A body top arms

Bozwell · Post by **Bozwell** » Fri Aug 09, 13 5:59 pm

i don't understand why the top arm is at such a silly angle to radically change caster at different ride heights

does anyone have any thought as to why they did this? i can't see it working as anti dive and can't see much of a point changing caster that much just under heavy braking. (race cars dont do this)

my thought is to modify the mounting point to reduce the angle (and not spend silly money buying off the shelf subframe kits) the mod will be to get rid of the caster change not just to be able to get more caster.

i also have an idea about changing it to RHD and will see if it'll work once i pick a power steering rack up tomorrow. another reason for running a fixed caster.

Bozwell · Post by **Bozwell** » Fri Aug 09, 13 11:31 pm

bit of research and it does appear to be done for antidive. but it seems as the spindle twists as it goes up and down this changes the angle of the steering arm. this affectively tunes in a bit of unwanted bump steer.

going stiffer on the suspension means that antidive isn't realy needed as much.

hmm. lots to think about.

drewcrane · Post by **drewcrane** » Sat Aug 10, 13 3:04 am

Stock works well with urethane bushes,how ever there are alot of options

http://www.magnumforce.com/magnumforce_ ... l_arms.htm

DaveBishop · Post by **DaveBishop** » Sat Aug 10, 13 8:41 am

Interesting post until you started tailing about converting to right hand drive

DaveBishop · Post by **DaveBishop** » Sat Aug 10, 13 8:41 am

Spelling mistake ment talking

Bozwell · Post by **Bozwell** » Sat Aug 10, 13 11:59 am

it doesn't matter how fancy a top arm you fit, if it's in the standard mountings there will be a huge caster change as the suspension goes up and down.

drag race cars will completely lose caster on the front until they step on the brakes. on droop the front suspension will go the opposite to what you want it to and must make for quite an interesting ride

as for RHD. whats the issue? it seems a car can be chopped, modified, Barstardised and its all great but go RHD and its a big no no? we are not in America

paolo_mangusta · Post by **paolo_mangusta** » Sat Aug 10, 13 12:41 pm

the mopar geometry is pretty good compared to the competition, they did all kinds of odd things on GM and Fords which is why the mounting points are moved eg the Shelby drop on mustangs. Obviously stiffer suspension will tend to limit travel and hence limit the geometry change but better it's somewhere near right in the first place

I'm going to do the offset Moog bush mod and front and rear anti-roll bars on mine in the next month or so, will be interesting to see the difference it makes.

Mopars were renowned for locking up the back wheels under braking so maybe that's why they were trying to get anti dive.

AutoXcuda has a long history of modding A body suspension, he is now using the Hotchkis set up but there are some details of the evolution here:

http://www.protouringmopar.com/showthre ... -evolution

Bozwell · Post by **Bozwell** » Sun Aug 11, 13 1:36 pm

paolo_mangusta wrote:the mopar geometry is pretty good compared to the competition, they did all kinds of odd things on GM and Fords which is why the mounting points are moved eg the Shelby drop on mustangs.

that would be to change the roll centre for racing more than being an design fault. on the Lightweight E types the top arm mounting point is lowered compared to the standard E Type which has a pretty good set up from the factory. lowering the top arm mounting point also gives the wheel more negative camber under braking without affecting the caster.

the normal way most cars with antidive built into the suspension is to have the front bush further inboard than the rear bush. the GT40 uses this set up and the MK2 Jag is another one i can think of.

linky