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Old 09-14-2010, 07:23 PM   #76
leftcoast66
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Re: Make it handle

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Originally Posted by robnolimit View Post
LeftCoast, Start with a plan. Wheel and tire size are important to know so you can establish axle/spindle center hieght and ride hieght. Give yourself 3 to 4" above the axle for travel, then lay out your rear step design. Do your best to keep the lower A-Arm level or running downhill 3 to 5 degrees at ride height.
but a copy of Herb Adams suspension book. If your a computer guy, buy a copy of "suspension geometry pro" Knowledge is power, and it is way cheaper to do it right the first time.
Thanks for the tips on that. I've got a notebook with all of my scribbles on those, and Herb's book is sitting next to my bed. That computer program sounds great, I'll pick that up and start playing with that. Its a huge help, so thanks for the tips, I'm sure I'll have more questions along the way, but its a great place to start learning more.
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Old 09-15-2010, 12:38 PM   #77
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Re: Make it handle

Here's a quick lesson we learned, or re-learned last night. We have a local road coarse that runs 'time-attack' on tuesday nights. It's a great place to test, and a heck of a lot of fun. A frustrated group with a pretty nice 32 roadster were unhappy with its handling, and set out to fix it. - Its a good runner, and it handles well. They unhooked the rear swaybar, AND make a big change in brake bias, shutting down the rear brakes as much as possible. Next run they spun the car into some tires, and ground it down the track curb. Scuffed paint, tweeked fender tip, (slight), and a tore up lower A-arm.
Lesson 1: ONE CHANGE AT A TIME
Lesson 2: DOCUMENT YOUR CHANGES - AND THE RESULTS
Lesson 3: FEEL THE CAR OUT AT LOW SPEEDS FIRST
I know not everybody has a test track available, but you can lay out a test run area on a back road. As you run it, note your speed or rpm through different areas, check tire temps at the end of a run. We use a hand help heat gun. check the temps at the center, and each side of the tread (inside/ouside) Compare your temps. Hot in the center - too much air. Cool in the center - low pressure. Lets say temps run 122 outside, 128 center, 136 inside. - too much neg camber. This is a great tuning tool. give it a try.

Last edited by robnolimit; 09-15-2010 at 12:40 PM. Reason: spelling
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Old 09-15-2010, 03:45 PM   #78
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Re: Make it handle

Did you do this backroad testing between the pizza place and the house ? I remember the 46 really likes that road..... and I didnt believe you when you said that car is like a good horse and knows its way home.....
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Old 09-15-2010, 04:20 PM   #79
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Re: Make it handle

hey, we made it home. that is a good test road. Waterman canyon is good too, but next time you're out here I'll take you out to Adams in the 'Bullit. We'll stop by Wally-mart and get you some depends first.
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Old 09-15-2010, 04:43 PM   #80
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Re: Make it handle

Depends.... ??? why did you finally put carpet in that thing?
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Old 09-15-2010, 05:22 PM   #81
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Re: Make it handle

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is the increased caster 'potential' on ride techs a-arms from both top & bottom arms or ?? I didn't know if the uppers or lowers were responsible for the increases.
ttt......
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Old 09-15-2010, 05:42 PM   #82
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Re: Make it handle

uppers......
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Old 09-15-2010, 08:23 PM   #83
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Re: Make it handle

Uppers? Downers? white ones, red ones? what??? Ohhh, A-Arms. got it.
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Old 09-15-2010, 10:43 PM   #84
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Re: Make it handle

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uppers......
Thanks!
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like a highly skilled Morrocan sword fighter with a Damascus Steel Scimitar.

Cubic inches is like Indiana Jones with a cheap pistol....
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Old 09-17-2010, 12:39 PM   #85
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Re: Make it handle

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Old 09-17-2010, 03:30 PM   #86
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Re: Make it handle

OK, so we finially figuered the video load out. Pretty cool. This was the winning run in Costa Mesa. A good teazer for ya.
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Old 09-17-2010, 06:38 PM   #87
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Re: Make it handle

Fun stuff Rob, thanks for sharing. I noticed that it ran very flat through most of the course. Almost zero tire squeal until you drifted through the S turn.

Looks like a fun way to spend the day. Once I get my 77 back together, I'll have to give it a try.
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Old 09-17-2010, 08:23 PM   #88
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Re: Make it handle

Yeah it was a lot of fun. We'll be at the Tx Goodguys in a few weeks, come by and see us.
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Old 09-17-2010, 08:24 PM   #89
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Re: Make it handle

Sometimes a little drift is the fast way around, - a lot of drift is not
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Old 09-17-2010, 08:26 PM   #90
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Re: Make it handle

should i get RideTech contingency? Nice sticker placement
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Old 09-17-2010, 10:59 PM   #91
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Re: Make it handle

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Yeah it was a lot of fun. We'll be at the Tx Goodguys in a few weeks, come by and see us.
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should i get RideTech contingency? Nice sticker placement
I think you should hit Tony up. I'm sure that would be good for a burrito at Ft Worth.

