4link woes...

[Z()LTAN]

Because ive made the car so much lower and diff so much larger im running into the issue of my links running down to the chassis.

Now, the calcs im using have a spaz when links are below parallel.

Dont really know where im going anymore lol

[brooksy]

What calculator are you using ??
The uppers I have on the winch lux build are lower at chassis when in top position. Which gives me a 115% antisquat.
Make your lowers at diff about 1-1 1/2" below centre (keeping in mind not having brackets too low) & take into account tyre pressure will have you lose 15-20mm on diff centre height. I am running 39" lowers & 37" uppers with I think 9" sep at diff & 4-6" sep at chassis depending on which hole we choose. My lowers have a total triangulation of 16* (8*/side) with uppers 42* included angle. Lowers at chassis are roughly 45mm below chassis rail.
This is all on 37's.



brooksy

[uninformed]

what vehicle what diff? post up some pics if you can.

[brooksy]

Come on Serg, not hard to work out. he is talking about his 75 build as Zoltan is just making threads specific to certain aspects of his build.



brooksy

[uninformed]

yes but no but yes but......

To me, it is more so the physical limitations of a build that determines the placement of such things as links. Thats why I thought pics might help. I dont know how wide the chassis is in relation to diff, how much clearance it has in spots etc.... also what AS /roll center height/ axle roll axis is he shooting for. Youve gone 115% on your AS....someone else might only want 50%????

[Micka]

yes but no but yes but......

To me, it is more so the physical limitations of a build that determines the placement of such things as links. Thats why I thought pics might help. I dont know how wide the chassis is in relation to diff, how much clearance it has in spots etc.... also what AS /roll center height/ axle roll axis is he shooting for. Youve gone 115% on your AS....someone else might only want 50%????

Stop overthinking everything and just go to his build thread in members and see

[Micka]

Because ive made the car so much lower and diff so much larger im running into the issue of my links running down to the chassis.

Now, the calcs im using have a spaz when links are below parallel.

Dont really know where im going anymore lol

Going by the pics in your build thread, I'm going to assume you mean the uppers will be sloping down towards your chassis, because I can't see how the lowers could. It looks as though your lowers are going to sit fairly flat and if the uppers are sloping down that's not a problem.

Maybe some more info about where you intend to mount them?

Micka

[Z()LTAN]

Cheers guys, ive made a bit of headway now. I modified some of the brackets so i could get the lowers higher at the chassis end.

Room is tight, i think at full bump all round (so not at the diff links highest points yet) im going to have about 5mm of clearance with my lower right arm.

Like its been stated before, its all a compromise.

If i build the diff vert seperation for 44" tires that should be in the ball park for both 40's and maby 46's... Not so sure yet though.

My chassis end uppers have 5 points to move around in. Although its only in a 4" spread i think it should allow me to tweak it enough for crawling and speed.

Edit: Issue i have currently is the diff end lowers. To send them out far enough for triangulation there is no way of getting the bolt out past the rotor/brake caliper... Anyone run their heims a little off parallel with the axle tube to get them out?

[uninformed]

Stop overthinking everything and just go to his build thread in members and see

ok......no chassis after the cab so what the fuck is the problem......

"links angle down towards chassis".............easy, raise links at chassis!....insert 1000hp and get on it

[Z()LTAN]

What is a good roll understeer value?

[uninformed]

What is a good roll understeer value?

