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Old 10-08-2007, 12:24 PM   #2086
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Thanks for the feedback guys. Here is some more info on how I built my car.

Front End Assembly:
When I setup the car, I took my time to make sure the front end was free but didn't have too much slack. I used a 1/8" drill bit to hand-ream out the steering knuckles. The upper arms were binding against the caster blocks when there was a shim on each side of the block. To correct this, I sanded a shim on each side (the one on the front side of the caster block) until the arm move and fell freely with very little front-to-back slop.

For installing the pivot balls, I don't have the CRC or IRS pivot ball tool, so I used a small hobby vise instead. The jaws on the vise are smooth and I used this to slowly press in the pivot balls making sure they were parallel the entire time. All four pivot balls move freely and don't have any slop in them.

For the steering linkage ball cups, I used the plastic bag trick to remove the slop but made sure I didn't go too far. To test them, I would check for no slop but made sure the linkage would freely fall when only connected to one side of the linkage.


Front End After Driving:
After driving the car for a couple packs and hitting the boards quite a few times, I have noticed additional slop in the front wheels. What I'm referring to is checking the front tires for camber slop when the chassis is lifted up. There is definitely more slop there now than when I first assembled the car. It appears that the steering knuckle is where the problem is but I still need to check for problems with the king pin in the pivot balls and/or any issues with the pivot balls and the arms.

Question: How much movement is acceptable on the front end? Is it ok for the camber to move +/- 1 degree? What about the steering toe? what's acceptable for that movement?


Rear End:
For the axle spacing, I did notice the clamping hub was backwards before I drove the car. I use an Integy setup board and lined up the balancing holes on the chassis with the center line on the setup board. That's where I noticed it when shimming the rear wheels. My car is using four axle shims on each side for the rear to get to 172mm while still keeping the chassis balancing hole centered on the board.

The diff is very smooth and it was difficult to move the spur gear while holding the rear wheels when I assembled the car. After driving the car for a couple packs, the spur gear was then able to move easier when holding the rear wheels so I tightened up the diff about 1/8th of a turn.


Balance:
I'm using an LRP QC2 ESC, a Spectrum Micro receiver, and an AMB PT in the car. With everything installed, including batteries and wiring, the car does balance when left static. I'm using the Hudy balancing pins as I don't have the IRS balancing balls yet. To compensate for any binding of the pin in the chassis hole, I would purposly tip the car to each side and made sure the "fall" point was even both left to right. I'm not sure how valid that test is but I did it anyway.


Tweak:
Before I drove the car, I put the car on a couple different tweak stations. I have a Speedmind bubble tweak station and the tweak was ok. I then used a buddy's Integy laser tweak station and the car was laser was splitting the center line in the middle. I also put it on another buddy's MIP bubble tweak station and it was off a bit. Not drastically, but some.

The reason I checked it on more than one station is because the rear pod isn't flat to the chassis when there is no load on the car. When you pick up the car and inspect the bottom, you can see that the rear pod isn't parallel to the chassis left to right. I haven't measured this difference yet with my calipers but to me, if you can visually see the difference, it's too much. When checking this, I made sure the motor wires weren't binding in any way either. I plan on rebuilding the L-plates to the chassis to see if this corrects it.

I find it strange that I can see the chassis difference but the tweak was ok (for the most part...) on the tweak stations.


Handling Question:
Aside from the specifics of my car, what would you guys do for a car that you can see the inside front tire lifting on high-speed turns? My thought is to stiffen up the side-to-side movement of the rear pod with either thicked dampening fluid and/or a heavier spring, T-plate, L-plate, etc (take your pick based on the chassis type). What do you guys think?

Thanks,

It is hard to say what the problem is buddy. I will need to see the car. I have not heard anything like this in any of the kits. If you would like to send the car to me to check out i can get things figured out. It is hard to say what the problem is without seeing it. Let me know and i will get it done quickly for you
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Old 10-08-2007, 12:30 PM   #2087
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I just wanted to get on the record saying that Jason has built and assembled a very fine race car worth every penny. My first impression opening the kit was: here's a guy that has put every cool & practical part need into a kit. I built the kit per the instruction minus the recommended 35wt center shock oil using 30 instead for our bumpy track. I glued the servo down instead of using the mounts (late night and it didn't have ears). Put a Speed 8 on top of it, a 19t in it. The Jaco Lilac/yellow combo was very good. The car has a great dispossition on the track. It's very fast right out of the wrapper.

Bravo!

