How much Anti-dive???

15195 Views 26 Replies 17 Participants Last post by TPIJeep, Feb 15, 2003

VooDoo

Discussion Starter · Feb 8, 2003

I've searched and cant find anywhere what the Ideal % of front anti-dive is??? I realize different people will think different things. But, at least with anti-squat I concluded two basic schools of thought,- either approx. 80% AS or 150%+ with a tight limit strap. What do you guys think about the front end??? PIG? elf cruiser??? zags??? anyone???

1 - 20 of 27 Posts

PIG

· #2 · Feb 9, 2003

Limit straps to control suspension characteristics are :rainbow:

bad76ih

· #3 · Feb 9, 2003 (Edited)

I've been wonder the same thing. I've found a lot of info on rear suspension design on the POR. How can this be a related to front link type suspension. Also, would a radius arm setup have good characteristics or would a multi-link (4-link) system be better?

Would the same characteristics that cause anti-squat problems (rear raising up) lead to the opposite effect in the front (front pull down)?

DSI

· #4 · Feb 9, 2003

PIG said:
Limit straps to control suspension characteristics are :rainbow:

so what your saying is a centered strap to keep rear coilover's from unloading while going down hill is not needed with the right link design

Air Ride

· #5 · Feb 9, 2003

I am thinking that over a 100% would be good. Going down hill in braking and or compression braking the front wont dive as much. Steep up hill the front wont lift as much.

Of course I maybe wrong.

elf_cruiser

· #6 · Feb 9, 2003

IMO, it's kinda the same as with the rear. There are situations where alot of AD is good, and situations where it's VERY bad. I've seen a couple of rigs roll themselves over with AD. Example - in reverse, the AD becomes AS in the front, and the front lifts up... If you have a single radius arm setup up front, then it'll lift only one side of the rig... If you are off camber so that side is unloaded, it'll flop itself sideways when you hit the gas... Am I making sense?? Anyways, it depends on what link config you're gonna use as well. Radius arms have their upsides and downsides. I kinda like the reversed wishbone 4 link, where the lowers converge in front of the Tcase, and the uppers are parallel. All depends on what you can fit under your rig, and blah blah blah...

TRD

· #7 · Feb 9, 2003

if you can't decide, be nuetral with 100%

KrustyKruiser

· #8 · Feb 9, 2003

I personly don't think that it matters as much as the rear does, and typicly you don't have all of the link placement oportunites like in the rear, because the motor is there. Find were your links will be out of the way of shit, and then try and get a little anti squat, but remember that its all facing backwards.

JEEP_TJ_FREAK

· #9 · Feb 9, 2003

Bump,

Oh yeah and tech please.

:flipoff2:

350 Samurai

· #10 · Feb 9, 2003

PIG said:
Limit straps to control suspension characteristics are :rainbow:

I bet Shupe would disagree with you. :flipoff2:

DSI

· #11 · Feb 9, 2003

350 Samurai said:
I bet Shupe would disagree with you. :flipoff2:

and probably the other 100 or so compeditor's running them

cruiserrg

· #12 · Feb 9, 2003

Here are my thoughts, and please note this is all theory as my rig is still being built. I think you are mixing up terms. Anti-dive is characteristic of braking and related to how much the front end dives during braking which IMHO is not that big of a concern for rock-crawling. I think the term you speak of is Anti-lift. *Anti-lift occurs in front suspensions only occurs with a front-wheel drive and it reduces the suspension droop deflection under forward acceleration.

I would say that you actually want some anti-lift and not anti-dive in a front end. This is especially the case in up hill climbs to keep the front end from lifting too much. As you can see from the pic most front end link suspensions in off road vehicles will exhibit some anti-lift. How much you want in a suspension design is up for debate, but as KrustyKruiser pointed out there isn't much room to play with link placement up front and you won't have a lot of choice to play with it.

Note for pic: tan0=IC length horizontally from front wheel centerline / height of IC vertically from font wheel centerline.
h=height of CG, l=length of wheelbase.
*pic and notes from Race Car Vehicle Dynamics by William F. Millken and Douglas L. Millken

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VooDoo

Discussion Starter · #13 · Feb 9, 2003 (Edited)

Anti-lift make more sense than AD. It seems to me that a front end set up with 150% or more AL ( in a 3-link for example) would be a good thing. Correct me if I'm wrong (I'm sure you will), but then the front would compress, or dare I say squat?, under load. On climbs that would be transferring weight to the front wheels. And on steep decents the front would lift when you hit the brakes, which would help you from endoing. I may be way off here

enlighten me.
I guess that's what AirRide already said

VooDoo

Discussion Starter · #14 · Feb 9, 2003

TPI that's exactly what I'm trying to find out.

TPIJeep

· #15 · Feb 9, 2003

VooDoo said:
TPI that's exactly what I'm trying to find out.

Sorry dude, the thread got so off topic with the limit strap thing I forgot to back up and read the first post.. :emb2: :emb2:

TPIJeep

· #16 · Feb 13, 2003

Lets get this topic moving again.... would be nice to have some anwers to this.

Mieser

· #17 · Feb 13, 2003

I am trying to play it safe with my buggy project....

I am going to keep the front links the same length top and bottom, with the mounting points the same distance apart on the axle and frame. The arms are 36" long and very close to level.

If I am thinking about this the right way this will create a neutral suspension right? The AS or AD will be 100%?

I am trying to find room for a high pinion diff with portals and a LOW CG so that I can run an inverted 4link with the lower links tri-angulated. My backup plan is half a lower wishbone in the same configuration....though that doesn't look to promising.

I am interested in learning more about all this!

TPIJeep

· #18 · Feb 13, 2003

Fine then, don't answer the question... FAwk it I am going to make adjustablity up there to, my numbers can be adjusted from 85%, 122%, 149%, 174%. So I guess after I get my junk together I can post what worked the best!

My gosh the fabricators on this board sure don't want to help out at all, thats a damn shame....

JEEP_TJ_FREAK

· #19 · Feb 13, 2003

TPIJeep said:
Fine then, don't answer the question... FAwk it I am going to make adjustablity up there to, my numbers can be adjusted from 85%, 122%, 149%, 174%. So I guess after I get my junk together I can post what worked the best!

My gosh the fabricators on this board sure don't want to help out at all, thats a damn shame....

I think part of what we are running into is lack of difinative knowledge. Nobody wants to say the magic number (which doesn't really exist IMHO) then you build the thing just to hate it and never let the first guy go about it.

I can see both sides but from your 85%-174% adjustment range I don't see how you could be too bad off.

ashmanjeepXJ

· #20 · Feb 14, 2003

cool thread...

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