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Old 11-02-2014, 05:12 PM   #5761
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Have you tried to take away steering instead of trying to gain rear traction ? You may be maxed out on rear traction. I've had to do this on some cars and it worked wounders.
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Old 11-02-2014, 09:09 PM   #5762
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That is one thing I've always disagreed with in terms of the commonly accepted set-up for rear diff fluid. Thinner rear diff fluid allows the outside wheel to spin faster than the inside wheel and when you drive hard, you tend to diff out the entire rear end and it rotates too fast thus making the rear end step out suddenly. To me this is less traction. Thicker rear fluid will slow the outside wheel down with respect to the inside wheel and keep the rear end from rotating as fast as thinner fluid and to me that is more traction. Thinner rear diff fluid allows the rear of the car to rotate through the turn off power but the downside is that on power you tend to spin the rear out. Thicker rear diff fluid makes the rear end lazy through a turn off power, but on power it feels like you can control how much rotation you get by a little more or less throttle pull. I like to drive a car through a turn so for me, more traction is thicker rear diff fluid.

Read this: http://jq-products.com/the-news/43-t.../160-the-guide -- The section on the effect of rear diff fluid is the best explanation I've found to date.

I disagree.. Thicker rear fluid is like having a rear locker on your car.

The outside or inside to needs spin faster freely, or it HAS to break lose. One wheel must travel a different distance while turning, inside or outside.

Thinner rear fluid will help the two rear tires spin at different speeds without breaking lose.
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Old 11-02-2014, 10:16 PM   #5763
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I disagree.. Thicker rear fluid is like having a rear locker on your car.

The outside or inside to needs spin faster freely, or it HAS to break lose. One wheel must travel a different distance while turning, inside or outside.

Thinner rear fluid will help the two rear tires spin at different speeds without breaking lose.
Agree and disagree

Thinner rear fluid will help the rear tyres spin at different speeds, but what will happen when grip moves out of the circle is that the tyre with least traction (usually the inside) will unload and the diff will spin that wheel and traction will be reduced to the tyre that used to have more traction; overall losing rear end traction.

You can run a more loose diff in high grip situations because the point at which the lesser loaded tyre unloads is much higher.
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Old 11-03-2014, 05:26 AM   #5764
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Is anyone using 12mm hubs if so which ones are you using.
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Old 11-03-2014, 05:30 AM   #5765
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Is anyone using 12mm hubs if so which ones are you using.
Just last evening I put on the JConcepts 12mm front and rear hexes. They fit very well. I was hoping to be able to leverage my B5M wheels on the XB4. However, the offset between the XB4 vs. AE wheels is as huge difference . Using AE front 12mm hex wheels, I think my front track width increased by close to 5mm per side. And in the rear I think I increased the width by 3mm per side.
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Old 11-03-2014, 05:34 AM   #5766
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I know Exotek makes a few different ones as well
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Old 11-03-2014, 05:36 AM   #5767
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Originally Posted by Landscaper View Post
Is anyone using 12mm hubs if so which ones are you using.
Exotek has nice ones. 7mm and 9mm width for the rear and 5mm width for the front:

http://www.exotekracing.com/xb4-12mm...ar-2-9mm-wide/
http://www.exotekracing.com/xb4-12mm...ar-2-7mm-wide/
http://www.exotekracing.com/xb4-12mm...nt-2-5mm-wide/
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Old 11-03-2014, 12:53 PM   #5768
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I use the exotek hexes, and like them just fine. As for the JQ guide, I think that much of what is said is accurate, but there is one key concept that is being missed. I have approached this many times over the years, and I find it holds true in nearly every situation. The concept is one of "bell curves" as they relate to setup. Any given peramiter on a car operates on a curve of some type. There will be an optimal setting for a given adjustment as it relates to all the other adjustments on a car as they work in unison. Any deviation from that optimal point will give less than desirable results. Lets take springs for example. Lets say a given car, setup, track, yield optimum side bite with a 2lb rear spring. IF you go stiffer, the car will produce less traction because it is not transfering enough weight to optimise the tires or camber positions used. If you go to a lighter spring, the chassis will roll too much, and not optimise the tires or camber positions used. Either way, the net result is a decrease in overall traction. So, most of opinions expressed here are in fact right as they are expressed sighting emperical data. It is the point of refernce that differs, e.g. where on that curve that you are starting from. One really cannot have a blanket statement saying "this does this", as it never takes into account a direction to look from. -J
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Old 11-05-2014, 10:18 PM   #5769
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I just finished my XB4 Shorty conversion, I cant wait to try this over next week down in So Cal area.

I also went with the graphite chassis from Amazon.

Any setup ideas that will work on clay with this conversion?