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Old 10-08-2007, 02:25 PM   #2088
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Thanks Brian. Looks like there are a few more kits shipping to the area by you. Seems like they really like the cars up there.
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Old 10-08-2007, 02:27 PM   #2089
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Ben ~ Even after all of that you still had the fastest lap of the day, Just wait 'till the next race day
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Old 10-08-2007, 03:03 PM   #2090
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Originally Posted by Chemical X View Post
Thanks for the feedback guys. Here is some more info on how I built my car.

Handling Question:
Aside from the specifics of my car, what would you guys do for a car that you can see the inside front tire lifting on high-speed turns? My thought is to stiffen up the side-to-side movement of the rear pod with either thicked dampening fluid and/or a heavier spring, T-plate, L-plate, etc (take your pick based on the chassis type). What do you guys think?

Thanks,
I'd go softer on the back, especially the damping. Increasing the side damping always seems to me to give good initial steering, but then the car doesn't straighten up on the exit, and I have to hold off the throttle until it points the way I want to go. Less side damping might give more initial steering, but hurts the rest of the turn.

If you don't have enough steering, fix that - camber, castor, T-bar, L-bar, centre spring, whatever - but simply increasing the damping doesn't work for me.

When measuring the axle width to be central to the chassis, use the stand-offs on the side of the car; those supporting the cross brace, or the body post/side damper plates on the DB12R. Place a steel rule against the post at 90deg to the chassis, then place a straight edge (or another ruler) along the edge of the wheels. Read off the dimension, repeat for the other side. This is far more accurate than trying to find the middle of the chassis, and reading from a mark on the car. HTH
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Old 10-08-2007, 06:11 PM   #2091
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I'd go softer on the back, especially the damping. Increasing the side damping always seems to me to give good initial steering, but then the car doesn't straighten up on the exit, and I have to hold off the throttle until it points the way I want to go. Less side damping might give more initial steering, but hurts the rest of the turn.

If you don't have enough steering, fix that - camber, castor, T-bar, L-bar, centre spring, whatever - but simply increasing the damping doesn't work for me.

When measuring the axle width to be central to the chassis, use the stand-offs on the side of the car; those supporting the cross brace, or the body post/side damper plates on the DB12R. Place a steel rule against the post at 90deg to the chassis, then place a straight edge (or another ruler) along the edge of the wheels. Read off the dimension, repeat for the other side. This is far more accurate than trying to find the middle of the chassis, and reading from a mark on the car. HTH
Thanks SlowerOne. What are your thoughts when you can see the inside front tire lifting during on-power turns?
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Old 10-08-2007, 06:15 PM   #2092
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Thanks SlowerOne. What are your thoughts when you can see the inside front tire lifting during on-power turns?
My first thought would be to thicken up the damping fluid......I think
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Old 10-08-2007, 06:34 PM   #2093
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It is hard to say what the problem is buddy. I will need to see the car. I have not heard anything like this in any of the kits. If you would like to send the car to me to check out i can get things figured out. It is hard to say what the problem is without seeing it. Let me know and i will get it done quickly for you
Thanks Jason. I think I'll hang on to the car for now and try rebuilding the L-Plate assemblies and see if that helps the tweak issue. I'll also be seeing Brian Bodine in about 1.5 weeks at a NorthWest series race at Seattle Indoor Raceway. I'll ask him to take a look at it if I'm still having problems.
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Old 10-08-2007, 06:43 PM   #2094
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ok buddy. I am sure you will get it all figured out. If you need any help just let me know. I will be happy to give the car a once over for you
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Old 10-08-2007, 07:00 PM   #2095
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Jason, Nice talking with you on the phone, The car is on its way, i sent it to your shop.

In response to my question earlier why my car wasnt handling, I put it together exactly how the manual says, The step where it tells you how to put the clamping hub carrier on, it says shallow end towards the rim.. Its supose to be deep end towards the rim. This is my first time runnign 12th, I didnt think i had to check the left to right rear wheel distance cause i put it together per manual. Jason said he is going to get the manual revise to fix that and some other things.

Thus, my car was spinning one way cause one side was longer, thus my tweek was way off!
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Old 10-08-2007, 08:16 PM   #2096
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cool ben. I will give it a full check and send it back right away
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Old 10-08-2007, 08:19 PM   #2097
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cool ben. I will give it a full check and send it back right away
And this is why I love being part of such an awesome team!!!! Team BMI fo' life....
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Old 10-08-2007, 08:22 PM   #2098
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Thanks bro.
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Old 10-08-2007, 08:22 PM   #2099
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Chemical X - maybe I missed it, but I had a few questions:

1) What size tires are you running front and rear?
2) How much are you rounding the tire edges (inside and outside edges) after truing the tires?
3) What ride height are you running (front, middle, and rear)?

-Rich
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Old 10-08-2007, 08:25 PM   #2100
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Plus there's that Rich Chang guy..........
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