Dose anybody know the alinment specs of a 69 notch?? as after my rebuild i cant get the car to go strait!!! as the 215/35/18 rubber picks up every twitch in the road!!
thanks
marco mansi......
Notch Going strait!!! on 18s!
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marcotheturbosteamengine
- Posts: 448
- Joined: Wed Aug 21, 2002 12:01 am
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raygreenwood
- Posts: 11895
- Joined: Wed Jan 22, 2003 12:01 am
No one will have the specs for that. They do not exist.
Here is why:
The original toe-in was set up probably for....a 155 or 165 SR-15 tire.
You now have roughly 40 %wider contact patch. If allthings were linear....you could count on roughly 40% more force being generated via forward motion and traction....to spread the tires apart. Which by the way is why toe-in exists.
You need more toe-in....and to keep from "tramlining"....you need more castor.
Mind you I work on type 4's mostly (411/412)...but going from the exact same tire stock that your car had to a 205/60-15....I had to add about 1.5 degrees extra of toe-in to each side. My car came from the factory with less castor than your car...but to get rid of tramlining and wind wandering...I needed roughly 4 degrees castor. Do the toe-in first.
the drawback is that at low speeds...say under 45 mph...you will experience slightly more inner toe wear. But at 45 and up...it should stay stable and quit changing lanes on you. Ray
Here is why:
The original toe-in was set up probably for....a 155 or 165 SR-15 tire.
You now have roughly 40 %wider contact patch. If allthings were linear....you could count on roughly 40% more force being generated via forward motion and traction....to spread the tires apart. Which by the way is why toe-in exists.
You need more toe-in....and to keep from "tramlining"....you need more castor.
Mind you I work on type 4's mostly (411/412)...but going from the exact same tire stock that your car had to a 205/60-15....I had to add about 1.5 degrees extra of toe-in to each side. My car came from the factory with less castor than your car...but to get rid of tramlining and wind wandering...I needed roughly 4 degrees castor. Do the toe-in first.
the drawback is that at low speeds...say under 45 mph...you will experience slightly more inner toe wear. But at 45 and up...it should stay stable and quit changing lanes on you. Ray
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raygreenwood
- Posts: 11895
- Joined: Wed Jan 22, 2003 12:01 am
"0" degrees toe-in....with a wider than stock tire? You can't even drive straight with a 4.5" rim without at least some toe in. The force of driving spreads the tires apart.....causing toe-out . Toe-out causes the vehicle to try to pull from one side to the other at speed. You have to have some toe in...and the need for toe-in gets higher as the wheels get wider. Ray
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raygreenwood
- Posts: 11895
- Joined: Wed Jan 22, 2003 12:01 am
No problem. But....here is where reality deviates from math. The measurements given by factory design are static measurements. They have to put in an angle known to work....on the alignment rack when the car is not moving...or under force. This measurement given is only correct for the rim diameter...AND....the tire diameter and profile that the car was designed with. Putting a larger diameter rim and/or a different profile tire does not mean that the same 1/8" toe-in....will be correct...even though it translates to a different angle.
What is not being factored is that the wider the contact patch...the more force is being applied to the contact patch through forward motion...and the more force is also being applied to flexible tolerances in the suspension (like bushings, tie rods, ball joints, tire side walls etc).....and the more the tires want to flex out of alignment toward the toe-out position.
Its also crucial to point out that rim offset changes this equation as well.
Here are the toe-in degree values based on 4 tires sizes with the stock 15" rim and then the 18" rim with the advertized tire size.
Stock 165/75-15.....1/8"=.80*
165/70-15.....1/8"=.59*
195/65-15.....1/8"=.57*
205/60-15.....1/8"=.58*
Stock 15" rim only: 1/8"=.95*
18" rim only: 1/8"=.8"
215/35-18.......1/8"=.6*
That .6* on the 18" rim may seem trivial....but without it, lots of things change. The suspension absorbs damage through tension applied to it by forward motion. The car likes to tramline....and its harder to feel that anything is wrong due to the wide contact patch.
Other qualifiers that help to absorb....and yes...possibly negate....SOME of the need for extra toe-in when going to a larger tire......
(a) very low profile side-walls....give less flexibility. That actually helps and can be some of the reason why extra toe-in may not be needed (this does not negate the need for initial toe-in)
(b) Having very stiff high performance suspension components made of high tech materials like urethane. These can give less flexibility to the suspension...and bolster toe-in from the road.
(c) Subframe braces and strut braces....can actually bolster against toe-in forces from the road.
It may be that with the wide contact patch....you don't need EXTRA toe-in. But you need to have teh minimum for best results.
The tire combo that needs extra toe-in the most.....is actually the 205/60-15. It has a 40mm wider contact patch than the stock tire and only marginally lower sidewall....so it exerts a lot of leverage and has lots of flexability. It typically needs average of one extra degree of toe-in...to make it about 1.5*. No more than two. Ray
What is not being factored is that the wider the contact patch...the more force is being applied to the contact patch through forward motion...and the more force is also being applied to flexible tolerances in the suspension (like bushings, tie rods, ball joints, tire side walls etc).....and the more the tires want to flex out of alignment toward the toe-out position.
Its also crucial to point out that rim offset changes this equation as well.
Here are the toe-in degree values based on 4 tires sizes with the stock 15" rim and then the 18" rim with the advertized tire size.
