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Old 08-16-2007, 10:07 PM   #19111
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Originally Posted by Tek Nickal View Post
So you have to apply grease between where the diff plate sits onto the outdrive?
Yes, it's very important. The diff lube (provided it's a good type) will provide bite and keep it the rings from spinning.
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Old 08-17-2007, 12:11 AM   #19112
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Yes, it's very important. The diff lube (provided it's a good type) will provide bite and keep it the rings from spinning.
I didn`t know that also

Thanks to share that with us
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Old 08-17-2007, 02:25 AM   #19113
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Yes, it's very important. The diff lube (provided it's a good type) will provide bite and keep it the rings from spinning.
So then... Schuey lube for the ring to outdrive (grips more), and AE for the balls? or are you better off just using the same lube throughout, to avoid contamination....

My parts for the mod are on the way, I'll be intrigued as too how much difference it will make. Since I've used ceramic balls and the sanded rings, I've had very smooth diffs (then again, the TRF's are good anyway ).

I'll be building the 16ball with ceramics and JAAD racing blue alloy diff halves (leaves the option of using the old diff if needed)... here's hoping I won't have to touch it anytime soon!

Regards
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Old 08-17-2007, 02:56 AM   #19114
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Now it`s time to go again. We have race weekend and tonight is free training session and tomorrow race day. I`ll test that new diff and 18t pulley in my MRE, so we`ll see how it goes

Hopefully the weather is mercy in this time

See you guys later...
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Old 08-17-2007, 04:28 AM   #19115
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Yeah, I was just kicking it to make sure it was dead.


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That and it was kinda funny to see you contradicting yourself.
Actually contradiction is a part of engineering It is something in the lines of "if you want more traction on the front then lower the traction on the rear" kind of deal

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Anyway for others that might like a good explanation
Sounds like I need more kicking to do

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There are so many things that affect the efficiency of our touring cars drive train. Here are just the key ones:

Required Preload (to handle drive train load)
Pulley diameters (belt wrap & tooth count)
Tooth profile (mesh and un-mesh of the teeth)
Material (Aramid or glass fiber and Rubber compounds)
Tooth profile although and important aspect of syncronous drives but for touring cars it is more like a constant as most companies (I say most because there maybe some that dont) use round profiled tooth belts.


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The required preload of a drive train probably has the most affect on the drive train efficiency if all else is equal.
Well, yeeees , but if all else is equal then a faulty bearing would have the most affect on the drive train efficiency if all else is equal. so this is irrelevant...

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For high load situations such as modified or off-road, you of course need more preload to avoid the belt from climbing/jumping teeth.
Agreed.... OOOOh my god... we agreed on something....

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Lower load conditions like stock, you can run much less preload.
well not sure about this one.... yes I agree that I lower the preload on stock a little but not too much. as my stock motors pump out quite alot of low end torque I always need a fair amount of preload even for stock.

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So yes, tension/pressure in general does increase resistance/drag.
actually "in general" part is not necessary. more tension or pressure more resistance or drag...



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However going from a 16 tooth center pulley to an 18 tooth (adding 2 teeth) is not adding more tension or pressure unless you increase preload.
Exactly because we are not going from 16 to 18 to increase preload. you have a preload adjuster for that.

The main reason we are swithcing from 16 to 18 is first of all changing the IR so we can change the FDR.

Second is more physical reason. As you mentioned earlier materials play a great role in the belts efficiency and its minimum turning radius or wrap. So by increasing the pulley you increase wrap or the truning radius of the belt .


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In fact, this is one of the primary reasons why itís LESS friction/pressure/drag because with the 18 tooth pulley, you can run less preload and maintain the same amount of load capability as the 16 tooth pulley had.
For different materials you will have different radiuses. So going to a 18T pulley you affectively increasing the turning radius of the belt in return this reduces the internal resitances to excess bending forces. This is the only friction you reduce by going to a larger pulley.

the 18T pulley has more loading capacity by default as it has 1 more teeth to come in contact with the belt wrap. hence if the applied force is the same, the distributed force over the pulley force side is divided in to 9 parts versus 8. now this is for the if force is the same. and it will not be as the IR is changed so the gear ratio will to comapnsate. there fore the forces will change...


