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PostPosted: November 12, 2010, 10:02 pm 
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I am considering using a WOBLINK as laid out in the standard illustration, as shown below.

Question: I can reduce the length and weight of the brackets for the links attached to the axle if the WOBLINK is placed so that the outboard ends of the links are farther forward than the floating link. That is, the plane of the WOBLINK will not be perpendicular to the centreplane, but will be at an angle of about 80 degrees to the centreplane, measured from forward. Will this skewed WOBLINK still work? I think so, but welcome comment from someone who's actually seen one work, or has examined the kinematics analytically.


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Isuzu Pickup/SR20DE, +401 COLD frame
Build Log: viewtopic.php?f=35&t=11601


Last edited by Warren Nethercote on November 24, 2010, 4:24 pm, edited 2 times in total.

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PostPosted: November 16, 2010, 2:49 am 
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As long as your floating link is 90 degrees to the ground it won't matter if your parallel links are on an angle (within reason).

I made one of wood pieces a few months ago to test it and it goes a long way before an arc starts forming eventually.

I decided against it because the links have to be designed for both compression and extension, not that thats a big deal but also the long link will always get twice the load making pivots wear sooner and exaggerating any play or clearance.

Other than chassis or ground clearance issues theres no reason to use this over a Panhard rod and it's not as good as a Watts.


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PostPosted: November 16, 2010, 10:20 am 
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Check out a Mumford link. It gives a low RC without the chassis having to be at the same height as the RC.

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PostPosted: November 16, 2010, 11:10 am 
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Thank you Cheapracer and KB58.

Going backwards through your comments, yes I have thought about a Mumford Link, but since my chassis appears to have been designed for a deDion it has two Z tubes that end up near the centreline of the Y tube (they point inboard as they run aft, rather than outboard as on the book chassis). The WOBLink doesn't require these tubes to be replaced or modified, but that may be a poor reason not to use the Mumford. Remember that I bought a chassis (see signature block), rather than scratch-built it, and am trying to limit structural changes. I should mock up a Mumford to see the real extent of interference.

At the moment I have my oil pan hanging down an inch below the chassis, and would allow the chassis mount for the WOBlink to do the same, leading to a 5 inch RC for the rear and a target 2 to 3 inch roll centre for the front. The simplicity of the book-style Panhard rod is attractive, but will drive me to about an 8 inch rear roll centre to avoid chassis interference on rebound. Comments elsewhere on LocostUSA suggest that an 8 inch rear roll centre is not a good thing. I have thought about running a panhard bar just aft of, and level with B1 (i.e., forward of the axle, running UNDER the pumpkin - giving a roll centre of 5 1/4 inches [correction: 6 1/4 inches]), but the panhard bar could not be as long the book style - although I have a +401 chassis to offset the shortening.

At the moment, my chassis is mocked up at a 5 3/4 inch ride height on the build table (see avatar), with the engine hanging down an inch. The net 4 3/4 clearance reflects my need to traverse a privately-owned gravel road between my house and the highway. I would push the engine even higher, but even now I think that I will need a slight blister on the hood, between the COLD nose and scuttle.

You have both given me food for thought.

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PostPosted: November 20, 2010, 4:27 am 
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I think this is the answer to most problems ...

2 gears and 2 links, the RC will be at the convergance of the 2 links. Easy to build (2 x reverse gear gears) and mount, very stable, easy to change RC height, extension and compression pressures are shared between the 2 links and little RC movement.


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PostPosted: November 20, 2010, 9:48 am 
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Cheapracer:

Interesting, and a potential solution to my own space issues.

One question arises: could you run gears 'in the open' without road grunge leading to accelerated wear or restricted rotation? I haven't looked, beyond a cursory Google search of industrial gearing suppliers, but there might well be suitable 'gearboxes' available from industrial suppliers, albeit not at Locost rates.

Warren


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PostPosted: November 20, 2010, 11:48 am 
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I'm having a hard time visualizing how the two gear setup would work. I'm thinking the overall objective is to keep the axle (and roll center) from moving too far laterally, or at all, while allowing vertical movement of the rear, beam axle. Am I focusing on the wrong thing or the wrong rear axle setup?

