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Team Losi JRXS Type-R

Old 08-21-2009, 10:09 AM
  #10276  
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Order straight from PRS!

http://www.precisionracingsystems.com/

Their Pro Lite series fit right on the layshaft and come in 2 tooth increments.
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Old 08-21-2009, 10:14 AM
  #10277  
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Originally Posted by liljohn1064 View Post
Order straight from PRS!

http://www.precisionracingsystems.com/

Their Pro Lite series fit right on the layshaft and come in 2 tooth increments.
sticking with my supplier, hes been good to me. Thanks thought

Originally Posted by YmeBP View Post
Yes i use the 2 hole ones, but they also have 6 or 8 holes around the outside as well. I just use the 2 holes on the inside.

I use 111 and 115 from this page:

http://www.robinsonracing.com/catalog/64pitchspur.html

Why would you need 6 holes? more rotating mass. Actually I'm sourcing some short titanium screws and short aluminum screws so we can reduce rotating mass even further.

You really only need 2 screws.
just want to make sure those 2 holes align with a shaft. 3 holes keeping spur more flat on the shaft IMO. ture spin object is better than light wobbly object IMO. I dont mean I withness 2 screws makes a spur wobble at all.

just peace of mind thingie.

having lighter screws is good Idea thought, I already put those aluminium screws from PRS spur adaptor on my type- R

I ll go ahead and order the Robinson Derlin spur then

Thanks

Last edited by SweepRacingUSA; 08-21-2009 at 10:28 AM.
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Old 08-21-2009, 11:02 AM
  #10278  
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I currently use the RW's in 48 pitch. They can be brought in 1 tooth increments. This coupled with easy spur changes on the flyingfoxrc shaft makes it quick and easy to change your ratio to excatly what you want fast. I currently use 98-88spurs for 10.5-Mod.

I am going to go crazy and do some big flex modding for this weekends racing. I'll take some pictures and let you know how it all went. Now all I need is to find some time to sleep too!
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Old 08-21-2009, 12:39 PM
  #10279  
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I try to do all I can with my LHS, but I've eaten so many slightly out of round Kimbroughs I don't think about it any more. Robinson's are good though. they are machined and not cast.
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Old 08-21-2009, 02:49 PM
  #10280  
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Originally Posted by liljohn1064 View Post
I try to do all I can with my LHS, but I've eaten so many slightly out of round Kimbroughs I don't think about it any more. Robinson's are good though. they are machined and not cast.

yes the car needs a strong spur gear, I wish I can use a Losi Kevlar gears.

Last edited by SweepRacingUSA; 08-21-2009 at 06:07 PM.
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Old 08-21-2009, 08:47 PM
  #10281  
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Hey guys,

I have just built up a new Type-R with the flying fox layshaft and spool (great products by the way) and am having some major dramas getting the chassis balance right.

I have 4 little digital pocket scales and am measuring the weight on each wheel. With the electronics and Lipo installed and no additional weight, the readings on the mini scales read something like:

Front left: 400g
Front right: 250g
Rear left: 220g
Rear right: 420g

I have tried moving the ESC and receiver around in all sorts of combinations without much effect on the weight distribution. Given that the servo and motor is immovable, there doesn't seem to be too much scope to get the balance right without going way over the 1425g limit.

I know I must be doing something wrong as I believe the balance of the Losi is pretty good. I have the shocks / droop / ride height equal for each side (but different for front and rear) so cannot for the life of me know what's going on. Overall the front/rear balance is generally about even and overall the left - right balance is about even, but the weight seems to be even on opposite corners of the car.

Can anyone help, or is this a general phenomenon with the Losi Type-R? Is anyone able to post a pic of a typical chassis layout that can best balance the chassis?

