Schumacher Corner
05-09-2003, 07:51 PM
#4261
Here is a setup by Dave Vera....He's been kicking butt including mine with this setup.
Front
tower/2
bulkhead/lower hole
arm/1/move arms 1 thin kwik clip forward
hub/inline
steering/2
arm sweep/2
piston/#3 vari
oil/45wt
spring/blue schuy
droop/2mm
swaybar/stock spaced 1mm
castor/middle
camber/neg 1
toe/ neg 1 out
ride height/4.5mm
tire/Take-off cs27glr
spool
Rear
tower/2
bulkhead/lower hole
arm/1
hub/inline
piston/#3 vari
oil/45wt
spring/red when highbite/blue for med-low bite
droop/3mm
swaybar/stock
in-board toe/0
toe-in/2.5deg
rear arm/middle
camber/neg 1
ride height/5mm
tire/Take-off cs27glr
body/protoform stratus 2.0
Front
tower/2
bulkhead/lower hole
arm/1/move arms 1 thin kwik clip forward
hub/inline
steering/2
arm sweep/2
piston/#3 vari
oil/45wt
spring/blue schuy
droop/2mm
swaybar/stock spaced 1mm
castor/middle
camber/neg 1
toe/ neg 1 out
ride height/4.5mm
tire/Take-off cs27glr
spool
Rear
tower/2
bulkhead/lower hole
arm/1
hub/inline
piston/#3 vari
oil/45wt
spring/red when highbite/blue for med-low bite
droop/3mm
swaybar/stock
in-board toe/0
toe-in/2.5deg
rear arm/middle
camber/neg 1
ride height/5mm
tire/Take-off cs27glr
body/protoform stratus 2.0
05-09-2003, 08:51 PM
#4262
Thanks guys. I guess were all up late!!! One other question, By using the lower hole for mounting the upper arm's it lowers or raises the roll center? And what effect will it have on handling?
I am looking to minimise chassis roll without using a real thick swaybar.
I am looking to minimise chassis roll without using a real thick swaybar.
05-09-2003, 09:35 PM
#4263
JayDub: You going to Ripon tomorrow? I plan on being there when the doors open for some spool testing. I'm interested in the bearings...
Hey Adrain and PW. See you survived the bus trip home from Vegas. I'll give you guys a call next week...
RCOldMan: Lower holes lowers the roll center. Make the car more agressive and react faster on high bite (asphalt) tracks...too much for carpet.
Hey Adrain and PW. See you survived the bus trip home from Vegas. I'll give you guys a call next week...
RCOldMan: Lower holes lowers the roll center. Make the car more agressive and react faster on high bite (asphalt) tracks...too much for carpet.
05-10-2003, 12:06 AM
#4264
Tech Regular
Yeah me and Dom will be there tomorow, I will bring the stuff.
05-10-2003, 06:14 AM
#4265
Tech Rookie
Re: Shocks lock up (see p141)
I just rebuilt my shocks with new foam compensators and they are now very smooth.
The old foams were the consistency of rubber washers and had very little compressability. They were also smaller than the replacement foams. (They shrunk)
I got 2 pair of replacement foams from Schumacher, but the foams in each package were different. One package had foams that were black and firm. The other package had foams that were gray and softer. I put one of each in each shock to assure consistency.
Thanks for your help.
The old foams were the consistency of rubber washers and had very little compressability. They were also smaller than the replacement foams. (They shrunk)
I got 2 pair of replacement foams from Schumacher, but the foams in each package were different. One package had foams that were black and firm. The other package had foams that were gray and softer. I put one of each in each shock to assure consistency.
Thanks for your help.
05-12-2003, 05:39 PM
#4266
Racer X...Not tryingto pull you up, but I have studied different over the years...and I feel this is one area racers get confused...
The lower hole on the Bulkhead RAISES the Roll CENTRE, and in turn LOWERS the Roll MOMENT..
The Roll Centre is the imaginary point in space where the Cornering forces are applied to the chassis.
