Making the final adjustments for the upcoming hillclimb season and there doesn't seem to be any consistancy to the recommendation for front and rear tracking. I've seen everything from 3/16" toe in to 3/16" toe out at the front and 1/8" toe in to 1/8" toe out at the rear.
I appreciate that the front is a trade off between straight line stability and quickness of turn in but what about the effect of rear toe in/out?
What settings do you guys use?
Tracking Advise Please
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Marvel
- Posts: 127
- Joined: Tue Jun 10, 2003 1:54 pm
Tracking Advise Please
Last edited by Marvel on Tue Apr 07, 2009 11:56 pm, edited 1 time in total.
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FJCamper
- Moderator
- Posts: 2910
- Joined: Wed Nov 14, 2007 2:19 pm
Toe-in
Hi Marvel,
You realize that the solicitation of advice legally binds you to an obligation to win.
Front toe for a Type 1 beam axle racer should be 1/8". No more, no less. If you increase the toe, you promote oversteer. (Amazingly, the "Porsche Unleased" racing game actually has this as a tuning option and has it right!)
Rear toe for an IRS should be zero. Rear toe for a swing axle should be 1/8" AS THE STARTING POINT.
An increase in rear toe dramatically contributes to "roll oversteer." This means as the body rolls, you get oversteer.
Be conservative and start with 1/8" front and rear. If you really feel the need to make the rear end swing out on the tight courses, and tyre pressures are not doing it for you, change the rear toe by increments of 1/8 inch.
Good hunting, FJC
You realize that the solicitation of advice legally binds you to an obligation to win.
Front toe for a Type 1 beam axle racer should be 1/8". No more, no less. If you increase the toe, you promote oversteer. (Amazingly, the "Porsche Unleased" racing game actually has this as a tuning option and has it right!)
Rear toe for an IRS should be zero. Rear toe for a swing axle should be 1/8" AS THE STARTING POINT.
An increase in rear toe dramatically contributes to "roll oversteer." This means as the body rolls, you get oversteer.
Be conservative and start with 1/8" front and rear. If you really feel the need to make the rear end swing out on the tight courses, and tyre pressures are not doing it for you, change the rear toe by increments of 1/8 inch.
Good hunting, FJC
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Marvel
- Posts: 127
- Joined: Tue Jun 10, 2003 1:54 pm
Hi FJCamper.
The Spyder uses KP+L front with SA rear. I just got finished this evening setting the front to 1/8" toe in and the rear to zero and then saw your post. A quick test drive and it feels stable with no suprises. Tomorrow I'll try 1/8" toe in at the rear and see if I can feel any difference or improvement. At least I've got a fall back setting now.
In my class this year I've currently only got a Frogeye Sprite and MGBGT must be soemthing to do with the 'credit crunch'.
The Spyder uses KP+L front with SA rear. I just got finished this evening setting the front to 1/8" toe in and the rear to zero and then saw your post. A quick test drive and it feels stable with no suprises. Tomorrow I'll try 1/8" toe in at the rear and see if I can feel any difference or improvement. At least I've got a fall back setting now.
In my class this year I've currently only got a Frogeye Sprite and MGBGT must be soemthing to do with the 'credit crunch'.
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FJCamper
- Moderator
- Posts: 2910
- Joined: Wed Nov 14, 2007 2:19 pm
Rear toe
Marvel,
Zero toe on a swing axle is also a good start, as you discovered, and all things being equal, will actually toe out at speed and give you a little neutral to understeer.
The 1/8" toe toes out to zero toe.
Being the Spyder Rennmeister that I know you are, I'm betting you live life on the oversteer edge and make rude hand gestures to Sprites and overweight MG's as you drift around the turns, never pointed in the direction you're actually going.
Give 'em hell and full throttle. -- FJC
Zero toe on a swing axle is also a good start, as you discovered, and all things being equal, will actually toe out at speed and give you a little neutral to understeer.
The 1/8" toe toes out to zero toe.
Being the Spyder Rennmeister that I know you are, I'm betting you live life on the oversteer edge and make rude hand gestures to Sprites and overweight MG's as you drift around the turns, never pointed in the direction you're actually going.
Give 'em hell and full throttle. -- FJC
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bedjo78
- Posts: 34
- Joined: Mon Mar 06, 2006 7:10 am
Hi..
I'm in the progress of finishing my Circuit racing bug. I use body of 61 bug. Lot of body modification
- Raised torsion Housing
- torsion bar 26mm
- Modified IRS
- 1303 front strut with koni shock, rear koni shock
- All CB disc with Porsche patern with wilwod calipers
- etc
The tranny ratio is exacly the same with yours with superdiff.
As I'm modified the front suspension I'm a bit worry of how it will work.
at front I have Koni insert on Custom made strut. It is a single rebound adjustable. adjustable col spring as well
On rear I used Koni Special D rebound adjustable with 26" torsion bar.
What do you think about this set up?
the engine is maximum 2060CC
80X90.5 webcam 121/125 with 1.25 ratio rocker. head 40in/37ex weber idf48 with 1-7/8 merged
any advice really apreciated
I'm in the progress of finishing my Circuit racing bug. I use body of 61 bug. Lot of body modification
- Raised torsion Housing
- torsion bar 26mm
- Modified IRS
- 1303 front strut with koni shock, rear koni shock
- All CB disc with Porsche patern with wilwod calipers
- etc
The tranny ratio is exacly the same with yours with superdiff.
