Track car alignment, Unsettled debate Options

[stephenpowless]

I have a 74 914 tub converted to a track car. Sheridan body kit, 3.6 varioram motor, 915 tranny(which I hate and may convert to G50), 935 front suspension, 944 turbo brakes, bilstein coil overs. On flat straightaways, it's debating which tire to follow and darts left and right, as if there is a strong cross wind. Had it re-aligned as follows; scale, L/F 497. R/F 458, L/RR 638, R/RR 590. Camber : L/F 3.5. R/F 3.6. L/RR 1.8. R/RR 2.0. Toe: L/R front 0, L/RR 1.5. R/RR 1.5. It's still "debating" at speed, which is very unnerving going into turn one at BIR. The questions are; is the alignment the problem or do I need some downforce via a wing? Appreciate any insight. This is my first visit to this forum. Thanks in advance.

[Matt Romanowski]

That is a ton of camber in the front combined with no toe. I would say to try a little toe in to see if it settles down.

How are your tire temps after a session?

And what tires do you run?

[brant]

Sounds like a car that should be on slicks with zero camber.

[old dog]

Radial race tires do run an outrageous amount of camber, but a little bit of toe in should help. Castor angle is also a stabilizer in a straight line , I didn't notice that measurement ? Also, make sure it is toe in at the rear and we haven't mistakenly given her toe out in the rear ( which can also be very exciting ). If it is "nervous " in a straight line , something is wrong.

[brant]

2178lbs?

[stephenpowless]

2178lbs?

2183 lbs. Hoosier 245/40ZR17 R6 front, 295/35ZR17 R6 rear

[brant]

I run about a quarter degree less negative camber in the front than in the back. So up your rear number and straighten out your front. Hoosiers also.

I always set my rear suspension to a balanced number that is close to what I can max the worse side at. And then set my front ratio for a quarter less than I got on the rear.
So for example rear at -2.50. And front at -2.25

I think your front end is skating down the straight on a very small corner of contact patch.

We noticed significant brake capability loss when we went more than -2.75 or -3 degrees in the front. Even though th Hoosier would like the negative camber in the corners it didn't like the contact patch under breaking.

We settled on -2.25 ish for our front setting

What suspension bushings do you run in the rear? With a bushing that has no movement like a metal mono ball you can go to zero toe. Otherwise a 16th of toe in.

I think you probably should realign. I don't know how often you are realigning but it changes much more than you would expect and frequent re alignments are a necessity on a track 914.

Our car weights are different which also has an impact on the tires and their temps so you may have slightly different alignment needs too

[ChrisFoley]

I run about a quarter degree less negative camber in the front than in the back. So up your rear number and straighten out your front. Hoosiers also.

I always set my rear suspension to a balanced number that is close to what I can max the worse side at. And then set my front ratio for a quarter less than I got on the rear.
So for example rear at -2.50. And front at -2.25

I think your front end is skating down the straight on a very small corner of contact patch.

We noticed significant brake capability loss when we went more than -2.75 or -3 degrees in the front. Even though th Hoosier would like the negative camber in the corners it didn't like the contact patch under breaking.

We settled on -2.25 ish for our front setting

What suspension bushings do you run in the rear? With a bushing that has no movement like a metal mono ball you can go to zero toe. Otherwise a 16th of toe in.

I think you probably should realign. I don't know how often you are realigning but it changes much more than you would expect and frequent re alignments are a necessity on a track 914.

Our car weights are different which also has an impact on the tires and their temps so you may have slightly different alignment needs too

I agree with Brant that you should be running less front camber.
You should also check bump steer on all 4 corners.
Depending on the how low the car is, the loaded rear tire could be toeing out quickly as you turn in, which means extra rear static toe-in is needed.

Without knowing the camber and toe curves of your suspension setup
raising the ride height may be the easiest way to improve handling.

[stugray]

We settled on -2.25 ish for our front setting

Brant,

I tried your suggestions on my front suspension to get more camber than stock.
I removed the kidney shaped "hats" and trimmed the inboard side off with a bandsaw to eliminate interference inside the shock tower.

(IMG:http://www.914world.com/bbs2/uploads_offsite/i366.photobucket.com-10819-1461363731.1.jpg)


I also enlarged the bolt holes in the in board direction.

Now I can get up to 2.0 degrees camber on that side before the "neck" of the shock top hits the side of the large opening.

So I am wondering if I can use the porting tool and remove the inboard lip of that hole to give me another .25 degrees.
Can I enlarge the big hole by ~0.25 in without ruining the rigidity?
I am sure the lip adds some stiffness in that area, but I dont think it will make much of a difference overall.

Here is where I would like to cut back about far enough to remove that lip entirely.
(IMG:http://www.914world.com/bbs2/uploads_offsite/i366.photobucket.com-10819-1461363732.2.jpg)

Thoughts?

I could buy the $350 offset billet tops but this costs essentially zero.

[ChrisFoley]

Can I enlarge the big hole by ~0.25 in without ruining the rigidity?

You can grind that lip away. That's how I got the last bit of negative camber in my car when I ran it in ITB.

[stownsen914]

As mentioned by others, that's a lot of neg. camber in the front.

Definitely check your bump steer if you haven't, as Chris suggests above. Often overlooked. If it's not right, the car can wander all over the track. If your bump steer is bad enough, even small undulations like you see on a straight can make the car wander.

You'll hear different opinions on what toe to run. I run 1/16" toe out in front and 3/16" toe in at the rear. 914 rear arms are known to flex a lot, so I run more toe in at the back than you might with other cars. I am running wide Goodyear radial slicks, for what it's worth.

[6freak]

tighten front sway bar more weight on front wheels JMO
HAVE FUN