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Or you can maintain the same preload and increase your load capability. Either way, you get an increase. Think of it like stage diving. You donít want to stage dive into a crowd of only a couple people. The more people you have to catch you, the less force is applied to each person. This is actually a similar reason the TRF guys make the modifications to the diffs. More on that later.
you see you are mixing the force distributed vs what we are saying increased surface drag due to larger pulley. With the current motors you definately need the bigger pulleys.

reason 1: you need the extra teeth so you gane transfer power more reliably
reason 2: larger pulley you can fit more balls to reduce the pressure load on teh balls themselves.
reason 3: the driver can live with the increase surface friction of the larger pulley when compared to the durability of the system.


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The increase in pulley diameter also reduces the amount of bending the belt must do so this further reduces friction.
Yes yes I said that as well earliear and before and the horse wasnt even born yet at that time.


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The tooth profile doesnít really benefit much from pulley size but it was on the list because it has to do with general drive train efficiency do to the meshing and un-meshing.
Yes the older trapezoidal teeth were less efficient. and the round teeth pulleys are easier to manufacture


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The material is very important because of the flexing the belt must do. Aramid fiber (aka Kevlar) is a great material but it has good and bad tendencies. It is stronger than glass fiber and heat resistant but it can expand slightly depending on humidity. Glass fiber is not as strong but is very stable. Then there is the rubber compound, softer compound will have less resistance to flex compared to harder compounds. How important is this? Itís why Tamiya Low Friction option belts are low friction, because of the fiber material and softer belt compound. Itís not because it has less surface area (they are all the same width). The softer rubber compounds of course donít last as long and break down much quicker. The also are a little less efficient at high speed because they begin to flutter more.
Yeap, the belt material affects the belt wrap radius, which in returnd determines the minmum suggested pulley size.

so harder and/or stronger the material the larger your pullys have to be. you can lower numbers but you have a life penalty on the belt.

thats why on my fist post I said we need tensioners on the chassis. to reduce flutter

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Back to the TRF diff mod, using the 501 diff rings and the outer diff holes puts the diff balls in a better position of leverage over the load they must sustain. This allows a big reduction in diff tension in itself for the same holding force as it would compared to stock. So, less tension, less wear. Adding more diff balls is similar to adding more teeth to the center pulley. The additional balls distribute/share the load which further allow less diff tension for the same holding force (like stage diving). This is why your diff will last much longer and stay more consistent with this diff set-up. Again, this is also why going from a 16 tooth center pulley to an 18 tooth will do one of two things, REDUCE friction/increase efficiency (less preload requirement) or increase load capability if you maintain the same preload.
by adding more balls to the diff you reduce the pressure on the balls. if the force applied is 1 newtons/mm2, with 8 balls you have 1/8 newtons perball vs with 16 youhave 1/16... so less force applied to the poor diff balls the more they can happily turn...

I am sure we will start seeing direct rear drives or gear diffs soon...
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Old 08-17-2007, 09:09 AM   #19116
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So then... Schuey lube for the ring to outdrive (grips more), and AE for the balls? or are you better off just using the same lube throughout, to avoid contamination....

My parts for the mod are on the way, I'll be intrigued as too how much difference it will make. Since I've used ceramic balls and the sanded rings, I've had very smooth diffs (then again, the TRF's are good anyway ).

I'll be building the 16ball with ceramics and JAAD racing blue alloy diff halves (leaves the option of using the old diff if needed)... here's hoping I won't have to touch it anytime soon!

Regards
Ed
No, I just use one type for rings and balls. The two brands were just my personal choices, sorry for the confusion. I think the Schumi lube is probably the best right now though.

