Trac Bar

[Zukinator]

Well had a great day yesterday prerunning the Quinn for the OVO's PJ Party and eventually Suzican.. But discovered I am getting axle wrap.. So it looks like I need to build a trac bar (or are there other options???).. I have never done this, so I thought I would get opinions on how too's..

I was thinking of welding a basic steel rod of some kind underneath and to the diff with a heim type joint on either end.. is tehre more to it then this? where is the best body spot to weld to? How long should it be?

Thanks,
Tim

:beer: :beer:

[Fullload]

With the low gears and small tires with a somewhat heavy foot i have had wrap even with the bar. Now that i am running Toy axles i can no longer cheat with an offset diff.
I found this on another sit and will copy the design for my truck. I hope it works.
On the top i'll run the princess auto tractor link heims on the top and the bottom i'll run a sleeved sidekick coil link.
In the pic you'll see that the bolts are horozontal which makes me belive that the pinion can still rotate with the bolt not effectivily reducing wrap.
On the spring plate i intend to do someting (haven't thought the details out yet) to run the bolt vertical so that you still get the flex needed but it fights against the way the bolt is pointing.
You with me so far? If you have more questions just shout.


I'll shut up now but here is the pic!!!!!!!!!!!

[lil beast]

your right fullload the bar will still move forward and back when the pinion goes up and down.

Let me give you my version of this set up with some editing.

[Zukinator]

I am mostly with you.. I am a little lost on the verticle bolt though..
I was thinking of a centrally mounted track bar. On top of the Diff with a joint that will allow horizontal twist, but not f/r movement. This would also allow for good twist flex, with the 2 trac bar on the outside edge would it not reduce the flex? I was thinking that using the pivot point would force the wheel as it flexed to pull forward, making it work against the suspension.. with a central trac bar it wouldn't limit flex, only if both are dropped at the same time, and if that happens to me, then I am screwed anyway.. Am I thinking wrong??

Thanks

[lil beast]

Here is my version, the orange section would be sleeved inside the red section to allow for extention at full droop. With it sleeved it will not allow the pinion angle to move up and down but will for forward and back movement.

The blue dot would be the bump stop. There is triangulation to keep the bar straight.

Give me your opinion on this set up.

[Depot]

lemme be the first to throw my hat in the ring and say "i dont think that design will work". lemme try to explain y...

the top of the axel tube is held firmly in place by the spting pack. Its the bottom that moves front to back under load. With that bar u'll reinforce the top mount but still leave the bottom weak. When under load.. the axel tube will try to spin in the opposite direction of the the tires - so lets look at going forwards for now. Looking at the rear axel from the drivers side.. the tires will spin counter clockwise trying to move the tube clockwise. With nothing stopping the bottom of the tube from moving forward, eventually it will... the shackle at the rear of the spring pack will alow the spring to move forward.. this forward play will alow the spring to bent in front of the perch like /\ and behind the perch like \/ - ur classic S bend. With the track bar where it is, mounted in that way, the bar will either bend or curve or kink.. especially since the bars strength is not designed to resist bending.

With the bolts both being horizontal, its kinda useless, it will let the axel tube spin whichever way it wants and when it does that it will simply change the ride height of ur rig when the springs s-wrap.

If u put the tube bolt vertical it will help a lot but I still think it will just bend the tube. Lil best ide of reinforcing the tube will help greatly but i still dont think it will be enough.... the axel tube will still try to spin.. the track bar will prevent the top from moving easily which will foce the bottm to move forward and up - inducing that s-spring wrap. when it does wrap, ur bar will still be there just higer since ur springs would have effectively flattned... kinda hard to splain without pics...

Its really really hard to stop soemthing from spinning if ur only grabbing one side of it - no matter how securely u grab that one side...

I think u'd be much further ahead grabiing the axel beow the tube to stop the wrap in the rear axel. perhaps even right under the u-bolts.. no real need to go 6" below tube center like in my truck unless u have a real heavy foot.

either which way, I'd be curious to see how it actually works out.. perhaps that design will provide just enough strength to stop the axel wrap for normal usage.

gl

D

[zc911]

isn;t what you are talking about depot, what muscle cars put under the rear springs?

I think the best way to go is somthing like this in the middle of the rear axle

[Depot]

thats a classic design.. works great if in center of diff. Full's dilemna is that now with a toy axels, he cant easily put a centered track bar and im sure he doesnt want bars like mine that hang soo low on both sides.

There is a kit out there that grabs a toy axel on the third member that uses that design.. some of u may rememebr that big beast of a track bar I used to have.. it uses the triangular design much like ur pic there. My problem with that design was I made my bar too short and on too steep an angle which caused the rear diff to ark forward.

the key to a track bar for the rear is to stop the bottom of the diff from moving since the springs do a decent job of stopping the top. stopping the top and bottom from moving with that tiangle design will relieve 99% of the wrap effect on the springs itself whereas having only a single bar on the bottom will prevent most of the wrap - it wont stop it all.

D

[zc911]

http://static.summitracing.com/global/images/prod/large/cee-2101.jpg


"they eliminate wheel hop and improve traction by applying the force that normally produces unwanted axle rotation into a downward force to make the tires stick to the pavement"


that is what i am talking about, stops spring wrap on hard lauches on drag cars, couldit not work for offroad too?

