Need some Knowledge... please shed some light on Truck Arms

[Offroad Outlaw]

Ok... befor i go askin questions let me throw a few things at you... I have ABSOLUTLY no road course or pro-touring experiance....

I do however have an extinsive background in metal fab in all areas and i have built show cars... Rock Crawlers... airbaggers... Hydrolics... and... well over 20+ Dirt track cars ranging from your... advrage knock the windows out of a camaro cut the roof off and put a cage in... to full blown tube chassis 3 wheelin dirt mods... aswell as some preety outragouse 4x4s... so there isnt too many types of suspensions that i havent layed my hands on....

EXCEPT..... truck arms... or better know as rear suspension for the nascar world that came from early 70s chevy trucks... hence the name... this is the subject that i need ANYONE with expieriance with this setup?

The Vehicle...
1993 chevy s10 blazer 2dr

Chassis....
Modified 1974-1982 camaro front clip...2x3 boxed framerails and Truck arms in the rear... o yea....fully gutted interior and caged like a full blown racecar but....for 4people

Modified dimensions...
100in wheelbase... 74in track width... 3300lbs with all 4 seats filled... 2500lbs no people

Body mods....
since the track width is wider... so must the body grow...8 inches to be exact.... so front is easy and will just be some fiberglass 4inch baja style s-10 fenders. Its easy....cheap...looks mean...and lighter... The rear i will be making my own flaired bed sides by usin long bed quater panels.... ill do the metal work since i have a big v8 up front... it will help with overall ballance... i know its going to resemble a baja truck slammed on the ground.... but thats the idea.... cuz baja or short course trucks looks mean as hell lol...

Drive train...
360 cid SBC 600hp@7800 rpm...aluminum heads... water pump and accessories... T56 6spd... 4.11 rear gears with a mini spool locker

Wheels and tires...
18x15 Hoosier Asphault slicks for track and 18x12 for street

The kicker...
STREET LEGAL!!!

My reasons....
(Front)
Well ive always heard important chassis builders and racing people in general say... "in thier opions the 2nd gen camaro is the best front suspension designs as far as steering geometry ever created"... And as i said befor ive spent many years in dirt track racing and have a hude knowledge of the 2nd gen camaro front suspension... so modifications will be including... relocating upper control arm mounts for better caster/camber... tubular upper control arms... chrylser style screw in ball joints and #2 gm spindles with 5x5 hubs...running outboard shocks and installing "screw jack" spring buckets... (i know its not the right name but if you would like to me explain i will)..... but bassically.... a 1978 camaro front sub frame haha... O yea... dont let me forget Speedway magazine... They supply us dirt track boys with any rate spring.. any shock... any lengh tubular control arms... all the bushings....ANYTHING possibly needed..all built to race specs for the camaro... AND CHEAP!!!

(Rear)
There are many reasons i want the truck arms... The main reason is because... well... why not? Ive never messed with it and wanna try it... Nascar has used it for years... there is no heim joints to make rattling noises... and from what ive heard.... could work well for what im building....

I live in a rual community in Bumfooked Arkansas....USA....And will be driving on ALOT of gravel roads.....i know what your thinking.... but i will have ride height adjustment and string rate stiffness at the turn of a 1/2 ratchet.... and could raise or lower all 4 corners of the car a total of 4 inches up or down in under 15 minutes..... so yes it may not be the most comfortable ride... but itll be one heck of a good time haha


Please... im not looking for people to hate on my ideas... i have my reason and have most of my parts.... this isnt some pipe dream but infact is a well thaught out idea... and will be finished in the year or so...

I know i gave way more info than needed but im hoping sombody has the knowledge im looking for.... mainly... truck arm rear suspension... i know from messing with 3 and 4 links... that lengh matters.... and there are alot of factors that go into me choosing a set of links for a specific setup... sooo how do i figure out my best lengh for a truck arm? Whats the best spring placement? Were should i hang shocks? Anything i should be away pf as far as the downside to truck arms? .... any experiance would help a ton


THANKS'

[RobNoLimit]

Well here's a couple of tips. 1. if you want to use the OE style front bushing (no rod end) DON'T box the arms, and DON'T build boxed arms. For this suspension to work well, the arms need to 'twist'. The twist allows the rear axle to tip, one side up, one side down. If they are boxed, they won't twist. So, if you want to fab boxed arms, use a rod end or Johnny-Joint. We have a Delron lined pivit joint called a Monster Ball. 9/16" through bolt and 1 1/4" thread shank. This is what we use on our T.A. rear suspensions. 2. keep the rear mounting points on the axle as wide as possible. 3. Try to get the front arm mounting points close to the front U-joint (within 10") and keep the arms reasonable long. The front mount point has a lot to do with the Instant Center, so keep it as high as you reasonably can. Packaging will be a fight, but I would shoot for 13" - 14" high at Ride Height. This way the pivit CL is even or higher than the axle CL. Hope this is of some help. Rob

[Offroad Outlaw]

Thanks for the insite rob... I also made a call to Steve at "Hot rods in hell" in norcal... and even thou he said it is possible and he could fab somthin up for me as a short art setup.... but he didnt sound to confident it being what i wanted as a final product... because my wheelbase is only 100in...engine sat back... and the t56... my driveshaft is only gunna be about 2ft MAX... it sounded like the setup works best on a larger platforms... i could have taken what he said wrong... please correct me if i ambut it has honestly got me thinkin about just bein simple and runnin a parallel 3link... with the 2in bushing rod ends instead of heims....... and a watts link.... i would really like to stay grassroots with my suspesion and go truck arms...and 12in high would put the front mounts to high in the back seating area due to the body drop.....

