Xray T4 '13

Old 01-04-2013, 08:16 PM
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Originally Posted by Skiddins View Post
It can't have the same tooth count and pitch etc whilst also being longer, unless the belt is really stretched.
I believe the TOP belt is looser not longer, bad wording. I think it's looser because of a difference in how the teeth are shaped or the depth of the tooth, whatever it is I promise you it is looser on the car and has the same # of teeth, even brand new. I feel that the gear diff is molded differently than the original ball diff, because a ball diff doesn't have the same issues, it's looser, yet the diameter is the same. I've seen this on at least 4 cars, two mine, two from a friend of mine, spanning t3 '11, '12 and a t4.

The difference in the height of the diff when the eccentrics are rotated is very small, the whole point of the diff eccentrics is that they have the notches specifically for tension, not tiny changes in diff height.
Well, you can use diff height as a tuning aid, run the diffs high or low, controlled via the eccentrics. Running the eccentrics nearly all the way back would run the diffs in the "middle", so it must be making some difference. Probably a mm or more in height lost or gained.

Using a belt tensioner to permanently supply all the tension will also add drag to the drivetrain.
Most people I know who use one have it just off the front belt so it stops the belt from resonating, they never use it to set the actual tension.

Skiddins
The way I see it, whether the tension is caused by running eccentrics back to tighten the belt, or by a belt tension, you should have nearly the exact same amount of drag. It's really all about the amount of slack in the belt before it start driving the front diff or spool, how tightly it's wrapped around the spool and lay shaft.
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Old 01-05-2013, 05:53 AM
  #2192  
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Originally Posted by erchn View Post
The way I see it, whether the tension is caused by running eccentrics back to tighten the belt, or by a belt tension, you should have nearly the exact same amount of drag. It's really all about the amount of slack in the belt before it start driving the front diff or spool, how tightly it's wrapped around the spool and lay shaft.
Surely if you add a belt tensioner and have it permanently creating the tension, that's a third point of contact, which although it includes bearings, is still going to add more friction.

But let us know how it goes.

Skiddins
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Old 01-05-2013, 06:21 AM
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As I stated before, as a quick change and see how the car felt, I would use the tensioner to make the belt tight, run a handful of laps, and if I liked the feel, I would adjust the diff. I would not recommend running the tensioner all the time tight against the belt. As Skiddins said, it would be another contact point, and if there is that much pressure on it, it could possibly effect handling in a negative way as the tensioner is mounted to the top deck.
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Old 01-05-2013, 08:54 AM
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I see what ur all saying, the extra friction/drag caused by belt tensioner is minimal miss the apex by a foot and u have the equivalent probably! In regards to power loss again minimal we loose more from having the rear toe uneven one side on the 3 degrees mark the other just on the outside of the mark.

Using the tensioner for belt tension is fine IMHO, but lets be frank the diff height position can u actually feel the difference from diff low to diff middle so to speak? I can feel a very very slight change from diff high to low but it is tiny and against the clock no change.

Not sure if everyone knows but u can have less teeth on a belt and nothing changes, there is just less belt! The internal ratio stays the same.

J
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Old 01-05-2013, 09:42 AM
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Originally Posted by Jampot View Post
I see what ur all saying, the extra friction/drag caused by belt tensioner is minimal miss the apex by a foot and u have the equivalent probably! In regards to power loss again minimal we loose more from having the rear toe uneven one side on the 3 degrees mark the other just on the outside of the mark.

Using the tensioner for belt tension is fine IMHO, but lets be frank the diff height position can u actually feel the difference from diff low to diff middle so to speak? I can feel a very very slight change from diff high to low but it is tiny and against the clock no change.

Not sure if everyone knows but u can have less teeth on a belt and nothing changes, there is just less belt! The internal ratio stays the same.

J

I have found a big difference in the handling of the car by moving the diffs up & down
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Old 01-05-2013, 10:31 AM
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I run my belts as loose as possible without skipping. Both belts are at full loose since the build with new belts. I run the belt tensioner but only to keep the belt from flopping around, not to add tension. The belt does not touch the tensioner at rest. I put a camera on the car and you would not believe how much the belt flops around without the tensioner. Belts are not the most efficient at transferring power, especially when too tight. For you experimenters try running it tight and then loose and see which one gives you lower motor temps.
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Old 01-05-2013, 10:35 AM
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After running my car with new tires I notice that at 1.5* front camber my front tires wear on the inside. running .5 to 1* camber gives me even tire wear. Should I adjust for even tire wear? I know that the rears should wear a little more on the inside but what about the fronts?
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Old 01-05-2013, 10:38 AM
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Just wondering about diff fluid. I have 1,000,000 in the front and want to try 500,000. The trouble is this still is so expensive for how much you use and I hate to buy another 15 dollar jug of so wing I might not like.

