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Rear Axle alignment odd tire wear


Tom1200

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So my  1200 race coupe has this bizarre wear pattern; inside edge of tires get scalloped out. Further inside edge is feathered as if the rubber is being pulled of to the inside. This could be a result of my somewhat driving style (read stop sling the car like a fiend) I don't think its a result of to much camber from something like bent axle tube (if it was i wouldn't expect the feathering)   Guesses welcome.  I think its possible the housing is moving around on the leaf spring centering pins.

 

 

 

 

 I suck at posting photos  it's here

 

http://datsun1200.com/modules/myalbum/photo.php?lid=26869&cid=18

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Is the wear the same on both sides of the car ?

If that were an independent rear suspension I'd have to say bad bushings. This same wear occurred on my BMW streetcar it allowed the rear toe to change as the suspension traveled.

Bad spring or shackle bushings possibly ? 

Nice lookin car too

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If the tube isn't bent, you won't have uneven wear on a solid axle. Gotta be driving style. If the axle is not aligned to the car.. you would change the thrust angle. The car would essentially just drive in a big circle if the fronts were dead straight.

 

Sounds like the car is defective and you should sell it. (To me)

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Wear pattern occurs on both sides of car; it's more pronounced on the driver's side.

 

Tire pressure is 24 psi hot. They tires are Hoosier vintage TDs, they are bias ply tires.

 

This coming weekend I'll be doing checking various things; the car is mix and match and one of the things I suspect could be an issue is the aforementioned leaf spring pins. The hosting is a 510 wagon H190 on 1200 Nissan Motorsports spring pack. 1200s use a 1/2 pin vs 5/8ths on a 510. The bits came off a 1200 sedan project so I'm not sure if whoever put it together used the 1200 pin to locate the H190 housing, if they did there'd be enough play to allow the housing to pivot foreman aft. In another post I noted that the axles were not,spaced correctly so it wouldn't surprise me if it's the pins. Of course I don't know if that's causing the wear pattern.

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Draker it's not the car thats defective, see the video link below, red coupe just in front of the Spitfire camera car. This video is how I figured out that the axle might have a bit of end play, as in 2 mm each side, so decided to check how it was assembled (it appeared be to right but wasn't once a high side load was applied). If it's possible for a driver to be to comfortable with oversteer I'd say it's me.

 

https://m.youtube.com/watch?v=7TsTgZJULSM

 

As for selling the car; you'll have to get past the wife; in 1984 I bought it from one friend and sold it to another the same day, then in 1989 got it back and turned it into a race car, then in 2000 sold it because I also had a single seat race car, got it back in 2003 and that's when the wife forbid me from selling it ever again.

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To quote a long time friend and professional driver coach "holy crap dude you drift that thing everywhere" so I think the answer is Yes. The consensus at the track days I instruct at is the same as well. Despite a good bit of single seater experience I'm a touring car driver at heart.

 

My fabricator, whose done some pretty high end work over the years was a bit taken aback by the wear; he's given me a list of things to check.

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@ Draker the video was shot before I took the excessive end play out the rear end, it no longer does those kind of tank slippers. Also passing guys half in the marbles doesn't help.

 

@ Wayno 24psi is normal, I've tried as low as 22 but that results in lower lap times

 

@ Kelmo, yes this is why I still race this car despite having a much faster single seater as well.

 

@ Datsunhead; after 30 years of racing I am familiar with training. The tires are indeed worn out, I buy a fresh set in the fall; I do two 3 day vintage race weekends followed by 3-4 local track days, so by the end of May they have something like 21-22 heat cycles on them. The issue isn't the graining but the scallop on the outside tread block; to me it's indicative of axle moving around or dampers gone south etc.

 

The Hoosiers will do about 12 heat cycles, they won't quite make 3 race weekends and so I don't have to worry about conserving the tires. There's no need to conserve them for track days as those don't matter.

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Jezuz, after watching that video, how many times have you backed this car into the Armco? Talk about lurid handling! wow!

 

on a side note you talk about the Datsun comp stuff, is that the T bar under the rear springs? or was that in the B210 Electromotive days?

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https://m.youtube.com/watch?v=7TsTgZJULSM

 

I'm no race car driver but what sliding are you all talking about???

 

Not much action in the first 20 seconds.. at all.  I guess I meant that more figuratively. Actually more like between 30 and 50 seconds in.  That red 1200 is all losing traction on corners.

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