Re: Make it handle
 

If any of you guys are seriously thinking about the Hotchkis system, you can get it through Summit for about $1000 less... http://www.summitracing.com/parts/HSS-80390/

Re: Make it handle
 

WOW! Great link, thank you!

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Ok, a quick visit to the No Limit site has converted me. Really impressive Rob! I think I know where I'll be getting the suspension for my truck when the time comes.

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One thing I will always push is education, and those are great questions. Search online and buy Herb Adams suspension design and tuning book. It is the best I have read, and it is understandable. NEXT, buy a copy of "suspension geometry pro" software. its only like 80 bucks. the rear suspension program isadaptable to mock up the questions that you are asking, and will show you the RC graphs for each. well worth the money.
Remember that "every action has an equal and oposite reaction" - physics class, so, the left/right force is a average of the two mount points of a P-rod - RC, and an average of the three points in a watts. As to radial deflection, yes, there is some. how much? get a 30" string and draw an arc with a 30" radius, and then measure out any 5 or 6 inches of the arc, the radial deflection is easily seen. Try it.

Re: Make it handle
 

YOUR INPUT NEEDED As I am testing A-Arms, vs. performance set-ups, one thing is becoming clear. If you dail in enough caster to make it turn, you create another problem. When tipping the spindle back to get the caster in range (7 to 9 deg), the steering arm lifts up, in relation to the other steering components. I.E. the center link. One solution is to drill out the hole for the Tie Rod End in the spindle, and use a Rod-End style TRE that can be bolted up from the bottom side of the steering arm. this type of TRE gives you the ability to adjust the hight of the TRE pivit point, and tune out any bumpsteer. So, Are you guys willing to drill out the spindle, or not??What do you think about this??

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I would drill mine. :)

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with my 2.5" drop spindles I added tubular upper control arms to my low budget build because I wanted the extra 5* of caster....if needed I'd drill for more.

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If it were part of a tested package, sure I would do it. Keep in mind, I am rather conservative about modding anything with out a proven reason.

Re: Make it handle
 

Rob,
I am setting up a 3 link wishbone(triang 4) and I am having trouble with fitting everything
around the driveshaft. What do you think about this set up, 57% Anit Squat,16RCH, 2* roll oversteer, Ic 127" 13", I think my Cog should be around 18 or 19. Wheel base is 116"
Thanks

Re: Make it handle
 

I'd have no problem drilling that out especially if it gave you the option of using a high quality Cro Mo rod end.

M5

Re: Make it handle
 

Good feedback, keep it coming. Those that know me, know that safety is a concern, and I tend to overbuild.
WvGearhead first off, you need to speek up more often. How about some picts. How are you getting your numbers? Are you using Suspension-Pro? You seem to be up on this stuff. Thats great. Your set-up seems to be pretty good, I'm guessing your tire is about 29" dia. thats puts your roll center a few inches above the axle center line (hieght). I would consider lowering it a bit, or at least allowing for an adjustment later, second set of forward holes. Some squat in a truck is good, to help with some weight transfer. Lets go over this on the forum so everyone can check out your work. How about shocks/springs?

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I'm going to have to do some reading....

Great thread BTW.

The questions I have are related to materials. Where does one find the right tubing and end links for fabricating things like rear end linkage?

Mabye it's covered in the recommended reading earlier in this thread.

Of course it probably makes sense to buy off the shelf on some items. Nothing like making your own pieces though.

Re: Make it handle
 

Rob,
I am building a 53 3100 on air, The front is a tci MII and the rear is a custom built Wishbone I picked up, The wishbone and the lowers both span 28", so it should keep constant pinion angle. My problem is, I didnt think about the driveshaft...hmmm, So now I am trying to get the best numbers I can without having to flip the wishbone around and put the single on the center section. I used a suspension calculator from a 4wheel drive form. I dont have any big intentions on racing the truck, but you never know. I figure I would atleast try to make it real fun to drive anyway. The numbers I am plugging in are: upper links ,frame end x=28 y=0 z=17.50 Axle end x=0 y=17 z=18.86 lower links frame end, x=28 y=17 z=9.14 axle end x=0 y=17 z=8.14. This equals AntiSquat=%57 RCH17", IC x=127" z= 13" Roll oversteer 2*, travel roll axis -2.78*. I am not sure about the roll steer, how much is too much. How do you think this set up would handle and ride? The Cog I am guessing to be around 19", and as for the tire size I am planning on running around a 26" tire.

