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Diff ratios

Posted: Sat Apr 09, 2011 7:34 am
by cruise75
Can someone help me. My 75 series originaly had 31 x 10.5 tyres on it and was revving its arse off. I changed the tyres to 33 x 12.5 x 15. Not revving as hard but at 100 km/h it still revs at 2400 rpm. My mate has the same size tyres and his revs at 1800rpm. Is it the diff ratios?. If so how do i find out what my ratios are and what should they be? Cheers guys.

Re: Diff ratios

Posted: Sat Apr 09, 2011 12:57 pm
by dogbreath_48
2400rpm sounds about right at 100km/h. To hazard a guess I'd say your diffs are the standard 4.11's. Nothing wrong with it, if you overgear it any more it'll be a pig to get off the line.

Don't know what setup your mate is running to cruise at 1800 rpm.

Re: Diff ratios

Posted: Sat Apr 09, 2011 1:03 pm
by SCANAS
x2 sounds like you have 4.11 ratio's to me. Your friend must have different ratios or transfer case gears?

Are you both talking indicated 100kph or a GPS or corrected read out

Re: Diff ratios

Posted: Sat Apr 16, 2011 7:49 pm
by cruise75
Thanks guys. not sure what hes running either but will askk at next meet. It is at indicated KPH. Dont trust GPS readings

Re: Diff ratios

Posted: Sat Apr 16, 2011 9:41 pm
by brissle
trust the gps not your speedo

Re: Diff ratios

Posted: Sun Apr 17, 2011 5:36 pm
by HUNTERLUX
Also are they both the exact same running gear eg turbo or not petrol or diesel ect ect

Re: Diff ratios

Posted: Wed Apr 20, 2011 5:44 pm
by cruise75
Both 1HZ models

Re: Diff ratios

Posted: Thu Apr 21, 2011 1:38 pm
by CustomTurbos
Does a stock 1HZ even have enough torque to push 100km/h at 1800rpm?

Sounds like tacho reading wrong......

cruise75 wrote:Can someone help me. My 75 series originaly had 31 x 10.5 tyres on it and was revving its arse off. I changed the tyres to 33 x 12.5 x 15. Not revving as hard but at 100 km/h it still revs at 2400 rpm. My mate has the same size tyres and his revs at 1800rpm. Is it the diff ratios?. If so how do i find out what my ratios are and what should they be? Cheers guys.

Re: Diff ratios

Posted: Thu Apr 21, 2011 3:08 pm
by cruise75
Have had the ol girl out to 125, but shes revving

Re: Diff ratios

Posted: Sun Apr 24, 2011 3:36 pm
by Mulcahy
i have a 2H engine with 31 inch tyres and i rev to 2500 with the 5 speed and can easily get 125 out of it it is reving but not flat out and i have 3.8 ratios