As I'm modified the front suspension I'm a bit worry of how it will work.
at front I have Koni insert on Custom made strut. It is a single rebound adjustable. adjustable col spring as well
On rear I used Koni Special D rebound adjustable with 26" torsion bar.
What do you think about this set up?
the engine is maximum 2060CC
80X90.5 webcam 121/125 with 1.25 ratio rocker. head 40in/37ex weber idf48 with 1-7/8 merged
any advice really apreciated
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FJCamper
- Moderator
- Posts: 2910
- Joined: Wed Nov 14, 2007 2:19 pm
Racing Around The World
Hi Bedjo78,
I've done some serious strut-frontend Superbug road racing (Daytona, Talladega, Road Atlanta, Sebring), and you need all the front suspension adjustability you can get. We had special slotted camber plates made for connection between the front strut and roll cage.
The actual Superbug front "tub" is too weak for racing loads unless you crossbrace it. And set for at least two degrees front negative camber to start with. The 1303 front suspension geometry is made to understeer, and more negative camber will reduce that.
Make the front end "stick" first, then work on the rear. Send us some photos if you can.
What's your competition there?
FJC
I've done some serious strut-frontend Superbug road racing (Daytona, Talladega, Road Atlanta, Sebring), and you need all the front suspension adjustability you can get. We had special slotted camber plates made for connection between the front strut and roll cage.
The actual Superbug front "tub" is too weak for racing loads unless you crossbrace it. And set for at least two degrees front negative camber to start with. The 1303 front suspension geometry is made to understeer, and more negative camber will reduce that.
Make the front end "stick" first, then work on the rear. Send us some photos if you can.
What's your competition there?
FJC
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bedjo78
- Posts: 34
- Joined: Mon Mar 06, 2006 7:10 am
I have tried to post the pic's of my suspension arrangement but no luck. So give up.
The front swing arm I tranplant from japanese Nissan Sedan with two mount link to get more ridgidity. The Ball joint also taken from Nissan. Only the spindle that I used 1303 74. this is because I already have a good set up front brake with Porsche pattern.
The front strut I have it custom made with Koni rebound adjustable. with adjustable coil over. The pattern is exacly the same as 1303 74 set up. complete with upper section.
Yes i have strengtened the strut with crossbar tubing that also used as stiffener the front end. There is a tubing frame on front end connected to roll bar.
I haven't made the slotted strut plate. instead I made a cam with an adjustable slot on swing arm mounting. The slot length is 1.5 inch. i think should be enough to set the Chamber. The sway bar I used ex Mitsubishi lancer with dia 7/8" all rubber god would be poliurethane.
really right now I just tryal and Error since I don't know where to get a better suspension set up. The suspension is real critical as my competitor would be have a better set up..ie retro japanesse car nissan sss, toyota corolla dx, bmw, porsche, mini, mitsubishi lancer, gallat...etc. most of the other got a suspension kit readily available.
I plan to utilize a dry ice to cool the engine..I made a box on inside of fire wall. fill up with dry ice and get air from chasis to blow the cool ait thru the engine fans. the oil cooler also will be spraying with cool water/alkohol a long the 15 laps
This is a 15 lap circuit racing grouped as retro class Free For All with max engine 2010cc.
The front swing arm I tranplant from japanese Nissan Sedan with two mount link to get more ridgidity. The Ball joint also taken from Nissan. Only the spindle that I used 1303 74. this is because I already have a good set up front brake with Porsche pattern.
The front strut I have it custom made with Koni rebound adjustable. with adjustable coil over. The pattern is exacly the same as 1303 74 set up. complete with upper section.
Yes i have strengtened the strut with crossbar tubing that also used as stiffener the front end. There is a tubing frame on front end connected to roll bar.
I haven't made the slotted strut plate. instead I made a cam with an adjustable slot on swing arm mounting. The slot length is 1.5 inch. i think should be enough to set the Chamber. The sway bar I used ex Mitsubishi lancer with dia 7/8" all rubber god would be poliurethane.
really right now I just tryal and Error since I don't know where to get a better suspension set up. The suspension is real critical as my competitor would be have a better set up..ie retro japanesse car nissan sss, toyota corolla dx, bmw, porsche, mini, mitsubishi lancer, gallat...etc. most of the other got a suspension kit readily available.
I plan to utilize a dry ice to cool the engine..I made a box on inside of fire wall. fill up with dry ice and get air from chasis to blow the cool ait thru the engine fans. the oil cooler also will be spraying with cool water/alkohol a long the 15 laps
This is a 15 lap circuit racing grouped as retro class Free For All with max engine 2010cc.
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FJCamper
- Moderator
- Posts: 2910
- Joined: Wed Nov 14, 2007 2:19 pm
Dry Ice
Hi Bedjo78,
So now you are an ice racer!
Your front suspension work sounds good. The only way to know is to get out there and run. We beat the ricegrinders here at their own game on the track. Spraying the oil cooler is a good idea.
Have somebody help you with the photos. You've got everyone's interest.
FJC
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gerico
- Posts: 672
- Joined: Thu Aug 14, 2003 9:12 pm