Aaron

Re: Make it handle
 

Oh yea just in case, X=0 on the axle y=0 at cl of chassis and z-=0 at shop floor

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Wvgearhead- What kind of power is your drivetrain puting out? You could always run a 2-piece driveshaft as well. It should take care of your clearance issues on your upper wishbone.

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We can sell you any of the necessary parts to make your own linkage and or make recommendations to help you out.

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Can't you just move to okc so I can work off materials and learn something as I go? Lol

I can't seem to find the books mentioned earlier on learning suspension. Anyone got the names of them?
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Re: Make it handle
 

Man looks I got some serious learning to get after.

M5

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I am running a 450 hp small block, hopefully a lt1 t56 if I can find one and a 8.8 rear with a locker and 373s. M5 there are books, but you can learn alot by google. I looked at some other forums geared for road racing. The best calculator I have found was actually on a 4 wheeldrive forum. I still need to read a lot more, but I'm learning.
Aaron
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Re: Make it handle
 

An extra ujoint scares me, I have been known to break things. Lol
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Re: Make it handle
 

Wv Do you have the motor/trans mocked up yet? Remember that it is helpfull to mount the motor as low, and as far back, as you can. Sometimes we notch the MII crossmembers and box them back up to create more oil pan clearance. The bottom of the pan can be even with the running board. it will look small in the engine bay, but it will drive/handle better. Also, the low motor/trans hieght may solve your driveshaft issue. Try to keep the carb base level with the frame, crank angle will then be about 3*, then match the pinion.

Info search, I'll post up some book/web/chart info later:smoke:

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Google Herb Adams "Chassis Engineering" and you will get several hits.

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Great rob, thanks
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Google "Carroll Smith". He has written several good books inlcuding Tune to Win, and Engineer to Win. These are great books that will really open your eyes and understaning. After the books, purchase a suspension analyzer program. Rob mentioned a great one earlier in the thread "Front Suspension Geometry Pro". It's a great and affordable program, just over $100. I bought one several years ago and even bought the new version a couple months back to see how I liked it. I also have some more expensive software including Bill Mitchell's WinGeo... It's more complicated to use. :)

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Thanks Nate for the info, I've read Herb Adams, I'm gonna have to pick up the Carroll Smith's books next. What would you guys suggest for material size for building a frame. What dimensions and thickness are working best for the frame builders.

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From another thread entitled- what size metal to build rear frame?

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We build a three piece main rail. 2 x 6, .188 wall in the middle (appx firewall to the start of the rear fick) and 2 x 4, .188 on each end. Yes, its a bit heavier, about 85 lbs over a 2 x 4 .120 wall pair of rail, but this is good weight. - low and centered. Our X-members for these trucks are 2 x 4 .120.

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Thanks Rob and N2TRUX for the help.

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[QUOTE=robnolimit;4167810]The whole goal of A arm swapping, and I don't know if this really works, is to increase positive 'Caster'. Stock C-10's spec out 1 or 2 degrees, but your truck will respond well to 6 to 7 deg, and more for the wide tire guys, bigger than 8". To my knowledge, nobody makes a set of arms to gain caster, may someone should. The trick is to move the lower ball joint forward about a 1/2", and the upper ball joint back about 7/8", this will keep the wheel centered and net about 8 deg. + caster.

Robnolimit,

I just found this. Hotckis make the corrected A arm. What do you think?


http://www.hotchkis.net/search.html?...mitForm=Search

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[quote=dnd1978;4234154]This kit was mentioned back on posts 116-118 (referred to as the 'H' kit).

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Right now I have 8 different sets of arms on my back bench, and a stock crossmember. I have been mocking them up and testing them. - not done yet. it takes a while to accurately measure the pivit points. Now let me put this out early, I will let you know of the arms with positive results, but I can't name names of the ones with negative results. - so, don't ask - read between the lines. I'm not going to start a pissin contest here. OK? Hopefully I am going to meet with Nate Porter during SEMA to discuss some of these thing you guys are interested in. i'm looking forward to it.

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Is there a minimum verticle separation that you would recommend between the upper and lower links at the axle and frame ends? In the off-road world it was 25% of the diameter of the tire you wanted to run at the axle and whatever you had room for at the frame. I havent seen it mentioned here. Also, do you think that running a non-parallel, non triangulated 4 link like your fat bar appears to be, offers advantages over a regular 3 link other than the obvious that it puts all the links outside the frame and adds a bit of strength. I'm not downing the idea, I just have been thinking about it alot lately. In fact I was set on a triangulated 4 link, but now am leaning more towards this set up with a panhard.

