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Old 09-06-2012, 10:53 AM   #8896
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On the Houston UF1 I read the same thing diff needs to be set correct. In a thread helping those new to F1 they described a well set diff as locked but smooth, but the author dosen't really expand on what that means. To me that means that if I turn one wheel forward the other also goes forward but if I grab them and turn them in opposite dirrections it feels smooth and there is not alot of friction stopping them, is that correct? Maybe you pro's could expand on exactly what a perfect set diff is.
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Old 09-06-2012, 11:37 AM   #8897
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To me that means that if I turn one wheel forward the other also goes forward but if I grab them and turn them in opposite dirrections it feels smooth and there is not alot of friction stopping them, is that correct? Maybe you pro's could expand on exactly what a perfect set diff is.
A very good place to start is the qouted text below.

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This really is one of the least talked about "secret" when tuning F1 cars. You really can't set the diff on the bench. You have to go out there and run your car on the track *just* so the diff is on the verge of slipping coming out of the tightest turn of the track. I've gone around and "fixed" oversteering F1 cars last weekend by loosening their diffs 1/16th of a turn and sending them back out on the track.

You want more on-power steering? Tighten the diff.
What this means is that to prevent your car from spinning out on a dusty, un-swept parking lot, the diff will feel so loose that you can make the spur slip with your fingers with "light to moderate" effort if you lock both rear wheels.

Using the same method above on a fully prepped asphalt track or on carpet, it would be very difficult to turn the spur gear with your fingers with both wheels locked.

Once you get to the point above and you have a car where you can pretty much mash the throttle with no on-power oversteer, you may want to experiment with tightening the diff to your liking to get the right amount of on-power oversteer.
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Old 09-06-2012, 12:07 PM   #8898
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so last weekend I was coming on to the straight with a left hand 90 deg turn when I got on the power too hard my car wanted to throw the rear end out to the right and spin out unless I was very carefull. So I should have tighten up the diff?
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Old 09-06-2012, 12:30 PM   #8899
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nope. you should have loosened the diff.
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Old 09-06-2012, 07:54 PM   #8900
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I'm convinced, the reality of this car is in the diff! And more sensitive to an adjustment than a 1/12. Keep it clean and smooth. Adjust it this side of slip to start. However, take a look at the bearings first. The least amount of grit in them will give you a false negative on your diff.
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Old 09-07-2012, 08:50 AM   #8901
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I'm convinced, the reality of this car is in the diff! And more sensitive to an adjustment than a 1/12. Keep it clean and smooth. Adjust it this side of slip to start. However, take a look at the bearings first. The least amount of grit in them will give you a false negative on your diff.
This is quite a few years back, but when racing the F103 on rubber, a lot of people essentially tuned rear traction with the diff. There was a lack of tire choices back then and we essentially let the diff slip for 6"-12" for traction and just rebuilt them every 4 runs (threw away the diff balls and thrust bearings and just flipped the diff rings). You could hammer the throttle and know the car would not spin out.
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Old 09-08-2012, 06:00 PM   #8902
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Originally Posted by JoeyE View Post
This is my F104 Pro with a shorty pack.

Hi.

Is that a regular TRF shock? The one without the springs or is it a hop-up?

Thanks.
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Old 09-08-2012, 07:19 PM   #8903
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Hi.

Is that a regular TRF shock? The one without the springs or is it a hop-up?

Thanks.
its the rm-01 damper upgrade

http://rc.marshall-banana.com/?p=146
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Old 09-09-2012, 12:12 AM   #8904
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its the rm-01 damper upgrade

http://rc.marshall-banana.com/?p=146
thanks.
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Old 09-12-2012, 02:38 PM   #8905
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whoops read post below!
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Old 09-12-2012, 02:41 PM   #8906
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ok after switching the steel drive shaft I see allmost no difference. It is still pushing the ass end out to the left hard when I get on the power. Now I think I know what the problem is I think my gear case is bent or tweaked or something.

My car handeled way better during it's first race. I watched the video again back on page 584 of this thread ( http://www.youtube.com/watch?v=-s5BR8XRlog ), in the video the ass end does not come out like it does now.

Question- can I rebuild the plastic gear case (https://www.tqrcracing.com/shop/prod..._id=&cart_seq=) I have now? or once these are messed up do I just need a new one?
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Old 09-12-2012, 05:31 PM   #8907
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ok after switching the steel drive shaft I see allmost no difference. It is still pushing the ass end out to the left hard when I get on the power. Now I think I know what the problem is I think my gear case is bent or tweaked or something.
If your car is always spinning out to one side, then the problem is usually a chassis tweak or weight imbalance. The way to test it ideally is to use a tweak board, or you can do it with the coin test.

Put the car on a flat surface, and press down on the chassis to settle the car. Put a dollar coin on the top of each front wheel, and then lift the front end putting a small screwdriver under the exact centre of the front of the chassis. Very slowly lever this up until the front wheels lift off the ground. The aim is for both front wheels to lift at the same time, shown by both coins dropping off the wheels simultaneously. If the tweak is incorrect one front wheel will lift before the other and that coin will drop off that front wheel first. If this happens there is a tweak in the chassis somewhere that you need to sort out. If both coins drop off the wheels at the same time the car will be balanced and should steer the same.

If the chassis is tweaked it will never run right and you need to work out where the problem is. Check the car has been built straight. Take the wheels off and loosen the top deck screws. Now put the car on a flat surface and while pushing it down tighten the top deck screws, this should square up the chassis. With the chassis sitting on your flat surface measure how high the front axles are from the surface to check the front suspension isn't tweaked. For the rear end take the pod off the lower plate and remove the axle. Now loosen all the pod screws, put the pod on your flat surface and tighten all the screws while holding it down. If when the pod is screwed together it still rocks on your flat surface it is twisted and needs replacing. Assemble it again and it should be built straight.
If there are still problems check the weight balance, motor choice can upset the balance of the rear pod, for example I run with brushed motors and need to add 30 grams of stick on weights to the left side of the pod to balance the weight out. Also make sure the motor wires aren't pushing the pod over and restricting movement.

Check your diff is smooth and adjust it so it is free. Loosen the diff, hold the rear axle by both wheels and try and push the spur hear with your thumb. If you can move the spur gear tighten the diff a little and try and turn the spur gear again. Keep on going until you can just move the spur gear with a good amount of force. The diff should be set now, so the diff action is free but the diff won't slip under power.
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Old 09-12-2012, 08:09 PM   #8908
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In addition to terry.sc's excellent post, also examine your T bar for stress lines or other signs of damage. Sometimes a fresh T bar will take care of tweak problems. Same goes for a fresh pair of front springs, as one or the other may take a set, causing one side of the car to ride low.
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Old 09-12-2012, 08:30 PM   #8909
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Nice Post Terry Thanks! Really great detailed advice, exactly what I needed. OK I'm off to tear it down and figure it out.

Last edited by 5VoltDetonator; 09-12-2012 at 08:41 PM.
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Old 09-12-2012, 09:13 PM   #8910
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A fresh T plate has solved my bad days a few times with both the F104 (especially the Hi Traction T plate which by the way, you should be using) and the F103. (screw hole wears out on these).
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