adj 4 link...why????

[ke70kid]

why do ppl run adj 4link,what are the pros and cons of this mod????

[timbo]

my understanding is they are used for adjusting the pinion angle which is the angle of the differential. when you lower a car alot of geometry is put out including pinion angle so adjustable trailing arms are used to correct this; you want the tail shaft and differential to be aligned horizontally in a straight line. personally im running adjustable upper trailing arms and aftermarket non-adjustable bottoms and i think some people on here do the same.

pros: more adjustment for aligning the diff

cons: not sure as i don't know the full ins and outs but someone will!

[Dom86]

Yep, that is correct Timbo.
The benefit of using them is you get more traction and feel from the rear end.
You are better off with both top and bottom adjustable so you can adjust them together.

[ke70dave]

Yep, that is correct Timbo.
The benefit of using them is you get more traction and feel from the rear end.
You are better off with both top and bottom adjustable so you can adjust them together.

this is assuming that you know what you are doing when you are adjusting them.

you can also do alot of bad with them as well.

i personally dont understand much about it. but its to do with "anti squat" and...."pro-squat" (or anti-anti-squat hehe) which has to do with how the rear suspension reacts when putting the power down. its very important for drag racing, as the race is either won or lost in the first second of the race.

here is a pretty neat article, i had a quick read seems to be pretty good.

http://www.whiteline.com.au/articles/WL_Solid_Axle_Antisquat.pdf

[blair]

Pros: If you run your car low, need to try and point the nose of the diff down to avoid slapping the floor! (or just cut a hole if your that way inclined)

Cons: almost all adjustable 4 links come with rosejoints -> although very stiff, if you actually drive your car hard alot be prepared to buy new ones again and again!

Way around it -> make your own with polyurethane bushes :)

[sundee]

i feel that just having the upper arms adj, you can just correct pinion angle, but having both upper and lower adjustable you can tune how much "squat" and "anti squat" the car has
im not really clued right up on the topic to give you a tech description but its used heaps in racing, lots in drag racing, i think the more squat you have the more traction you gain.. or something like that.
and you have options of busings, rubber, nolthane, rose joints - (from softest to stiffest)
the stiffer the bushing the greater the feedback to the driver

[FAST EDDIE]

i put upper adj arms in froma dvise for a fairly well known drifter and it did a whole lot of fuck all!!!!!

[Evocom]

I am unsure on the whole "pro/anti squat" deal, can sort of understand the pinion angle thing and I plan on putting them on my track car for none of the above reasons. I am doing it because I have a 31 skyline diff in my KE and the mounts haven't been welded in the perfect spot so my back end can not be aligned with properly with the front.

[Skylar]

The length of the arm directly does not affect the anti-squat geometry. In changing the length of the arms (and changing pinion angle) you move the pivot points on the diff side of the arms. This changes the angle of the arms. The imaginary lines drawn by the trailing arms determines how much anti-squat you're running along with CG height, CG location front to rear and rear tire contact patch location.

As far as I understand, anti-squat is a sort of mechanical binding caused by acceleration/deceleration forces. It determines how much of the acceleration force is absorbed by the rear springs (in case of RWD car) or how much is fed into the chassis. If I remember right, 100% anti-squat means the rear springs don't get compressed at all as you accelerate and all the force is absorbed by the metal of the chassis. The further you go away from 100% anti-squat means the springs are doing more work in holding the rear of the car up as you slam the throttle into the firewall and the car will squat.

What all that means to traction, I don't know. I tend to find that guys decrease anti-squat to get more drive out of the car while drifting. What puzzles me is why we fit traction brackets to increase anti-squat. All this is off the top of my head and been a while since I was looking at doing stuff to suspension so some of it is probably not right.

[H8CHIR6KU]

pretty sure the main reason is too set the pinion angle of the diff. i do find that having the rosejoints in itself was worth the change. the feedback from the back end of the car is awesome compared to the bushes i had origanlly. i wouldnt use it on the street though, way too hard.

anti-squat is another thing all together but you will need adjustable arms to set up

[DOG the rolla hunter]

in the toyotas for sale section there is a sprinter "formerly known as dirty ibis" that looks like the upper control arms are coming into the car. why do this ? why not just have adjustable uppers mounted to the standard position? (i may be wrong on this one)

[Sam-Q]

Cons: almost all adjustable 4 links come with rosejoints -> although very stiff, if you actually drive your car hard alot be prepared to buy new ones again and again!


don't forget about the noise and extra vibrations

[Skylar]

The dirty ibis car has the trailing arms as they are so the diff isn't over-constrained in roll. Also puts the side view instant centre on the ground getting rid of a lot of the anti-squat.

blair, how often are you talking about in having to replace them over and over?

