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end ratio and new tyres

Posted: Sat May 09, 2009 6:50 pm
by irwin83r
hey all
just wondering if anyone knows how readily available 4.4 ring and pinons are and how that will effect things as a percentage at the wheels? im looking at changing to a different size tyre/wheel and its going to be like a 7.6% change in Dia at the tyre. through my calcs going from a 4.1 to a 4.4 will be about a 7.3% change in end ratio so that should pretty much even things out right?

4.4-4.1= .3 (so thats the amount of change)

100(.3/4.1)=7.3 (thats how much of a change in a percentage over the old)

guess what im sayin is the 7.6 change at the tyre the same as a 7.6 change made at the ring gear..? should be i guess..

looking at going to a 17 inch rim with thoughts of better brakes but all just thoughts at the moment. most brake upgrades wont fit under 15s i also wanted to go a little wider than current 205. would like to go 16 but there dosnt seem to be alot of tyre choice around that size 225/45R17 seem to be rather common within competition tyres.

end ratio and new tyres

Posted: Sat May 09, 2009 10:20 pm
by Matty
Yes.

(ie, yes, a change in ratio at the wheels will have the same effect as a change in ratio at the diff.)

4.44s can be found in a van wreckers, ask for an Econovan diff (late 80s to 90s I think), look for M054 stamped on the ring gear. It will probably have a bazillion k's on it, but they don't really wear out.

end ratio and new tyres

Posted: Sat May 09, 2009 10:25 pm
by Matty
by the way a 225/45R17 will be about 10% bigger diameter, not 7%. (based on a standard 195/50R15 anyway)

You might have fitment issues, and the car will ride over one inch higher (you can lower to compensate, but it will bone your geometry and bump travel).

end ratio and new tyres

Posted: Sun May 10, 2009 12:26 pm
by Boyracer
You will only need to go to bigger wheels and brakes if you plan to put on a turbo...and if you run a turbo 4.4 is way to short a ratio.

If you don't plan to go turbo then you don't really need to have bigger brakes...

end ratio and new tyres

Posted: Sun May 10, 2009 12:38 pm
by irwin83r
turbo is later on in plans short term is high comp nat asp.. i do notice minor amounts of fade already and thats only running a stock motor.. worried with the new motor i might start hitting corners at harsher speeds.

sorry matt your right about the 10% i was going off my current setup of 205/50R15 should of mentioned that :P

is there anything shorter than the 4.44 thats comon out of curiosity?

end ratio and new tyres

Posted: Sun May 10, 2009 12:50 pm
by Boyracer
I run the stock NA8 brakes and hawk blues on my green car with no problems at all....

You can get a 4.8...i comes out of a Mazda van or something like that...

end ratio and new tyres

Posted: Sun May 10, 2009 1:14 pm
by Hellmun
Change the pads man... you expecting too much out of those Hawk HP+ . My old DS3000's your using are dam thin too which doesn't help them, plus they were run on my calipers when they were sticking and copped many >700C moments. They were only meant to be a once-off finish a day before going home pad :mrgreen: . You've had them like 3 track days now.... You've tried my car and if you like the pads those are the Carbotech XP10's. You could go XP12's on front, XP10's rear. Or just go the blues and see how bad they really are getting to the track. I'd say you'd have 2F racecar power level and a few of the quick guys were on Blues. I doubt they would've put up with fade on a proper race.