[Terranaut]

Drag cars do not flex the suspension up nears as much as a 4x4.
I think that would be great for on road driving but as soon as that axle tries to stuff the tire into the quarter panel that thing will be in the way .
It also kills clearance there too.
Depot I would think the Toyota axle would be great for that classic design because you could weld on the back for the upper mount without have a diff cover there.
At full compression how much room do you have above the diff center ?

[lil beast]

Originally posted by zc911
http://static.summitracing.com/global/images/prod/large/cee-2101.jpg


"they eliminate wheel hop and improve traction by applying the force that normally produces unwanted axle rotation into a downward force to make the tires stick to the pavement"


that is what i am talking about, stops spring wrap on hard lauches on drag cars, couldit not work for offroad too?

We are looking for ground clearance and a traction bar like the ones on a drag car will be useless for our application.

Why?

1-Beacause when at full flex you would have this bar which is attatched to the spring stopping you from flexing.

2- This is only for a spung under application.

Depot, I see your point with the bottom moving but the pivot point (axis) will be at the top of the axle isnt it? So going 6" under or 6" over the pivot point (axis) would stop the wrap either way.

[Fullload]

Depot i'll let you know how it goes. And you'll see for your self the next time we go wheeling after you back from the east coast.
Zukinator, i'll probally end up doing a similar design to the one in the pic except (the horzontal bolt thing)
look on the spring plate. You will see that between the 4 u-bolt Nuts it has two tabs welded and the bolt passes through the bushing horozontally. I'll probally change that to a vertical bolt passing through the bushing.
I think the horozontal bolt as in the pic allows the pinion under wrap conditions to "pivot" with the bolt allowing actaul Wrap. Hopefully by putting that one bolt in a vertical position it will help keep the pinion from flying all over the place because it will have to "break" (for a lack of a better word) the bolt to make movement in the axle.

I hope that explains it a bit better.

[Depot]

Originally posted by lil beast
So going 6" under or 6" over the pivot point (axis) would stop the wrap either way.

not really no... by installing a trac bar 6" over the original axis center, all u've done is reinforced the top hold (being the springs). So now u have a perch plate that is 6" tall with a fixed point... the bottom of the axel will still try to move forard and backard and with the shackle allowing the spring to move, U'll still get that infamous s-wrap. the only diff I can see with that set up is moving the s-wrap from right around the perches to further out from the center of the pack. where there are even less leafs and less strength.

Full, I look forward to seeing ur rig in action and seeing just how well that design does hold up. It may be enough reinforcement for u to make it work but I'll bet with the lead in my foot and those few extra horses under my hood this year I'd destroy springs within a day with that set-up.

l8r

D

[Fullload]

Sometimes there is just no wayto know unless you do it.

New spring packs with bushings are pretty cheap and i'd rather run new anyway.
Something about a 20 year old spring that has been re-arched 40 million times leaves me a little funny.

[MuddMachine]

Zukinator, your bar will work. Fullload fukd his springs with a single bar on the bottom of the diff but at the same time he bent his axle cuz he's geared and no reinforced diff. Ive had good luck with a single link on the bottom, simple, less weight.

Fullload, I hate to rain on you buddy, but Depot is right in what he's saying. Top mounted wrap bars can actually 'induce' rap cuz of the leverage points. Ive seen bad cases of it. And watched the top mount style in action. Not the route I would go dude.

[Fullload]

Lil beast and i have come up with a great idea. It will allow flex and keep the pinion from moving in nay direction and the idea will only work with a centered diff.
I'm not gonna go through the trouble to explain right now. You'll just have to wait for the pics and either a write up on the damage or the success.

Trust us :321:

[Zukinator]

Zukinator, your bar will work. Fullload fukd his springs with a single bar on the bottom of the diff but at the same time he bent his axle cuz he's geared and no reinforced diff. Ive had good luck with a single link on the bottom, simple, less weight.


Well time to get to it then.. Will try to get to tit this weekend.. Thanks for the tips :urock:

Cheers
Tim

[szabotage]

I am in the works of building a trac bar and have researched the different possibilities to conclude that the style that breeze industries sells is the way to go, with one small modification.

it seems that a solid trac bar design that breeze has may limit the amount of droop/flex on the axle when in full articulation. I'm wondering if a slip yoke or slider on the main bar (section attached to the frame)was added this will allow the unit to compress or expand accordingly.

if this theory is correct what I might ghetto fab for the main bar is the slip yokes from an old driveshaft that I grenaded at the u-joint ass. and give it a second life. basically I'd just chop the u-joint end off and weld in a jonny joint or the princess auto rod-end-equivalent.

has anyone or know anyone who has done this? and how did it work out?

[Fullload]

I belive that breeze has allowed side twist as well by a slip style bar. They even tapped it for a grease fitting.
The idea with the driveshaft splines will only work for droop when both axles go down at the same time. (Ie. when you jack up the truck) when you stuff one tire it has to twist as well as droop. On the actual working shaft in the truck, the pinion on the diff side, rotates as well as the t-case flange. If you have the male and the female of the shaft in the trac bar it will not twist * unless* you use the Princess Joints.
With the joints it will be a great idea.

[szabotage]

kewl, I'm gonna fab it up this weekend coming up, pics will be taken and scannd soon( disposable camera, that's all I got)

mike

[MuddMachine]

Sorry guys...... I moved the thread to BootyFab but didnt give you a redirect, my bad.

:bang: