[Zook_Fan]

What's the best link ends for high speed offroad driving? The car will be a 4 linked rear, 3 link front, chasing 14" travel and my biggest concern is what to put at the ends of the links.

Options:
Ruffstuff heims
FK heims
Normal bushed joint
Johnny joint
???

I want the car to be controllable at at least 140kph and I want it to be reliable. So what's people's experiences? I've searched pirate for hours and have a bit of an idea but it is hard to dictate between guys that give their opinions when they never leave low range so if that is you I'd still like to hear your experience but please note if your car is just a crawler.

[Ethann]

I'm running 1.25" lower and 7/8 upper Ruffstuff Heims.

Have been in a buggy with 7/8s all round, v6 and 14" coilovers and easily done 100kph +

[TZAR]

http://www.offroadracing.com.au/index.p ... Itemid=455

ask these guys. They are off road racong people who could help you out far better than what we ever could

[31zook]

I have the LROR 3/4 heims one end and Pootrol bushes on the other.

I do 110kph down the freeway and it's okay in corners. The biggest down fall a 3-link has is no roll stiffness, so without a sway bar mine has some decent body roll. I chose to use the link end combo cause it will marginally raise the roll stiffness and also stops vibrations from the front end working. I have 14" in mine also, when I get around to fitting a better sway bar I'll be better on road and more stable off. Don't get me wrong I am happy with it as it is, it's just got a bit of room for improvement.

For a quick car I see your combo looking pretty good.

[SierraDan]

I like overkill. So i wouldnt touch anything smaller than 7/8.

[Zook_Fan]

Thanks Ethan, just the info I was chasing.

Tzar I know there are possibly better sources, thanks for that one I'll be looking over the various links there for a while. The purpose of this was more for similar weighted rigs in similar conditions but variety is never a bad thing.

31zook the roll stiffness in the front has me slightly concerned. I think that with the coilovers I should be able to tune the suspension decently to avoid running a sway bar because I extremely doubt I'll find room for one. Thanks for the input though, I was thinking patrol bushes on the chassis end of the lowers might go a long way for impact absorbsion when hitting the lowers on rocks. However I'm thinking the only time the rubber bush is likely to even start to flex is after the heim has completely rotated and is leveraging off the spacer which would be harsh on the heim.

I'm more on the side of the minimalistic view Dan, I want it to be just stronger than it has to be. Beyond that you are introducing excessive weight and packaging issues. I do agree it has to be at least 7/8 for the application though

[Fatzook]

I'd find room for a front swaybar if I were you. Look at running a currie Anti-rock torsion type swaybar through the front tube cross member.

[Red89]

Fatzook wrote:

I'd find room for a front swaybar if I were you. Look at running a currie Anti-rock torsion type swaybar through the front tube cross member.

A lot of the KOH buggies run them backwards like this.

[Fatzook]

Red89 wrote:

Fatzook wrote:

I'd find room for a front swaybar if I were you. Look at running a currie Anti-rock torsion type swaybar through the front tube cross member.

A lot of the KOH buggies run them backwards like this.

I've seen a few mounted to the lower links with link pins attached to the chassis.

[Zook_Fan]

I've seen a few mounted to the lower links too. I was looking at that option but it will be real tight with the steering box. Is my understanding wrong of coilovers that with correct spring selection and valving you can run without a sway bar? Firm valving will help to slow down any inherent body roll even even though it doesn't actually stop it. Add that to a correctly postioned dual rate slider, which once activated can introduce more than double the spring rate on that shock compared to ride hieght/suspension droop, and the car should theoretically handle pretty good. The only thing extra that the swaybar will do is "pull up" inside wheel flattening the car out further?

Perhaps I should expand on the vehicle specifications so people understand what I'm shooting for here..

LWB Sierra, full body
37"s
105"ish wb
17" belly perhaps an inch higher
Shooting for about 40% uptravel
14" coilovers
2.5" hydraulic bumpstops

It will be used/compliant for winch truck challenges, rally's, Aust4, TT, basically as much as I possibly can. The aim is for a fast, well handling car with the main focus on the winch truck events (due to being local).

[Ethann]

31zook wrote:

The biggest down fall a 3-link has is no roll stiffness

Sorry Josh but I have to disagree..
With mechanical steering you will have poor roll centre due to having to run your draglink and panhard parallel to limit bump steer. Assuming Zook_fan will be running full hydro, he can build his 3 link to have a good amount of roll centre.
With a 3 link + panhard the roll centre is determined by the height of the centre point of the panhard. If the centre of the panhard is pretty low you will suffer a lot more body roll. If the centre of the panhard is higher, the less body roll there will be.

[SierraDan]

He mentioned steering box.

