Kinematics advice please
10-15-2018, 12:31 PM
#1
Race Car
Thread Starter
Kinematics advice please
Steering is slightly off centre so time for an alignment. Problem is only the dealers seem to have the levelling tool required to do the kinematics and of course their alignment prices are quite substantial. Is it necessary to do the kinematics? How can you tell if they need to be done? Any advice you can shed would be very helpful.
10-15-2018, 01:59 PM
#2
Rennlist Member
Many US based alignment / set-up shops have a Kinematic Toe tool.
Ask around your local CA area, you may find one that does.
But unless you have excessive rear tyre wear and / or track your car and feel the rear end "squirming" around under threshold braking............. I would not worry about setting the K-Toe. IMO for street use, it's more mental m@sturb@>>>>> than a real-world concern.
Good luck
Craig
Ask around your local CA area, you may find one that does.
But unless you have excessive rear tyre wear and / or track your car and feel the rear end "squirming" around under threshold braking............. I would not worry about setting the K-Toe. IMO for street use, it's more mental m@sturb@>>>>> than a real-world concern.
Good luck
Craig
10-15-2018, 04:14 PM
#3
RL Technical Advisor
KT makes a VERY big difference when its out of spec or uneven, side to side with street, track, or race cars.
Its one of the biggest differences between an excellent handling 993 and an average (or poor-handling one).
There is no "Kentucky windage" here,....this value MUST be spot on for these cars to handle properly!!
You would never believe what I've seen with these particular cars after 23 years and I've learned a thing or two.
10-15-2018, 05:06 PM
#4
Uhhhhh,....not really.
KT makes a VERY big difference when its out of spec or uneven, side to side with street, track, or race cars.
Its one of the biggest differences between an excellent handling 993 and an average (or poor-handling one).
There is no "Kentucky windage" here,....this value MUST be spot on for these cars to handle properly!!
You would never believe what I've seen with these particular cars after 23 years and I've learned a thing or two.
KT makes a VERY big difference when its out of spec or uneven, side to side with street, track, or race cars.
Its one of the biggest differences between an excellent handling 993 and an average (or poor-handling one).
There is no "Kentucky windage" here,....this value MUST be spot on for these cars to handle properly!!
You would never believe what I've seen with these particular cars after 23 years and I've learned a thing or two.
Rear steer is a far more powerful tool than front steer, don't believe me? Try driving you car fast in reverse.
Besides turning the steering wheel steer comes from toe and toe change w/ suspension travel
In the front too much toe change, aka bump or roll steer is an annoyance. It back it can make the car undriveable.
Both ends of a 993 have the ability to adjust static and dynamic(aka Kinetic) toe.
static toe is just what it sounds like, when the car is stationary at the suspension is in it's base state there is a certain amount of toe, spec in front is+5+/-5', in back +15' +/-5'
when in motion the toe changes, becoming more neg. in bump and more pos. in droop
The rate of toe change is determined by the caster, more caster meants the rate of toe change increases, less caster has the opposite effect
spec for castor is front is 5°20'+15'-30' in back it is +3° to 3° 30'
The more caster the faster that end of the car will turn, too fast and the car is uncontrollable, too slow and the car feels numb, the balance f/r affects under and oversteer as well.
If there are no shops in Toronto I'm sure that there are in Rochester, worst case drive to Ct. where there are some great shops.
10-15-2018, 05:48 PM
#5
Three Wheelin'
I’m going to echo the experts here and say it is 100% necessary to get this right. I’ve driven with kinematic toe (KT) way off, slightly off and spot-on. With it way off, I didn’t even want to leave the neighborhood. With it slightly off, the rear would steer the front constantly, requiring continuous corrections, making the car feel nervous and unstable. With it spot on, the car is a rock.
Every alignment on these cars is a four wheel alignment, you don’t do just the front. So you always have to check and set KT, since it is tightly coupled to the toe and camber adjustments. You can’t adjust just one without impacting KT, if that makes sense.
I’m in an area with very little 993 alignment expertise, so I bought the KT tool myself from auto metrics (http://www.autometricsmotorsports.co...-tool-for-993/). It has been more than worth the investment. With the tool in hand, the instructions, and a working knowledge of how all this works, I was able to talk my local alignment shop through the procedure and got a good result. I’ve also found a local guy who knows how to do the job (from past experience) but didn’t have the tool. So if I bring the tool in, I can get a good result from him as well.
Since the 993 alignment requires specialized knowledge, that is fading everywhere, and impossible to find in some places, I think its worth buying the tool and learning enough about it that you can get a good alignment from any decent alignment shop.
Every alignment on these cars is a four wheel alignment, you don’t do just the front. So you always have to check and set KT, since it is tightly coupled to the toe and camber adjustments. You can’t adjust just one without impacting KT, if that makes sense.
I’m in an area with very little 993 alignment expertise, so I bought the KT tool myself from auto metrics (http://www.autometricsmotorsports.co...-tool-for-993/). It has been more than worth the investment. With the tool in hand, the instructions, and a working knowledge of how all this works, I was able to talk my local alignment shop through the procedure and got a good result. I’ve also found a local guy who knows how to do the job (from past experience) but didn’t have the tool. So if I bring the tool in, I can get a good result from him as well.
Since the 993 alignment requires specialized knowledge, that is fading everywhere, and impossible to find in some places, I think its worth buying the tool and learning enough about it that you can get a good alignment from any decent alignment shop.
10-16-2018, 10:28 AM
#6
Race Car
Thread Starter
Thanks for the input guys. Car is extremely stable now but with the slight off centre steering. Looks like I better find a decent shop that can do the kinematics or buy the tool myself. You'd think with a Greater Toronto population of around 6 million and the biggest PCA membership there'd be someone decent who could handle this. I'll keep looking and finish off this thread with my course of action.
10-16-2018, 10:57 AM
#7
Three Wheelin'
When did the steering go wonky on you? Is it pulling? If your tires are old, that alone can account for an uneven steering wheel, without pulling. I’ve had that happen before.
Not that you shouldn’t get an alignment, but if you are worried about getting a good one and your tires are bad, that would be the first place to start. And see where that leaves you.
Not that you shouldn’t get an alignment, but if you are worried about getting a good one and your tires are bad, that would be the first place to start. And see where that leaves you.
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10-16-2018, 11:19 AM
#8
Steering is slightly off centre so time for an alignment. Problem is only the dealers seem to have the levelling tool required to do the kinematics and of course their alignment prices are quite substantial. Is it necessary to do the kinematics? How can you tell if they need to be done? Any advice you can shed would be very helpful.
The wheel needs to be clocked to the rack before an alignment using tool 9116, basically a bolt that goes into the rack and mates to a niche at the center of the rack
After that and a height check a full alignment is done starting in back
10-16-2018, 12:33 PM
#9
Race Car
Thread Starter
Tires are new (500 miles) Michelin PS2's. I'm pretty sure it's just crappy road misalignment though I did have one of the tires replaced on warranty right after it was installed......felt flat spotted all the time. Don't think most folks would even notice the slightly off centre wheel but being a bit ****....
10-16-2018, 04:09 PM
#11
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KT
If you’re only off center on steering, just get that squared away. If rear is within spec, no need for any changes.
I bought my own KT Motorsports gauge, and bring it to a guy, I trust who has years of 993 experience. If the “tech” is about as old as your car, he doesn’t have enough experience.
I bought my own KT Motorsports gauge, and bring it to a guy, I trust who has years of 993 experience. If the “tech” is about as old as your car, he doesn’t have enough experience.