Soo..... lets do it this way.... ive got $500 to spend on springs.... and my rod ends...heims...bushings...johnny joints... or whatver except shocks... tha ks to my dirt mod i have a wall full of rebuildable QA1s lol... Im a fab guy and have all the access i need to build any mount or brackets...bars or arms i will need for free.... WHAT WOULD YOU BUILD? nothin is off limits.... just keep in mind i hate noise and the jarring effect from heims... so anything i build will be on bushings any takers????

Parallel 3....triangle 3... parallel 4... triangle 4... Z links...wishbone.... or even truck arms....

Again... i have absolutly no road course experiance so please explain from a drivers feal and point of view why i should go with your idea

[jaybee]

Not to say there aren't some perfectly good truck arm setups out there, but consider this;

Nowhere in the competition world do they use truck arms unless it's required by the rules. Since you have the bits and fab skills to make whatever you want...build a three link with panhard bar or watts link...your choice.

[srh3trinity]

I have always read that truck arms have to be long and create packaging issues to work well. I have read that the Nascar guys wouldn't use them if it wasn't sanctioned. You could look at the 5000 dollar budget mustang build by Ron S. He used truck arms on it. I like the idea of a three link and watts

[RobNoLimit]

OK, now that I know about the driveshaft length, stop. Your going in the wrong direction. T.Arms need to be 45" + to be effective. So that's a no go. You just don't have enough room. It comes down to packaging. Start searching about 3-link.

[Offroad Outlaw]

Thanks yall... ive decided to go with the parallel 3 link with some custom bushing style rod ends.... the bushing i plan to build off of is the 2nd gen camaro front leaf bushing....that gives me the abillity to have 3 diffrent options...or chassis feal.... stock rubber.... poly urathane... and i duno if its just for dirt ....but they make metal orbital front leaf bushing that works like a heim for a leaf spring... yall ever use em?...... so peronally i think maby end up runnin stock rubbers to drive to the track... reach under it with a cpl 3/4 wrenches (and a jack) and change the links to ones with the orbitals or polys wile at the track...at the track lol


Hey... atleast on dirt.... you can never have to many options for suspension tuning.... provided u dont get lost in ur setup like many do at times

[Offroad Outlaw]

My buddy made a joke just now...

Dude...ur a dirt track boy tryin to go roadcourse racing... somthin tells me ur car will turn left on 3 wheels VERY well....

Got me thinkin.... how funny it woud be to pass a vette on 3 wheels turnin left in somthin that looks like1990 s10 blazer with 4 helmets ........... o boy!

I bet the dude in the vette has a...... accident....... inside the car... not outside hahahaha

[Offroad Outlaw]

Ok..... lets see about ur ideas on this.... THE PULL BAR... in dirt track racing we repace the top link (3link) with a bar with eather rubber biscuts(bushings) or a small coil spring... instead of a solid bar...

This allowed us to let the pinion rotate back like it naturally wants to... but because the spring rate is pussing in the opposite dirrection it plants the tires HARDCORE depending on the aggressiveness of the setup.... enuf to make a 2500lbs car do a 3ft wheelie off the corner...at speed... ON DIRT.... simular to a pro street drag car lettin go of a trans brake....

i havent been able to find ANY info on this topic... and im wondering if its simply because maby it hasnt been tried?? I think i can dial the agressiveness WAY down to the point that it might barley work

The reason im wonderin about this is well... 100in wheelbase... 74in track width... 600hp and 2500 lbs..... Shes gunna be a handfull off the corner.... and my thaught is i might be able to make it wanna plant and go

[wendell]

You don't see many spring links on road cars for a couple reasons; less travel, less weight transfer, more traction and a equal priority on braking when compared to a dirt car. Those are also reasons for less aggressive anti squat values when compared to dirt. The few times I've seen spring links, it's been less than 1/2" of extension on acceleration. Even rarer to see a decoupled top link (one link for acceleration w/ high AS and one for deceleration w/ low AS). One reason you don't see it is because it's more trouble than its worth.

I'd focus on braking and turn in more than trying to three wheel motion out of the corner.

[CA B4C]

Rob MacGregor has given you some pretty good advise in this thread. You might check out his build thread of "Hellboy." Once you take a look at his truck it may help you with some direction on your project. If I remember correctly, Rob won the Goodguys autocross season championship in 2013, validating his design principles.

[Offroad Outlaw]

Yes he did... and i soaked up every word like a sponge... the turnin left on 3 wheels was a joke... its actually what i DONT want to happen so now im forced to unlearn so much and try to learn somthin completly new haha... Im going to start a new thread about some varrious 3 link designs with pics for examples... cuz even the link lengh and angle im at a loss for.... im almost posotive my 14in @14deg links eye to eye "like on the modified" would be outragously so short and way to agressive... so thanks everyone for getting pointed in the right dirrection and please stay on the lookout for my next post.... gunna need some detail.... orderin parts soon for whatever i decide to build THANKS AGAIN