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alfadriver
alfadriver MegaDork
9/12/17 6:49 a.m.

Forgive me for not going back 30 or 40 pages-  but you are running with a live axle, right?

If yes, then have you looked into torque wedge, and fixing that?  I may have brought that up before.  My Alfa does that really badly- one way to deal with it was to move the panahrd connection below the axle centerline so that when cornering, that force will try to pull the outside wheel down.  But the other is to put the upper third arm in a location that counters the torque of the engine. 

As for the season- you battled through some very major de-bugging- things that would take lesser people down.  Once you get those fully fixed, the small stuff will let you get more seat time, which will fix more stuff, and that will certainly move you up.

 

Great job.  Very inspirational.  (well, if I were ever to autocross again)

loosecannon
loosecannon Dork
9/12/17 8:57 a.m.

Funny you should mention that, I have been trying to figure out how far over I need to move the top link to counter the torque. I will be moving it over once I know where to put it.

alfadriver
alfadriver MegaDork
9/12/17 9:23 a.m.

Years ago, I lurked on corner carvers, and found what seemed to be a good discussion.  Which also lead to an old web page that you could put in some calculations....  

Not sure if that discussion still exists.

loosecannon
loosecannon Dork
9/12/17 11:18 a.m.

I am currently communicating with some people much smarter than I am about the suspension set up so hopefully that proves to be fruitful 

slowcamaro
slowcamaro New Reader
9/12/17 11:50 a.m.
alfadriver said:

Years ago, I lurked on corner carvers, and found what seemed to be a good discussion.  Which also lead to an old web page that you could put in some calculations....  

Not sure if that discussion still exists.

The bill shope website perhaps?

http://www.shopeshop.org/contentsDrag.htm

loosecannon
loosecannon Dork
9/12/17 11:53 a.m.

I was on that website yesterday and plugged my numbers into the 3 link calculator and it spit out some ridiculous top link offset number. I'm sure my numbers are correct so not sure what went wrong

alfadriver
alfadriver MegaDork
9/12/17 12:28 p.m.
slowcamaro said:
alfadriver said:

Years ago, I lurked on corner carvers, and found what seemed to be a good discussion.  Which also lead to an old web page that you could put in some calculations....  

Not sure if that discussion still exists.

The bill shope website perhaps?

http://www.shopeshop.org/contentsDrag.htm

That looks like the one.  What I liked about their work was that they were drag racing on an open diff.  And making it work.

Ideally, if one can autocross on an open diff, and eliminate the need of any locking, you eliminate a cause of understeer.  When I was building my Alfa racer, that was one of the things I had planned on engineering (along with the SPICA pump).  Alas....

loosecannon
loosecannon Dork
9/13/17 9:32 a.m.

69 pages on this thread!

[URL=http://smg.photobucket.com/user/loosecannon/media/MGB-GT/DSC_5883_zpsuvusygvd.jpg.html][/URL]

759NRNG
759NRNG Dork
9/13/17 10:24 a.m.

And many more(pages) to come as you sort out the issues that stand in your way to success. Great pavement level shot!!!

loosecannon
loosecannon Dork
9/13/17 8:07 p.m.

GRM posted a video clip about the Pink Panther!

https://www.youtube.com/embed/lsS_0Ho55Zc

759NRNG
759NRNG Dork
9/14/17 9:33 p.m.

In layman terms, is the top link of the 3link allowing the diff  to rise and drop (left to right) due to the attachment point within the frame itself?

loosecannon
loosecannon Dork
9/14/17 10:47 p.m.

I don't quite get what you're asking. The top link is right in the middle of the diff and as far as I can tell, there is no bind during suspension movement. I have been looking into how to reduce torque steer through the diff and the solution appears to be offsetting the top link to the right. I will be moving some things around over the winter.

759NRNG
759NRNG Dork
9/15/17 12:10 p.m.

Loose, my apologies for the confusion. I went back almost four years in this thread to find shots of the diff setup. Two years ago you were asked about a watts versus panhard. I believe the response was the switch to a watts was weight related (negative). So with the nationals still fresh in your mind and the issues you experienced, I went in search for this ......mumford links. Before you reposition  the top link check this out . Sir Arthur Mallock used this in sports racers built by his sons(live axle) to embarrass high powered beasts while sporting a 2.5 liter or less bullet. Yes there are more components involved ,but the ability to plant either tire is the goal. Also is a clutch diff in the works? 

loosecannon
loosecannon Dork
9/15/17 6:06 p.m.

I have a clutch diff in it now and it didn't solve the problem. It's a Variloc and is used by some top Indy, NASCAR and autocrossers but we need to fine tune it. Here's how it works: http://icpcitation.com/variloc_theory.htm

759NRNG
759NRNG Dork
9/15/17 8:23 p.m.

But you're still lifting the inside rear tire using your current panhard setup right?

loosecannon
loosecannon Dork
9/15/17 9:31 p.m.

Yes, still lifting and spinning inside rear tire, probably because I don't have enough droop in the suspension

alfadriver
alfadriver MegaDork
9/16/17 4:18 a.m.
759NRNG said:

But you're still lifting the inside rear tire using your current panhard setup right?

Lowering the rear roll center to fix a traction problem like this also has some pretty decent trade offs, too. Primarily, without changing the spring rates, roll stiffness. 

Fixing via geometry to combat torque wedge has less trade offs. At least that's how I see it. 

loosecannon
loosecannon Dork
9/16/17 8:59 a.m.

Is a Mumford linkage the best way to fix this? Got some links about this?

alfadriver
alfadriver MegaDork
9/16/17 9:39 a.m.
loosecannon said:

Is a Mumford linkage the best way to fix this? Got some links about this?

A Mumford link is a different way to laterally locate the axle. It's easier to move the roll center than the pahnard or watts set ups. 

It can help, with the draw backs of lowering the roll center. 

loosecannon
loosecannon Dork
9/16/17 10:02 a.m.

I have had the Woblink, triangulated 4 link and now a Panhard in the car and would have to see some strong evidence that a Mumford is superior before I'm going to change it again

759NRNG
759NRNG Dork
9/16/17 8:54 p.m.

I'll google foo  on your behalf cuz I ain't got much else to do 'cept tear flooded houses apart ....lately wink

loosecannon
loosecannon Dork
9/16/17 10:28 p.m.

Lateral G Forum  I Googled some stuff and got this rabbit hole and read the first 3 pages-it's got a lot of good stuff

759NRNG
759NRNG Dork
9/17/17 1:00 p.m.
loosecannon
loosecannon Dork
9/17/17 7:19 p.m.

Some very knowledgeable people say the Panhard and 3 link are perfect for an EM autocross car so I'm not going to just tear it out on some speculation that a Mumford "might" be better

SkinnyG
SkinnyG SuperDork
9/17/17 10:27 p.m.

I doubt you'd hop in -any- car and go "Hey! This this totally has a [lateral-locator-of-your-choice], I can feel the difference!"

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