14 replies to this topic

[tommycrf450]

Hi can anyone tell me how to work out gear ratios in relation to top speeds. For instance my busa z car has a 12 tooth front and 40 rear sprocket. Base these calculations on 13'' wheels and 175/50 tyres. I would like to know the difference in outright speed by reducing or increasing the rear sprocket and front sprocket by one tooth at a time. It'll be handy to know for different track setups. Any help would be appreciated. Any rocket scientists out there!

Thanks

Tommy

[R1mini]

Hi can anyone tell me how to work out gear ratios in relation to top speeds. For instance my busa z car has a 12 tooth front and 40 rear sprocket. Base these calculations on 13'' wheels and 175/50 tyres. I would like to know the difference in outright speed by reducing or increasing the rear sprocket and front sprocket by one tooth at a time. It'll be handy to know for different track setups. Any help would be appreciated. Any rocket scientists out there!

Thanks

Tommy

I never heard of a front sprocket that small, but here goes, assuming a max rpm of 11,000

12/40 115mph
13/40 125mph
14/40 135mph

I have a spreadsheet form Locostbuilders if your interested you can experiment with, send me your Email and I will send it

Cheers
David

[tommycrf450]

Hi can anyone tell me how to work out gear ratios in relation to top speeds. For instance my busa z car has a 12 tooth front and 40 rear sprocket. Base these calculations on 13'' wheels and 175/50 tyres. I would like to know the difference in outright speed by reducing or increasing the rear sprocket and front sprocket by one tooth at a time. It'll be handy to know for different track setups. Any help would be appreciated. Any rocket scientists out there!

Thanks

Tommy

I never heard of a front sprocket that small, but here goes, assuming a max rpm of 11,000

12/40 115mph
13/40 125mph
14/40 135mph

I have a spreadsheet form Locostbuilders if your interested you can experiment with, send me your Email and I will send it

Cheers
David

Thanks very much. I have pm'd you.

Tom

[markrally]

Tommy, you best re check your sprocket size, i got a 13 on the motor and 40 on the diff, unless chris has changed the gearing slightly but on tooth on the motor is a big change to be honest.


cheers


ps, ready for cadwell??

and just to throw something else into the mix, busa redline is 10,500 realisticaly and the michelin slicks we will be using are a lot taller, i will measure the rolling radius of them and report back later.

Edited by markrally73, 10 February 2008 - 01:00 PM.

[tommycrf450]

I'll go re check in a bit. I have now calculated a big list with various sprocket sizes which i'll post later. I have based the calculations on a rolling circumference of 1.542m which are my road tyres. The calculations are also with the 10900 redline. Yes i'll be at cadwell. I'm booked but will probably not be in my mini as it is still at the painters. I'll try my best though. Otherwise i'll be in my rusty old golf GTi. Still be fun though.

[tommycrf450]

I have attached the list of top speeds with various ratios for a busa engine on 175/50 13 road tyres. I have got the speeds in all 6 gears too if anyone wants it. I'm bored as you can see by the pointless graph. If you can get the rolling circumference of the race slicks that would be helpful as i can set the data on my dash display for both road and track. The figures are with the engine at 10900 rpm start of redline.

[markrally]

I have attached the list of top speeds with various ratios for a busa engine on 175/50 13 road tyres. I have got the speeds in all 6 gears too if anyone wants it. I'm bored as you can see by the pointless graph. If you can get the rolling circumference of the race slicks that would be helpful as i can set the data on my dash display for both road and track. The figures are with the engine at 10900 rpm start of redline.

The rolling radius of the michelin slick is 1664mm.

can you send us the conversion chart to Email clicky

cheers

[tommycrf450]

The rolling radius of the michelin slick is 1664mm.

can you send us the conversion chart to Email clicky

cheers
[/quote]

I will work it out and send it later.

Tom

[tommycrf450]

Here are the top speeds using the michelin slicks.

Front - 11 12 13 14 15 16

Rear
36 - 124 135 146 158 169 180

37 - 120 131 142 153 164 175

38 - 117 128 138 149 160 171

39 - 114 124 135 145 156 166

40 - 111 121 132 142 152 162

41 - 108 118 128 138 148 158

42 - 106 116 125 135 145 154



Tom

Edited by tommycrf450, 10 February 2008 - 08:17 PM.

[markrally]

Here are the top speeds using the michelin slicks.

Front - 11 12 13 14 15 16

Rear
36 - 124 135 146 158 169 180

37 - 120 131 142 153 164 175

38 - 117 128 138 149 160 171

39 - 114 124 135 145 156 166

40 - 111 121 132 142 152 162

41 - 108 118 128 138 148 158

42 - 106 116 125 135 145 154



Tom

It makes quite a bit of a difference then!!

How many revoloutions per min is the engine srocket doing at 10900 in each gear?? i got the rest of the formula from my rallying days where i new all the gear ratio's etc at the sprocket ratios are just like a diff ratio but the gearbox etc had a 1:1 ratio in top gear.

Cheers

Edited by markrally73, 10 February 2008 - 08:34 PM.

[tommycrf450]

You've lost me! The primary gear ratio is 1.596. Does that answer the question for you? It is interesting to see the difference between slick and road tyres. I will email you all of the speeds in all gears sometime in the week. Its really exciting. NOT. I don't suppose you have a wiring diagram for the busa do you?

[R1mini]

Hello Mark,
If you need any answers I will try and help

Cheers
David

[gizmo]

It would be nice to have a wiring diagram for Busa in a mini. One that show's whats removed, whats modified, whats added, etc. etc.. Have been checking the diff BEC forums and cant get answeres for a Busa.. thanks much, hope to see something

[markrally]

It would be nice to have a wiring diagram for Busa in a mini. One that show's whats removed, whats modified, whats added, etc. etc.. Have been checking the diff BEC forums and cant get answeres for a Busa.. thanks much, hope to see something

Im sure chris can help you out with sorting your loom, he now does an off the shelf item on a exchang basis i think and a complete car loom now.
I managed to do mine from the suzuki diagram and some help off chris. I just have some scribblings on paper which would probably mean nothing to anyone else but it makes sense to me, well it did do when i made the last loom!!!


Cheers


Ps david, what im after is the ratio of what the sproket is doing / engine speed etc in each gear etc, the ret is quite simple to work out with rolling radius and sprocket ratios.

cheers

Edited by markrally73, 10 February 2008 - 10:58 PM.

[R1mini]

Hello Mark,
I was bored so I done it anyway

GSXR1300 1st 2nd 3rd 4th 5th 6th
Gear Ratio 2.613 1.936 1.529 1.284 1.134 1.040
Sprocket 2518 3398 4303 5122 5801 6325
Ratio 24% 32% 41% 49% 55% 60%

Rev Limit 10500

Cheers
David

Edited by R1mini, 11 February 2008 - 01:17 PM.