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  #16  
Old 04-11-2007, 06:23 PM
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Thanks

Quote:
Originally Posted by Trevor
The transmission distributes the available unaltered engine power/torque regardless of wheel size. The wheel size in affect fixes, sets or alters, the absolute final drive ratio, with no alteration in respect of the forces transmitted via the transmission.

The only aspect for consideration is a possible change in the ratios selected for a particular duty or circumstance. This aspect would involve marginal tolerances, which are beyond consideration. What is more there is also the operation of the torque converter to consider, as this "smoothes" the application of power in all gears.

It can not be truly conceived that larger diameter tyres (within reason that is), will be "harder" on the transmission. In point of fact on a long run, the wear factor will be reduced as a result of a taller effective overall ratio.
Thanks for the response. While I could not explain it or even begin to figure it out, I suspected such might be the case.

Lee
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  #17  
Old 04-11-2007, 09:33 PM
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Quote:
Originally Posted by Trevor
The transmission distributes the available unaltered engine power/torque regardless of wheel size. The wheel size in affect fixes, sets or alters, the absolute final drive ratio, with no alteration in respect of the forces transmitted via the transmission.

The only aspect for consideration is a possible change in the ratios selected for a particular duty or circumstance. This aspect would involve marginal tolerances, which are beyond consideration. What is more there is also the operation of the torque converter to consider, as this "smoothes" the application of power in all gears.

It can not be truly conceived that larger diameter tyres (within reason that is), will be "harder" on the transmission. In point of fact on a long run, the wear factor will be reduced as a result of a taller effective overall ratio.
In 1996 I ordered four tires for my XT6 from my tire guy.
Instead of the 205-60-14s that I ordered, he sent me four 205-70-14s.
I needed tires.
I thought, what the heck, it's only 1.61" taller, only 6.8% greater diameter, what could happen???
The next day my 74,000 mile well serviced XT6 lunched the trans.(4EAT w/3.70 ratio)
If we did not have a history of smoked transmissions I would not worry about it.
But....
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Last edited by svxfiles; 04-12-2007 at 07:43 AM.
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  #18  
Old 04-11-2007, 11:04 PM
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Trevor, a larger tire acts much like a smaller gear on a bycicle. It gets harder to turn the smaller the rear gear gets. So, the wheel will get harder to turn as the wheel diameter gets larger... While the difference of an inch is not very significant in diameter, it is still an adverse effect on an already finicky slush box. It is advised not to make it go any quicker

Tom
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  #19  
Old 04-12-2007, 02:42 AM
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Quote:
Originally Posted by TomsSVX
Trevor, a larger tire acts much like a smaller gear on a bycicle. It gets harder to turn the smaller the rear gear gets. So, the wheel will get harder to turn as the wheel diameter gets larger... While the difference of an inch is not very significant in diameter, it is still an adverse effect on an already finicky slush box. It is advised not to make it go any quicker

Tom
Tom,

It is good to be involved in a subject with one of your intelligence. I agree with the basis of what you suggest and which aligns with my point regarding “wear factor”.

When it comes to the understanding of that involved, the geared bicycle is a very good model. Cycle racing was once my sport and I know all the affects involved first hand.

The applicable post and question was :- It's only 0.11" taller than stock.
A 225-50-17 would be 1 full inch taller and HARDER on your transmission!

We therefore are called upon to interpret “harder” as I tried to do. I applied the words towards including in the main torque stress, rather than just wear, as you have done. With caution I stated,”It can not be truly conceived that larger diameter tyres (within reason that is), will be "harder" on the transmission. In point of fact on a long run, the wear factor will be reduced as a result of a taller effective overall ratio.”

Does a cyclist work harder pushing a high gear or a low gear in delivering the power necessary to travel a set distance at an equal time? I used muscle and torque, others revs and stamina. I tended to bend cranks, others wear out chains. Which was “harder” on the transmission? I never did work out which was best for the man.

I made the point that “The only aspect for consideration is a possible change in the ratios selected for a particular duty or circumstance” and tried to cover all points of view. What is important is that we have both indicated that any event issue is minor and the driver/rider is the deciding factor, with his foot/feet on the peddles.

Others may be bored, but a good discussion. I hope no one is silly enough to imagine controversy.

