10's seem high, but this is do to the A-arm ratio. Here are some stock spring rates
Moog # 6082 722 lbs/in 6 cyl, and light v-8
Moog # 6542 842 lbs/in std v-8
Moog # 6102 1015 lbs/in bigblock, longbed c.s.
Moog # 6104 1016 lbs/in 3/4 ton, sits 1/2" higher than #6102
Moog # 6454 1060 lbs/in 3/4t bbc, c.s, 1ton
So, Hotchkis' 1100lb may not be so heavy. I currently have the #6082 spring with one coil cut in the JT project, and it is too soft for me. I'm going to swap in the #6102 springs next week. Going to track test it tues. with the soft springs. All my number crunching shows me a 950 spring, but we'll see.
When it comes to frame boxing, i'm not a big fan of full chassis boxing, as it can lead to a cracked frame. Bracing key areas, and creating triangles is a better aproach, check the earlier posts.

Jonboy.......We're refering to the Moog # 6102. robnolimit posted this a ways back.....

[robnolimit]

Thanks, I was just going to post that.

[INSIDIOUS '86]

Originally Posted by Matt R

So does this apply to the stock sway bar? I guess I was under
The impression your not supposed to weld sway bars or springs.
If it is ok that would be an easy way to make a bar adjustable.
Or stiffen it up if needed.
Posted via Mobile Device

If one drills multiple positions for the end link on the swaybar then yes it will be adjustable.
Posted via Mobile Device

[Matt R]

Originally Posted by INSIDIOUS '86

If one drills multiple positions for the end link on the swaybar then yes it will be adjustable.
Posted via Mobile Device

My question was regarding welding tabs to the swaybar as mentioned in an earlier post.

Thanks, Matt