4 link rear end... wtf?

[johl]

ok alot of people lately have been really rating modifications to do with rose jointed 4 link rear ends and what not... i honestly dont have a clue of what a 4 link rear end is, what it does to the handling of your car. and also while we'r at it what is so different about rose joins on say a panhard rod versus a normal adjustable one? pro's con's on that also besides the obvious legality of rose joins. before i get flamed yes i have used the search feature but could not come up with an answer to my questions. thanks
-johl

[riceburner]

I am no way suggesting i know all about cars but my knowledge spans this far.

The ae86 along with many 80's cars using solid diff technology use what is called a 5 link rear end. http://www.ae86drivingclub.com.au/forums/emoticons/blink.gif

Link 1* panhard rod/lateral rod

is just that, a hard bar that holds your chassis and diff inline, its run parralel with the diff, when you lower your ride due to the panhard rod it pushes your diff to 1 side so then it becames non-centered to the car (also known as crabbing, if its bad enough).

Link 2 & 3* Upper trailing arms

2 short bars used to keep diff center angle set in 1 place, they run parrallel to the chassis, if you can imagine the twisting force applied when you accelerate these bars hold your diff center square.

Link 4 & 5* Lower trailing arms

2 longer bars they run parrallel to the chassis, usually used to keep wheel base length in check as well as keep diff square.

now all these bars are solid fixed with a rubber bush used to stop vibration and movement thru out the car.

When used with adjusters/rose joints they can be set to perform better then stock applications, especially when lowered.

If you can imagine that all the set angles used with stock gear is different when lowered.

So suffice to say that when your car is lowered say more then 20mm you will need to atleast a panhard rod thats adjustable, but its better to have all of the 5 link adjustable.

Dont forget that rose joint are a solid mount thats adjustable and will transfer a considerable amount of noise and vibration thru out the cabin. They can be legal if you use teflon lined version of them as per pic.

http://www.mcdonaldbrosracing.com.au/images/4linkstreet.jpg

You can see here a 4 link with stockish rubber on 1 side and rosejoints/rodends on the other end.

http://www.club4ag.com/faq%20and%20tech_pages/Control%20Arms/DSC00141.JPG

Reading this may help you
http://www.club4ag.com/faq%20and%20tech_pa...%20Version.html (http://www.club4ag.com/faq%20and%20tech_pages/SHOPS/Battle%20Version.html)
http://www.technotoytuning.com/faq/

[Konakid]

Dude....top post http://www.ae86drivingclub.com.au/forums/emoticons/2thumbs.gif

[riceburner]

Thanks KonaKid i always try my best to answer when i think i can, but wether the info is usful or not is another matter.

Naturally there is alot more involved to setting up your 4 link then what i have outlined, such as traction brackets/Tuned trailing arms/diff center-pinion angles etc etc , but its a start for Johl & others that may read it.

[rthy]

hey whers that picture from? I want to buy some bushes like that

[rthy]

i found the ones on the website, but they arnt like the first ones

[johl]

yeh dude top post. definately answered my q's... but what would be better in my 71 that is quite low (more than 2 inches), would it be better to have the trailing arms shorter or longer? or do u just adjust it till the wheel sits as much to the centre as possible as the lower process would effect this?

[Gilly]

the key to a quality 4 link is all in the rose joints used. teflon raced balljoints are the ultimate and will significantly out last any other joint. teflon joints in a heavily used track/daily for ultimate longevity. all others flog out.

[RobertoX]

Always go teflon lined joints, I have pulled out teflon joints and normal ones used in the same locations for the same amount of kms on different sides of the car and the non-teflon ones are either seized or have a hell of a lot of slop (and seize up when you load them anyway)after only a small amount of use wheras the teflon ones are good for many more kms.

Another thing to note is that when you have a 4 link the linkage is actually over constrained in roll (which means that it is not free to move). In the factory installation this doesn't matter because the bushes take up this but when you put in rose joints the diff housing does not want to roll with respect to the chassis. The roll comes from chassis flex, flex in the links and joints and twisting of the diff housing and mounts etc. So when you install a rose jointed 4 link rear it appears to stiffen up the rear a lot which can feel really great but is not the best for traction.
You can see this on Billzilla's site where he has used a drilled out rubber bush on one of the links and rose joints on the rest, this way the axle can still roll like it should and you get the control offered by the adjustable joints.

[rthy]

where can I get those PTFE lined joints? also wheres that first pic from?

[Gilly]

you can buy them in Australia but the cheapest i could find was around $75 per joint. they are the best though and will outlast all others. if you want some Sam (not that price) and can wait a little while drop me a pm.

