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Rear Axle alignment odd tire wear


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#21 datzenmike

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Posted 03 August 2017 - 06:20 PM

Seriously, not seeing anything.  If over steering wouldn't you be seeing more corrective steering??? like drifting???


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#22 Draker

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Posted 03 August 2017 - 07:44 PM

Seriously, not seeing anything.  If over steering wouldn't you be seeing more corrective steering??? like drifting???

 

 

Maybe? I'm not a racer either.


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#23 datzenmike

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Posted 03 August 2017 - 08:02 PM

Looks like it holds the road pretty good to me. Seems to be parallel with the other cars in the corners. I'm saying if it's out of shape it's very subtle.


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#24 Draker

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Posted 03 August 2017 - 08:17 PM

Are we watching the same video? Red car? Anyone else have thoughts on this? lol


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#25 datzenmike

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Posted 04 August 2017 - 05:45 AM

Ahhh now I get it. :blush: Yah that back end really wants to come around. Try cures for over steer.


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#26 Tom1200

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Posted 07 August 2017 - 08:35 PM

@docbainey I've looped the car twice in the past 25 years; both times in the rain, once there was mud on the track and most recently was pretty much on purpose playing drift king on cool of lap with dry set-up (dry set up not good on wet track). Like most guys who switched from road racing on 2 wheels to 4 I'm used to the vehicle moving around on the tires. Note the video is before I discovered the end play in the axle. As for the T-bar set up under the leafs, yes it has exactly that set up.

Mike normal adjustment to cure oversteer won't come into play here; while the frequency of the oscillation is reduced the car still squirms around. Besides if you want to go fast in a 1200 oversteer is your friend. The car is not capable of power oversteer above around 60-65 mph, you want the car to keep rotating while you have the gas pedal to the floor. If you drive it ultra tidy with minimal tire squirm like my Formula 500 you'll be 2-3 seconds a lap slower this if you drive like a fiend.

I talked to another local racer who ran a leaf sprung car (Corolla GTS) and he said his car would show similar wear pattern on the rear just not as pronounced. He ran the car on radials so that me be the difference.

I've been docking with the bodywork on the Formula 500 and haven't got chance to check everything yet.

#27 docbainey

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Posted 08 August 2017 - 04:30 AM

Tom, If you can get the car on a latest greatest alignment rack do it. It will give you all kinds of useful info. Sit in the car when its aligned or put suitable weight in the drivers seat. We tried the 'T' bar on our roadster initially. Actually tried 3 or 4 different suspension configurations on the rear. Leaf springs just aren't two cooperative. We ended up removing the 't' on the T bar made spacers to fit around the spring and the axel attaching points so the spring could 'float' a bit instead of being clamped solid and used a panhard bar, massive custom re-valveable Monroe shocks and an adjustable roll bar. We took a leaf out of the comp springs to try and soften the rear up and had the springs de-arched even more.



#28 Tom1200

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Posted 08 August 2017 - 08:42 PM

The original set up had the T bar at the front spring mount but it now has a set of heim joints at both ends. The 1200 competition suspension manual has a note to remove one leaf but I believe mine are as supplier from Nissan Competition. I don't find them overly stiff as I pound over the curbs like a touring car driver and that doesn't upset the rear end.

The in both vintage GT-lite B-sedan the rules allow me to switch to coil rear shocks; this is the other part of the equation if we are going to install a panhard or Watts Link why not just go all in and add coil rear springs. Naturally being drain bramaged as I am I enjoy the hoon factor of a leaf spring car.

Off topic a bit but where does one get custom valves Monroe shocks?

#29 docbainey

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Posted 09 August 2017 - 08:24 AM

Not to sound old, cough, cough, back in the seventies Monroe had a racing div. They where big at Indy & stock car racing.

 

Our rule structure back then mandated that we had to keep the leaf springs.

 

I'd still install a panhard bar even with the leafs, cheap and simple.



#30 Tom1200

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Posted 10 August 2017 - 08:27 PM

The first suspension set up the car used cut down Z car springs in the front, motorcycle fork oil in the struts, lower blocks and some Munroe shocks that were on sale at Pep Boys. Worked pretty well.

The intention was to put a panhard bar on the car, until my fabricator saw the funky wear pattern. He wants me double check everything before we do any upgrades. Having a housing that doesn't move will not thing if the axles end play in them. I got,the last bit I needed to fab for the Formula 500 done last night so I'll finally get back to the 1200. I've got 6 weeks to our next event, which is a track day so I'll be able to do some testing.