Speed UTV

DTA said:
Regarding the clevis.

It is a chit design, no matter what Honda or Nissan it's been applied to.

Or a kibbetech or what not.

The proper design for 4wd offroad is either a single shock (or even co/bypass) with clearance or portal hubs.

Portals have been proven time and time again from the H1 to ultra4 cars and now 4wd TTs.

The clevis design is a bandaid to make things fit. 

It is not progression and it has been shown to be hindrance in a high travel and aggressive application. 

The Pro R design as I've stated before was a design from Polaris to either bypass the RG patents or simply to try a design which is not standard.

The latter really doesn't make sense since the Pro R was supposedly a ground up design/build and anybody with half a brain would mount the lower shock directly to the lower arm as it's been done for the last 30 years. 

It's not rocket science. 

It was done for a reason and it is not ideal. No matter which way you spin it.

ETA

I had a long edit here and it disappeared but basically stated, I belive in my uneducated opinion: the dual mounted system of a clevis fails in comparison to a single mounted shock system using a uniball/monorail. The single mounting point allows the little bit of give in the suspension deflection vs the dual mounted clevis.

I'm no engineer and I could be wrong.

I look at the top racecars in offroad and don't see any clevises front or rear. They were a flash in the pan.

It comes down to this, to any of the people here for or against, honest question here.

Based on you experience and opinion, if you had a choice, and money and design was no object would you rather your shock be mounted directly to the lower arm at a single point or would you favor having a clevis?

Disregard brand, make or model and be objective.
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Portals have negative drive traits as they create a lever on the end of the suspension, add cost/complexity, reduce travel for a given track width, and add unsprung weight.

If I had the choice between a simple clevis and portals, I’m picking the clevis, especially considering the cost involved (which can’t be ignored).   

Design wise, a clevis simply moves some load from the suspension arm to the shock end.  As long as the system is designed properly, the marginal difference in weight and cost isn’t concerning. 

Keep in mind that the force imparted by the shock isn’t going away because you used a heim. Rather than the clevis being beefy, you have to make the arm beefy since the heim will concentrate this load more. Since a heim can’t connect through the wheel centerline (axle in the way), you either have torsional loading on the arm (requiring moar beef) or you have to do something like portals as you mentioned to move the axle off of centerline, which (in addition to cost and complexity) would have a lot of really bad handling characteristics under power if it’s offset to the front or rear. I have a feeling we’d all miss “RZR bumps” if everything out there had portals to offset the axle centerline front:rear.

This is why a lot of OEMs with front wheel drive either use McStruts, crazy multilink designs (generally with the shock mounted to the upright),  a simple clevis or a narrow shock extension below the body (to get the shock as close to the wheel centerline as possible) with conventional A arms. 

 
DTA said:
I believe that. 

However it's been argued patents don't matter and are easily overcome.

Stating again.

Either Polaris was discouraged by patent infringement.

Or.

They made a stupid decision.

I stand by my statement the clevis is in no way superior to a single point mounted shock.

ETA

So I asked a buddy who is on a Mason team, why aren't celvises used. 

His exact response:

It's all about strength and reliability 

The clevis needs to exceed 42,000psi which is what it takes to bend a aircraft bolt, that clevis can't take it 
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Uh. Why exceed 42,000psi (6061-T6 is 42,000 and standard on most shock ends)? Are we trying to save weight by going harder? The aluminum in the clevis, if designed properly, should not be in direct contact with the bolt, just like in a standard shock. 

 
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DTA said:
Here we are comparing standard rod end to a clevis. Speed vs Polaris.

I simply used the portal as an example as it is the highest tech and what is used on top racecars at this time. Yes it's more expensive, complex, more parts etc etc.

However choice between rod end and clevis and the choice is simple.

I think what is comes down to is what do you want to rely on for maximum abuse?

A rigid mounted celvis which can't take any deflection whatsoever?

Or a single milspec bolt on a monoball with the majority of the load being transferred directly to the "beefy" (Polaris lingo) lower arm?

ETA: show me one modern race vehicle in any class that is somewhat successful using a clevis anywhere in their suspension design? (Barring the Pro R)

From what I remember the King clevis on trailing arms was incredibly short lived and saw many failures. They attempted to fix an issue which was non existent. It sure looked cool when it came out though. I believe they actually had more shafts being bent than the clevis actually failing.
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Clevis on a trailing arm wouldn’t be the best design unless there was some sort of spherical bearing or rubber bushing it bolts to. Trailing arms twist, especially on a live axle.

Bushed A arms don’t see much twist in normal circumstances. Sufficient compliance in the bushing the clevis mounts to (or in the clevis itself) would likely take care of that. 

