BA5
BA5 GRM+ Memberand HalfDork
7/30/24 11:35 a.m.

I was just doing some fun car browsing and came across this car:

European 1st Gen Viper GTS-R

A really beautiful Le Mans Viper. They have lots of pretty pictures of the car.  And then I saw this picture:

Apparently they needed ALL of the front roll stiffness.  All of it.  There is none left for any of the rest of us.

I tried to find some reference for the restrictor size or the roll bar size to see if I could determine how big that front sway bar is, but I couldn't.  It's gotta be at least 2", if not more.

Colin Wood
Colin Wood Associate Editor
7/30/24 12:05 p.m.

Those competition Vipers are so cool.

While we're talking about Viper racer cars for sale, LBI Limited has the Le Mans class-winning Chrysler Viper GTS R for sale, and there's a later (2011) Viper Competition Coupe that raced in the 2012 Daytona 24 for sale over on Wirewheel.com.

kb58
kb58 UltraDork
7/30/24 12:06 p.m.

You can get a close approximation by comparing and scaling it to something that's known, like perhaps the front spring OD, the width of the tire, or even the length of the valve cover. That said, anti-roll bar stiffness is proportional to their diameter - cubed (incorrect, to the fourth power) - so a tiny difference in OD can make a pretty big difference in stiffness.

Mr_Asa
Mr_Asa MegaDork
7/30/24 12:13 p.m.
kb58 said:

You can get a close approximation by comparing and scaling it to something that's known, like perhaps the front spring OD, the width of the tire, or even the length of the valve cover. That said, anti-roll bar stiffness is proportional to their diameter - cubed - so a tiny difference in OD can make a pretty big difference in stiffness.

Id go with something universal to Dodge, then Viper, then Racecar Viper.

The windshield wiper is in view, as well as the nut holding it on.

wearymicrobe
wearymicrobe PowerDork
7/30/24 12:25 p.m.

Gen IV motor by the intake and the valve cover changes. That thing must boogie. Much better motor then the early Gen1-2 stuff. 

racerfink
racerfink UberDork
7/30/24 12:47 p.m.

There were several Vipers that ran in European events with V8's.

I wonder, with that tube being hollow, if there isn't a blade type bar inside it, and they're using the hollow tube to hide it from spying eyes. The way the part outside of the clamps is separate from the tube itself...

BA5
BA5 GRM+ Memberand HalfDork
7/30/24 1:34 p.m.
kb58 said:

You can get a close approximation by comparing and scaling it to something that's known, like perhaps the front spring OD, the width of the tire, or even the length of the valve cover. That said, anti-roll bar stiffness is proportional to their diameter - cubed - so a tiny difference in OD can make a pretty big difference in stiffness.

Yeah, that's what I was trying to do by finding the restrictor diameter or the roll bar diameter rules. 

Unfortunately I can't find any hard numbers for anything I can see in the picture.

Mr_Asa
Mr_Asa MegaDork
7/30/24 1:52 p.m.
BA5 said:
kb58 said:

You can get a close approximation by comparing and scaling it to something that's known, like perhaps the front spring OD, the width of the tire, or even the length of the valve cover. That said, anti-roll bar stiffness is proportional to their diameter - cubed - so a tiny difference in OD can make a pretty big difference in stiffness.

Yeah, that's what I was trying to do by finding the restrictor diameter or the roll bar diameter rules. 

Unfortunately I can't find any hard numbers for anything I can see in the picture.

The washer nut is an M6x1.00  McMaster gives that as 10mm wide.

10mm x 6 = 60mm, or 2.36"

cyow5
cyow5 Reader
7/30/24 3:53 p.m.
kb58 said:

You can get a close approximation by comparing and scaling it to something that's known, like perhaps the front spring OD, the width of the tire, or even the length of the valve cover. That said, anti-roll bar stiffness is proportional to their diameter - cubed - so a tiny difference in OD can make a pretty big difference in stiffness.

I thought it was the 4th power, not third. Changing the ID has a similar effect in the negative direction though. If you can get a really thin wall to be stable, a large OD roll bar of the same stiffness as a small OD bar is lighter. Given how they are attaching the arms, a large OD is also more convenient (for the arms). 

BA5
BA5 GRM+ Memberand HalfDork
7/30/24 4:17 p.m.
cyow5 said:
kb58 said:

You can get a close approximation by comparing and scaling it to something that's known, like perhaps the front spring OD, the width of the tire, or even the length of the valve cover. That said, anti-roll bar stiffness is proportional to their diameter - cubed - so a tiny difference in OD can make a pretty big difference in stiffness.

I thought it was the 4th power, not third. Changing the ID has a similar effect in the negative direction though. If you can get a really thin wall to be stable, a large OD roll bar of the same stiffness as a small OD bar is lighter. Given how they are attaching the arms, a large OD is also more convenient (for the arms). 

You are correct.  It is to the 4th power.

Colin Wood
Colin Wood Associate Editor
7/30/24 4:34 p.m.

Not to distract too much from the conversation, but earlier Vipers without a crazy amount of miles can be had for a little less than $40,000–like this one or this one.

Definitely tempting in my opinion.

kb58
kb58 UltraDork
7/30/24 5:58 p.m.

In reply to BA5 :

You're correct, I was thinking of suspension spring material... fixed my original post, thanks.

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