[appsie]

it seems from one of your above posts a steering box is still on the cards??

on this ethann, as it appears you have done alot of reading or been learning from tim, mine suffers alot from this same issue with the panhard. it is very low as i tried to keep the car low and couldnt really get any more height from it or seperation at my upper with the ride height i chose and uptravel. i have had a few people tell me this would make a huge difference on my car, shy of lifting my front chassis section up tho its not possible but thanks for the info id say im a good few inches lower than where id ideally want it to be

zook_ fan as per everyone else here with the style of rig you are planning 7/8 sound good and if really keen 1.25 heims on lowers. comes down to weight and power tho i believe. As ethann has said jases rig is running 7/8" now and has been for some time with what i believe minimal to no faults. thats rock crawling and fast stuff, zook powered and v6, 40s and 37s over a few different builds.

Rigs like matt dunks all have these crazy big diffs, 1.25 heims etc and even antirocks front and rear. nice soft coil setups, try to keep your spring rates down, atleast a 14" coilover will let you do this. Theres probably even a few QLD based rigs in the works at the moment that will help you with info yeah?i look forward to seeing a buildup of this thing it will be cool

[Ethann]

SierraDan wrote:

He mentioned steering box.

Oops, missed that haha.

appsie wrote:

on this ethann, as it appears you have done alot of reading or been learning from tim, mine suffers alot from this same issue with the panhard. it is very low as i tried to keep the car low and couldnt really get any more height from it or seperation at my upper with the ride height i chose and uptravel. i have had a few people tell me this would make a huge difference on my car, shy of lifting my front chassis section up tho its not possible but thanks for the info id say im a good few inches lower than where id ideally want it to be

Haha, reading and help from Tim.
I tried to keep mine as low as possible, but it come to the point where I was compromising stuff just to 'appear low', so i lifted it about 75mm from where I wanted it and gained so much more, in a few different aspects.
I have approx 10.5-10.75" of vertical seperation in the front

[Zook_Fan]

Sorry guys, forgot about steering. It will be hydro assisted, need to maintain a mechanical link for winch comps.

Thanks Appsie, I'll be putting the build thread up in a while when everything is here. It'll have plenty of power but no more than those rigs.

Thanks again to everyone in this thread, it's confirmed my thinking and now I'm back to the drawing board regarding the swaybar

[appsie]

just measured mine at 6" seperation on my 3 link up front ethann. panard inline with that so definately way too low.
watching matty white/ jases rig even with the coilovers it still suffers because of this a little bit as my front end is the same as it, it reacts alot different to other coilovered rigs on the same climbs but my shit box just multiplies the problem with what i have. i should of read before i built a car lol

theres a few measurements for you to try aim for zf, id say ethann is gonna end up with a very well setup rig, keep an eye on it for yours in the future, along with many other cool builds on here

[31zook]

Ethann wrote:

31zook wrote:

The biggest down fall a 3-link has is no roll stiffness

Sorry Josh but I have to disagree..
With mechanical steering you will have poor roll centre due to having to run your draglink and panhard parallel to limit bump steer. Assuming Zook_fan will be running full hydro, he can build his 3 link to have a good amount of roll centre.
With a 3 link + panhard the roll centre is determined by the height of the centre point of the panhard. If the centre of the panhard is pretty low you will suffer a lot more body roll. If the centre of the panhard is higher, the less body roll there will be.

True, and even without hydro, his still probably going to need allot of chassis to compete, so the links will always be compromised to make do/fit in the OE chassis.

On a tube (tube ) buggy you can perfect the links, and get everything set perfect for every situation, but I think 14" of stroke even an extremely close 3-link will behave very well.

Also I have a full roof, lining, panels of glass, dash, and big head up above my links so I'm not sure if that is exacerbating the roll stiffness or not.

[Zook_Fan]

31zook wrote:

Ethann wrote:

31zook wrote:

The biggest down fall a 3-link has is no roll stiffness

Sorry Josh but I have to disagree..
With mechanical steering you will have poor roll centre due to having to run your draglink and panhard parallel to limit bump steer. Assuming Zook_fan will be running full hydro, he can build his 3 link to have a good amount of roll centre.
With a 3 link + panhard the roll centre is determined by the height of the centre point of the panhard. If the centre of the panhard is pretty low you will suffer a lot more body roll. If the centre of the panhard is higher, the less body roll there will be.

True, and even without hydro, his still probably going to need allot of chassis to compete, so the links will always be compromised to make do/fit in the OE chassis.

On a tube (tube ) buggy you can perfect the links, and get everything set perfect for every situation, but I think 14" of stroke even an extremely close 3-link will behave very well.

Also I have a full roof, lining, panels of glass, dash, and big head up above my links so I'm not sure if that is exacerbating the roll stiffness or not.