Re: Make it handle
 

IAN30, good questions. First rule, "every action creates an equal and oposite reaction", so as the axle is trying to rotate the tire forward (lets say clockwise), the axle housing wants to rotate the oposite direction (counter-clockwise). The 25% rule is so that you have enough leverage to control the axle rotation, its a good rule of thumb. one more note, we want the truck to go "forward" under acceleration, so to get the leverage to help, put 2/3 of your bar span below the axle CL, and 1/3 above. * top bars that are right on the axle CL (elevation) WILL NOT transfer any wieght. ** 4-bars that are parallel (top to bottom bar) WILL NOT transfer any wieght. When it comes to three links (wishbone style) and triangulated four bars, BE CAREFULL, these set-ups build with urathane bushings all around start to bind any time they move away from ride hieght. you can help this by runnung rod-ends in the upper bars to allow them to articulate. Our kits are desinged to have the lower bar level to the ground and the upper bar slopping down at 4-5deg. at RH.

On another note, we now have custom tank-crossmember kits to fir 67-87's with Porterbuilt and others step notch kits. I'l post up some picts on the 67-72 section.

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Rob, I appreciate you giving out all this advice, I've had a hard time finding the information that you've given here so freely. It's interesting how much of the information out there is just people spreading hear say and not actual practical stuff. I just want to start off with a decent handling suspension without any major quirks that I can possibly tweak in the future if I want more. Can I just recap what you have suggested regarding rear suspension setups and ask a few more questions just for clarification.

Low long Panhard bar - ideally equal to axle centerline.
A light swaybar - Do I run without at first and add it if needed later on?
Mount the links wide
2/3 of link verticle separation below axle centerline
Lower link approx. level at ride height, top link sloping down 4-5 degrees
Instant center should be in front of the front axle
anti-squat less than 100%Would it be better with a number below 50%??? How low is too low??

OK, thats all I can think of for now. I am also attaching some free excel link calculators that I found. I am using the 3 link for this setup even though it will have 2 upper links as the four link calc is more for triangulated setups. I don't think that changes any of the numbers having two upper links. I don't know if you have seen these before, but can you please look at them and give me your opinion if you think they are crap or a good starting point.

Thanks again, Ian:metal:

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ok, I have thought of another question. I have a bunch of pivot joints from another project. Would it be better to use these at the axle end or would it be best to use all polyurethane bushings everywhere? assuming no cost involved.

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pivot joint being a rod end or heim joint? I'd personally use them everywhere i could, though.. i'm not a huge fan of poly.. the heim's will transmit a bit more vibration but will be butter smooth compared to poly.

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A flex joint like this:
http://www.summitmachine.com/index.p...tomParts&cp=fj

I have a bunch of these and wondering if there is any disadvantage/advantage to using some or all of these or poly bushings.

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Ian, those joints are good. We use a pivit like that on our Track-Arm kits. If you have them, use them all around, the transmitted vibration you hear about is not noticable. I have both of those calculators handy, and they are fine, thanks for posting them. When it comes to anti-squat, remember that the trucks are very light in the rear, so we need some, less than 40% seems to unload my silver 55 (Bullit) so I would try to keep it around 50-55%, it is a balance between chassis reaction - vs - traction. Keep going, you'r on the right track!!!!

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i keep hearing the term anti-squat and seen anti-squat kits for sale online what exacly does this mean or do?

Re: Make it handle
 

Anti-squat, is a term for rear suspension. And, Anti-dive, is for front suspension. This is discussed in a % number, such as 50%, to compare how much of the wieght transfer, or load, is put into the spring, and how much of it goes to the tire. The front is easier to visualise. With low anti-dive, the front of the truck nose dives when you apply the brakes, most of the load goes to compress the suspension, not into the tire. with more anti-dive the energy would go into the tire, and not compress the suspension as much. In the rear, anti-squat is similar. Drag cars often have anti-squat values of more than 100%, all load to the tire +, But they don't have to worry about corners or braking off-camber. High anti-squat values tend to lead to wheel hop during hard braking. Anti-dive, and anti-squat geometry are linked to CG, RC, and ft/rr wieght bias. In a pickup, with a high CG, typically low RC, and an average of 58% nose wt, we shoot fot anti-dive in the 60-70% range, and anti-squat in the 40-45% range.:smoke: