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Old 02-05-2006, 09:51 AM   #12646
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I bought my car used and it did not come with a one way setup. I have been running either a diff or a spool in my car and am looking to try a one way. I just bought a front one way housing but wondering if I need the center one way as well? what advantages will I have running a double one way vs just a front?
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Old 02-05-2006, 05:25 PM   #12647
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Quote:
Originally Posted by Kevin CBR
The aluminum outdrive rear ball diff has the small aluminum spacer in the middle (between the inner bearings) and the diff screw is shorter than the regular delrin outdrive ball diff. You need to remove the center spacer, and use the longer diff screw from a regular 415 or 415MS.
Really?? I had no idea. I have left out that spacer it seems. I had to cut my diff screw to fit the new diff too.

However - it does work fine so not sure why the spacer is needed.
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Old 02-05-2006, 10:05 PM   #12648
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What does adding a 1mm spacer under all of the suspension blocks do? I understand it effects rollcenter but how?
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Old 02-05-2006, 10:15 PM   #12649
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Quote:
Originally Posted by RayWarner
What does adding a 1mm spacer under all of the suspension blocks do? I understand it effects rollcenter but how?
here's my understanding:
closer gap between the arm inner hinge pin and the inner camber link, will result in less traction. and vice versa.

someone correct me if i'm wrong
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Old 02-06-2006, 12:20 AM   #12650
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I added shims yesterday on high grip carpet (only 0.5mm). Made it more responsive as it seemed 'bogged-down' in the corners before. I would say it takes away grip

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Old 02-06-2006, 02:07 AM   #12651
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My take on roll centres and suspesion stiffness.

Roll centres is one of those adjustments that no-one ever seems to agree on - there never seems to be a definitive answer.

Raising the suspension mounts off the chassis = higher roll centre.

In theory the car will be stiffer, therefore less body roll, and less grip.

I have found it to be the complete opposite, when it comes to the "less grip" part. I find a car that rolls too much to be very easy to drive, but simply too slow through the corners.

Whenever I make an adjustment that makes the car stiffer (either raising the roll centre or stiffer springs etc) I find my car becomes noticeably quicker thru the corners - I can simply maintain a higher corner speed when the car has less roll.

Most people believe that the more roll you have, the more grip.
All of the info I have researched tells me that this is wrong - and that body roll gives an overall net LOSS of grip.

The reason is that the increased grip of the outside "loaded" wheel is not in proportion to the decreased grip of the inside "unloaded" wheel.

As an example: When the car starts to roll, the outside tyre may gain 10% traction, but the inside tyre will lose 15% traction - so overall there is a net loss.

Obviously, when the car is softer, it is easier to drive, so it feels like it has more grip, but in reality it is an illusion.

When the car is stiffer, it seems like less grip because the car feels "twitchy" or "edgy" - the reality is the car feels like this because the tyres are being pressed onto the track surface harder, and both the rear AND front tyres are responding quicker.

Last weekend, we had our first major meeting, the Summer Cup, run on low grip asphalt with rubber tyres. My car (19T class) was initially ok, running a fairly stiff setup (18pound springs front, 16 rear).

I went to a softer spring combo (16 front, 14 rear) and the car went slower - but it was much easier to drive. By the time we started the finals I was back on my original spring combo. Qualified 5th.

Finished 3rd and 4th in the first 2 A-Finals, and for the 3rd final I raised the roll centre. The car was harder to drive - but much quicker through the corners - and I won the last A-Final

What was most noticeable was that though I made a few mistakes getting used to the car, I was able to catch the leader each time and finally make the pass. The car simply out-cornered the opposition in this race.
It was my best time of the day and substantially quicker than my qualifying time.

As I said this was on fairly low-grip dusty asphalt, but I have found the same thing on very-low grip, bumpy concrete (my local track) - when the car is stiffer, it's harder to drive, but it's MUCH quicker.
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Old 02-06-2006, 02:32 AM   #12652
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hmm your explanation seems right.

just a quick one from me:
you wrote:
When the car is stiffer, it seems like less grip because the car feels "twitchy" or "edgy" - the reality is the car feels like this because the tyres are being pressed onto the track surface harder, and both the rear AND front tyres are responding quicker.

my question:
what about the case of traction roll? most people say that traction roll happened due to the increase in grip. normally we will raise the roll center to fix it (makes the car stiffer). But if raising roll center makes the tyres 'planted' harder to the surface, it will increase the grip on the 'loaded' outer wheels and hence won't fix traction roll?

I'm asking this because i find that reducing roll generally fix traction rolls.
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Old 02-06-2006, 02:37 AM   #12653
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So raise to your hearts delight, until its too difficult to drive.
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Old 02-06-2006, 11:55 AM   #12654
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Quote:
Originally Posted by dodo
hmm your explanation seems right.

just a quick one from me:
you wrote:
When the car is stiffer, it seems like less grip because the car feels "twitchy" or "edgy" - the reality is the car feels like this because the tyres are being pressed onto the track surface harder, and both the rear AND front tyres are responding quicker.

my question:
what about the case of traction roll? most people say that traction roll happened due to the increase in grip. normally we will raise the roll center to fix it (makes the car stiffer). But if raising roll center makes the tyres 'planted' harder to the surface, it will increase the grip on the 'loaded' outer wheels and hence won't fix traction roll?

