Looking at ideas for rear leaf springs . Running an off road only sj410 doing short course competition's . Front suspension is unlimited mod's so no issues there . Rear susp must bolt in to factory mount points . Torque rod (thats what I will call it , rod from chassis to top of diff to stop rolling the diff under power) is installed .
Currently we are spitting out factory main leaves , bending them near the chassis mount eye . Trying to think of different options now as we can now change to aftermarket springs . Thought about a main leaf that was very thick from the chassis eye to behind the axle mount then tappering off . Combinèd with the rod this would solve the bending issue but would mean the last half of the leaf is doing all the flexing . The torque rod would need some play otherwise it would not let the diff roll with the main leaf as it would no flex .
Any other ideas out there ? No one seems to do parabolic springs anymore , would not solve our issue anyway . Want half parabolic springs .
This tread is not about the "trac bar" , it is about seeing if anyone has come up with a way to run stronger springs but still retaining reasonable flex . As with most threads on here I am just waiting for all the "you are doing it wrong" or "that wont work" negative comments to be made and then we will hopefully get some positive comments and ideas .
For what its worth to answer the assumptions . From what I have been told "trac bar" runs off top of diff forward to some point on the chassis , dont ask me about the geometry of it not looked or measured it . vehicle was build by someone that builds these for a living and has been competing for 20 odd years , so maybe not perfect but I expect its pretty good . Rear must be sprung under , ie as I said mounted to the factory positions . Front is a custom 3 link coil over , so irrelevant . "Trac bar" is a contributing factor in bending the spring at the eye . It is there to prevent axle wrap and does that job . Currently been running standard suzuki rear springs per the rules , so 4 leave I believe ? Rules have only just changed allowing aftermarket springs , hence the question for ideas .
As I said the is an offroad only vehicle used for short stages . The "trac bar" and the factory springs do there best but the springs lose out against the 220hp pulsar engine and the 33" tyres . I never said the situation was perfect but at the moment the springs are the weak link .
Dont quote me on it but im pretty sure Westralia springs do parabolic for sierra?
Dont know why youd spend the $$$ though..
You should be able to run 2 full length leaves in your pack with a clamp near the eye to stop it bending so easily.
They never came up in a google today so will look into them tomorrow . Agree with the two full length leaves idea , considered bolting the two together in the leading half but I do not think they would like that , bet they crack on me . This is what we will probably try as I can't see anyone game enough to make me a single taper leaf like I imagine . Think two mains will be too stiff though , there is no weight in the back bar a dive bottle so much lighter than factory .
This tread is not about the "trac bar" , it is about seeing if anyone has come up with a way to run stronger springs but still retaining reasonable flex . As with most threads on here I am just waiting for all the "you are doing it wrong" or "that wont work" negative comments to be made and then we will hopefully get some positive comments and ideas .
You've just had a couple of very knowledgeable people ask you about the set up as a 'whole' they were not giving you a "that wont work" they were trying to understand the entire set up so they could suggest a best outcome for you.
My thought (along with others it seems) is that the trac bar is incorrectly set up and still allowing the leaves to wrap. Fitting parabolic springs won't solve this. Running stiffer ones will help but you'll lose your flex and it will still wrap eventually as the leaves fatigue.
building a caltracs style trac bar, while it will reduce clearance, will 100% stop your leaves wrapping and may be the cheapest and easiest solution as it does not modify the existing spring mount points, but rather piggy backs off them.
Once you have that right you won't need to worry about expensive / custom spring packs.
If it is spring under and the trac bar is only a bar on the top, this will rape the springs.
Spring under and trac bars The top of the diff pulls back and bottom will thrust forwards. The bar on top is in simple tension and the lower leaves take all the thrust in end on compression, causing them to buckle and wrap etc.
I would retweak your trac bar before making custom springs.