OK first of all I am just a web wheeler, so take it for what you want. A stock rover is about 0 degrees in the front and about +4 degrees axle roll OVERsteer in the rear. IT is also constant 4wd. One of the reasons they built some Oversteer into the rear was, that the early rangies (which most coil rovers are based on) had quite soft springs and hence body roll. If the vehicle was drivn over a bridge that crosses a valley and had strong side winds hit it and roll the body over a little, it would axle steer slighty into said wind to correct....SO.. a little wont hurt and I have about +4-+5 in the front and like +10 in the rear. This only becasue It is lifted on stock arms...Alot of the USA guys run zero or even shoot for understeer...I have NOT driven a vehicle with understeer and Im not sure it would be great. My rig is DD on the road and sees hwy speed. Im not saying shoot for + numbers IE high OVERsteer, But If me I would be happy with keeping the front as close to zero (neutral) and a touch more oversteer in the rear. I think the longer your links the more you can get away with. Beacause as the axle moves through its arc, it is softer, hence the axle moving less front to rear (steering). Another thing to consider is the Roll Center heights front and rear and their relation to each other. A rover has it higher in the rear (which is what is called loose and that would tend to have the rear let go first in a corner) A nissan patrol has the rear lower....I havent been in them much at all, but have heard they dont drive that great when lifted...an ex race car mate told me for them Roll center heights were built around the COG above that axle...the higher the COG the higher the RC....but a 4wd is not a race car so who knows. I have tried to visulise if the nissan front end with tall engine would have a higher COG than the rear say of a wagon????????

another thing to think about is how much axle housing you have outboard of the link....the more housing out there, the more travel will be amplified and the more oversteer etc will be to

probably just confused ya ....best weight for someone with experience to come along

[TheBigBoy]

After raising my panhard and high steer in my current truck 5". And not as yet had time to do the back. Meaning much lower rolling centre in the rear. Its not a good thing. Although my truck still drives dead straight with no bump steer. I feel the arse moving around. I would just aim for 0.

[Z()LTAN]

What yas rekon?

[uninformed]

from a guess not to bad....hahaha

looks like your uppers are about 70% length of your lowers?? if so i wouldnt go any shorter (any less %) Did you check it through bump and droop and see the prop shaft angles?

what link set up are you running in the front?

[TheBigBoy]

44" tyres? It will need the 1000 hp .

[Z()LTAN]

not with 287:1 crawl ratio

40's for faster stuff

[redzook]

i think u will have less AS then 86% as i find it hard to belive your COG is only 34" from the ground on 44" tires
id build it with the roll center as high as i could get it (helps body roll, and and the diff swings to the side that is compressing helping keep the tire out of the tubework/body)
and id get the roll axis flat or in the negatives

[uninformed]

how did you come up with your COG?

[Z()LTAN]

COG i cheated an measured to the top trans bolt... I think i may have chop and changed so much that, that COG may be on 40's

[uninformed]

ok, I know it is far from stock, but I would have guessed the top of trans be higher than 14 inches above axle center line???? (like I said, GUESS)

[Z()LTAN]

Thanks for the help fellas, i think i have got it reasonable now. Must have been smoking some good drugs before lol

[Baja Burley]

How touchy is the Roll axis angle? Can a driver tell the difference between -1* and -5*?? Im calcing up mine now and cant get the frame end lower link mount high enough to flatten out the roll axis without skyrocketing the AS.

I want the dif end upper mount as high as possible to keep the roll centre high. Aiming for around 90%AS with around 50% adjustability. rock crawler.

Please forgive the hijack but just wana keep similar tech in the one spot.

Cheers
Luke

[Z()LTAN]

No worrys Luke good idea, at the end of the day mate these calculators are there to just help you see if you are on the right track. They are totally not the deciding factor whether your car is going to perform good or bad.

Spring rates, valving and driving style all play a much bigger part in how a car performs.

I poured over this crap for weeks on end trying to get all the golden numbers, only to find out that there is no golden number and every car will perform differently.

Use it as a rough guide then crack out that grinder and welder and get to fabbin!

[Baja Burley]

Haha! The fabbin' will begin soon enough!! I just don't want the rear steer that a patrol gets. My god it's disgusting!

Does anyone know what the roll axis is for a big lift patrol? Just to give some comparison?

[Z()LTAN]

Patrols get flex steer because they have short parallel lower links.

As they move up/down they swing in an arc. When you lift them their arc origin position is at more of an angle so they walk around alot worse.

Longer lowers at close to level at ride height will solve this.

[redzook]

Haha! The fabbin' will begin soon enough!! I just don't want the rear steer that a patrol gets. My god it's disgusting!

Does anyone know what the roll axis is for a big lift patrol? Just to give some comparison?

if the links are parallel the roll axis angle is the exact same angle of the links

[Baja Burley]

Oh wow so a patrol would be something in 10-15* territory!