This is true, I will have to compromise and make it around a lot of the OE chassis. I will try to tuck the panhard up as high as possible though, I was unaware of that influincing the roll centre. Again also a good point to note, there will be a lot of the weight as low as possible in the build. The engine and drivetrain aren't light and basically the only thing up high is the cage and a very thin roof.

appsie wrote:

just measured mine at 6" seperation on my 3 link up front ethann. panard inline with that so definately way too low.
watching matty white/ jases rig even with the coilovers it still suffers because of this a little bit as my front end is the same as it, it reacts alot different to other coilovered rigs on the same climbs but my shit box just multiplies the problem with what i have. i should of read before i built a car lol

theres a few measurements for you to try aim for zf, id say ethann is gonna end up with a very well setup rig, keep an eye on it for yours in the future, along with many other cool builds on here

What is the negative reaction that you talk about? Is it unloading the front? Hopping? Wish I was around newcastle at the moment to check out some of your cars . I watch Ethan's and a few others, yours included, through every update

[SierraDan]

The front unloads on climbs. Not so much side to side. So difficult to get grip on very steep climbs without a suck down winch.

[appsie]

is mattys old bracketry still up front for a winch dan? will one be fitted before TT? that day on the bonus rock of heartbreak was a perfect example of that, jas drives it really well tho, he was getting close on that climb and just keepin cool
rear links could also be the cause of that a bit? back when mine had no seperation nearly at the chassis end on the rears it would sit down in the ass alot, torque up alot and unload the front. i got it better now but without a full redesign of the chassis its still not quite where id want it, thats what future builds are for improvements

[SierraDan]

Its still there yeah. I think he's just gonna chuck a small one on for now. Hopefully be on for TT, but some wireless comms are priority for us.
We adjusted the swaybar a little which made it better. But I think it's just a characteristic of the front end regardless.

On the big rock over the back by Tomahawk was where a suck down was definitely needed.

[appsie]

its crazy up there, how did he go?
hopefully yas do well at TT anyway. Yeah even if a few characteristics arent spot on the car is proven and keeps workin so why change. there will never be a perfect setup i guess

[SierraDan]

Good on the side coming toward tomahawk
Couldnt get grip going up the other side(Very vert/undercut)
Yeah, thats it. Super capable, just little bugs that you can work around.

[Zook_Fan]

SierraDan wrote:

Hopefully be on for TT, but some wireless comms are priority for us.

Get them from this place: http://www.mrmobile.net.au/

I have the Sena SMH10 pack and it is great. Easy to connect, 900m range and even if you go out of range they automatically connect when you come back in. With a speaker in each ear it's extremely clear.

Appsie did you ever put your figures into a 4 link calculator for the back? If it is squatting a lot I'd love to know what the antisquat value in the back is.

[SierraDan]

Yep thats tthe ones we're grtting. Used them on the final track at Toperi and had to get them haha.

[appsie]

NO i have never put any figures through anything lol, but it is a whole lot better now and pretty well right in the rear.
it used to be terrible, the figures woulda been up the poo

one day ill measure again n put the figures through

[Zook_Fan]

That would be interesting to hear the results from appsie!

7/8 Ruffstuff heims have been ordered

Rather then start another thread, or derail a current one, IF I run a sway bar in the front to try and limit the body roll and the unloading due to the low panhard how is that going to affect the front to rear flex?

This is in a current thread:

Gwagensteve wrote:

Rear travel is a bit of a poisoned chalice. The most critical time you need to get the car to balance is whilst climbing, at which point the best thing you can do to make the car feel balanced is to stop the rear flexing, because when the car is on a compound angle, rear flex will make the car want to flop over.

Considering this car will spend a lot of time going up hills I don't want that characteristic. Although if I run a front swaybar the rear is going to move easier than the front. What I'm getting at is:

A rear swaybar is going to exacerbate the front unloading going up hills
A front swaybar will help the unloading up hills but I believe will increase the amount the rear of the car flexes.

If I have both, I'd need to run the rear on a softer setting than the front to get a compromise of both? Someone tell me I'm overthinking or over looking something simple...

[31zook]

A sway bar won't help with unloading it will control the roll of the body.

And I see where Gwagon is going with that train of thought, but it only really comes into effect if you have a (severely) incorrect 4-link or 16+inches of travel on each wheel.... I rekon with careful rear 4-link you shouldn't run into these sorts of problems.

Plus your not running 400+ hp through it so I think that standing up on its back wheels is less of an issue.

Flame suit on, I'm quiet ready to be told I'm wrong.

[got_bar_work]

I recon u want the rear stiffer then the front
U want the rear to stay level and the front to do the work
My coily was the opposite and it use to lift the front up off the ground all the time because the rear was so much softer then the front

[SierraDan]

31zook wrote:

A sway bar won't help with unloading it will control the roll of the body .