Cheers, Trevor.
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  #20  
Old 04-12-2007, 06:27 AM
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Quote:
Originally Posted by SVXRide
Always thinking, my friend

I talked with Paul alot this morning when he dropped the 'reX off and he noted that the suspension might be too stiff. I might just be swapping suspension assemblies around between cars

Paul also mentioned that he strongly believed that the car would get into the 12s. He felt that he was traction-limited, thus only able to do 4 wheel burn outs

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  #21  
Old 04-12-2007, 07:17 AM
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Quote:
Originally Posted by Trevor
Tom,

It is good to be involved in a subject with one of your intelligence. I agree with the basis of what you suggest and which aligns with my point regarding “wear factor”.

When it comes to the understanding of that involved, the geared bicycle is a very good model. Cycle racing was once my sport and I know all the affects involved first hand.

The applicable post and question was :- It's only 0.11" taller than stock.
A 225-50-17 would be 1 full inch taller and HARDER on your transmission!

We therefore are called upon to interpret “harder” as I tried to do. I applied the words towards including in the main torque stress, rather than just wear, as you have done. With caution I stated,”It can not be truly conceived that larger diameter tyres (within reason that is), will be "harder" on the transmission. In point of fact on a long run, the wear factor will be reduced as a result of a taller effective overall ratio.”

Does a cyclist work harder pushing a high gear or a low gear in delivering the power necessary to travel a set distance at an equal time? I used muscle and torque, others revs and stamina. I tended to bend cranks, others wear out chains. Which was “harder” on the transmission? I never did work out which was best for the man.

I made the point that “The only aspect for consideration is a possible change in the ratios selected for a particular duty or circumstance” and tried to cover all points of view. What is important is that we have both indicated that any event issue is minor and the driver/rider is the deciding factor, with his foot/feet on the peddles.

Others may be bored, but a good discussion. I hope no one is silly enough to imagine controversy.

Cheers, Trevor.
You are right... I did not pay attention the the language you were using and thus lost the fact that you were merely trying find a definition for "harder". Take care Trevor

Tom
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  #22  
Old 04-12-2007, 07:43 AM
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One More Step

Now lets take this discussion one more step. I would like the issue of different wheels and tires discussed. Assume for discussion sake that the total diameter of wheel and tire remain the same. Say a stock rim and tire weigh a total of 45 lbs. If aftermarket rims and tires of say 18 inches were put on the car weighing a total of 56 lbs, is there any additional wear OR strain on the transmission? (Of course the 18 inch figure is irrelevant since total diameter is assumed equal.)

Lee
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  #23  
Old 04-12-2007, 07:47 AM
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Quote:
Originally Posted by lhopp77
Now lets take this discussion one more step. I would like the issue of different wheels and tires discussed. Assume for discussion sake that the total diameter of wheel and tire remain the same. Say a stock rim and tire weigh a total of 45 lbs. If aftermarket rims and tires of say 18 inches were put on the car weighing a total of 56 lbs, is there any additional wear OR strain on the transmission? (Of course the 18 inch figure is irrelevant since total diameter is assumed equal.)

Lee
Yes.
From post #13.
The tire and wheel weight also comes into play.
The less rotational mass the quicker accelerating and decelerating.
If you went from stock wheels and tires that weighed about 40#s, up to the same diameter heavy wheel and tire like some Lexus or Mustang wheels out there that weighed say 48#s, you would feel the differance on your first drive.
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  #24  
Old 04-12-2007, 12:53 PM
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Understand

Quote:
Originally Posted by svxfiles
Yes.
From post #13.
The tire and wheel weight also comes into play.
The less rotational mass the quicker accelerating and decelerating.
If you went from stock wheels and tires that weighed about 40#s, up to the same diameter heavy wheel and tire like some Lexus or Mustang wheels out there that weighed say 48#s, you would feel the differance on your first drive.
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I did take quite a bit of physics so do understand the role rotational mass would play, but the question is does it place a strain or significantly increase wear in the tranny.

I guess my over all point is that this discussion started with tires that were larger in overall diameter being a significant factor and I have moved it on to different weight wheel/tire mods.

Are wheel/tire mods of heavier weight increasing our tranny failure rates? Or is all of this so insignificant in relationship to our tranny wear that is is not worthy of further discussion?

