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CV Plunge

Printed From: Official Baja SAE Forums
Category: General
Forum Name: Design Discussion
Forum Description: Discuss Design, Tech, Cost, and related issues
URL: http://forums.bajasae.net/forum/forum_posts.asp?TID=263
Printed Date: Sep/15/2019 at 6:56pm


Topic: CV Plunge
Posted By: iwm
Subject: CV Plunge
Date Posted: Nov/22/2009 at 12:50pm
How do teams deal with plunge using OEM ATV Rzeppa CV's?

The three options I see are...

1. Design suspension as to not require CV plunge

2. Plunge somewhere along the length of the halfshaft itself (like the propshaft on a RWD car...)

3. Plunge in and out of the gearbox, where the CV attaches

From looking at pictures around the web... it doesn't seem like many teams do option #2, but it's hard to tell.

Also have teams been able to completely replace the halfshaft in the assembly, just using the inboard/outboard CV's?  I know there has been some discussion of welding an extension in, but we would prefer to entirely replace it if possible.




Replies:
Posted By: blue2kss
Date Posted: Nov/22/2009 at 1:12pm
When I designed for it, I measured the plunge the lightest CV's I could find gave me and used Susprog 3D (the suspension software that we use) to tell me how much I was going to have according to the multiple inputs that the program had.  I had the plunge down to the order of 0.03" according to the program.  In actual use the CV's were fine and we never broke one.  We were also a team that spliced the half shafts.  

I would really recommend against the plunge along the half shaft.  Most of the ones that I have seen use U joints (which I am not a fan of due to second order vibrations that can be generated in the joint and will cause ‘whirl’ in the driveshaft).  The simple Rzeppa joints permit drive, articulation and plunge in one simple component.




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Dustin Bride
University of South Florida SAE Alumni/Consultant
Mechanical Engineer - Naval Surface Warfare Center, Marine Corps. Counter IED Development


Posted By: johnfar109
Date Posted: Nov/22/2009 at 1:15pm
when i was at RIT We Ran an NTN CV half-shaft. we would get a stock Shaft off of Some Quad (Don't Remember) and swap out the stock shaft for our own custom shaft we had designed and fabricated. This process took lots of time in both the design and manufacture.
What ever shaft you pick you will have to reverse engineer its Characteristics. 

Here is one of the NTN Guides http://www.ntn.co.jp/english/products/pdf/cvj-automobile/pdf/CVJ-ForAutomobile_en.pdf - http://www.ntn.co.jp/english/products/pdf/cvj-automobile/pdf/CVJ-ForAutomobile_en.pdf

The OEM Shafts that you are talking about do they have a Fixed end and A slip End?
i know we have added a slip shaft section to the shaft when we were not able to get eneough slip out of the stock end.






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- John Farnach

RIT BAJA SAE

That Guy 04-09'

RIT 2010 Maneuverability Captain & Track Prep and Construction
RIT 2013, 2016, 2019 Electronic Scoring & Track Prep and Construction


Posted By: dillon_b12
Date Posted: Nov/22/2009 at 1:45pm
The Honda CVs that we use have some plunge built into them in the inboard cups.  Go past that, and there is a retaining ring that attempts to keep the CV from flying apart.  Our suspension guys measured how much angle they could get out of the shafts before hitting that ring and worked with the suspension to get the plunge within an allowable range.

In '08 we ran sliding shafts and I do not recommend them.  There are ways to do them nicely I suppose but they were a pain for us.  We used thick-wall 4130 box tubing that was machined for a tight fit and they ended up being very heavy.  They did last the whole season though without any problems.

I have seen teams use PTO shafts for their sliding action but can't say how well it worked for them.

We cut and extend our axles.  Replacing the whole shaft would be really nice but you have to figure out the spline data.  Depending on the manufacturer of the axle you use, they may give you this.  I know our Formula team uses the same Honda axles that we do and they never had any luck getting the spline geometry out of Honda.


Posted By: DrewT
Date Posted: Nov/22/2009 at 7:45pm
Originally posted by iwm iwm wrote:

How do teams deal with plunge using OEM ATV Rzeppa CV's?

The three options I see are...

1. Design suspension as to not require CV plunge

2. Plunge somewhere along the length of the halfshaft itself (like the propshaft on a RWD car...)

3. Plunge in and out of the gearbox, where the CV attaches

From looking at pictures around the web... it doesn't seem like many teams do option #2, but it's hard to tell.

Also have teams been able to completely replace the halfshaft in the assembly, just using the inboard/outboard CV's?  I know there has been some discussion of welding an extension in, but we would prefer to entirely replace it if possible.

 
We've done your option #2 for a couple years now.  We've used non-plunging CV's with our own custom splined plunging shafts.  They are a little heavy, but were the only way we could accomodate the 14" of travel from our trailing arm rear suspension with our previous drivetrain packaging.  The first time we did this, we used VW CV's, the next time we used Polaris CV's (I think from a Sportsman 500).  Basically we do just like you describe and use only the CV portion of the original shafts and make our own shafts that go between them. I've seen plenty of teams do the square tubing shafts to get a plunging shaft, but I hate that idea because square tubing is not that strong in torsion, so it has to be very heavy to handle the loads they are put under; splined shafts are capable of being much lighter and accomplishing the same end result.  It's alot more work than some other methods, but our shafts have been bomb-proof over the last few years.


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WWU Baja SAE team captain 2009-10
NC Process Engineer - Janicki Industries


Posted By: Shocker Racer
Date Posted: Nov/22/2009 at 8:53pm
gorilla axles makes custom axles and thats who we use.  their axles also use really high misalignment cv joints.  then all you have to do is design suspension or be within the range of the cvs and you are golden.  a lot of times it requires nothing extra to make this happen. The other option with gorilla is getting them splined for any make of gearbox or diff.   Just be prepared to wait when you order them.  It will take probably a month to get your stuff, maybe longer.

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Wichita State University
Shocker Baja Racing



Posted By: Mohit Yadav
Date Posted: Jul/07/2018 at 8:35am
How you will get plunging through Rzeppa joint? It can provide higher articulation but gives no plunging.
Is there any other method to get plunging without compromising higher articulation(greater than 35 degree)? 



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