I personally very much dislike Polaris products, but I doubt the failure experienced in the race was any indication of an overall flawed design. This type of shock mount, while not on fabricated one-off racecars, isn’t something new. More likely, they had a metallurgy issue and it failed. I’m fine with it, and if it has problems, it had more to do with execution than the concept. It’s not like they’ll have to completely redesign the front end…

I still don’t get why the material on a clevis needs to be over 42,000 psi. Odd to specify material hardness for a shock mount without some other goal like dimensional or weight constraints. 

 
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DTA said:
Most likely because of team orders added on to the fact there are not many non-sponsored pro r racecars out there right now.

Same as the old Polaris racecars. The so called "stock" arms and trailing arms which were required at the time for certain classes were specially built out of non oem materials and powdered to look like oem parts.

Polaris does have tricks up their sleeves. 

I am confident the clevises you see in the racecars are not the same as what is oem.

Either way it's all a moot point.

I am simply describing my own opinion of the differences between the designs of two different oem manufacturers and the reasons why I believe one is better than the other.

I would love to have a 2000cc NA car. I personally hate turbos in the dirt. More things to go wrong. 

I like simple.

I would love a 2000cc NA engine inside a Speed UTV chassis. It would be the ultimate ripper and simple. 

We cant always get what we want.

I do believe the speed chassis is far superior in most ways over its counterparts for the simple reason it uses tried and true designs. 

No funky toe links or 5 link, no rear steer, no clevis shock mounts, no fancy electronic shocks. 

Don't get me wrong, there are some things on the speed car I am hesitant about.

First and foremost the mounting of the front rack. I love the hydraulic steering but the way the rack is mounted gives me pause. It is believed it is the reason RG was having steering feedback issues and nobody knows for sure if those issues have been resolved.

I wish the hubs were 5 lug.

I wish the engine was NA.

I wish the fuel cell was rear mounted.

I wish the suspension allowed for standard offset with wider tires.

I wish the engine was proven and they has used a widely produced engine already in existence.

However I still feel as a user end product it will be superior to what is currently on the market, except for the engine.

I have said from the beginning, I had started the original thread before the crash, I believe the biggest question mark is still the engine in this car.

That in itself I believe will make or break the success of Speed UTV.

Everything else is acceptable or far exceeds the competition. 
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Have you seen the suspension arms Guthrie is running?  Interesting set up. We will see how he does this weekend at the Silverstate race. 
 

https://www.instagram.com/reel/CczKX4flxPk/?igshid=YmMyMTA2M2Y=

 
DTA said:
Didn't know he was running those.

They have been around as a prototype for maybe a year or 2. A guy I know had a hand in designing them.

I still don't understand how they work.

https://www.instagram.com/p/CRJ1I2Yh0WS/?igshid=YmMyMTA2M2Y=
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All it does is move the SAI and KPI. Makes for less scrub and less steering wheel feedback from the road.

Also, the clevis for the Xtravel car had to be made MUCH wider to account for the CV's motion with the Xtravel suspension.

That clevis better be forged and designed properly.

More fuel for the fire: 

Brenthel TT's use a clevis.

UT it is FORGED and PROPERLY DESIGNED FOR RACE CONDITIONS

https://www.offroadxtreme.com/news/checking-in-brenthel-industries-gen-3-trophy-truck/

checking-in-brenthel-industries-gen-3-trophy-truck-2019-07-15_15-24-46_306688.jpg


 
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michael.gonzalez said:
All it does is move the SAI and KPI. Makes for less scrub and less steering wheel feedback from the road.

Also, the clevis for the Xtravel car had to be made MUCH wider to account for the CV's motion with the Xtravel suspension.

That clevis better be forged and designed properly.

More fuel for the fire: 

Brenthel TT's use a clevis.

UT it is FORGED and PROPERLY DESIGNED FOR RACE CONDITIONS

https://www.offroadxtreme.com/news/checking-in-brenthel-industries-gen-3-trophy-truck/

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Are they still running this set up on the latest generation Trophy Truck/Spec Truck?  I knew I have seen a clevis on a trailing arm, just could not remember which truck.  

 
michael.gonzalez said:
All it does is move the SAI and KPI. Makes for less scrub and less steering wheel feedback from the road.

Also, the clevis for the Xtravel car had to be made MUCH wider to account for the CV's motion with the Xtravel suspension.

That clevis better be forged and designed properly.

More fuel for the fire: 

Brenthel TT's use a clevis.

UT it is FORGED and PROPERLY DESIGNED FOR RACE CONDITIONS

https://www.offroadxtreme.com/news/checking-in-brenthel-industries-gen-3-trophy-truck/

Click to expand...
Did you read the article, that's not forged, thats BILLET! :makerain:

 
that X-travel is interesting, but they are almost as secretive as RG. Nothing on their site shows what/how it works....

 
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