Thanks in advance,

Steve
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Old 08-21-2009, 09:04 PM
  #10282  
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Originally Posted by stephenianjames View Post
Can anyone help, or is this a general phenomenon with the Losi Type-R? Is anyone able to post a pic of a typical chassis layout that can best balance the chassis?
Thanks in advance,
Steve
Hey Steve, judging from the way you worded the question, it sounds like you simply measured the ride height/droop and thought the corner weighting would be even from side to side. Despite your exacting measurements to set ride height and droop, the final adjustments to the spring perches need to be made on the scales or a tweak station (balance beam style). Even something as untweakable as the Type-R needs final adjustments to be measured this way, IMO.
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Old 08-21-2009, 09:13 PM
  #10283  
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Originally Posted by stephenianjames View Post
Hey guys,

I have just built up a new Type-R with the flying fox layshaft and spool (great products by the way) and am having some major dramas getting the chassis balance right.

I have 4 little digital pocket scales and am measuring the weight on each wheel. With the electronics and Lipo installed and no additional weight, the readings on the mini scales read something like:

Front left: 400g
Front right: 250g
Rear left: 220g
Rear right: 420g

I have tried moving the ESC and receiver around in all sorts of combinations without much effect on the weight distribution. Given that the servo and motor is immovable, there doesn't seem to be too much scope to get the balance right without going way over the 1425g limit.

I know I must be doing something wrong as I believe the balance of the Losi is pretty good. I have the shocks / droop / ride height equal for each side (but different for front and rear) so cannot for the life of me know what's going on. Overall the front/rear balance is generally about even and overall the left - right balance is about even, but the weight seems to be even on opposite corners of the car.

Can anyone help, or is this a general phenomenon with the Losi Type-R? Is anyone able to post a pic of a typical chassis layout that can best balance the chassis?

Thanks in advance,

Steve

Your chassis is tweaked


this is how I straight em.
  1. remove all 4 wheels
  2. Losen all 8 top deck screws, remove Front screw on rear bulk head from the bottom.
  3. while lightly push down FR/RR shock tower, re-tighten all 8 top deck screws and put back bottom rear bulk head screws.
this will do it. to check if chassis is done right do followings
  1. loosen all 4 shock collars, tighten back down exact same amount left to rite.(make a mark on collar help) until collars barley touch the springs.
  2. do same for front and rear.
  3. check on a tweak station or a Scale
  4. Adjust Ride height
  5. re check the tweak. should be same.
hope this help
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Old 08-21-2009, 09:22 PM
  #10284  
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Thanks guys. I'll try and un-tweak the chassis. I didn't realise tweak could have such a massive effect. I confess to not knowing much at all about chassis setup.


Thanks again,

Steve
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Old 08-21-2009, 10:11 PM
  #10285  
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Originally Posted by stephenianjames View Post
Thanks guys. I'll try and un-tweak the chassis. I didn't realise tweak could have such a massive effect. I confess to not knowing much at all about chassis setup.


Thanks again,

Steve
Steve Its also possible that your scales are not accurate. A proper corner weight setup is a very expennsive bit of gear. They must all be the same height as each other to a fraction of a millimeter. Not just the surface you put them on but the scales themselves.

To check the scales are all working try measuring your corner weights then move the scales into different positions untill you have tried each scale under each of your 4 wheels. If you get different results then that proves the scales are not accurate.
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Old 08-21-2009, 10:14 PM
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Originally Posted by da_John_wee View Post
Pablo can you make a center shaft for Losi spurs? more and more ESC's coming with boost timing that will increase RPM that need bigger spur gears.
I have a feeling that once you've run some quality machined spurs from RW or Robinson you will never want to run a molded spur again.
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Old 08-22-2009, 03:32 AM
  #10287  
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Originally Posted by da_John_wee View Post
HPI makes kevlar spur? do you have a part number or link for that? nothing in the Tower
Here is a link from the HPI website:

http://www.hpiracing.com/products/en/6996/

I have used these spur gears extensively in the past, and have always found them very reliable and durable due to the carbon content in them. If you are running softer aluminium pinions (the really cheap stuff), you'll find that the pinion will wear a bit quicker. Most of the 'racing' quality pinions will be ok with it. The spur gear takes a lot of effort to bend it out of shape, and mesh is good. Best thing is that I can now use it with the FlyingFox Layshafts!!!

Most kevlar/carbon spurs spurs from HPI start with the '69' part number. Only in 48dp in kevlar/carbon.