If I imagine either gear turning, let's say the right gear as you're looking at the rear view, then I see the lever arm linkage attached to it as moving latterly and vertically of necessity since the links are inclined. Since the two gears are meshed, that would force the left lever arm to move laterally and vertically too. As both linkages are fixed length, won't that mean they have to move the axle itself right or left to allow for gear rotation?

Perhaps I didn't go back far enough in the thread to see something else at play here? Or, maybe I just don't understand the kinematics of the situation?

As to the gearbox question (a very sensible one) it would seem to me if you built the gear/lever assembly on a very solid rectangular plate (I'm assuming it would be fixed to the chassis) with the levers on one side and the gears on the other side, a simple plastic or metal cover could be screwed and sealed to the gear side of the plate providing a weather-proof housing for them and some grease too.

Cheers,

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PostPosted: November 21, 2010, 10:28 am 
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I believe the point of using the gears is that it stops lateral movement and only allows vertical movement.

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PostPosted: November 22, 2010, 3:41 am 
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Warren Nethercote wrote:
Cheapracer:

Interesting, and a potential solution to my own space issues.

One question arises: could you run gears 'in the open' without road grunge leading to accelerated wear or restricted rotation? I haven't looked, beyond a cursory Google search of industrial gearing suppliers, but there might well be suitable 'gearboxes' available from industrial suppliers, albeit not at Locost rates.

Warren


You need reverse gears from a smaller car gearbox, they have the flange for the reverse fork and thats where you can weld your quadrant into. I'll take some pictures of my gears that I use.

I will be making one up this week so I can post some pictures for you of the setup in a few days time.


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PostPosted: November 24, 2010, 11:27 am 
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Looks something like this ...

Note the angles of the paper under the plan view - if you make them this is important to jig them while the gears are meshed as such before welding because the teeth will offset the quadrants from each other otherwise. The initial angle you use (90 in this case) is not important just that it is symmetrical from the centerline. The quadrants are about 3" swing for no reason other than seems about right from experience. Note the brass center bushes that will mount directly onto 14mm bolts.

More to come as I make it all up this week or next, depends on the consumption of Scotch and Cola :cheers:

Oh and since it's my idea I hereby name it the "Bex Link" TM and hereby proclaim this a public disclosure so no [Fatherless Child] can patent it :mrgreen:


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PostPosted: July 25, 2011, 12:51 am 
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Just a couple more pictures ...


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PostPosted: July 25, 2011, 6:10 pm 
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More to come as I make it all up this week or next, depends on the consumption of Scotch and Cola

Must have been a lot of scotch and cola involved :lol:


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PostPosted: July 25, 2011, 8:13 pm 
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Warren Nethercote wrote:
Cheapracer:

Interesting, and a potential solution to my own space issues.

One question arises: could you run gears 'in the open' without road grunge leading to accelerated wear or restricted rotation? I haven't looked, beyond a cursory Google search of industrial gearing suppliers, but there might well be suitable 'gearboxes' available from industrial suppliers, albeit not at Locost rates.

Warren



I wouldn't worry about wear, the gears are hardened for use in the car and see very little rotation using them for the axle. Give them a splash shield of some sort and you're probably fine for 100k+


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PostPosted: July 25, 2011, 11:32 pm 
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Lurch wrote:
Quote:
More to come as I make it all up this week or next, depends on the consumption of Scotch and Cola

Must have been a lot of scotch and cola involved :lol:


And very much enjoyed :cheers:

I simply forget threads until another thread reminds me of it as the other lateral link thread did for this one.


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PostPosted: July 26, 2011, 8:25 am 
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Cheapracer,

This was worth the wait!

It looks like you are using a deDion set-up. One question: You have located the BEX gears on the deDion tube and the ends of the link on the chassis. Had you done it the other way around as per most Mumfords I've seen (on this site), a lower RC might have been possible. But perhaps you weren't looking for a lower RC.

Warren

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Build Log: viewtopic.php?f=35&t=11601


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