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Spool vs. Diff

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Old 06-28-2018, 02:30 PM
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I dropped in a spool my second race ever with 1/12 and I dropped half a second on my average lap. Guess I don't know what I'm doing lol
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Old 06-28-2018, 03:36 PM
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In a touring car a front spool can always be a good idea, maybe not ideal but it won't be terrible either.

On black carpet, switching from a diff to a spool in my 1/12 car made the car go from decent to driving like a slot car, it felt like there was a post between the front wheels guiding the car around. What is important to remember about 1/12 is that when you lift that inside rear tire in a corner its basically like hitting the brakes, with a spool you can keep power on the outside front and keeps the car from looping or scrubbing all of its speed in a corner. The only downside is that it amplifies dips in the track during acceleration, such as one dip in the track at the Mile High that would make the car do a 3/4 turn pivot for no reason.
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Old 06-28-2018, 06:39 PM
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Originally Posted by Marcos.J View Post
now with the high grip Black CRC carpet you pretty much need a spool in the rear for 1/12th
But on a high-traction surface you shouldn't have to worry about wheelspin, so running a diff ought to be better. It will allow the wheels to rotate at different speeds in corners, the way they're supposed to, rather than forcing the inner tire to break traction. Why does this logic not actually apply?
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Old 06-28-2018, 07:15 PM
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Originally Posted by fyrstormer View Post
But on a high-traction surface you shouldn't have to worry about wheelspin, so running a diff ought to be better. It will allow the wheels to rotate at different speeds in corners, the way they're supposed to, rather than forcing the inner tire to break traction. Why does this logic not actually apply?
On high traction, you're on the verge of traction rolling. The inner wheel will be lifting from the ground, and all power will transfer to it, diffing out.
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Old 06-28-2018, 07:28 PM
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Even with a pan car? I thought their suspensions were more of a vaguely-imagined idea than a fact.
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Old 06-28-2018, 10:56 PM
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Originally Posted by fyrstormer View Post
Even with a pan car? I thought their suspensions were more of a vaguely-imagined idea than a fact.
Yes, regardless of suspension, if the car starts to roll over due to cornering too hard, the inner wheel will lift. And even if it doesn't actually lift off the ground completely, the weight will still shift such that the outer wheel will have more traction than the inner wheel. A ball diff (set fairly loose) is an equal-torque device, so both tyres will receive roughy the same torque. If one of those wheels breaks traction due to bearing less weight, then both wheels will lose torque as it diffs out.
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Old 06-29-2018, 04:37 AM
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Originally Posted by iTz Nicholas72 View Post
I dropped in a spool my second race ever with 1/12 and I dropped half a second on my average lap. Guess I don't know what I'm doing lol
I would suggest that you read my starter post.

The subject was spools (in pan cars) and new racers.
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Old 06-29-2018, 08:50 AM
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Originally Posted by old_dude View Post
I would suggest that you read my starter post.

The subject was spools (in pan cars) and new racers.
Really? You might be expecting too much...LOL
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Old 06-29-2018, 08:57 AM
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Originally Posted by old_dude View Post
I would suggest that you read my starter post.

The subject was spools (in pan cars) and new racers.
I'm new to 1/12 PAN car 🙄
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Old 06-29-2018, 09:33 AM
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Originally Posted by old_dude View Post
OK, I want to make a comment about this. I see this mad rush to the spool diffs in pan cars. They do work but there is a * to that. They work in the right place with the right conditions, car and driver. I would encourage anyone that is new to not try running them until they now when all of those conditions are right.

---To a new racer running on black carpet I would recommend a spool for their first run.

I have seen racers run them because the allstar at their local track does and they are all over the place. It only takes one incident because you were running that locked diff to negate the advantage you had by running one.

---By the same logic it only takes one mistake made with a diff that may have been negated by a spool to negate its advantage. You can't really point at a car and say "Hey, if you had listened and put a diff in the car you would have won."

To that all star, make sure you know the skill level of the racer before you suggest he run it. The worst comment is to tell someone is that "I see why you are slow, you are running a diff". Sometimes the diff is faster and I can tell you, ball or gear they are more consistent.
I keep all three available and know when to use them. Help others to know the same.

---Spools are situational. BUT if you are on high grip it is worth trying, and in my opinion it is probably your best starting point. If your car goes "dead" and becomes slower running a spool you can always switch back, but I have not seen a car go from good to undriveable due to a spool switch.
Some quick answers to the original question for the thread. Spools are situational but there are some surfaces and conditions where it should be your starting point, no matter your experience in pan car.
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Old 06-29-2018, 10:19 AM
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Originally Posted by gigaplex View Post
Yes, regardless of suspension, if the car starts to roll over due to cornering too hard, the inner wheel will lift. And even if it doesn't actually lift off the ground completely, the weight will still shift such that the outer wheel will have more traction than the inner wheel. A ball diff (set fairly loose) is an equal-torque device, so both tyres will receive roughy the same torque. If one of those wheels breaks traction due to bearing less weight, then both wheels will lose torque as it diffs out.
I guess I don't adequately appreciate just how hard the cars are cornering.
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Old 06-29-2018, 11:54 AM
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Originally Posted by fyrstormer View Post
I guess I don't adequately appreciate just how hard the cars are cornering.
Iíve only seen cars run on carpet briefly. Itís almost freaky looking how much traction they have. In a way the whole traction roll thing is one of the things kept me away from carpet.
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Old 06-29-2018, 12:39 PM
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I have seen ball diffs on pancars that replace some of the balls with pegs to slow down the diff. Kind of a middle ground between a spool and diff
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Old 06-29-2018, 01:02 PM
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Originally Posted by Lone Drifter View Post
I have seen ball diffs on pancars that replace some of the balls with pegs to slow down the diff. Kind of a middle ground between a spool and diff
I tried that with a touring car I built last year that came with ball diffs. I inserted one Teflon peg in place of a diff ball. It worked great for the first few minutes, but as soon as the diff lube worked its way out from between the peg and the thrust washers, the diff got really sticky. I had to loosen it to the point the diff balls weren't really doing their job anymore. I never bothered to try it again.
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Old 06-29-2018, 01:11 PM
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Originally Posted by fyrstormer View Post
I tried that with a touring car I built last year that came with ball diffs. I inserted one Teflon peg in place of a diff ball. It worked great for the first few minutes, but as soon as the diff lube worked its way out from between the peg and the thrust washers, the diff got really sticky. I had to loosen it to the point the diff balls weren't really doing their job anymore. I never bothered to try it again.
I have seen it done on F1 cars , it didnt look like they lubed the diff though. I think they were made uf the same slipper pegs that my old Traxxas Blue Eagle sadium truck had.
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