Teeth counts are 75, 78, 81, 84, 87, 90 and 93.


hope this helps someone...
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Old 08-22-2009, 04:52 AM
  #10288  
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Originally Posted by stephenianjames View Post
Hey guys,

I have just built up a new Type-R with the flying fox layshaft and spool (great products by the way) and am having some major dramas getting the chassis balance right.

I have 4 little digital pocket scales and am measuring the weight on each wheel. With the electronics and Lipo installed and no additional weight, the readings on the mini scales read something like:

Front left: 400g
Front right: 250g
Rear left: 220g
Rear right: 420g

I have tried moving the ESC and receiver around in all sorts of combinations without much effect on the weight distribution. Given that the servo and motor is immovable, there doesn't seem to be too much scope to get the balance right without going way over the 1425g limit.

I know I must be doing something wrong as I believe the balance of the Losi is pretty good. I have the shocks / droop / ride height equal for each side (but different for front and rear) so cannot for the life of me know what's going on. Overall the front/rear balance is generally about even and overall the left - right balance is about even, but the weight seems to be even on opposite corners of the car.

Can anyone help, or is this a general phenomenon with the Losi Type-R? Is anyone able to post a pic of a typical chassis layout that can best balance the chassis?

Thanks in advance,

Steve
What you are looking at there is chassis tweak, not weight balance. To do weight balance you check the left/right and front/rear vs each other off the chassis itself, not the suspension. Try this....

*Place all gear on you assembled chassis lightly held in place so it won't move around.
*Use two points or a round object up the center of the chassis (the center is marked with a small hole at each end) to balance on.
*Add weight on either the left or right to get it balancing right.
*Now get out your scales (at least 1kg) and a similar size solid object like a car stand. You will also need two objects to place the chassis on (I use my tools with a flat edge).
*Place the objects on the scales and base and adjust so the tools or what ever you use match the wheel base of your chassis.
*Now zero the scales and place the chassis on both objects making sure the axles are straight over the balance points (tools or whatever). Note the reading.
*Now switch the chassis around and repeat for the other end.
*You now have your front rear ratio so add weight to get it right. You can also move the weight you used for left to right balance forward or aft to help as long as it is the same distance from the center of the chassis.

Generally a balanced chassis is faster than unbalanced and light. The losi seems to like A 52/48% F/R balance.

Also here is a pic of the upper deck I just killed to try out tomorrow. I picked what parts to cut so I could also secure all the wiring neatly. I doubt there would be much in it anyway but the chassis is very flexy now.
Attached Thumbnails Team Losi JRXS Type-R-pic_00091.jpg  
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Old 08-22-2009, 05:27 AM
  #10289  
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Thanks again for the in depth explanations of tweak vs weight balance.

I will follow the advice given and sort the problems out prior to the cars' race debut this Wednesday.

Cheers,

Steve
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Old 08-22-2009, 08:29 AM
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Originally Posted by stephenianjames View Post
Thanks again for the in depth explanations of tweak vs weight balance.

I will follow the advice given and sort the problems out prior to the cars' race debut this Wednesday.

Cheers,

Steve
Just as a personal note. I have tried playing with the scale tweak system on more than one occasion, even for a couple of hours at last years nats while waiting for the rain to stop. Heaps of us all in the A-finals all chucked our chassis on the scales and got all sorts of weird results. Interestingly enough was that the best car on the scales (within 5g on all four corners) was way slower on the track than some of the fast guys inc myself which where over 30g out in some corners. I understand the theory but I have never seen proof that it converts to on track speed. I have always found the best tweak measurement to be lifting the chassis off the ground in the center with correctly set droop. This gives you a car that tracks straight on and off power.

On another topic my chassis is all back together with a cut up upper deck. I think I still need to put the front tray supports back in (cut down of course) to keep the battery still and am also looking at cutting the rear bulkheads up at the front so they clear the deck and don't rub when the chassis flex's. It looks like I have lost a massive 40g off the weight of the chassis though I also removed a bearing that the front belt ran over. It wouldn't take much more work and I could achieve a good f/r balance at a low weight limit like 1425.
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