The Roll MOMENT is the distance between the Roll Centre and the Chassis centre of gravity...
Usually In Cars the Roll centre is below the Centre of Gravity, usually placed between the track surface and the underside of the chassis (generalised)
It is said that if the Roll centre was above the cars centre of gravity, the car would lean into a turn...would be interesting to see=)
A High roll centre (using the lower holes in the bulkhead resists cornering forces acting apon the chassis to a greater extent, allowing the car to take a turn with less chassis roll.
A low roll center ( using the upper Paralell hole allows greater Chassis roll during cornering.
In this exampleIf the lower arm is paralel with the track surface, and the Upper arm is angled downward so the inner (bulkhead) end ballcup of the upper arm is lower than the outerballcup on the Hub, the roll centre will be RAISED or HIGHER...Less Roll, less force is applied through the cars suspension points and chassis
this can be accomlished by going to a lower hole on the Bulkhead, or shimming the outer ballstud on the hub to raise it, steepening the angle...
When the Upper arm is paralel with the lower arm, the Roll centre is Lowered.
More forces are applied through the suspension Points, springs, swaybars and if the car was sprung the same as the example above, the car would roll more..
The lower hole on the Bulkhead RAISES the Roll CENTRE, and in turn LOWERS the Roll MOMENT..
The Roll Centre is the imaginary point in space where the Cornering forces are applied to the chassis.
The Roll MOMENT is the distance between the Roll Centre and the Chassis centre of gravity...
Usually In Cars the Roll centre is below the Centre of Gravity, usually placed between the track surface and the underside of the chassis (generalised)
It is said that if the Roll centre was above the cars centre of gravity, the car would lean into a turn...would be interesting to see=)
A High roll centre (using the lower holes in the bulkhead resists cornering forces acting apon the chassis to a greater extent, allowing the car to take a turn with less chassis roll.
A low roll center ( using the upper Paralell hole allows greater Chassis roll during cornering.
In this exampleIf the lower arm is paralel with the track surface, and the Upper arm is angled downward so the inner (bulkhead) end ballcup of the upper arm is lower than the outerballcup on the Hub, the roll centre will be RAISED or HIGHER...Less Roll, less force is applied through the cars suspension points and chassis
this can be accomlished by going to a lower hole on the Bulkhead, or shimming the outer ballstud on the hub to raise it, steepening the angle...
When the Upper arm is paralel with the lower arm, the Roll centre is Lowered.
More forces are applied through the suspension Points, springs, swaybars and if the car was sprung the same as the example above, the car would roll more..
Last edited by King-G; 05-12-2003 at 05:59 PM.
05-12-2003, 06:07 PM
#4267
srry double post
Last edited by King-G; 05-12-2003 at 08:33 PM.
05-12-2003, 06:08 PM
#4268
On this topic of roll centres, One good way of adjusting the Roll centre to Lower is in fine increments is to make some shim plates out of carbon to sit under the bulkhead...
I have made them from 1mm Carbon sheet, and they are cut to a squarish shape to fit directly under the bulkhead,,,it is crutial to make sure the 4 holes are Perfectly in line with the bulkhead holes, or you can tweak the car or bind the drivetrain..
To ensure this doesnt happen i suggest you over size the holes slightly...
its a good tuning aid, as Allot of the Schuey drivers feel that the Lower hole is too low, and the Upper is too high...somewher inbetween is more preferable.
Teemu was playing with this idea long ago, using shims
give it a try..I suggest you use the lower hole in the bulkhead and shim it up approx 1-2 mm.
One side effect is that the shock towers are of course raised by this same amount, and shock length, droop and ride height needs re adjusting.
I have made them from 1mm Carbon sheet, and they are cut to a squarish shape to fit directly under the bulkhead,,,it is crutial to make sure the 4 holes are Perfectly in line with the bulkhead holes, or you can tweak the car or bind the drivetrain..
To ensure this doesnt happen i suggest you over size the holes slightly...
its a good tuning aid, as Allot of the Schuey drivers feel that the Lower hole is too low, and the Upper is too high...somewher inbetween is more preferable.
