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PostPosted: December 23, 2018, 9:49 am 
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An interesting read for those of us who are without an intimate knowledge of suspension tuning.
http://lateral-g.net/forums/showthread.php4?t=42568
Ron

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PostPosted: December 23, 2018, 12:40 pm 
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That's an interesting site, Ron. Have you participated there yet?

I've been looking for a place where suspension is the focus, but it looks like they are focused on the American muscle car and I'm not sure how well a Locost guy will fit in there.

Cheers,

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Damn! That front slip angle is way too large and the Ackerman is just a muddle.

Build Log: viewtopic.php?f=35&t=5886


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PostPosted: December 23, 2018, 4:16 pm 
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Lonnie,
Read on. At least until you get to the video of the Porsches. The conversation is about how you want the inside rear tire to disengage in a turn, and to what degree..
Though mainly referring to road racing, mention is made when the setup for a mainly street driven vehicle is different. He (Ron Sutton) explains how to build a tun-able suspension, and performance changes you want to be able to effect and why. I hope to use whatever knowledge I can take away to help with the MGB GT. The insight into performance tuning could easily apply to a 7.
And, no, I haven't joined the site. After reading just two pages, I don't feel that I know enough to ask an intelligent question . Or to put it in Locoster terms, still at the very beginning of the lurking phase.
Ron

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PostPosted: December 24, 2018, 7:04 am 
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I can't say that I actually care much for his 'disengage the inside rear tire' explanation...It's a purely empirical description that doesn't do the actual underlying principle of Tire Lateral Load Transfer Distribution (TLLTD) justice. In my opinion, the Porsche video is also being used somewhat out of context, probably more because it offers a fairly dramatic visual and less that the visual is necessarily happening for the same reason being stated.

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Last edited by Driven5 on December 24, 2018, 4:56 pm, edited 1 time in total.

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PostPosted: December 24, 2018, 10:18 am 
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Justin,
You are, without a doubt,absolutely right. What's offered is " Suspension Tuning 101".
It is an opportunity to gain a frame of reference for relationships that are new to me and possibility others here.
A lot has been shared about setting up the front suspension. Not so much about the balancing the front and rear.
From what I read in the build logs, there are a few folks who might be helped.
Ron
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Anything you are able to expand upon, I'm sure will be welcome.

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PostPosted: December 25, 2018, 11:48 pm 
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If the idea of disengaging the inside rear tire makes sense to you (and others) in a way that other explanations don't, then that's certainly a good thing. From my point of view though, it fails to provide any real information of value, even in an introductory setting. Technically, it would be equally valid to promote engaging the inside front tire instead, as they're flip sides of the same coin. Much like Lonnie noted though, these comments are also specifically in reference to cars that naturally understeer in steady state cornering. Which is also probably why the author specifically references only being able to go around a corner as fast as the front tires can grip. With most Locosts naturally having a noticeable rear weight bias, this would not necessarily hold true in the same way for many here.

The 'suspension 101' answer for balancing the front vs rear is that if the car understeers you need to increase the rear and/or decrease the front roll stiffness, and if the car oversteers you need to decrease the rear and/or increase the front roll stiffness...And if doing so doesn't have the desired effect, there is another issue that needs to be addressed first.

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PostPosted: January 14, 2019, 1:43 pm 
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Quote:
If the idea of disengaging the inside rear tire makes sense to you (and others) in a way that other explanations don't, then that's certainly a good thing.


It took me a week or two but it came to me one day he was talking about cars with locked diffs. His focus is Pro Touring and locked diffs and high CG are probably normal.

So that's my problem with his site, it seems a little difficult to follow his explanations or put them into context. People who are do'ers are not always good at explaining or even understanding how they come to their decisions.

I strongly recommend the Mark Ortiz Chassis Newsletter for this type of information. He does a better job of talking the physics withut being any more confusing than this guy is. So, all in all, a better job at being thought provoking. This newsletter is free and widely available through an internet search. We should host it too, actually.

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PostPosted: January 14, 2019, 4:09 pm 
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Driven5 wrote:
... The 'suspension 101' answer for balancing the front vs rear is that if the car understeers you need to increase the rear and/or decrease the front roll stiffness, and if the car oversteers you need to decrease the rear and/or increase the front roll stiffness...

Or as my buddy says, you have to degrade the end of the car that's sticking better...

Regarding the rear end tricks that site discusses, my brother set up his Stalker so that his rear suspension has very little droop. His thinking is that in a turn, the inside tire isn't doing much, so it could serve better as ballast. He said that ever since he switched to that setup, his lap times dropped markedly. I have mixed feelings about it, specifically the "discontinuity" that must occur as the tire is lifted up off the ground, but it seems to work for him.

Regarding their use of locked rear ends, yeah that would explain why they may be doing that. With a proper LSD, that's not necessary.

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PostPosted: January 14, 2019, 4:50 pm 
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Getting the inside rear to disengage was one of the great struggles with my A Mod. So much so, that after a full season of breaking things and spinning out countless times I dumped the spool in favor of a diff.

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PostPosted: January 15, 2019, 9:53 am 
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Based on my cursory search, it looks like the Mark Ortiz Chassis Newsletter ended in 2017. Does that sound right? I'm looking for more of an interactive site or forum, and especially one that deals with testing.

Does anyone have a suggestion or two?

Cheers,

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Damn! That front slip angle is way too large and the Ackerman is just a muddle.

Build Log: viewtopic.php?f=35&t=5886


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PostPosted: January 15, 2019, 10:07 am 
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Lonnie-S wrote:
Based on my cursory search, it looks like the Mark Ortiz Chassis Newsletter ended in 2017...

I still get his newsletters; don't know whether he stores them somewhere online.

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