I did not ask for an analysis of the setup , I asked for ideas on running stronger springs that can bolt into the factory position . So unless you have something to add , like alien frankly butt out . You guys want to read the posts here from an outside perspective , its just a joke these days . There is a post today , someone wanting info from someone that HAS a similar type of tyrewheel setup . First reply , cant do that wont fit , cut that hits this blah blah , next post shep saying he fitted a very similar setup with a little bashing . I don't know the first posters setup but I bet he has not run anything like what was asked about . Still that an assumption but since we are all making those .
Anyway , just because I don't want to seem like a complete ass (too late they cry) Want33 read my reply post , the rear must be spring under , ok , get that , it must be spring under .
Alien , a caltracs bar will stop the spring bend but would not stop the diff rap and is not allowed in the rules , the torque rod that is there is all that is allowed .
jdk81 yes the lower spring is in compression , the torque bar is there to stop the diff rotating and snapping the pinion/uj off the diff on acceleration . Hence my idea of a stiff first half of the spring , in effect a lower link , then a thining trailing half for flex . Not an ideal solution but a left field idea for sure .
I think every question I have asked here has resulted in a you cant do that reply , I asked if anyone had put bigger than v6 brakes on a suzuki axle , ohhh can't do that it, wont work . Well I've done it (rx7 4 pots all round with v6 disc's)and for what I asked about it works a treat . So as different spring ideas is just too much for the general run of the mill here , I expect no more helpful replys . I will scurry back to my little world and carry on . Shame as I have got some good info off here for my road going 4wds over the time . Maybe if I was not so crock I would have better manners ....
Alien , a caltracs bar will stop the spring bend but would not stop the diff rap and is not allowed in the rules , the torque rod that is there is all that is allowed .
WTF is diff rap? Spring wrap allows the diff to rotate in the opposite direction to the desired wheel direction - moving forward, this is pinion up - so the uni gets thrashed and the front ends of the leaves go S shaped - leading to snapped leaves. It is the leaves themselves that control the axle/diff position and control the rotation of the diff while also allowing for up/down travel - the leaves are the only connection between the diff and the chassis (short of the shocks of course but they don't locate shit).
A caltracs setup completely eliminates spring wrap - as the twisting force of acceleration is transferred to the top side of the front of the leaf - infinitely countering any wrap effect and keeping the pinion pointing where its supposed to.
I run SPOA on lux fronts with nearly no leaves in the packs, AND a 1.6 with 5.14 tcase reduction on 31s... everything in the world wants my diff to do backflips rather than drive the car forwards but the trac bars cancel that all out and it just works. It also doesnt limit flex other than having removed the bushes in the front of the leaves in favour of solid bushes to locate the outer plates of the bars.
While i may have suggested a supplier to give you what you asked for, its likely not what you really want... which is to control your spring wrap. Caltracs etc were designed for Fords and whatnot with lots of power and heaps of traction (sort of like a sierra running a 220hp engine and 33s) to control spring wrap in a SPUA configuration. They don't muck with the spring rate, they address the issue of the spring wrap separately - no different to a coil sprung car having control arms to locate the diff front/back and allow the coils to worry about moving up/down.
Why didn't you provide more info about the "torque rod" rules etc? Instead of appearing to be a cock about it? You're solving a problem a trac bar fixes, not providing enough info and being a knobjockey about it. And you are blaming others for making the forum worse. Anyway, enough of that.
Can you provide the rules please?
Vehicle manufacturers use spring design to avoid the wrap, whilst maintaining some flex and load carrying ability. off centre pins, second leaf clamped and overlapping at hanger and/or partially wrapped etc
Due to the rules you are vague about, im guessing you cant do off-centre pin. You can try overlapping the wrap and clamping another to it and have them a lot shorter on shackle side, but the front half of the leaves wont flex anymore and may load the leaves behind the diff very funny.
Joined: Thu Mar 13, 2008 10:30 pm Posts: 4530 Location: Toowoomba
Vehicle: Maruti and LJ80's
Posted: Thu Nov 20, 2014 7:15 am
chris77 wrote:
IThere is a post today , someone wanting info from someone that HAS a similar type of tyrewheel setup . First reply , cant do that wont fit , cut that hits this blah blah , next post shep saying he fitted a very similar setup with a little bashing . I don't know the first posters setup but I bet he has not run anything like what was asked about . Still that an assumption but since we are all making those .
