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PostPosted: October 17, 2018, 11:43 am 
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This is one of those "Will it work?" things... I'm building a BEC- link at viewtopic.php?f=36&t=19397 ...and it requires the inclusion of a Giubo (rubber flex disc) in the driveline..

This giubo mandates a straight-line in it's section of the driveshaft, which presents some issues... the artsy drawing I've included is a 'can I do this' thought to help me simplify things.. In short, I wonder if I can run the engine and diff in near perfect parallel, giving me the straight line that the Giubo wants... But as a result, it will require the axle CVs to operate with about 5 degrees in them before any up-down suspension travel..

What makes me think this might be ok is the suspension travel in this car is limited to about 4" total, so these CVs should never see the end of their available travel/angle, even at full bump/droop, even including the 'extra' 5 degrees I put in them front/back.. I liken it to a sand buggy running CVs with a static swept-back axle angle design (the tranny drive flanges live a few inches in front of the wheel drive flanges)... on those rigs, the CVs are also seeing several degrees of axle angle even before the suspension travels up/down.

I know it's a bit unconventional, and my artsy drawing is not to scale (it's exaggerated to make my issue more obvious)..

So, any thoughts on 'will this work?'

As always- thanks :D

--ccrunner


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PostPosted: October 17, 2018, 12:00 pm 
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depending on the length of your 1/2 shafts, the angle will probably be a lot more than 5 degrees.
Again, with the A Mod I have some static angle built into the 1/2 shafts. It looks pretty large without my 200+ lbs in the car. I climb in and it's less than 1/2 shown in the pic.

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PostPosted: October 17, 2018, 12:16 pm 
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Why do you think the Guibo has to remain perfectly strait?
Take a look at the range of load/motion they go through in other applications, Alfa-Romeo Spider and Mercedes driveshafts, and for a more extreme sample Triumph GT6+ axles which really give them a work-out and still last for several years.
It is true that they will last longer with less angle but a QUALITY Guibo is not that fragile or sensitive to angles.
You might also want to add a "Guibo saver" which is a sheet-metal cage assembly that holds the joint halves together if the Guibo ever fails.
If an oversize Mercedes can use them in the driveshaft your application will hardly stress the Guibo at all.

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PostPosted: October 17, 2018, 12:44 pm 
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RichardSIA wrote:
Why do you think the Guibo has to remain perfectly strait?
Take a look at the range of load/motion they go through in other applications, Alfa-Romeo Spider and Mercedes driveshafts, and for a more extreme sample Triumph GT6+ axles which really give them a work-out and still last for several years.
It is true that they will last longer with less angle but a QUALITY Guibo is not that fragile or sensitive to angles.
You might also want to add a "Guibo saver" which is a sheet-metal cage assembly that holds the joint halves together if the Guibo ever fails.
If an oversize Mercedes can use them in the driveshaft your application will hardly stress the Guibo at all.



"Why do you think the Guibo has to remain perfectly strait?" I honestly don't know where I got this idea.. :| .. bad info on my part it seems! :roll:

I love the thought that I can put at least a few degrees of angle/stress on the Giubo.. taking the system as a whole, putting a few degrees into the giubo angle would at least help spread around these degrees of misalignment around a bit more...

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PostPosted: October 17, 2018, 6:39 pm 
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Diff-guibo-stub-carrier bearing-cv-shaft-cv.


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PostPosted: October 17, 2018, 6:46 pm 
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Guibo's are not noted for being compact.
Adding a CV to the back side would be a fairly large package.
Guibo at one end and CV at the other might work better, if any CV is actually needed.

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PostPosted: October 17, 2018, 7:13 pm 
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You could also run a chain or belt drive box to offset the driveshaft input as well as gear it up or down slightly (space limited) if you want before it reaches the pinion. Like a final drive but with little to no reduction.

I don't think a guibo would last very long at these angles. I think cvs are necessary. Just another opinion log for the fire!

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PostPosted: October 18, 2018, 10:38 am 
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Thanks for all the great insight guys.. part of the fun in solving the puzzle..

Not sure which way I'll go on this, but certainly there's a solution in these many posts..

As always, thanks :cheers:

--ccrunner

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My '72 Honda N600 build log (bike engine in a microcar)...
http://www.locostusa.com/forums/viewtop ... 36&t=14452

My '63 Volvo 1800 with a turbo inline 4 build log (LNF Ecotec compliments a Svelte Swede)
http://locostusa.com/forums/viewtopic.php?f=36&t=16309

My '59 Berkeley SE492 / Honda VFR800 transplant build: "A Berkeley With Bite!"


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