Attached Thumbnails
Xray XB4 thread-img_20141102_103007239.jpg   Xray XB4 thread-img_20141105_205240356.jpg   Xray XB4 thread-img_20141105_205429461_hdr%5B1%5D.jpg  
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Old 11-06-2014, 05:59 AM   #5770
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Looks Good!!
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Old 11-06-2014, 04:12 PM   #5771
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Originally Posted by Wease View Post
I started out with the kit set-up since we run on such high traction, but made the following changes:

1. Took the transmission plate chassis spacer out from under the rear transmission - little to no difference. I still have this plate removed.

2. Lengthened the rear camber link - little to no different.

3. Shortest rear camber link possible - while the rear of the car was still loose, it was much more controllable with the shortest link.

4. Removed all the optional screws from the rear of the chassis - little to no different. Left all the screws out

5. Loosened the center slipper to the max distance recommend at about 6mm. This made the rear end slightly less loose, but still too loose.

6. Went to only .5mm of anti squat and max rear toe - helped a little, but nothing dramatic. I'm still running .5mm of anti squat and max toe.

7. Went down from 10K in the front diff to 7k - little to no difference. Still running 7K in the front.

7. Went up in the rear diff from 5k to 7k - biggest improvement so far. The rear is better, but still not as planted as my 2013 car was on this same track with the same tires. Got desperate and went from 7k in the rear to 10K just to see what would happen - but I actually didn't notice any more change.

8. Went to 3 dot front spring and sway bar which is stiffer than stock - little to no difference.

I'm still running the kit set-up for shock pistons and oils.

The rear is o.k. on long progressive turns, but in quick 180 degree turns or chicanes where I'm trying to make quick direction changes, or trying to pitch the car in to the turn - the rear is just too loose. Or should I say, the front is just stuck to the track and the rear wants to skip about 45 degrees in one direction or the other. It won't spin out completely, but it loses enough traction to point the front end in the wrong place.
Your slipper is still too tight.
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Old 11-06-2014, 04:18 PM   #5772
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Quote:
Originally Posted by Wease View Post
Just last evening I put on the JConcepts 12mm front and rear hexes. They fit very well. I was hoping to be able to leverage my B5M wheels on the XB4. However, the offset between the XB4 vs. AE wheels is as huge difference . Using AE front 12mm hex wheels, I think my front track width increased by close to 5mm per side. And in the rear I think I increased the width by 3mm per side.
I found they clamped the rear hub bearings together once you tighten your wheel nut, as if they made the clearance to deep for the pin that goes through the axle. I won't run them in the rear.
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Old 11-06-2014, 06:16 PM   #5773
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Hi, any advice on how to make the xb4 lighter? I also use a 12mm kyosho wheel hex at the front and a 12mm wheel hex at the rears by jconcepts.

for the rear jconcept 12mm rear hex you have to sand or grind the back a little bit so it wont squiz the bearings when you tight the wheels.

Last edited by Texas Racer; 11-06-2014 at 06:27 PM.
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Old 11-07-2014, 06:17 AM   #5774
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Hi, any advice on how to make the xb4 lighter? I also use a 12mm kyosho wheel hex at the front and a 12mm wheel hex at the rears by jconcepts.

for the rear jconcept 12mm rear hex you have to sand or grind the back a little bit so it wont squiz the bearings when you tight the wheels.

post #5769 above.
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Old 11-07-2014, 09:50 AM   #5775
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What confuses and frustrates me is that my 2013 car was pretty dialed at this track. My shock set-up, diffs, electronics package & tires are all basically the same as the previous car, yet this 2014 car is darty as hell because it totally drives from the front end. I just copied 90% of Tyler Vik's set-up and for experiment sake, I went to 5K front and 2K rear in the diffs. I'll get a chance to practice with it this thursday. The really nice thing about this car is how damn easy it is to change the diff oils. So if the diff changes don't work /I don't like how that drives, I can easily go back to 10K front and 7k rear.
Wease- Sounds like we are running on the same type of traction. I am having the exact issue with my 14' xb4. I purchased it from a friend after he ran it only a couple times and it was so dialed I could push it as hard as I wanted in every direction and was afraid to touch anything. After 3 months of running the car on our indoor rubber/carpet high bite track I decided to rebuild the shocks and diffs just to keep it maintained. I was not sure what my buddy built the car with so I just went to 37.5 in front/27.5 AE in rear and 10K F/5K Rear using AE Diff oil. Now the car does exactly what you are describing on 180* turns. Sweeper turns on power handle pretty good but transitioning to full off power then tight 180* it just over rotates and does a 360* instantly. Very radical so I am puzzled. I tried going to 7K in the rear but it did not change.

Checked all the hub bearings also. The one thing I did notice is that the diffs were pretty empty when I rebuilt them but mesh was great so I just cleaned and added new AE diff oil

I am thinking the car likes lighter diff fluid to free up the car or the the AE diff oil is just much thicker than what the Hudy oil is and the CST ratings don't match what the manual or Vics setup is.

At a lost what to try next since. Hopefully we figure this one out with all the knowledge on this thread. I will try backing off the slipper this weekend.
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