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Author Topic:   trailing arm location
Dirt Forum Racer

Total posts: 88
posted March 07, 2003 03:16 PM  
I run in the streetstock class with a 85 monte ss chassis on a 1/2 mile flat track.The car handles pretty well but lacks a little forward bite comming off the corners.I am focusing on the rear trailing arm angles now and have read that you wantthe lowers about level and the uppers down in the front 10-15 degrees.I have seen cars with the lowers moved up where they mount to the housing.does moving the mounting point closer to the axle center line have any adverse affects or any great advantages.I am looking at as many ideas as I can so I would appriciate your input .Thanks in advance

Dirt Roller

Total posts: 20
posted March 08, 2003 10:28 PM  
I am REALLY interested in seeing what people have to say also, come on guys give a couple cats a little help....

Dirt Full Roller

Total posts: 49
posted March 08, 2003 11:16 PM  
that is agood question im kinda struglin with the same

Dirt Full Roller

Total posts: 68
posted March 09, 2003 08:04 AM  
i bought a pure stock and it came with some extra trailing arms, uppers and lowers. the seller told me they were different lengths to change pinion angle. i haven't even looked at the spares because the rear already looks good. slightly angled down. i'll measure these over the ones that are already installed and see what i come up with. but, i won't know what they came off of.

rico 08
Dirt Forum Champ
Total posts: 1139
posted March 09, 2003 12:45 PM  
Maybe they consider it a secret! my experience was to lower the rear mounting hole on lower arm where it mounts to rear end on drivers side,this will make this corner bite harder but may create an overbite situation.also this will introduce a little roll steer.

Dirt Forum Champ
Total posts: 823
posted March 09, 2003 02:37 PM  
if you run your rear lower control arms at a uphill angle toward the front you will get more bite.

level should be very bad......

steve smith motorsports books will explain it all in detail, dont be afraid to read about a latemodel 3 link type suspension etc, it all applies..

in short the uphill angle puts more wt on that tire, for example my pavement latemodel liked 2.5 degrees lr and 1-1.5 rr. moving a half degree made a noticeable difference.

i avoided answering this earlier cus its very complicated, and i have seen a lot of stock 4 link cars working fine, but if and when i have one, i will be checking angles, rear steer under compression etc,

everyone ive talked to about these cars says they dont check that stuff because they cant change it.

shorter arms, and different mounts left and right will make it all adjustable. im wondering if imca will allow bolt on lower trailing arm mounts, thus allowing a person to rotate them for rear steer change, and bolt on diff ones for diff angles.

all you would need is the right size tubing to split and build your own.


Dirt Maniac

Total posts: 113
posted March 10, 2003 06:20 AM  
You can't talk about the angle of lower arms on a four link, without considerining the angle of the top. The imaginary point where the bars would cross if extended is called the Instant Center of the suspension. This is the point that the torque of the axle is countered. If the IC is ahead of the axle the car will lift under acceleration, and squat under braking. The IC can actually be located behind the axle. 68-72 A-bodies have this stock. It plants the tires on braking and unloads (squatS) under acceleration.

Dirt Forum Champ
Total posts: 823
posted March 10, 2003 05:48 PM  
kinda lost me, wouldnt almost all 4 links stock, intersect way back, behind the rearend..

changing the lowers to more angle would move the IC down and forward a little.

Dirt Freak

Total posts: 370
posted May 17, 2004 08:29 PM  
What ghainsey is saying is that if the upper bars point downhill towards the front and the lower bars run uphill towards the front then they are going to cross in front of the rear end.[IMG] If lowers run downhill and uppers run uphill then they will cross behind the rear. Thus creating the phenomena he is speaking of.


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