You're going to love the 16 ball diff. If I run mod, I'm lucky to get 5 runs out of my standard diff with carbide balls. The 16 ball diff can go at least 3-4 times longer for me.

Last edited by jinsc; 08-17-2007 at 09:33 AM.
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Old 08-17-2007, 09:18 AM   #19117
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Actually contradiction is a part of engineering It is something in the lines of "if you want more traction on the front then lower the traction on the rear" kind of deal
Uh...no it's not. Contradiction is not part of engineering (well at least good engineering). However, compromise is.

BTW, if I'm lacking traction in the front.......I'll increase traction in the front instead of removing rear traction. I think your way of thinking is......uh...unique.
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Old 08-17-2007, 05:31 PM   #19118
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guys, would the trf415 msxx lower deck set for stick type battery in the attached picture fit the mre? will this chassis be able to accept side-by-side packs, stick type battery, lipo 3200's and lipo 4800's?
anyone
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Old 08-17-2007, 05:59 PM   #19119
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anyone
Can't see why it shouldn't mate.
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Old 08-17-2007, 08:23 PM   #19120
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anyone
If that's the 49378 option part, Orion/Peak 3200's won't fit between the battery posts. However, using the stick pack upper deck and bulkhead with the stock chassis works well. Assuming you can get it to balance.
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Old 08-18-2007, 09:39 AM   #19121
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Uh...no it's not. Contradiction is not part of engineering (well at least good engineering). However, compromise is.

BTW, if I'm lacking traction in the front.......I'll increase traction in the front instead of removing rear traction. I think your way of thinking is......uh...unique.

Everyone has their own way of doing things...


Uniqueness differs us form the rest... If we are not unique then we are just common.....
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Old 08-18-2007, 07:20 PM   #19122
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If that's the 49378 option part, Orion/Peak 3200's won't fit between the battery posts. However, using the stick pack upper deck and bulkhead with the stock chassis works well. Assuming you can get it to balance.
it's the Tamiya (#49436) - Tamiya TRF415 MSXX Lower Deck for Stick Battery

With this conversion set, stick-type 7.2V battery packs can be installed in the previously released high-performance 2-belt 4WD TRF415MSXX chassis. Set includes 2.5mm carbon fiber lower deck, 2mm carbon fiber upper deck, and carbon fiber battery plate. Specially redesigned lightweight blue anodized aluminum rear bulkhead, rear upper brace, and center post are also included.
*Compatible Chassis: TRF415MSXX



looking at the chassis, looks like it's designed for 4-cell, 6-cell, stick type battery. will the 4800's lipo fit? the bulkhead has been redesigned so that the 6-cells and stick type won't be under the old bulkhead design.

what do you guys think?
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Old 08-18-2007, 09:39 PM   #19123
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I am sure we will start seeing direct rear drives or gear diffs soon...
I am surprised we dont have at least 1 manufacturer running sealed gear diffs yet. It made a huge difference in onroad nitro. and weigh is unlikely the issue, a compact gear diff could be created.
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Old 08-19-2007, 12:07 AM   #19124
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I am surprised we dont have at least 1 manufacturer running sealed gear diffs yet. It made a huge difference in onroad nitro. and weigh is unlikely the issue, a compact gear diff could be created.
Corally used to have sealed balldiffs on the Assassin.
Weight WAS a big disadvantage then!
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Old 08-19-2007, 01:51 AM   #19125
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Corally used to have sealed balldiffs on the Assassin.
Weight WAS a big disadvantage then!
we have sealed ball diffs now, we just use tape though. so it is light now. a light weight gear diff might be a good option to test. It will deifnately be heavier due to all the metal inside but worth a try...

1/10 gas cars used to have ball diffs... they are all running gear diffs now.

but weight penatlty as u said would be a problem...

but I can see a future in direct rear and oneway fronts
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