Anyone ??? <IMG SRC="smilies/confused.gif" border="0">Originally posted by 2highToy:
<STRONG>Why wouldn't you want the pinion to be pointed at the x-fer case throughout its range of motion with a normal driveshaft too? So by running parallel links it doesn't keep the same pinion angle but converging links do? So how do you determine the ideal convergence angle of the upper and lower links (when looking at them from the side)</STRONG>
i all ready answered this, sort of. Read above dude.Originally posted by 2highToy:
<STRONG>Anyone ??? <IMG SRC="smilies/confused.gif" border="0">
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Benefits???? Ok dude, mount the link on top of the axle housing and get a flatter roll axis and less anti squat and the same amount of clearance. A straight tube is always stronger than a bent one. GET ITOriginally posted by ToyFamily:
<STRONG>Hey guys this is an example of the benefits of the bent link and how I was talking about making it like a fin for strength.
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You can use a compass, a tape measure and a piece of paper to figure it out. ; )Originally posted by 2highToy:
<STRONG>Why wouldn't you want the pinion to be pointed at the x-fer case throughout its range of motion with a normal driveshaft too? So by running parallel links it doesn't keep the same pinion angle but converging links do? So how do you determine the ideal convergence angle of the upper and lower links (when looking at them from the side)</STRONG>
With a regular drive shaft the pinion angle hs to be the same (or close to) the flange on the t-case. The reason you can point the cv is cause your suppost to have it pointed straight at the t-case (or within a few degrees)Originally posted by 2highToy:
<STRONG>Anyone ??? <IMG SRC="smilies/confused.gif" border="0">
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If your axle housing rotates that much through it's range of travel then under articulation it is going to be trying to twist. It seems like your links could be fighting each other enough to limit articulation.Originally posted by dirtrod:
<STRONG> I like the pinion to rotate so I don't get alot of angle in the U-joint at full travel. </STRONG>
Originally posted by ToyFamily:
<STRONG>Does anyone see anything wrong with this concept, I have been kicking it around for about a year.
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THANK YOU SAM!!! I am building a rear 4 link/60 setup right now and this type of good technical post is waht I need! I do want a little bit of clarification. What you are saying is that for the purposes of four wheeling the upper and lower links should be roughly parallel, and that anti-squat is bad for four wheeling, right? My upper and lower links will be sloped down from the frame to the axle, but I can make them parallel if that would be best. If you need info on my rig to help I am running the stock 4.0 engine, the AX-15 tranny, and the stock np231 (for now), the rear (and front) will both be 60s, the rear control arms will all be roughly 45 inches long. My crawl ratio is a pathetic 60 to one. Thanks.Originally posted by Strange Rover:
<STRONG>More numbers!!
The effect of the angle of the links (when looking from the side) isnt as great as the effect of converging arms on anti squat.
Say the same 100ftlb at 50:1 gives 5000ftlb at the axle. If we have 36in tyres this gives a tyre radius of 1.5ft. So that the forward push on the links from the tyres will be 5000 / 1.5 = 3333lb.
If the same 4ft links are at an angle coming down from the chassis to the axle with a 1ft drop then the lift on the chassis will be about in the ratio of 4 to 1 so that with every 4lb pushing you will get 1lb lifting at the chassis mount point.
So with 3333lb pushing you will get 833lb lifting at the chassis. And if you mounted all the links on top of the axle to get the arms as horizontal as possible I doubt that you will have 1ft drop from the chassis mount point to the axle mount point. So that the 4 : 1 ratio should be much less. So that the 833lb should also be much less in reality.
This compares with the 1250lb lift caused by the convergent arms which if you do have converging arms to get the pinion always facing the transfer you will always get and there is no other way around it.
Sam</STRONG>
Thank you. Finally, a great old style hard-core POR tech post...Originally posted by Strange Rover:
<STRONG>I threw a few numbers around just to demonstrate what anti squat actually does. When you gas it and have anti squat in the rear the effect is the same as if you moved the rear axle forward on the rig and had a big honkin rear overhang. Anti squat takes weight off the front and loads it on the rear because part of the weight the rear springs support is actually supported where the links attach to the chassis ie forward of the rear axle.
It dosent really mater what the numbers and ration and lengths you end up with but you should understand what anti squat is, what causes it, and how to minimise it because it is the difference between building a four link that can flex and one that can flex and hook up and get the power to the ground when you gas it.
To minimise the anti squat the upper and lower links should be parallel. The biggest cause of antisquat is using links that converge to one point on the chassis (when looking from the side)
The other cause is the links coming down from the chassis to the axle on an angle although this dosent cause as bad an effect as converging links. If the links came down at an angle of 45 deg this would be really bad but if they dropped by say 6 to 10 inches over a 45 inch long arm then this would be good.
If the arms were totally horizontal and parallel then you would have no anti squat and the rig would squat on the rear springs when you gassed it (cause there is no lift from the links to help). This may not be such a good thing either cause as the rig squats on the rear springs you will again get a weight shift to the rear so some anti squat could be a good thing.
Generally to build the links and fit everything into your rig you will have the arms coming down at a bit of an angle from the chassis to the axle and you probable will have them converging a little bit as well so I feel that just fitting everything in gets enough anti squat and you should just try to minimise it.
Sam</STRONG>
READ THE SUSPENSION GOD THREAD, AND BUY THE MILKIN BOOK CALLED GROUND VEHICLE DYNAMICS.1TONTJ said:This is all very interesting discussion, and I am learning. But are there any good references out there for a home fabricator like myself to better understand the concepts?
Thanks,
Phil