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Hi guys
Any reason I coannot use a 4 link bar system to locate my LCA's as I dont think I can get the Radius rods to run at the correct position ie inline with inner pivot points.
I would use rose joints on the parallel bars and run staright forward. They work on a beam axle buty would they work on the IRS?
Cheers for any comments
Gary
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Welcome aboard Gary.
What type of IRS are you using? Anytime you move locations you'll be changing the geometry. Not saying it can't be done, we need more information. What type of car also?
Ralphy
Last edited by Ralphy (12/27/2013 2:33 am)
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Hi Ralphy
Using a Jag XJS Powerlok 3.07 IRS narrowed to 54 ".
Going on a kitcar/hotrod based on replica of a 1930's Riley. Car can be seen on madabout kitcars in Vintage/Classic kits ,Ol Peggys rebuild'.
Currently has a Vauxhall magnum live rear axle. I have used a 4 link on a live axle before and they stayed the same length when axle moved up and down.
I thought that maybe a 4 link would work on the Jag IRS. this will have similar up down movement of 3 to 4 inches max so 1.5 to 2 each way.
Will have a problem getting the radius rods to the right location for best working movement.
I thought I could use rose joints each end of parallel bars to they had some side ways twist available, I mean you get a limited anount of that on a live axle anyway.
The car weighs approx 800kgs.
Hope that helps.
Cheers G
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Here are links to my Car rebuild. Already 31 years old and still going.
Last edited by Badgrizzly (12/27/2013 9:02 am)
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This has got to be the #1 question on this board!
First off you don't need a 4 link design, all you need is two. With an IRS you don't need to be concerned with pinion angles since it's fixed and already set. Second, you may not think or see fore and aft movement, but it does. The radius rod is just that, moving in a radius never being in the same fore or aft position at any suspension height. Going straight forward will cause toe changes and pull/push the LCA/dog bone, also causing binding. What your doing is taking two links and moving them radially at a 90 degree angle. They can't follow each others position!
The right way is to go forward or rearward even. With one link on the same axis of the inner pivot of the LCA. Boy that's a mouth full ain't it? In effect you've built an A arm moving in the exact radius.
Here's a builders guide put out by the Austrailian Government. It's shown clearly on page 1 of mounting a Jaguar IRS. Note, the distance forward is not critical, you can go pretty much anywhere forward. However, to far back near the LCA's inner front pivot will give veryy little aid. Check out the other sections as well, especially suspension.
Street Rod Manual
Mounting Jaguar independent rear suspension
Note: The link does not need a bend like this. However the shafting coming from the LCA gives a good visual image. That' a members car, Jim Blackwood. Go to the Jag picture thread, pinned at the top of this board for more.
Okay I did say you can go back also, here's a photo. This setup is on the LCA's inner points axis. Look in the shadow you can see the position right at the back of the IRS.
Last edited by Ralphy (12/28/2013 5:07 am)
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But?
But now there's still another issue. The axle centerline is above the LCA. With enough HP you can wrap up, load or twist the LCA! Causing wheel hop and even breaking the LCA. A fella has built a setup that pins the upright at the top in position with a Watts Link. Not from my experience because I don't have this setup.
Here's an upper Watts Link
Location of the fixed ends have to be positioned just so, as to follow the same linear path as the LCA. So take a look at this photo? There's no trailing link! Maybe if you beef up the LCA and add a Watts Link you can forget about adding a radius rod all together, hmmmm...........
Here's some videos. I just noticed it appears the first video has trailing link like your talking about, straight forward. It looks like he struggles a bit from binding?
Nick/Mickmate is here in the states. He sells a made up kit.
Here's a company that makes an all new LCA and Watts for racing. Aluminum LCA and a single coilover or double.
Ralphy
Last edited by Ralphy (12/28/2013 5:04 am)
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Cheers Ralphy.
Have a good measure up and can do a radius rod setup but only have 20" inches forward and in to the pivot points, should be enough to give strength. going to use a rubber bush at axle end and rose joint at front pivot point. Cheers Gary
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Well if you are going straight forward? If you can move the chassis link mount any toward center of the car, it would reduce toeing a little. Also I would make sure the link is level. So it will only create a toe-in with jounce/rebound. Toe-out is not desireable. A 20" link at 1 inch of travel would equal 19.9749. Then at two inches of travel it would equal 19.8997. Putting the link as far out on the LCA and as far in on the chassis will reduce effects. Just an observation! Other factors such as static LCA angle outward would need considered. Plus the anti-squat of your LCA, what is the angle your LCA front to rear inner mount, zero would be good? If it's not you may want to raise the trailing link up a bit at the chassis. Anyhow I think most Jag units have at least 3 degrees, others here know more. So many factors!
Ralphy
Last edited by Ralphy (12/30/2013 8:02 am)
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Hi Ralphy
Sorry mate probably me not being clear, I can run radius rods at an angle to the chassis and line up with the centre pivot points so as to make it move in conjunction with the LCA but they will on ly be 20 inches forward of the Outer LCA mounting. Quite a tight triangle but should do the trick. The Engine is only approx 220bhp and car is only 800kg max so should not have too much stress. Cheers Gary
PS I like the look of the watts linkage but way beyond me and chassis mounting points.
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Oh, great, that should be fine. There's guys running with no support at all and more HP. They are the ones with real problems.
You probably do not need a Watts.
Ralphy
Last edited by Ralphy (12/30/2013 8:34 am)
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Gary,
I was in the same boat, limited space for the radius arm.
Mine is 19" long, 9 1/2" forward of the LCA pivot point. I couldn't make it any longer since as it is now, the forward pivot point of that radius arm is right against the back of the seat.
I'm using Heim joints both ends.
Ken
Photos:
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