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TR6 TR6 Alignment Results *DELETED*

piman

Darth Vader
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Re: TR6 Alignment Results

Hello Larry,

caster is the angle between the top and bottom outer pivots on the wishbones, usually the top pivot is behind the bottom so tha a line drawn through the pivots to the ground would touch the ground in front of the tyre contact patch. This gives a self centreing action to the steering. (just think of the inclination of the steering on a bicycle.)
I am not that familiar with the TR6 but there are shims (or provisions for them) between the bottom wishbone and the chassis frame. Adding shims to the rear of the wishbone or removing shims from the front will adjust the caster. Once that is right an equal amount of shims front and back may need to be added or removed to get the camber correct.

Alec
 
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Guest

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Re: TR6 Alignment Results

Alec,
Because a two-wheeled vehicle's (bicycle or motorcycle)front wheel is steered or pointed in the opposite direction of the actual vehicle direction AT SPEED, does a car's steering setup allow for this phenomenon or is this just created by drift?

Bill
 
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SCguy

SCguy

Jedi Warrior
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Re: TR6 Alignment Results

Thanks for the explanation. It's sinking in.

Here's the problem... There are no shims on the front, either side. The passenger rear has six shims and can't fit any more. This is why the alignment tech felt that this was the best he could do. He thought that the car could have been in an accident or that the frame could have fatigued with age and the tops fulcum brackets could have falled in a bit (remember that I had to flip these so that they are already in their most outward position).

So what to do now? Live with it the way it is? Go to a frame shop?
 

bobh

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Re: TR6 Alignment Results

SCGuy,
This link will help explain alignment
https://www.familycar.com/alignment.htm
Another more compact example that will help with the visualization is the front wheels on a shopping cart. They have a noticeable amount of caster.

Bill,
It's been a number of years since I owned a motorcycle. As I recall, the only time, at speed, where the front wheel is pointed at an angle away from the line of travel is during a slide or drift. Flat track racers are a good example. When taking a turn at speed the front wheel is pointed slightly into the turn. I've heard about a technique where the rider approaching a turn will bump the handle bars in the direction away from the turn to start the bikes lean into the turn. I have never tried this. My guess is the reaction to the bump is the steering swinging into the turn which decreases the time required to lean the bike.
Under narmal conditions the front wheel is angled slightly into the turn isn't it? I could be wrong?
 

piman

Darth Vader
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Re: TR6 Alignment Results

Hello Larry,

"(remember that I had to flip these so that they are already in their most outward position)."
I must have missed that, please explain?
I have to assume that all the top and bottom pivot bushes are correctly assembled with no incorrectled placed washers etc that would move the trunnion assembly fore or aft of their correct location. What about the upper fulcrum pins, is there any room for mevement there? Incidentally, Jaguar use shims in the upper trunnion, between the trunnion and the wishbone, to adjust camber. This could be one possible point to look at, but would entail an equal thicknes of shim on the inner piviot of the opposite wishbone to maintain parallelism.
Certainly, it is a good idea to do a frame check, which can be done with just a plumbline on a level surface, as long as you can get the dimensions from a good manual.
Bill, I don't see that the direction of steer matters, it is still a steering input and the caster always tends to return the wheel to straight ahead. (just like a chair caster also.)

Alec
 

tr6lover

Jedi Trainee
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Re: TR6 Alignment Results

you may also like to look at www.goodparts.com which has some adjustable rear brackets for the trailing arms. this way you could get rid of the shims in the back and maybe have more adjustment.
Randy
 
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SCguy

SCguy

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Re: TR6 Alignment Results

Guess I confusing people with my uses of the words "front" and "back".

Specifically I am only referring to the front end of my car and the front or back of the front lower wishbone were shims may be added and "Yes" at this point I'm pretty sure that everything has been installed correctly.
 

Simon TR4a

Jedi Knight
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Re: TR6 Alignment Results

Larry it seems to me that your camber, caster and toe settings are all within spec (and much better than before), so I don't think you need worry.
I assume the SAI is what used to be called KPI, the angle of king pin inclination, or now steering axis inclination, which is not adjustable. so if this is not within the specified range it might indicate prevbious front end damage. The table gives a 2 degree range for this, but it has not been measured, likely because you can't adjust it!

There will be slight changes in some of these measurements as the weight of driver and any passengers or luggage is added, specifically you will get slightly more negative camber (top of the wheels leaning in towards each other), and from suspension movement over uneven road surfaces.
To summarise, everything seems fine.
Simon.
 
G

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Re: TR6 Alignment Results

Bob,
I love this question as you can always win a bet on it. Definately the front wheel is turned IN THE OPPOSITE DIRECTION from the turn. That is a question that gets everyone that takes the Louisiana motorcycle license test. Watch the speed channel when they have bike races. These guys aren't sliding at all, full traction, and the wheel is always turned out. Only when you are rolling the bike or traveling at almost zero speed. It's just physics.

Bill
 
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Re: TR6 Alignment Results

Larry, if it tracks well, steers with control and feels good when you drive it, then all is ok. Just keep the tires inflated to proper pressure.