[sundee]

replacing spherical bearings in the trailing arms often = crappy bearings or bad setup.
NHV or NVH which ever way it goes is not that bad really, if u want a peaceful car buy a camry

[AJPS]

don't forget about the noise and extra vibrations

they snap t series axles

chris did 3, then chet did 2...

[Sam-Q]

I am unsure how they would add extra stress to the axles

[sundee]

i cant see how they will cause axels to snap - both shafts are supported by bearings so thier is not direct link from the housing to the shafts... bet both cars had locked diffs

[AJPS]

chris had a locker, chet didnt, ill let them post their results, but it was directly related to the 4 link, once it was out, chris stopped snapping axles - both big ports with t series trailing arms at factory length

Need bush at one end at least in my opinion

[sundee]

mayb setup incorrect? just doesnt seem right

[pen15]

trav aka ae71neo runs them and he has never had any issues with them at all from what i gathered as i was asking him his opinion on them he loved them

[sundee]

I think he runs T3 arms doesnt he?

[pen15]

I think he runs T3 arms doesnt he?

that is correct i am thinking of getting some from you joel soon but ill be getting them when i get back from japan

when i was looking under my car tonight prepping it for the track i noticed that the pinion angle was perfect and my ares are stock if the car is rolling stock ride height wouldn't the pinion angle be wrong?

[biggo]

At normal ride height yes it would be incorrect. But it also goes up and down a far lot more than your car ever does. If your worried weld up your suspension and deal with it.

[blair]

Bushes have a 3 year warranty.

With how much driving i do, i'd be happy to get a year out of rosejoints (from talking to guys who have experienced first hand)

I also believe, that if you cant steer a car well enough with polyurethane bushes (90A) and NEED rosejoints... maybe give up? THIS COMMENT IS NOT RELEVANT TO TRACK ONLY CARS OBVIOUSLY.

[sundee]

changing the cars anti squat or squat affects the pinion angle. having more anti squat transfers the compression load from the springs through the all the trailing arm links and the chasis.
so having lots of anti squat will affect and reduce the life of the rose joints.

i dont think ppl need rose joints to make them steer?......

[blair]

They might not need them, but people like you sure do a good job of making them think they need them!

haaa :P

ANYWAY this thread is about the adjustable part. NOT about bush vs rose joint.

I'm out.

[sundee]

yeah cant u see i like to twist arms,
last i checked the the joints are a part of the adjustable arms....

[blair]

Hence why i mentioned it as a con of adjustable arms ....

only reason i posted again is because you only said like a third of a sentence: I'll finish it for you?



the stiffer the bushing the greater the feedback to the driver and the harsher it is on the car and you, and the shorter the life of the bushing

comprende?

[H8CHIR6KU]

i agree for the street that adjustable arms are prob over the top esp with rose　joints, but for the track you cant go past rose joints. nothing beats a direct and instant response and feeling from the car

[sundee]

Gee Blair lucky your here, you just stated the obvious.

And also having a stiffer bush doesn't really equate to a shorter life but the setup of the 4 link does.

[blair]

Some things arent as obvious to some people?

Just trying to help people out before they dive in to something thinking its the latest and greatest things since sliced brread,

then suffer the negatives and go "oh damn i got stooged!"

and yes i believe strongly that the stiffer the bush the shorter the life.

Would you back your rosejoints to last 25 years? i pulled out some original rubber bushes the other day, they were like new!

Look at all the cars that came with factory rosejoints (camry's etc)
There are a millllllllllllllllion for sale because they die so often.

[Skylar]

I don't think it's the stiffer material lasting less, it's the polyurethane that has the short life. I think if you bought TRD's hard rubber bushes, they'd last maybe as long as OEM rubber bushes.

Rose joints used on unequal length trailing arms WILL flog themselves out quickly, simply because that area NEEDS some play/movement. I figured the stress required to deform the sheetmetal of the chassis/twist the diff housing is probably more than the rose joints were designed for.

Rose joints in other apps, I got no idea.

[blair]

Have a read of this man

http://www.fulcrumsuspensions.com.au/images/stories/superpro_technical_pdfs/SuperPro_history_of_properties.pdf

[Skylar]

So, I read that. It says they use thermoplastic polyurethane, which is an elastomer. Natural Rubber and all sorts of other rubbers are also elastomers. This means both materials last the same?!? I hard a look around wikipedia looking for life of stuff or what causes degradation of the materials but couldn't really find much.

[AJPS]

The super pro stuff really does out last the nolothanes etc.

From my understanding super pro - over cured, others - air cured

[sundee]

No one can get stooged by choosing to go from rubber to poly or to solid mount, in the end it's up to the driver to choose what they want to run in regard to use and needs.
The setup of the 4 link will gauge the life of the bush,
I guess without arguing to much you could fairly say that their COULD be a trade off of life for rigidity?

But is it a worth while trade off? .... I think so