Teemu was playing with this idea long ago, using shims
give it a try..I suggest you use the lower hole in the bulkhead and shim it up approx 1-2 mm.
One side effect is that the shock towers are of course raised by this same amount, and shock length, droop and ride height needs re adjusting.
05-12-2003, 06:36 PM
#4270
Good points King-G. And BTW, a car leaning into the corner, while it actually works, will give you less cornering grip than a car that leans out.
Another thing is that you can shim up the upper ball stud on the hub, or screw out the lower ball stud (not recomended) to change the geometry without affecring your shocks, but this is only a prob if your shocks are marginal (for length) to begin with.
Another thing is that you can shim up the upper ball stud on the hub, or screw out the lower ball stud (not recomended) to change the geometry without affecring your shocks, but this is only a prob if your shocks are marginal (for length) to begin with.
05-13-2003, 06:14 AM
#4271
Hi guys,
Just making a couple of enquiries. A few months back we talked about cutting the bottom shock ballcups down to get the correct ride height. It seemed that people were doing that but are you doing it now? I am not and dont really have a problem. However my springs seem to be under quite a bit of preload at ride height. Rideheight is 5-6mm with shocks at 66-67mm. Do you guys have the springs almost floating in the shock at ride height?
Im having problems getting my car perfectly tweaked and think I may be doing something wrong in this area. Just interested to hear from others about this.
Just making a couple of enquiries. A few months back we talked about cutting the bottom shock ballcups down to get the correct ride height. It seemed that people were doing that but are you doing it now? I am not and dont really have a problem. However my springs seem to be under quite a bit of preload at ride height. Rideheight is 5-6mm with shocks at 66-67mm. Do you guys have the springs almost floating in the shock at ride height?
Im having problems getting my car perfectly tweaked and think I may be doing something wrong in this area. Just interested to hear from others about this.
05-13-2003, 07:15 AM
#4272
oasis-Are you using the number 1 or 2 hole for the lower shock mount? If you are using the number 1 hole, then your shocks are too long in my experience. They need to be 64 mm. The piston would hit the top of the shock body if they are 66mm or longer. Check it out, see what you think.
05-13-2003, 01:05 PM
#4274
ottorman i would thank that the top hole sence it allows the chassis and suspention to lean more. the bottom hole makes it more redgid and you would break traction sooner. just like if you was to run a swaybar or stiffen up you suspention.
that is how i understand it man. But im new at this stuff also!!!
that is how i understand it man. But im new at this stuff also!!!
05-13-2003, 04:37 PM
#4275
Good question Ottoman, and In theory you would run the upperholes as they give the car more weight transfer...BUT
They dont give the car as much side bite or camber change...
I personally run the lower holes, and try to spring the car more softly, this has the benefets of allowing more fore and aft weight transfer, but the car rides flatter mid corner...Low Bite conditions generally require soft springs and oils to rely on weight transfer to gain steering off power, and plant the rear end on power prevent the car from over rotating because the weight will transfer rearward under acceleration.
Others may like to share their experiences.
On this topic, I note that allot of carpet racers use the Upper holes in the bulkhead but spring the car more stiffly to reduce body roll. To me the reason for doing this is to reduce sitebite in the turns and allow the car to corner more freely. The upper links provide less side bite and camber changewithout bogging down.
They dont give the car as much side bite or camber change...
I personally run the lower holes, and try to spring the car more softly, this has the benefets of allowing more fore and aft weight transfer, but the car rides flatter mid corner...Low Bite conditions generally require soft springs and oils to rely on weight transfer to gain steering off power, and plant the rear end on power prevent the car from over rotating because the weight will transfer rearward under acceleration.
Others may like to share their experiences.
On this topic, I note that allot of carpet racers use the Upper holes in the bulkhead but spring the car more stiffly to reduce body roll. To me the reason for doing this is to reduce sitebite in the turns and allow the car to corner more freely. The upper links provide less side bite and camber changewithout bogging down.