Lee
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  #25  
Old 04-12-2007, 05:53 PM
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Quote:
Originally Posted by lhopp77
I did take quite a bit of physics so do understand the role rotational mass would play, but the question is does it place a strain or significantly increase wear in the tranny.

I guess my over all point is that this discussion started with tires that were larger in overall diameter being a significant factor and I have moved it on to different weight wheel/tire mods.

Are wheel/tire mods of heavier weight increasing our tranny failure rates? Or is all of this so insignificant in relationship to our tranny wear that is is not worthy of further discussion?

Lee
The rotational weight of the wheel/tyre in absolute theory, can be brought into the argument, but so can tyre rolling resistance and rim width affecting this; variations in offset affecting turning radius; spoke pattern affecting possible vibration.

I think that I covered the most pertinent points and even these are trivial.
It is my opinion that the the last last query presented above calls for a resounding, YES.
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  #26  
Old 04-12-2007, 06:02 PM
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Gotcha

Read the YES loud and clear.

Lee
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  #27  
Old 04-12-2007, 07:55 PM
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[QUOTE=Trevor]Does a cyclist work harder pushing a high gear or a low gear in delivering the power necessary to travel a set distance at an equal time? I used muscle and torque, others revs and stamina. I tended to bend cranks, others wear out chains. Which was “harder” on the transmission? I never did work out which was best for the man.

QUOTE]

I know relatively nothing about transmissions, however I can comment on the cyling question - and I'm surprised this question is difficult for you Trevor.
The higher "cadence" you are able to maintain, the less energy you will use over a set distance. Novice cyclists don't understand this, they want to get up on the big gears because it doesn't take as many revolutions of the crank - yet it's a much harder "push" and it ends up wearing them out. Meanwhile the more experienced cyclists passes them by, turning at much higher crank rpms but expending much less energy.

Perhaps this is analogous to the tranny question
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  #28  
Old 04-12-2007, 09:26 PM
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Well said Jerry.

The differance between getting up to speed and mantaining speed is easy to understand.
Take your 3580# SVX, and start pushing it on smooth level ground.
Once its moving you can run with it with relative ease, but getting started generates more heat, sweat, and colorful language.
The wear in transmissions comes from starting out, not light throttle cruising.
Taller tires make it harder to get the car up to speed.














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  #29  
Old 04-12-2007, 11:17 PM
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[QUOTE=svxxx26]
Quote:
Originally Posted by Trevor
Does a cyclist work harder pushing a high gear or a low gear in delivering the power necessary to travel a set distance at an equal time? I used muscle and torque, others revs and stamina. I tended to bend cranks, others wear out chains. Which was “harder” on the transmission? I never did work out which was best for the man.

QUOTE]

I know relatively nothing about transmissions, however I can comment on the cyling question - and I'm surprised this question is difficult for you Trevor.
The higher "cadence" you are able to maintain, the less energy you will use over a set distance. Novice cyclists don't understand this, they want to get up on the big gears because it doesn't take as many revolutions of the crank - yet it's a much harder "push" and it ends up wearing them out. Meanwhile the more experienced cyclists passes them by, turning at much higher crank rpms but expending much less energy.

Perhaps this is analogous to the tranny question
Jerry, the theory is rather simplistic. Those who derived the theory knew nothing about transmissions. A definitive rule can not be applied to all riders. Gearing can be used to average out physical attributes/deficiencies, such is science. Experienced cyclists do take this into account.

In respect of a bicycle, gear ratios, crank length and seat position can be and are adjusted to suit individual Physique. Mechanical aspects must be take into account in any end result.

I was above average hight, strong in the legs, but short on lung capacity. A higher than average gear and longer than standard cranks, worked to my advantage. Peddlers did not pass me in a sprint finish. Before you raise the issue, less turns per mile also suited my body better over a distance.
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  #30  
Old 04-12-2007, 11:33 PM
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Quote:
Originally Posted by svxfiles
Well said Jerry.

The differance between getting up to speed and mantaining speed is easy to understand.
Take your 3580# SVX, and start pushing it on smooth level ground.
Once its moving you can run with it with relative ease, but getting started generates more heat, sweat, and colorful language.
The wear in transmissions comes from starting out, not light throttle cruising.
Taller tires make it harder to get the car up to speed.
What is stated could be very well be applied to the torque converter as a separate item.

However overall, wear is the issue over a distance travelled, and load on the transmission (torque) is the issue at start up.
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