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Toe; front, back, in Or out

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arturo64 Avatar
arturo64 Arthur T
Billings, Montana, USA   USA
So AutoCross season is here again! Oh yeah. My first race went well though it was a fast course and suited the peddle stompers. Had a blast and my mods all worked
Mods so far
- 1500 long axles(new)
- 14 in Miata rims(new)
- quick steering rack (new)
- alternator (new)
- electric fan(new)
- gt6 front axles and brakes
- lowered front and back w stiffer springs up front and CC in back
- 7/8 sway bar
- strategically placed Go Fast red paint!

Since I messed with the alignment both front and back I took it to have it aligned. I only had them adjust the front and we went with 1/16 IN. On the back he only gave me measurements since it involves shims behind the proper trailing arm brackets.
With measurements I used the philosophy the needed change in measurement directly correlated to the thickness of the shims. I went 0 (at least i hope) in the back.

What is best for AutoX???
I was pushing in the tightest hairpin corner (I think the term understeer is the same) had I had more runs(long story there) I know I could have used better technique. But...
What is best for best maneuvering with sacrifice to top speed stability???



Arthur
68 spit
70 gt6+

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arturo64 Avatar
arturo64 Arthur T
Billings, Montana, USA   USA
anybody? know this forum can go unnoticed sometimes, but it is that time of year, time for racing! and I can clarify that this is on my mk3 spit



Arthur
68 spit
70 gt6+

tapkaJohnD Avatar
tapkaJohnD John Davies
Lancaster, Lancashire, UK   GBR
Do you have any of the books of the late Alan Staniforth?
He was an expert builder, tuner and driver of hill climb cars, so his expertise suits Autocross as well.
Apart from his many, many other words of wisdom, he had flow charts to deal with understeer, and oversteer.

There is a scan of his understeer scheme here: https://robrobinette.com/S2000KWV3Tuning.htm (Halfway down the page) but I cannot recommend his whole output more.
Worth a read for anyone competing!

John

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arturo64 Avatar
arturo64 Arthur T
Billings, Montana, USA   USA
wow, that is awesome...largely beyond my knowledge base but exactly what I'll need to be studying. thanks

any other opinions or experiences welcome too!



Arthur
68 spit
70 gt6+

tapkaJohnD Avatar
tapkaJohnD John Davies
Lancaster, Lancashire, UK   GBR
Just ask, Arthur!

arturo64 Avatar
arturo64 Arthur T
Billings, Montana, USA   USA
Yeah now my head is spinning, really thought my understeer was my toe. But it may have to do with my shocks and maybe my caster. It's felt this way since putting in the lowered and updated springs in with new shocks. I also went with a larger roll bar at the same time though. Ugh. Might have to research, experiment and find my own answers...



Arthur
68 spit
70 gt6+

tapkaJohnD Avatar
tapkaJohnD John Davies
Lancaster, Lancashire, UK   GBR
Suspension is always a compromise. You win some, you ... know the saying.
Most important is to change one thing at a time, else you lose your way entirely.
The good thing is that as you approach the ideal set up, even small changes have a big, usually bad, effect!

My latest effort is to introduce droop control. This is mandatory in single seaters which may have zero droop on the front, even though they don't change camber very much, and they can tune it out as they have ride height adjustment and spring tension preset. May be important with shorter wishboned Triumph suspension with significant camber change. I'm using a simple cable control, popular with off-roaders, and have so far halved the droop possible, but don't know yet if it makes a difference!

John



Edited 1 time(s). Last edit at 2017-05-17 04:01 AM by tapkaJohnD.

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tlcgt6 Avatar
tlcgt6 Tommy Cook
Colleyville, texas, USA   USA
1971 Triumph GT6 MkIII "Banana Hannah"
1972 Triumph GT6 "The T"
is that the Austin princess brake caliper?

tapkaJohnD Avatar
tapkaJohnD John Davies
Lancaster, Lancashire, UK   GBR
Bingo!

I'm amazed that you recognised it, unless you are a UK expat.
The Princess can't have sold more than handfuls in the US, if at all.

It had an early attempt at safety by redundancy, as the two pistons were on separate circuits, which many people used in other cars by joining them. Hence the extra pipes.
But they are now rarer than crows' teeth, and there are lots of 4-pots about for modifying .

John

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clshore Carter Shore
Beverly Hills, Florida, USA   USA
Many folks find that running toe OUT at the rear can help with turn-in.
This makes the car somewhat twitchy and unstable, but in shorter tighter courses with lower top speeds
the trade-off yields better times.
The settings may reach what would be unsuitable for a street car, ie 1/4" toe OUT.
You should experiment, adding/removing one shim pair at a time, until you are satisfied.
Different courses will respond to different settings, so keep a logbook of how many shims.
Tire wear may be horrible, so if you are not trailering the car, make the changes at the track,
and then return them to 'normal' afterwards.

quikrx Ralph Hansen
Antioch, Illinois, USA   USA
1962 Triumph Herald 1200
1969 Triumph Spitfire MkIII "Gloria"
1987 Mazda RX-7 "Mistress"
2003 Toyota Celica GT-S "Natasha"    & more
if you have a brake zone going into a corner and have understeer (push) you can also add a little more rear brake to help lighten the rear on turn-in - will help some, just be careful because it might be too much on other sections of track - ideally you need adjustable brake bias within reach of the driver

clshore Carter Shore
Beverly Hills, Florida, USA   USA
The parking brake is an easy way to help with getting the car to rotate, rally and offroad drivers do this all the time.
Spitfire e-brake handle is especially easy, leave the locking button alone.
The opposite effect can be gained to correct for a loose rear (in RWD cars) by applying brakes and a bit of power at the same time.

arturo64 Avatar
arturo64 Arthur T
Billings, Montana, USA   USA
I recently got two new tires, which were cheap...but worth a try. they are different tires but they have the exact same tread pattern of my 'good' tires in front. once mounted they went on the back, where the 'bad' tires had been. that made for interesting racing and the push was worse. so for the last race I moved the front tires from the back to the front. so it seemed like the best tread was in front and the Push in corners was Way less. very happy with this. I still think I have a lot to learn in the suspension department. the other thing that really helped was my approach into the turns (so a little tuning of the nut behind the wheel).



Arthur
68 spit
70 gt6+

clshore Carter Shore
Beverly Hills, Florida, USA   USA
Racing Spitfires respond well to more negative camber up front, reduces push (understeer) and make them stick.
This is accomplished by simply inserting shims between the wishbone pivot brackets and frame:

https://www.rimmerbros.co.uk/Item--i-122022
https://www.rimmerbros.co.uk/Item--i-GRID005743

Start with one on each pivot bracket (for a total of 4), and then add more if needed.
You don't have to remove anything, just loosen the nut holding the pivot bracket, insert shim, tighten nut.

This will cause an increase in front toe, but try it out before correcting toe.

arturo64 Avatar
arturo64 Arthur T
Billings, Montana, USA   USA
I did adjust my negative camber with minding the shims. can't remember the figure they are at but i'll look. what figure would you think be a good one for a racing set up 5*? or 2*? or?? (negative of course)



Arthur
68 spit
70 gt6+

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