Yeah bad example. Shep hacked that car which he referred to very lightly with "little bashing" later to retract that with he used an air chisel and had no regard for the body panels. The first poster knows what will fit on a vitara and gave a pretty good reply as well.
Prove us wrong. Add an extra leg to the trac bar so it connects on the top and bottom of your diff, put a set of decent springs in there and show us that they had the same life. If you can mimmick the rotation of the differential through its travel range there will be no binding.
Joined: Mon Aug 02, 2010 3:44 am Posts: 5 Location: New Zealand
Posted: Thu Nov 20, 2014 7:22 am
Hi Guys. Its my zuk he is talking about. I will try and get a copy of the rules and/or pics of the current set up in a day or 2 so you know what we are dealing with. The initial question was about anyone running a "stronger" leaf spring than a standard one. Understand the current track bar design may be not helping the situation and will be looked at. Even with a well designed track bar I still think there will be an issue of the leaf spring acting as a lower link (happy to be proven wrong!). It is a lot for a zuk spring to cope with, current set up of the vehicle is SR20DET midmounted with a primera fwd gearbox (locked front diff to act as a transfer case) running to FJ40 Landcruiser axles and beadlocked 33" tyres, so plenty of power and traction, especially on some of the surfaces we compete on.
This is the sort of competition we do so yes the springs get a beating
Joined: Wed Dec 19, 2012 7:43 am Posts: 685
Vehicle: 85 ' Drover
Posted: Thu Nov 20, 2014 8:20 am
That looks like so much fun.
That gearbox setup sounds very interesting. FWD gearbox mounted to the back of a RWD engine, and you use the now north south orientation of the differential to run your diffs? very cool.
Joined: Mon Aug 02, 2010 3:44 am Posts: 5 Location: New Zealand
Posted: Thu Nov 20, 2014 8:56 am
droverdave wrote:
That looks like so much fun.
That gearbox setup sounds very interesting. FWD gearbox mounted to the back of a RWD engine, and you use the now north south orientation of the differential to run your diffs? very cool.
Joined: Thu Mar 13, 2008 10:30 pm Posts: 4530 Location: Toowoomba
Vehicle: Maruti and LJ80's
Posted: Thu Nov 20, 2014 9:01 am
Can you change the suspension mounts? Earlier they said it had to be to the stock suspension points, which can be interpreted as the location on the frame rather than the actual mount. If you can I would be changing up to a wider 60mm spring that gives you a greater amount of material opposing the moment force.
And no, regardless of your track bar design you will still have the leaf spring acting as a lower link. That's 50% of it's job. It locates the axle and provides ride height. If you want your ride height to remain in the same location you cannot increase your spring rate so you will end up with less leaves with more length to achieve what you want.
Joined: Mon Aug 02, 2010 3:44 am Posts: 5 Location: New Zealand
Posted: Thu Nov 20, 2014 9:34 am
One end of the vehicle must retain factory suspension, ie what ever rear springs are put in they have to be able to be bolted into another Suzuki of that model, so no, cant use wider springs. So at this stage it is getting some OME heavy duty rear springs or getting some custom made with the idea Chris had in the first post of thicker at the leading end and tapering off once past the axle as the stresses are at the front. Was throwing the idea out there incase anyone had been down this track. But granted its much easier on a club truck/bush basher/comp vehicle (with out annoying class rules!) to use thicker/wider springs out of a lux etc.
Caltracs style trac bar does not affect the factory suspension setup - the leaf can be taken out and bolted into another car no probs and will solve all your issues.
Thanks for the info and explanation, it makes a lot more sense.
Id like to see pics of the trac bar/torque rod and the rules.
if you can only do leaf mods, A second partially wrapped at hanger end (and normal 2nd length on shackle end) and a 3rd leaf where 2nd normally goes (and normal 3rd spot at rear) Then clamp the hanger side.
You will need to tweak it to get the rate you want.
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