Rear camber

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Rear camber

Postby egrant5329 » Mon Sep 05, 2016 12:42 pm

While on FB I saw a pic of a Spyder that had the rear wheels really tucked into the wheel wells. It looks like it has a ton of negative camber. Wouldn't it burn up the bearings with that much camber?

I have often wondered how to get the wheels up higher in the fender without adding the negative camber. Do the builder set the engine and transaxle up higher to tuck them in without the neg camber?

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Re: Rear camber

Postby RicardoSwe » Sat Sep 10, 2016 12:02 pm

My Vintage Spyder ran like that until I took the time to measure and adjust the rear camber. Now it's "normal". Mostly tire wear and sub-optimum handling I suspect, not bearing wear. Just my estimate.

I first did a full alignment myself then had a local race shop do a corner weighting & alignment. I was close with my DIY alignment. Full equal corner weighting was limited by the suspension (front camber I think -- I can check what they reported if interested).
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Re: Rear camber

Postby TomD » Wed Sep 14, 2016 3:24 pm

Richard,
I would be interested it what your shop set for toe and camber both front and rear.
Thanks!
Tom
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Rear camber

Postby egrant5329 » Wed Sep 14, 2016 3:38 pm

If the axle angle slopes down toward the transaxle, I would think bearing lubrication would be a problem in a swing axle.
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Re: Rear camber

Postby WILL » Thu Sep 15, 2016 9:41 am

I Think Most Of Us Have Seen A Lot Of Replicars Running A Good Amount Of Negative Swing Axel Camber.
We Don't Hear Much About Bearing Failures Though.
My Guess, Is That A Few Brisk Turns On A Twisty Road Floods The Bearings With Oil Due To Centrifugal Force. :-k

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Re: Rear camber

Postby TomD » Thu Sep 15, 2016 10:56 am

Depending upon model/year, stock swing axle VWs usually run plus 1 / minus 1 degree of rear camber. Racers discovered large negative settings help to compensate for wheel jacking during hard cornering. VW introduced the Z-bar towards the end of their swing axle production to deal with wheel jacking before they moved on to IRS as a final solution. If you are auto crossing and run large negative camber (3 degrees plus) then (1) violent cornering should move oil to wheel bearings, (2) race cars expect disassembly / maintenance / repairs. Running large negative camber settings on the street likely will lead to bearing failure ‘one day’ due to oil starvation. Swing axles had their day in the performance world however IRS now rules (IMO). Driving a swing axle car has risks and taking these cars to limits in a safe environment is worthwhile (i.e. auto cross, track day, driver education).
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Re: Rear camber

Postby RicardoSwe » Fri Sep 16, 2016 8:49 am

TomD wrote:Richard,
I would be interested it what your shop set for toe and camber both front and rear.
Thanks!
Tom


Tom,

Sorry I'm slow -- took me a while to get out the info from my files.

The alignment specs I gave for the shop doing the alignment:
Front:
Camber -1.0 to -1.5 degrees
Toe-in 0.0"
Caster: set by suspension. Not adjustable.

Rear:
Camber -2.0 degrees
Toe-in 1/8"-3/16" (difficult to adjust on my Vintage Spyder based on where I mounted the oil filter)
Caster: set by suspension. Not adjustable

I had the alignment & corner weighting done by Roger Kraus Racing in Castro Valley, CA. Good guys. Very helpful. Included putting weight in drivers seat for corner weighting.

I'll try to attach PDFs here since there are a lot of numbers. (Done, but it's not clear if they're visible to readers.)
They adjusted corner weighting "to the limit" as the suspension would allow.

If the PDF files don't work -- some numbers:
Corner weights
LF 21.9%
RF 21.2%
LR 31.0%
RR 25.8%

The DIY alignment tools I use are QuickTrickAlignment. They work well. My alignment numbers were close to Roger Kraus' numbers.

Vintage Spyder corner weighting.pdf
Vintage Spyder corner weighting
(40.83 KiB) Downloaded 1273 times


Vintage Spyder alignment.pdf
Vintage Spyder alignment
(44.32 KiB) Downloaded 1302 times
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Re: Rear camber

Postby RicardoSwe » Fri Sep 16, 2016 9:00 am

I agree about effect of camber on VW-like suspension in racing/autocross. I'm still searching to find an autocross group that will let me autocross the Spyder without roll bar. I may have one, but haven't followed up still. When I do this, I'll try it as aligned and with much more camber on rear. Easy to adjust on site.

Anyone have autocross ideas in SF Bay Area? The best I've found for my use is the BMW Club who autocross in Marina, CA near Monterrey. I'm not keen to drive that far to be there at the crack of dawn when they start (~1-1/2 hr freeway drive). They've told me they probably can let me do it without the roll bar. Most around here will not do this, as I understand it.
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Re: Rear camber

Postby TomD » Fri Sep 16, 2016 10:41 am

Richard,
Thanks for the response and the pdf files! It does not look like they gave you the amount of front camber you requested hence I wondered if they dialed it back based on their experience.
Thanks again,
Tom
Good luck with the auto crossing
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Re: Rear camber

Postby RVosari » Fri Sep 16, 2016 5:15 pm

Now here is some useful information…it seems that a Vintage is some 245 lbs. heavier than my Brazilian built Beck Spyder…so that front hoop on the Vintage must weigh a fair piece.

With my front ride height -.6 Camber on the passenger and -.5 on the driver was the best we could do…

The rear without coil-overs (non-IRS) worked out to an even -.9…-1.0 Camber

Unfortunately I don’t have Left weight or Cross weight :(

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Re: Rear camber

Postby RicardoSwe » Fri Sep 16, 2016 9:02 pm

ReV,

Well, let's take out the 190 lb driver weight... :-) ...then you only have a 55 lb advantage...!

Then there is the Brazilian Southern hemisphere Coriolis effect... (just kidding)(I think).

They're both light regardless!
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Re: Rear camber

Postby RVosari » Sat Sep 17, 2016 4:27 am

Aaaah...I read it as 1525 without driver... [B)]

245 lbs. is a friend you don't need along for the ride [-X

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Re: Rear camber

Postby RVosari » Sat Sep 17, 2016 7:41 am

Regarding a roll bar...according to C. Beck...these cars are difficult to put upside-down. I put a stiff 1" rubber block on the frame rail preventing the swing axle from attaining too much positive camber, while "jacking" in turns. You can always put a thicker block to limit travel should you so desire.

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Re: Rear camber

Postby RS-60 mark » Sat Sep 17, 2016 10:30 am

Ricardo,
The Sonoma County Airport has a "back-lot" area used for police driver training and alternately as an autocross course. The area is more like a baby road course than the usual parking lot with cones. The PCA has autocrosses routinely, at least once a month, if the PCA is your cup of tea. More "run-what-you-brung" friendly is ESCA, the Empire Sports Car Association: http://www.empiresportscar.org/
This is the group that also sponsors the really fun April Fools Rallye (open to anyone who shows up with an entry fee, which is cheap). Check out the pictures of the Rallye and Autocross events on the link. Rollbars don't seem to be required.
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Re: Rear camber

Postby RicardoSwe » Sat Sep 17, 2016 2:44 pm

Thanks -- I'll check out the autocross options. I appreciate the note.

SCCA requires roll bars, at least that's what they've told me in reply to my inquiries. BMW CCA is much friendlier, but the location is a bit distant for me. Sonoma should work better.

I agree this Spyder isn't going to roll, especially in Autocross, but to some the rules come first.
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