Anti-squat + other characteristics of a 4 link rear end

[monkeymajik]

Too much anti-squat? I read that too much anti-squat can cause the back end to start hopping under hard braking, I want to see if its possible to dial that much into a Sprinter.

I have the T3 traction brackets and their 4link. My car was hopping occasionally under hard braking at QR. Feels like the car is going to shake to bits heh.

Rear springs i think were too hard and their was alot of pinon angle dialed in to attempt to find some more rear grip.

I have softened up the rear springs and I hope this well help with the hopping, wont find out till next year when the sprints start up again though.

[Sam_Q]

Jedi: I did some reading and it must of been different because they were rock crawlers but they really dislike to much anti-squat. This is because they would hit a rock and it would cause hopping because the anti squat would grib and be an uneven distrobution of power. To get it engineered I will just put everything back in the original pivot points.

monkey: sounds interesting keep us posted how it works out

[Jedi]

Jedi: I did some reading and it must of been different because they were rock crawlers but they really dislike to much anti-squat. This is because they would hit a rock and it would cause hopping because the anti squat would grib and be an uneven distrobution of power. To get it engineered I will just put everything back in the original pivot points.

Hence the limiting strap on the rear diff. Keeps hopping to a minimum and allows the power to be put to the ground rather than unloading the suspension causing the rear end to bounce.
My experience is with 4wds but as I said, the principles and applications should remain constant regardless of the type of vehicle.

[Sam_Q]

could you please explain more about this limiting strap

[kingmick]

You dont need a limit strap on a road,drag or circuit car!
The only limit strap ive seen on 4wd is for when its jacked up to change a wheel etc it stops the wheel going to the ground so you dont have to have a 8 foot jacking height!
I would imagine even with extreem 4X4 stuff the travel is still what the shocks can go out to!
I was looking at the setup of a monster truck a few weeks ago and it didnt have limiting straps and it has massive travel!
You sure the straps where not for jacking it up?
That said, they are useless on a performance car!

[Jedi]

Actually, monster trucks dont have that much suspension travel (relative to their size) at all. A limiting strap is attached from the chassis (or a crossbrace, whatever, somewhere strong) to the centre of the rear diff. It basically prevents the rear springs from unloading on steep inclines or declines (in a 4wd situation). They are used by comp guys as a means of retarding rear suspension travel in order to maintain correct geometry. It doesnt matter how much flex you have if you dont have traction.

In a racing situation, when under heavy brakes, the front springs compress, causing the rear springs to unload, which, when combined with a high degree of AS, creates a hopping effect.
If a limiting strap is on the rear, it would prevent the rear suspension from unloading under brakes and keep the car theoretically stable, thus allowing a high degree of AS to be run, without the undesirable handling effects. Im not disagreeing with kingmick, a properly set up rear suspension wont need a limiting strap. I was just throwing it out there as a possible option

Disclaimer- I have absolutely zero experience with limiting straps in racing cars or racing in general so please seek advice from those who are more in touch with that aspect of motorsport. I do know how a 4-link works though and know what AS, roll centres etc. mean and I cant see why a limiting strap wouldnt stop hopping under brakes, but I could be wrong and it wouldnt be the first time.

Anyway here's a pic of a limiting strap so you know what im going on about

[kingmick]

That has a limiting strap to stop breaking shocks i would imagine! The monster truck i looked at had pretty big travel compared to anything ive ever seen?

[roadsailing]

IMHO all those straps do is stop you yanking the eyes off the end of your shocks, can't see how they are any different from topping out your suspension

(haha, kingmick beat me to it)

[kingmick]

hahah look again i had to edit so you beat me

[roadsailing]

you mean the slack in the strap? if its jacked up then maybeye it is there as a safety measure AFTER the shocks have failed

[kingmick]

slack?? , must have been from before i edited
could also be a saftey measure, something i didnt think of.

[Jedi]

I think you guys may be getting the diff limiting strap confused with a shock limiting strap.

The diff limitng strap is located at the middle of the diff i.e the pivot point. It has very little bearing on the shocks travel at all. It's there to prevent the entire diff, not one side of it, drooping down and letting the springs unload and creating bounce. Wheel travel is not affected much if at all.

This is a shock limiting strap.



Note that it is located close to the actual shock(s) itself, not at the centre point of the diff. This would impede wheel travel and prevent shocks from maxing out but has nothing, or very little, to do with containing axle hop.

[Sam_Q]

I see no way that a stroke limiting strap would stop the car from hopping when doing rock climbing or anything related to us.

[nztoygt]

this is what we did to my 86

even length four links changed the shock mounting points turreted the top
and changed from panhard to a watts linkage

it's a truck load of work but i'm hoping it will make a difference

see link

http://s112.photobucket.com/albums/n...20mega%20build

i hope the link works i'm new at this

[Sam_Q]

link works fine and theres some nice work in there.

I have a question though- why did you cut and fit a larger section in the floor above the diff snout? was the diff hitting the floor?