Alfa Romeo Owners Club of Australia Forum

Racing => Rear Wheel Drive => Topic started by: redsky on March 04, 2014, 11:54:04 PM

Title: Alignment for the 75.
Post by: redsky on March 04, 2014, 11:54:04 PM
Time to get a wheel balance and front end alignment on the 75 TS. I'm looking to continue using it for sprint days and not much else, maybe the odd weekend trip to the hills. The car is stock with standard suspension and dampers.
What specs should I get it set to?

Cheers

Darren.
Title: Re: Alignment for the 75.
Post by: Mick A on March 05, 2014, 09:24:13 PM
Gday Darren,

I think a good setup for your car would be about 2 degrees negative camber (this is about all you will get with standard length bolts), 1mm toe in, and as much positive castor as you can get without scrubbing the inner guards.

Cheers.

Mick.
Title: Re: Alignment for the 75.
Post by: Neil Choi on March 05, 2014, 10:02:37 PM
Ditto on that, it is about 5 degree on the castor.  If not done, change the castor bushes to the polyurethane ones.
It will be like on rails.

Just in time for Winton, right Darren?
Send me your entry form.
Title: Re: Alignment for the 75.
Post by: redsky on March 06, 2014, 09:26:35 PM
Thanks guys for the advice. Yes, very keen to be at Winton and the Island, see you there.
Title: Re: Alignment for the 75.
Post by: redsky on March 25, 2014, 10:26:20 PM
We'll that didn't work too well. If the figures are to be believed, I ended up with 4 degrees positive castor, 1 degree neg camber ( they wouldn't have go a adjusting using the bolts) and 1 degree toe in.
Fine in a straight line but when turning into corners under steered worse than usual and was accompanied by a unsettling vibration that persisted for the whole time steering lock was applied.
Frustrating day and seconds slower than I thought I'd be.
Title: Re: Alignment for the 75.
Post by: Jekyll and Hyde on March 26, 2014, 06:36:23 AM
Hmmm.... Choderboy, are you sure that was supposed to be toe in and not toe out? I had a feeling it was supposed to be out, but my memory isn't too good...
Title: Re: Alignment for the 75.
Post by: mad dog 75 on March 26, 2014, 12:53:36 PM
Roger that Jekyll and Hyde l'm with you, nothing wrong with your memory, looks like Darren had a shit full day at Winton, he has been a lot quicker at past Winton meeting.

l have heard that a block of cheese and two mice under the bonnet of a GTV6 can work as well, but l'm yet to try it out, think l will stick to me old four pot screamers and a nice cold beer at the end of the day all in good fun.

Cheers Mad dog 75
Title: Re: Alignment for the 75.
Post by: Neil Choi on March 26, 2014, 04:33:55 PM
Hi Darren


I just checked my maintenance records of my GTV, I have 0 toe and 5'40" castor L+R. 


See how much thread is left on the A-arm bolts for more negative camber, you might get a degree more, maybe.


See if you can go maximum in castor, to 5 degrees.


You can come down to PI to try it out.


Neil
Title: Re: Alignment for the 75.
Post by: mad dog 75 on March 26, 2014, 07:48:51 PM
why so much castor?  just asking ;D

cheers mad dog 75
Title: Re: Alignment for the 75.
Post by: redsky on March 26, 2014, 07:56:23 PM
Yes, the car's heading in for alignment again tomorrow, make sure nothing has come loose, and reset to some different specs, including fixing the pits side adjustments I made, which helped a bit on the day.
If I get the vibration sorted, I'll have the car at P.I. I was a good 6 or 7 seconds off November's Broadford pace on the short track.
Thanks guys,

Darren.
Title: Re: Alignment for the 75.
Post by: colcol on March 26, 2014, 08:11:00 PM
It was in my 33 racing days, but set the toe out alignment to standard toe out of 2mm, and the car felt good, ran off the track and clobbered a kerb, and then the steering wheel was 'on the piss', and the car handled terrible with terminal understeer, checked it at home, and it was toeing in 4 mm, no wonder.
Usually toe out front wheel drives from the factory as they are stable, and they slightly toe in rear wheel drives for stability, Colin.
Title: Re: Alignment for the 75.
Post by: Neil Choi on March 26, 2014, 08:22:54 PM
why so much castor?  just asking ;D

cheers mad dog 75


Oil or sugar?


Maximum caster to help the inside turning wheel lean more, ie like a motorbike.  As I am led to believe.  Also takes more effort to turn the steering wheel.


Toe out helps the inside turning wheel more to pull the car around the corner better, shorter radius than the outer wheel would turn, again, as I am led to believe.  Go karts has something like that, can't remember the terminology, accumen or something like..., you can see the inside turning wheel has a much more turn angle.


But I am only a keyboard warrior.



Title: Re: Alignment for the 75.
Post by: mad dog 75 on March 26, 2014, 08:57:35 PM
way to much castor there Neil and l would choose castor sugar every time over castor oil ;)
Title: Re: Alignment for the 75.
Post by: colcol on March 26, 2014, 09:13:03 PM
Ackerman effect, the inside wheel turns more than the outer wheel, hooking the car through the corner, with toe out.
Non Ackerman effect, when you have clobbered a kerb and the outer wheel turns more than the inner wheel, causing horrendous understeer, solution to problem, go home and drink a lot of beer and think about that kerb you hit, Colin.
Title: Re: Alignment for the 75.
Post by: redsky on March 26, 2014, 09:45:23 PM
I'm sure most people hit more kerbs rafter a few beers than before  ;) I seem to do it trying to squeeze that extra couple of tenths out of a bog stock 25 yr old twinspark!