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Author Topic: Lakester rear suspension  (Read 35714 times)

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Offline Interested Observer

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Re: Lakester rear suspension
« Reply #30 on: February 02, 2017, 08:24:08 AM »
While OJ is correct to raise the consideration of  squat and lift, the description he gives of how to deal with it is not correct.  What he describes applies to an independent rear suspension system, while what is considered here is a solid axle on control arms, the control arms being the rear sub-frame and the suspension instant center being the sub-frame pivot point.  The relationship of the axle centerline and the pivot has nothing to do with the squatting characteristics if the axle is attached to the sub-frame.
Any time forward tractive effort is applied (at ground level), the reaction will be to raise the pivot point, and consequently the chassis.  The only way to mitigate this reaction is to lower the pivot point, giving zero lift when it is at ground level.  Likewise, any rear braking will induce squat to the chassis.

Offline oj

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Re: Lakester rear suspension
« Reply #31 on: February 02, 2017, 03:37:45 PM »
I see the 'rear subframe' as nothing more than an extended 4 link.

Offline oj

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Re: Lakester rear suspension
« Reply #32 on: February 16, 2017, 08:00:38 AM »
After thinking things thru I see it is more complicated than I thought.  It is quite a bit different from a 4 link, the problem as I see it the 2 lower attachment points to the chassis are more a hinge.  Hmm.

Offline Peter Jack

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Re: Lakester rear suspension
« Reply #33 on: February 16, 2017, 08:46:07 AM »
The thing it's closest to is ladder bars with the engine mounted on the bars. Depending on where the engine is mounted in relation to the pivot point more or less weight will fall in the unsprung category. My feeling is it's way too much work for the dubious results that may occur.

Pete

Offline SPARKY

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Re: Lakester rear suspension
« Reply #34 on: February 16, 2017, 10:45:27 AM »
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Offline Elmo Rodge

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Re: Lakester rear suspension
« Reply #35 on: February 16, 2017, 11:33:26 PM »
On my Lakester, it is solid in the rear. My thinking is; No engineering is better than bad engineering.  :wink: Wayno

Offline Jack Gifford

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Re: Lakester rear suspension
« Reply #36 on: February 17, 2017, 12:06:08 AM »
... The thing it's closest to is ladder bars with the engine mounted on the bars. Depending on where the engine is mounted in relation to the pivot point more or less weight will fall in the unsprung category. My feeling is it's way too much work for the dubious results that may occur...
I agree with all of that. Except that in my case the "way too much work" is offset somewhat by the fact that the nicely designed torsion bar suspension is already in place for the rear wheels. So the only "work" I'd be left with is design & fabrication of the subframe and its frame-anchored pivot. [While avoiding the "work" of mounting the rear axle rigidly]

With an A-shaped subframe, it's closest to ladder bars with their front pivots moved together. This would preserve the non-binding independent travel of each rear wheel.

As for "dubious results", I've seen a number of examples of satisfied landspeed racers using some form of suspended rear subframe.

Thanks for all the comments.
« Last Edit: February 17, 2017, 12:08:20 AM by Jack Gifford »
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Offline Jack Gifford

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Re: Lakester rear suspension
« Reply #37 on: September 25, 2017, 11:06:22 PM »
Although I'm usually not a fan of swing axles, it looks like I should at  least consider them. It has the attraction of true independent suspension, and limited travel would keep the tires reasonably "upright". And by doing quite a bit of the machining myself it might even be inexpensive to convert my 8" Ford center section- depending on what "works" for axle U-joints.
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Offline manta22

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Re: Lakester rear suspension
« Reply #38 on: September 25, 2017, 11:48:39 PM »
Jack;

Have a look at a Dedion rear suspension, it should be better than a swing axle (think old VWs).

https://en.wikipedia.org/wiki/De_Dion_tube

Regards, Neil  Tucson, AZ
Regards, Neil  Tucson, AZ

Offline ntsqd

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Re: Lakester rear suspension
« Reply #39 on: February 17, 2019, 03:38:53 PM »
I was just about to suggest the same, the deDion axle design. Seems to me that a deDion axle might be a better choice IF the 1/2 shafts are set such that they're level at speed (CVJ's running with no angle) to keep parasitic losses to the bare minimum. I would place the deDion tube behind the1/2 shafts so that I could use the pin/bearing in a slot (that is attached to the diff housing) method for lateral location. This would allow servicing the diff w/o having to disassemble the whole rear suspension too.

I did read 8" Ford, right? Just a slightly smaller & lighter 9" in design. A friend built a 9" housing narrower than Currie said it could be done. He literally cut the housing so that normal semi-float bearing ends fit up against the diff adjusters with *just* enough clearance should the diff be really offset in the drop-out. Application was different, but the approach worked then and still is working in that IFS 4WD truck 20-odd years later. I think it was Summers Bros who made the flanged axle shafts for him.

I would use the aero version of this CVJ boot: https://www.pegasusautoracing.com/productselection.asp?Product=1472 or this aero boot: https://www.pegasusautoracing.com/productdetails.asp?RecID=5549 depending on the CVJ size chosen. Could even attach a simple aero fairing to the deDion tube to enclose the outboard CVJ's and and 1/2 shafts.
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Offline Jack Gifford

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Re: Lakester rear suspension
« Reply #40 on: February 17, 2019, 10:38:25 PM »
Thanks for the reminder of the DeDion option.
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Offline Jack Gifford

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Re: Lakester rear suspension
« Reply #41 on: June 27, 2019, 12:12:41 AM »
Spent the last few weeks cramming all the "stuff" into the lakester. As expected, only room for a 3" driveshaft. So, for expediency, I'll try running without any rear suspension. To "freeze" the rear axle in place I simply replaced the shocks with heim-end rods.
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Offline Peter Jack

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Re: Lakester rear suspension
« Reply #42 on: June 27, 2019, 01:27:12 AM »
I've always been somewhat partial to using some sort of elastomer in the suspension such that you have almost a solid mount suspension but there's a little give to aid traction. It may be worth thinking about as in many cases it can be self damping.

Pete

Offline ronnieroadster

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Re: Lakester rear suspension
« Reply #43 on: June 27, 2019, 02:27:30 PM »
Spent the last few weeks cramming all the "stuff" into the lakester. As expected, only room for a 3" driveshaft. So, for expediency, I'll try running without any rear suspension. To "freeze" the rear axle in place I simply replaced the shocks with heim-end rods.




   In my lakester in place of such a short driveshaft I simply used a four wheel drive transfer cash H yoke thats for the front driveshaft. This gave me two U joints placed about 2 -3/4 inch on center along with the transmission slip yoke it worked perfectly at Maxton ,Wilmington and Loring with my rear suspension.
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