4 link conversion discussion

[Dimitri]

i am wanting to convert the rear end of my corolla to proper equal length 4 link set up.

i have found a supplier that has the rod ends, and pre made links with threads.

they also sell ready made cone spacers, (for either side of the bearing) and pre drilled flat brackets i can use to fab' mounts.

using 1/2" rod ends, and their standard cone spacers, my brackets are going to end up being about 28.5mm wide inside.

Is this too narrow? the lower brackets end up fairly long (over 150mm off the diff) and im thinking it being narrower makes it twist easier, but maybe not? or maybe its not under alot of twisting force?

if so can anyone suggest where i might be able to get some wider spacers off the shelf that i can add to the outside of the cone spacers, so i can use a wider bracket?

[oldcorollas]

err.. weld a tube to the end and use a poly or rubber bush instead?
any particular reason for using the rod-ends?

what happens when every link is a rod-end and the car rolls? does it still have freedom to roll, or only move up and down?

for road or track?

[Dimitri]

too much compliance/friction with a poly bush for what im trying to achieve with the car.

and yes, it can roll. though i have a hard time visualizing/explaining, ive seen it on stationary cars, where the diff can move freely in all necessary directions.

car is built for the track but will be driven on the road (to and from events mostly).

[LeeRoy]

What type of car?

[Dimitri]

see avatar.

[Rodger]

The idea of a fully rose jointed four link is to have total freedom in vertical movement. Any lateral movement is controlled by a Panhard or Watts type linkage. The angled spacers allow the rod ends clearance for movement of one end up or down of the live axle compared to the other end, ie one wheel over a bump. The "roll" old corollas is speaking of.

Poly, unless lubricated correctly, binds up and hinders the desired movement of the suspension and actually has none or very little sideways or twist compliance and is, I feel, a worse choice for lack of it, even when compared to the OEM rubber. It does not allow one end of the axle to move up and down.

Without springs and shocks in place, the other suspension components should not hinder the movement of the rear axle. It should be free to move through its full range of travel.

As long as there is enough clearance for the rod ends to rock over and do not touch the side mounting brackets then it will be ok width wise. If the brackets are just two flat pieces then you would really need to turn them into at least a "U" by welding on a back, as the OEM ones did. You could also weld in braces perpendicular to the bracket up to the diff if still concerned.

Regards

Rodger

[Dimitri]

ok. just cant remember ever seening even full fabricated rear ends with brackets that small.

i guess most of the ones you see are drag cars though, which run much bigger rod ends.

i think 1/2" will be fine though as im using steel rods and it will probably never seen much more than 200hp.

maybe 300hp one day if i did a turbo engine.

also yeah i will enclose the back.

[Rodger]

Had you considered what T3 has to offer Dimitri?

http://www.technotoytuning.com/productdetail.php?p=688

I have purchased a set and I really beleive it is good value for money. At least you can compare what others are doing.

Regards

Rodger

[Dimitri]

it is for sure pretty good value for money, they use great rod ends and are well made.

but they dont add up with what i am planing.

as i am having to re bracket the diff anyway, i dont really have the need to use parts that are OEM comaptible.

because of this i can actually source whats required, ready made, for ALOT less than the T3 gear.

less bling, but still high quality and using good motor sport teflon lined rod ends.

[Rodger]

I agree there Dimitri. If you have access to all the parts you can do it well and a lot cheaper. The T3 parts are a good buy for someone who up until now had no means to fabricate my own.
Just having a metal working lathe makes a hell of a difference to being able to do such jobs.

Now that I have a good lathe I am going to use the T3 lower arms and to do an equal length 4 link set up I am adapting the OEM lower arms by cutting and turning off the old bushed ends, turning up threaded sleeves (no LHT as I am not that good yet) and good 5/8rod ends.
Then turn up the spacers. I plan to use an already re-worked AE86 diff housing in the TA-22 shell I am building, so OEM width brackets are in place.

Regards

Rodger

[Ben Wilson]

It might be worth looking in the UK, there are a lot of kits out there for five link conversions for Escorts, they may be fairly easy to adapt..

[crostek]

here is a set up in a drift car that I have seen

[Dimitri]

yeah ive had a look at the pomy stuff, it would make it easy but by the time you get it here it wouldnt end up being that cheap.

re above, yeah beaus car is awesome in a lot of ways, but i dont wanna do my 4 link the same as his.

that (his set up) is maybe the easier way around it, but as im doing my diff and rear end at the same time, im going to position the top links directly above the lowers (i can do this as im using rear coilovers too). that way the arms intrude less obviously into the cabin, and theyre not floating in the middle of no where.

i have decided to just do the upper link at this stage, and leave the lower ones stock (except for lowering the the mount on the bracket).

its only about $100 in parts, which is pretty easy to swallow. and the top is all fabricated and needs to be co-ordinated with the cage some what. the bottom can be left for now as its basically just a case of unbolting it a replacing them once ive got some made up.

[Rodger]

Keep us informed as to how it goes Dimitri.

And any pics would be great.

Regards

Rodger

[Dimitri]

some progress.

basically this is where its at, the passenger side channel needs finishing, and a brace for the shock towers as they now support the rear of the vehicle, tack the sway bar brackets on, diff out and painted.

cage was going to be incorporated into the stucture, but more custom work means more build time and im not really up for it at this stage. at a later date i may do a proper cage, with a tansverse brace of the main hoop for the upper radius arms to attach too.