I'm asking this because i find that reducing roll generally fix traction rolls.
n gebneral you want a soft car for low bite tracks and stiffer for high bite tracks.
traction rolling is when you have too much grip and then tyres dig in too much.
if you have a soft suspension on high bite tracks you get less grip which is what yopu do when you traction roll.you soften the suspension,if you stiffen it you will traction roll even more.
same as if your on a low bite track and you stiffen the car,you get less traction but more stabilty.
alot of people can get confused between grip and stabilty.
also if your on a low bite set up and your suspension is too soft and if you stiffen it you may see a increase in what you may call grip actual fact it is stability.
now the trick is to set up is to get the best grip AND stabilty compromise you can.
if both are wrong both can slow you down,going to stiff is bad and going too soft is also bad.
traction roll only takes place ENTERING a corner.
and really roll center effects both entry and mid of the corner.
if you rise the roll center ie more shims under the toe blocks or less shims on the inside of the camber links or more shims on the outside of the camber links this has the effect of lessing the tractioon on low bite tracks but increase stabilty.this WILL cause traction rioll problems.
the oppsite to above will give more grip but less turn in there for aiding traction roll problems.
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Old 02-06-2006, 12:47 PM   #12655
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This is why racers get confused

Quote:
Originally Posted by trf racer
in general you want a soft car for low bite tracks and stiffer for high bite tracks.
So far I have found the exact opposite


Quote:
also if your on a low bite set up and your suspension is too soft and if you stiffen it you may see a increase in what you may call grip actual fact it is stability.
When I stiffen my car there is LESS stability but faster cornering speeds.

Quote:
if you rise the roll center ie more shims under the toe blocks or less shims on the inside of the camber links or more shims on the outside of the camber links this has the effect of lessing the tractioon on low bite tracks but increase stabilty.
Again, my experience has been the exact opposite. I spent last year trying to tune my old car based on this logic, and I just got slower. Now, when I'm not quick enough thru corners- I raise the roll centre or run stiffer springs, works well so far.
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Old 02-06-2006, 12:50 PM   #12656
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Quote:
Originally Posted by Kenneth Tan
So raise to your hearts delight, until its too difficult to drive.
Works for me

What i'm going to try sometime is these two combinations to see which is faster:

1) stiff springs with very low roll centre
2) soft springs with very high roll centre
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Old 02-06-2006, 12:52 PM   #12657
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Quote:
Originally Posted by bender
This is why racers get confused


So far I have found the exact opposite



When I stiffen my car there is LESS stability but faster cornering speeds.

Again, my experience has been the exact opposite. I spent last year trying to tune my old car based on this logic, and I just got slower. Now, when I'm not quick enough thru corners- I raise the roll centre or run stiffer springs, works well so far.
remind me to run 33pound springs outdoors next time and 40 pound in the rain lol.
iam sorry but iam writte.
oh also il use 5 pound springs in very high grip carpet.
me thinks your experiance isnt very good
by the way what class,tyres and surface you running also what is the grip like?
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Old 02-06-2006, 01:11 PM   #12658
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Quote:
Originally Posted by trf racer
remind me to run 33pound springs outdoors next time and 40 pound in the rain lol.
iam sorry but iam writte.
oh also il use 5 pound springs in very high grip carpet.
me thinks your experiance isnt very good
by the way what class,tyres and surface you running also what is the grip like?
I was not saying that I was right, nor that you were wrong

I was just relating my findings.

And there's no need for smart-ar$ed comments, I've been racing for 22 years so I'm not exactly a noob.

I race stock, 19, and mod classes - usually on very low grip and dusty, asphalt or concrete tracks, with rubber tyres.
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Old 02-06-2006, 01:31 PM   #12659
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Quote:
Originally Posted by bender
I was not saying that I was right, nor that you were wrong

I was just relating my findings.

And there's no need for smart-ar$ed comments, I've been racing for 22 years so I'm not exactly a noob.

I race stock, 19, and mod classes - usually on very low grip and dusty, asphalt or concrete tracks, with rubber tyres.
22 years of bad experiance is worse then only one good year of experience.lol,jk.

if your finding 'grip' by going stiffer then your not finding grip your finding stabilty.
you can only get grip if you go softer only to a certain point though.
you seemed on your last post you were saying what i was saying wasnt true.
well iam saying what ive found is true.
my basis of thinking put me in an A final twice almost at national level.
if your finding oposite then i will try a few things but a hint.
once you get a good roll center just leave it.for carpet i just use the 3mm chassis with 2mm of spacers on the front under top link and 1mm spacer on the outside of the rear top link.
unles the grip increases and i traction roll 3 mm of spacer up front,that all i do to roll centre. old suspension used.
outdoors LWT suspension between 2 and 4 mm spacers depending on grip and 2 mm of spacer on rear inner and 3 mm spacers outside rear.
so i only ever chjange the ront roll center to suit.
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Old 02-06-2006, 01:34 PM   #12660
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Quote:
Originally Posted by bender
I was not saying that I was right, nor that you were wrong

I was just relating my findings.

And there's no need for smart-ar$ed comments, I've been racing for 22 years so I'm not exactly a noob.

I race stock, 19, and mod classes - usually on very low grip and dusty, asphalt or concrete tracks, with rubber tyres.
sorry i didnt mean to sound smart assed.
its good to share info.
what your full set up were you race.
because springs shock position shock oil can all effect the type of roll center you have
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