[RobertoX]

Yeah is the first joint like a rod end but with some urethane in it or somthing? More like an adjustable rubber bush than a rose joint with a spherical bearing... interesting

There are a fair few ptfe joints available in Aus and I have found that most bearing places can get them in (not the CBC I went to though http://www.ae86drivingclub.com.au/forums/emoticons/tongue.gif). Have a look at the Aurora catalog on their website for part numbers etc, I have not had a problem getting any of these but you have to wait and they are expensive. The 'motorsport' ones are awesome (but stupidly expensive)
http://www.aurorabearing.com/product-catalogs/default.html

Gilly what price can you get ptfe rodends for? I will need about 40+ quite soon and am always looking for a good price (mostly m6 and m8 metric thread)

[ae86hachiroku]

The roll comes from chassis flex, flex in the links and joints and twisting of the diff housing and mounts etc. So when you install a rose jointed 4 link rear it appears to stiffen up the rear a lot which can feel really great but is not the best for traction.[/b]

So, rose joints, good for slides, no good for grip according to what you said

[RobertoX]

sort of but not really, 4 link rose joints would be good for slides and rose jointed arms properly set up so that they don't bind up on roll would also be an upgrade for grip because they offer greater control and adjustability.

[RobertoX]

i have a box of joints i have access too, they are very sharply priced, teflon and all the shiz, heat treated etc

pm me if you want to buy just the joints

[riceburner]

where can I get those PTFE lined joints? also wheres that first pic from?[/b]

All you had to do was left click>properties on the pic and it tells where the pic came from.
http://www.mcdonaldbrosracing.com.au/rods.html

Prices are at http://www.mcdonaldbrosracing.com.au/prices.html just download the PDF.

[rthy]

lookig at this product more from macdonal bros:

http://www.mcdonaldbrosracing.com.au/images/4linkstreet.jpg

it doesnt list the dimentions however they are $50 each. I think I will call tomorrow and find out. I would think they would have more of the advantages of the heim joins but still with some insulation.

It does look like all these joints are made in imperial sizes, no big deal though as I will just adapt it. What I might do is make a setup like this for my 5 link:


top left hand linkage: stock but chopped down either end to make the bush width very narrow and hence not do much at all, a safety only

top right hand linkage: solid heim joints

bottom linkages: rubber bushed rod ends


sounds odd but theres a method in my madness though

[rthy]

that pic above is for a pan-hard rod kit most likely for big diffs, so I would asume that they have a big enough hole in the middle to suit my needs, $50 is affordable too

[RobertoX]

sounds good sam, keep us posted on how it goes!

[rthy]

ok I checked it out, heres the deal with the bushed one:

Width: 32mm

Bore diameter: 3/8 (9.525), but the guy says the middle can be pushed out and he himself has succesfully bored them out to 15.87. So I would do that but bore it out to 10 (toyota use 10mm right??).

Thread: 3/8 UNC left or right threaded

Price: $50


I want to look at in one person and see what its like, I also want to tomorrow measure up the dimentions of the standard bars and use that as a guide for what pipe I need buy to have the right strength.

[floody31]

Jonny Rochester would be a better man to comment but he'd pulled a bunch of spherical joints out of camrys at the wreckers; I'm not 100% on which model of camry or where they came from, but they had a really neat rubber seal encapsulating the joint. Might be worth considering for anyone planning to build their own arms, or panhard rods at least.

[RobertoX]

Oh yeah, dont forget that when you make a rod to use left hand thread on one end and right hand thread on the other. That way you don't have to pull the joint off its clevis to adjust it. (you probably know anyway but just in case http://www.ae86drivingclub.com.au/forums/emoticons/smile.gif )

[rthy]

Oh yeah, dont forget that when you make a rod to use left hand thread on one end and right hand thread on the other. That way you don't have to pull the joint off its clevis to adjust it. (you probably know anyway but just in case http://www.ae86drivingclub.com.au/forums/emoticons/smile.gif )[/b]

As good an idea that is I only have right hand threads laying around and also for the saftey reason alone I would only go with rights.

[driftke70]

whats the easiest way to set these up, mine will be going in tomorrow, im assuming I would like to try and make my top arms shorter and the bottom ones longer than stock to try and point the diff upwards to encourage wheel spin for drift. any help would be greatly appreciated.

[rthy]

if your prepared to do some redrilling you can make it do that easy by reducing the antisquat angle

[driftke70]

my 4 links are adjustable, no need to drill. I was just hoping noone would say, no thats not how you do it do it like this. But it looks like thats what ill do and see what happens. They are already in just stock length and they feel amazing.

[jdmcoupe]

adjust your upper arms as they changes angle of the diff... and leave the lower arms stock as that effects your wheel base

[driftke70]

makes a lot of sense cheers