Stock 165/75-15.....1/8"=.80*
165/70-15.....1/8"=.59*
195/65-15.....1/8"=.57*
205/60-15.....1/8"=.58*
Stock 15" rim only: 1/8"=.95*
18" rim only: 1/8"=.8"
215/35-18.......1/8"=.6*
That .6* on the 18" rim may seem trivial....but without it, lots of things change. The suspension absorbs damage through tension applied to it by forward motion. The car likes to tramline....and its harder to feel that anything is wrong due to the wide contact patch.
Other qualifiers that help to absorb....and yes...possibly negate....SOME of the need for extra toe-in when going to a larger tire......
(a) very low profile side-walls....give less flexibility. That actually helps and can be some of the reason why extra toe-in may not be needed (this does not negate the need for initial toe-in)
(b) Having very stiff high performance suspension components made of high tech materials like urethane. These can give less flexibility to the suspension...and bolster toe-in from the road.
(c) Subframe braces and strut braces....can actually bolster against toe-in forces from the road.
It may be that with the wide contact patch....you don't need EXTRA toe-in. But you need to have teh minimum for best results.
The tire combo that needs extra toe-in the most.....is actually the 205/60-15. It has a 40mm wider contact patch than the stock tire and only marginally lower sidewall....so it exerts a lot of leverage and has lots of flexability. It typically needs average of one extra degree of toe-in...to make it about 1.5*. No more than two. Ray
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raygreenwood
- Posts: 11895
- Joined: Wed Jan 22, 2003 12:01 am
No problem. But....here is where reality deviates from math. The measurements given by factory design are static measurements. They have to put in an angle known to work....on the alignment rack when the car is not moving...or under force. This measurement given is only correct for the rim diameter...AND....the tire diameter and profile that the car was designed with. Putting a larger diameter rim and/or a different profile tire does not mean that the same 1/8" toe-in....will be correct...even though it translates to a different angle.
What is not being factored is that the wider the contact patch...the more force is being applied to the contact patch through forward motion...and the more force is also being applied to flexible tolerances in the suspension (like bushings, tie rods, ball joints, tire side walls etc).....and the more the tires want to flex out of alignment toward the toe-out position.
Its also crucial to point out that rim offset changes this equation as well.
Here are the toe-in degree values based on 4 tires sizes with the stock 15" rim and then the 18" rim with the advertized tire size.
Stock 165/75-15.....1/8"=.80*
165/70-15.....1/8"=.59*
195/65-15.....1/8"=.57*
205/60-15.....1/8"=.58*
Stock 15" rim only: 1/8"=.95*
18" rim only: 1/8"=.8"
215/35-18.......1/8"=.6*
That .6* on the 18" rim may seem trivial....but without it, lots of things change. The suspension absorbs damage through tension applied to it by forward motion. The car likes to tramline....and its harder to feel that anything is wrong due to the wide contact patch.
Other qualifiers that help to absorb....and yes...possibly negate....SOME of the need for extra toe-in when going to a larger tire......
(a) very low profile side-walls....give less flexibility. That actually helps and can be some of the reason why extra toe-in may not be needed (this does not negate the need for initial toe-in)
(b) Having very stiff high performance suspension components made of high tech materials like urethane. These can give less flexibility to the suspension...and bolster toe-in from the road.
(c) Subframe braces and strut braces....can actually bolster against toe-in forces from the road.
It may be that with the wide contact patch....you don't need EXTRA toe-in. But you need to have teh minimum for best results.
The tire combo that needs extra toe-in the most.....is actually the 205/60-15. It has a 40mm wider contact patch than the stock tire and only marginally lower sidewall....so it exerts a lot of leverage and has lots of flexability. It typically needs average of one extra degree of toe-in...to make it about 1.5*. No more than two. Ray
What is not being factored is that the wider the contact patch...the more force is being applied to the contact patch through forward motion...and the more force is also being applied to flexible tolerances in the suspension (like bushings, tie rods, ball joints, tire side walls etc).....and the more the tires want to flex out of alignment toward the toe-out position.
Its also crucial to point out that rim offset changes this equation as well.
Here are the toe-in degree values based on 4 tires sizes with the stock 15" rim and then the 18" rim with the advertized tire size.
Stock 165/75-15.....1/8"=.80*
165/70-15.....1/8"=.59*
195/65-15.....1/8"=.57*
205/60-15.....1/8"=.58*
Stock 15" rim only: 1/8"=.95*
18" rim only: 1/8"=.8"
215/35-18.......1/8"=.6*
That .6* on the 18" rim may seem trivial....but without it, lots of things change. The suspension absorbs damage through tension applied to it by forward motion. The car likes to tramline....and its harder to feel that anything is wrong due to the wide contact patch.
Other qualifiers that help to absorb....and yes...possibly negate....SOME of the need for extra toe-in when going to a larger tire......
(a) very low profile side-walls....give less flexibility. That actually helps and can be some of the reason why extra toe-in may not be needed (this does not negate the need for initial toe-in)
(b) Having very stiff high performance suspension components made of high tech materials like urethane. These can give less flexibility to the suspension...and bolster toe-in from the road.
(c) Subframe braces and strut braces....can actually bolster against toe-in forces from the road.
It may be that with the wide contact patch....you don't need EXTRA toe-in. But you need to have teh minimum for best results.
The tire combo that needs extra toe-in the most.....is actually the 205/60-15. It has a 40mm wider contact patch than the stock tire and only marginally lower sidewall....so it exerts a lot of leverage and has lots of flexability. It typically needs average of one extra degree of toe-in...to make it about 1.5*. No more than two. Ray