I'll be in Ft Worth as well, with the 77 in the Ride Tech display.
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Old 09-18-2010, 02:16 AM   #92
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Re: Make it handle

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Yeah it was a lot of fun. We'll be at the Tx Goodguys in a few weeks, come by and see us.
Rob
Truck looked good going around the cones,we will be in texas as well
see you there.
Justin
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Old 09-18-2010, 10:18 AM   #93
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Re: Make it handle

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Rob
Truck looked good going around the cones,we will be in texas as well
see you there.
Justin
Justin- You guys bringing anything to run, or just coming as a vendor?
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Old 09-18-2010, 01:49 PM   #94
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Re: Make it handle

OK class, todays topic, rear locators. I chose my words carefully. Diagonal locators, Panhard rods, Watts link, wishbone,...... there are many. More than one way to skin a cat. for street performers, I like a panhard rod. I know, many favor other types. I have two reasons. 1. K.I.S.S. - keep it simple stupid! - fewer moving parts, easy to set up correctly. 2. Panhard rods allow you to set the rear roll center, and adjust it easily, without a complicated formula. While we may think (dream) about a high roll center with a low center of gravity, we are playing with trucks, not corvettes. High roll centers on the back of a truck will help keep it flat, it will also keep it spinning around. The high roll center plan works if you have a low C.G. and close to 50/50 weight balance. We dont get those with a p/u. So, you need to create some "side bite" to keep it on line.The lower you roll center the more side-bite you create, thats a plus, also, the lower the R.C., the more the truck leans over (bad). Thats why you need to be able to test/tune. Here's some tips. Made your panhard rods as long as possible, this has less angle change and pulls/pushes the rear less side to side. (Radial Deflection) Try to keep the P.R. close to level at ride height. If you are building mounts, put two or three mount holes on each set of brackets - housing and chassis. Try to start with a centered mount (height) about even with the axle center (height). You can tame some of the induced roll with a sway bar, but this also reduces side bite. It's all a balance. some amount of body roll is OK, as long is you can tune out its bad and keep its good effects. In a truck, at some point you will have to rely on the outside tire to keep you on line, and the tire will be the limiting factor. The trick is to tune up to the ability of the tire, with just enough side bite to keep it stuck.
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Old 09-22-2010, 03:53 PM   #95
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Re: Make it handle

Did I go too fast on that one?
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Old 09-22-2010, 04:57 PM   #96
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Re: Make it handle

Can you briefly explain what you mean by rear roll center? feel dumb for asking but I just want to make sure I understand what you are saying here
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Old 09-22-2010, 06:16 PM   #97
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Re: Make it handle

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Can you briefly explain what you mean by rear roll center? feel dumb for asking but I just want to make sure I understand what you are saying here
Don't 'feel' dumb for not knowing; it's a good question.
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Building a small, high rpm engine
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Cubic inches is like Indiana Jones with a cheap pistol....
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Old 09-22-2010, 09:04 PM   #98
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Re: Make it handle

Not a problem. Sometimes I go by this stuff so fast I get lost myself. Lets start with "roll center" or R.C., or RC for us lazy ones. The RC is the point that the truck wants to pivit around. OK, may have lost ya. When you put your truck into a corner, there are all sorts of things happening. The laws of physics are acting out all at one time. And all of these forces add together to force the truck to lean over. The RC is the pivit point, and we can change it, a bit. If you think of a picture of a truck, from straight in front of it, you would see it the front view. If you could mentally 'cut the picture out' and then hold it with a tack, you can imagine rotating the truck around the tack - ya? if you put the tack between the front wheels, even with the ground, this would be a LOW RC. And, no matter where you push on the truck, it tips over easily to the other side. Now imagine the tack throught the mirror, at the top of the winshield, and if you push on most of the lower part of the truck, it leans the other way. A HIGH RC. Now RC is only important when you compare it to something, like CG (center of gravity) think about this as the center of mass, or the balance point. Front to back is easy to understant. its the balance point front to rear. But height wise, theCG is the point at which there is equal weight above and below. For a standard, most vehicle CG hieght is about the center of the camshaft. This is where the 'Push" comes from. Now think about it, the closer you 'push' sideways on the RC, the less our picture wants to tip, or lean. Sounds great - but, it doesn't force any tires onto the pavement. In the front, where there is a motor and other weight, gravity is helping to keep the tires stuck. In the back, no weight, so no sticky-sticky. So, in the back, if we get the RC lower than the CG, it will force the truck to lean, and put pressure on the outside tire "bite"
I'm going to stop here. This is tough to describe without pictures. Let me know if this makes sense to you. RC and CG are pretty important if you want a good handle on this stuff. (pun)
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Old 09-22-2010, 09:24 PM   #99
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Re: Make it handle

Excellent description for explaining the difference RC & CG can play on a truck vs. a car. I hope to see your rig go round & round @ GG's Ft.Worth.
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Cubic inches is like Indiana Jones with a cheap pistol....
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Old 09-22-2010, 11:55 PM   #100
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Re: Make it handle

Had to read... and re-read... but got it! Thanks for the explanation. I'm going to be running a rear trailing arm set up and just trying to get a better understanding of how it all ties together, and get the most out of my ride!
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