Can I add some 700 diff fluid to lighten it up a bit? Is there a formula I could use to get a certain viscosity?
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Old 01-05-2013, 11:42 AM
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Originally Posted by Barry_Hughes View Post
I have found a big difference in the handling of the car by moving the diffs up & down
me too, i saw at least a tenth or 2 of better lap times, and more consistent lap times from 5-10-20 laps when i lowered the diff. when i want more steering, rear diff in the upper, when i want the car to be easier to drive, diff in lower.

Originally Posted by kmags View Post
I run my belts as loose as possible without skipping. Both belts are at full loose since the build with new belts. I run the belt tensioner but only to keep the belt from flopping around, not to add tension. The belt does not touch the tensioner at rest. I put a camera on the car and you would not believe how much the belt flops around without the tensioner. Belts are not the most efficient at transferring power, especially when too tight. For you experimenters try running it tight and then loose and see which one gives you lower motor temps.
yeah i was told run the belts as loose as possible w/ out the belt slipping. i too run the belt tensioner and i too only let it take away the slapping of the belt on the top deck. i hate watching the front belt flopping around.

Originally Posted by kmags View Post
After running my car with new tires I notice that at 1.5* front camber my front tires wear on the inside. running .5 to 1* camber gives me even tire wear. Should I adjust for even tire wear? I know that the rears should wear a little more on the inside but what about the fronts?
what tires are you running? i know when i run Sweeps, you get the ring of death. lately i have ran Jacos, and they seem to wear evenly, and i run 2 degrees of camber.
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Old 01-05-2013, 12:08 PM
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Is there any difference in the 2 designs of rod ends XRay uses? My T4 came with the camber link ends that have the small hole in the top, but the steering links are the open ones. My T3'12 has the open ones thru out the car. Is there any durability difference in the 2?
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Old 01-05-2013, 12:23 PM
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Originally Posted by alloyslash View Post
Is there any difference in the 2 designs of rod ends XRay uses? My T4 came with the camber link ends that have the small hole in the top, but the steering links are the open ones. My T3'12 has the open ones thru out the car. Is there any durability difference in the 2?
The full ballcups with the hole in the top have a larger range of motion, but may have wheel clearance issues depending on how many shims you have over the top of the caster block or rr hubs. They both have their place...
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Old 01-05-2013, 12:29 PM
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Originally Posted by kmags View Post
I run my belts as loose as possible without skipping. Both belts are at full loose since the build with new belts. I run the belt tensioner but only to keep the belt from flopping around, not to add tension. The belt does not touch the tensioner at rest. I put a camera on the car and you would not believe how much the belt flops around without the tensioner. Belts are not the most efficient at transferring power, especially when too tight. For you experimenters try running it tight and then loose and see which one gives you lower motor temps.
I run the rear belt pretty loose, but the front one relatively tight. While it's not as efficient, it definitely makes the car drive better off the corner as it tends to drive the front wheels first, causing the car to pull cleaner (more stable on power) off the corner. In an open motor class that can make a pretty big difference.
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Old 01-05-2013, 01:09 PM
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Originally Posted by alloyslash View Post
Is there any difference in the 2 designs of rod ends XRay uses? My T4 came with the camber link ends that have the small hole in the top, but the steering links are the open ones. My T3'12 has the open ones thru out the car. Is there any durability difference in the 2?
The closed cups with holes are designed to have a ball stud left in them, the holes are so you can unscrew them to add/remove shims. These also have a lower profile so you can add more shims to camber links without fouling on the wheels

The completely open cups with a permanently fitted open ball are so the screw can be changed for a different length item, this is useful where a much larger change of shims might be required, like bump steer etc.

If you mean the closed cups without holes, they will slowly become loose as you cannot get the driver into them

I have NEVER had either pop out in a crash with Xray!

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Old 01-05-2013, 01:19 PM
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[QUOTE=
Can I add some 700 diff fluid to lighten it up a bit? Is there a formula I could use to get a certain viscosity?[/QUOTE]

Yes.

The formula is:
(first viscosity + (second viscosity times x))/(x+1)=ending viscosity

solve for x, that is the ratio of second viscosity to first viscosity.

x=(first visc. + second visc. - ending viscosity)/ ending viscosity.

In your case you need to add 1.0014 ounces/grams of 700 per 1 oz./grams of 1000000 oil.

If you mix it half and half you end of with 500350 weight which is pretty close to what you want.
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Old 01-05-2013, 02:59 PM
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Originally Posted by kmags View Post
Yes.

The formula is:
(first viscosity + (second viscosity times x))/(x+1)=ending viscosity

solve for x, that is the ratio of second viscosity to first viscosity.

x=(first visc. + second visc. - ending viscosity)/ ending viscosity.

In your case you need to add 1.0014 ounces/grams of 700 per 1 oz./grams of 1000000 oil.

If you mix it half and half you end of with 500350 weight which is pretty close to what you want.
This is perfect! Thanks so much!
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