Bill
 

bobh

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Re: TR6 Alignment Results

Bill,

Before I posted my response I searched Google Images for head on pictures of Superbike racers. The head on shots show the front wheel inline with the centerline of the bike or slightly turned into the turn. Take a look at some of the pictures.
I also discussed this with my brother last night. He still rides a Sportster. He agreed with my observation. He read an article about bumping the handlebars in the opposite direction of the turn to accelerate the set up going into a turn. This was discussed in a bike magazine as a technique to use in an emergency avoidance situation. The article said to practice it before you try it in a real emergency. Poor execution can have catastrophic results.
Back to the point of contention... I agree that the front wheel is pointing away from the turn at the moment the rider begins to lean the bike. However while in the turn it is not. With the exception of slides. Sit on a bicycle or motorcycle without holding the handle bars. Lean to the left. The front wheel will fall to the left. At speed there is a gyroscopic effect from the wheel that opposes the change in direction, however it is not enough to prevent you from making the turn. Lean into the turn and the wheel will follow. Riding with "no hands" is a good example. You can do it on a bicycle or a motor cycle.
If the drivers test is talking about the forces involved, yes the force from the tire is directed into the pavement which is the opposite direction of the turn.
Are they talking the centerline of the wheel? About an imaginary line drawn at the center of the tire from top to bottom as you face the motorcycle head on? With a static bike sitting perpendicular on a level surface this is a vertical line. At speed this line changes with the angle of lean on the bike.
If they are talking about the trailing side of the wheel it is angled away from the turn.
I suspect the dirrerence in opinion is due to us looking at the same thing from a different perspective.
Any chance you can send the exact question as asked on the exam? I'd like to read it and their answer. It's no too hard to imagine a Physics professor producing an answer that is the opposite of how someone more practicle would answer the question. Keep in mind, in pure physics positive rotation is counter clockwise. In my mind CCW is negative. I base this on the tightening of most fasteners and the sweep of the hande on a clock. Tighten is positive, loosen is negative. My physics professor and I had quite a few discussions about a number of his ideas.
 
G

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Re: TR6 Alignment Results

So that's why I kept wrecking when I ran Motos in the 70s.

Still think there is a certain outward tilt of the front wheel at speed.

Bill
 

machinemd

Jedi Hopeful
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Re: TR6 Alignment Results

The "bump" of the handlebars is called counter steering. When that deer or dog dashes out in front of you, counter steering will get you aimed in the direction of avoidance a heck of a lot quicker than leaning. At the speeds these kids, and this old guy, drive todays crotch rockets it's a needed skill. And just like everything else, you gotta practice it in an empty lot first to know its capabilities and limits so you can do it with confidence when needed. After all, with a bike you have even less protection than our LBCs offer.
 

bobh

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Re: TR6 Alignment Results

Machine,
Thanks, I couldn't remember the name.

Bill,
Crashed a couple of times myself. Now I stick with 4 wheels.
 

Adrio

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Re: TR6 Alignment Results

[ QUOTE ]
The "bump" of the handlebars is called counter steering. ... counter steering will get you aimed in the direction of avoidance a heck of a lot quicker than leaning

[/ QUOTE ]

I agree with counter steer being the name and that it gets you there quicker. I do not agree with the previous posting when it compares the physics prove and the "practical". With all due respect the prof trumps the "practical" every time. But I digress. Back to the counter steer. I think the issue with the counter steer (and it has been 20 years since I did any of this physics or the math involved so forgive me if I am off a bit) is that a gyroscope reacts at 90 degrees to the force applied to it. For th "practical" person this can be demonstrated buy taking a large bicycle wheel and holding it by the axle in your two hands (so the axle is horizontal in front of you and you are looking into the dege of the wheel). Now give that wheel a good hard spin (so that it is spinning on the axle real fast). At this point you have a wheel spinning with a horizontal axis (paralell to your shoulders) and the wheel disk pependicular to your shoulders. Now try to move your hands so that the axle of the wheel remians horizontal but is rotated by 45 degrees (as if you want to turn the wheel to your left (or right) but keeping the wheel vertical. guess what happens. The wheel (gyroscope) tilts (unless you are the governor of California and have the strenth of 10 men). The reason for this is the reaction of the gyro at 90 degrees to the force applied. The other thing you will notice is how much more effort it takes to resist this 90 degree motion then it did to apply the "turn". The reason for this is the inertia in the gyroscope. I think the reason counter steer gets you into a turn faster is that it exploits the physics of the gyroscope that is your front wheel to get you into the lean faster. I love this sort of discussion, keep it alive.
 

machinemd

Jedi Hopeful
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Re: TR6 Alignment Results:Adrio

Adrio,
I don't know boo of the physics/gyroscope theory, I only know from 30+ years of 2 wheeling that it works. As it was explained in the mag Motorcycle Consumer News, basically if you want to turn left, normally you lean left which gradually puts you more on the sidewall of the tire and you turn. But for a quick avoidance move bumping the bars momentarily to the right immediately puts the tire onto the left sidewall resulting in a much quicker turn. There are several deer and coons in the White Mountains of New Hampshire that are grateful that it works....me too! In the end, at 50 y/o I decided to no longer challenge the laws of physics....or common sense and commit fully to the comfort? and safety? of my Spitfire and TR6 over my BMW K75, but I miss it dearly.
Steve
 

MDCanaday

Jedi Knight
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Re: TR6 Alignment Results

Larry , I guess you got your front end issues taken care of OK, but on a 6 the rear suspension alignment is SUPER critical. Just getting the front end aligned can be like putting a bandaid on burst artery, they should both be done at the same time !!! Camber toe and thrust problems in the rear can make a nice car drive nasty.
MD(mad dog)
 
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