Tezza1
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 posted on 2/4/10 at 02:40 PM |
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gear ratio
Hi all
Could anyone tell me what diff I may have /gear ratio if when Im doing 105 at 11000 revs and it feels like it hasnt got much more to give, Its a 94
Blade engine Mk indy about 450kg
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blakep82
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| posted on 2/4/10 at 02:43 PM |
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would need to know the size of the wheels and tyres etc. they would affect the spped at any given engine speed.
easiest way is to put the car on flat ground, roll it forwards (in neutral) and count the number of turns of the prop for 1 turn of the wheels, and
thats your answer.
eg, if i did it on my car, 1 turn of the wheels would turn the prop 3.44 times, because its a 3.44:1 diff
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Steve Hignett
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| posted on 2/4/10 at 02:44 PM |
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Depends on how accurate your speedo is too really!
Using 195.50/15's and a 1:1.362 Sierra Diff - A Blade in top should be pulling 1000 Revs per 10mph...
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Tezza1
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| posted on 2/4/10 at 02:55 PM |
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wheels are 195 45 15s and my speedo is running 3mph more with a road angel attached
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blakep82
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| posted on 2/4/10 at 03:33 PM |
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ah, hang on though, you say you want to know what ratio the diff would be, AND what gear you'd be in?
any idea what the fireblade gearbox ratios are?
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don't write OT on a new thread title, you're creating the topic, everything you write is very much ON topic!
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matt_gsxr
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| posted on 2/4/10 at 03:38 PM |
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If you use the calculator in the sticky (max speed calculator), and assume a Fireblade 98, then it suggests 105mph at 10500rpm.
Its a nice little excel spreadsheet.
[edited to say 3.89, sorry forgot to give the answer!]
[Edited on 2/4/10 by matt_gsxr]
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blakep82
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| posted on 2/4/10 at 04:03 PM |
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or 3.54 in 4th
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coozer
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| posted on 2/4/10 at 04:08 PM |
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Its a Sierra back end not English as your ratios suggest.
Based on 105mph at the red line Terry wants to know what diff he has. The tag is missing off the diff.
The car was built as a racer and I suspect it runs out of revs that low because its got a 4.1 in there.
Before I offer to do the swap to a 3.62 we need to know what ratio is in there.
It is a push in shaft diff if that helps...
Steve
[Edited on 2/4/10 by coozer]
1972 V8 Jago
1980 Z750
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Tezza1
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| posted on 2/4/10 at 04:10 PM |
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So am I to think this is ok for road use was thinking it maybe set up for track use and was revving to high thinking it might of been a 4.1 /4.4 ? And
have to change it
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blakep82
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| posted on 2/4/10 at 04:10 PM |
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quote:
Originally posted by Tezza1
Could anyone tell me what diff I may have /gear ratio if when...
dunno, could be taken both ways i guess
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don't write OT on a new thread title, you're creating the topic, everything you write is very much ON topic!
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Tezza1
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| posted on 2/4/10 at 04:11 PM |
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Thanx Steve much better put
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Brommers
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| posted on 2/4/10 at 05:02 PM |
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3.92. Swapping to a 3.62 will increase your top speed to 115mph or thereabouts.
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bigrich
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| posted on 2/4/10 at 05:11 PM |
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would agree you have a 3.92 diff, fitting a 3.62 will give you the equivalent of 1 extra gear. what happens in 6th now will be the same as 5th with
the taller diff. A 3.62 should show 125 ish at limiter, dependant on tyre size
Rich
.JPG)
A pint for the gent and a white wine/fruit based drink for the lady. Those are the rules
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Tezza1
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| posted on 2/4/10 at 05:34 PM |
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So in all your opinions do I change my diff ? Other than extra speed (top end )
What other benifits are there to changing ?
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daviep
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| posted on 2/4/10 at 07:19 PM |
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quote:
Originally posted by Tezza1
So in all your opinions do I change my diff ? Other than extra speed (top end )
What other benifits are there to changing ?
Chances are none of us will ever drive your car, so the question really is do you want to change the diff
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matt_gsxr
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| posted on 2/4/10 at 08:53 PM |
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The other reason for a sensible diff is that you presently cruise at 70mph at around 7100rpm. This isn't particularly good for the ears, or for
economy, or anything really.
Matt
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mad-butcher
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| posted on 3/4/10 at 07:36 AM |
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Just to add my toyo's have a rolling circumference of 68.94 inches and 919 revolutions per mile whereas my yokohamas have a rolling
circumference of 71.27 inches and 889 revolutions per mile, my yokohamas are actualy 4 mph faster on top end , both sets are 195/50/15
tony
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Tezza1
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| posted on 3/4/10 at 02:54 PM |
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Thanx Guys for all your replies and advise,
I think i will change the diff not so much for top end but more for the noise and the feel of being in a lower gear than i am.
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mad-butcher
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| posted on 3/4/10 at 06:04 PM |
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Rev Limit enter limit 11000
Primary Reduction 1.52
1st Gear 2.727 44.19623286
2nd Gear 1.933 62.35029851
3rd Gear 1.6 75.32695438
4th Gear 1.4 86.08794787
5th Gear 1.263 95.42607048
6th Gear 1.167 103.27603
Differential Ratio enter option 3.92
I'd deffo say you've got a 3.92
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