Flat Spot

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LORENZO73
Posts: 142
Joined: Sun Apr 06, 2014 7:26 pm
Location: Tarxien Malta

Re: Flat Spot

Post by LORENZO73 » Wed May 13, 2020 5:34 pm

MarinaCoupe wrote:
Wed May 13, 2020 3:20 pm
Hi Renzo,

I have checked your teeth count and recalculated the gear ratios with the aid of a spreadsheet. Initially I got the same answers as David Painter. These are clearly wrong. However, I think that you have written down the teeth count for the second and third gear Mainshaft and layshaft the wrong way round, so if you write

Second gear as Laygear 21 and Mainshaft 26 then the calculation comes out exactly right at 1.92:1

Equally for third gear as Laygear 25 and Mainshaft 21 then the calculation comes out exactly right at 1.31:1

So this is a 1.8 gearbox - its an easy mistake to make.

Gear Ratio Calculations.png
Hi chris, and david,
Many thanks for help, i am so happy that i know more, about my car.
Next step, what do you thing chris? :crazy:

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locost_bryan
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Location: Auckland, New Zealand

Re: Flat Spot

Post by locost_bryan » Wed May 13, 2020 9:29 pm

Looks like Renzo just needs to get the correct speedo drive gear for the 3.63 axle.

Could be useful to have a chart pinned in the tech thread that lists the gearbox and diff stuff all together - the gear tooth counts and ratios, the standard combinations, rpm vs speed for standard tyres, speedo drive gears, etc.
Bryan
Auckland NZ

1972 Morris Marina 1750 TC Coupe "Ozzy"
2008 Honda Jazz 1.3 CVT

Nothing gets the ladies hotter than software development analogies. Leonard Hofstadter - The Big Bang Theory.

david painter
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Re: Flat Spot

Post by david painter » Wed May 13, 2020 10:08 pm

Chris and myself have spent a long time sorting them out his spread sheet is good I have learnt a lot myself while working this one out spent ages looking at part numbers and cross references
Dave

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locost_bryan
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Re: Flat Spot

Post by locost_bryan » Wed May 13, 2020 11:04 pm

Would be good to pin it in a thread in the tech section for future reference. :ugeek:
Bryan
Auckland NZ

1972 Morris Marina 1750 TC Coupe "Ozzy"
2008 Honda Jazz 1.3 CVT

Nothing gets the ladies hotter than software development analogies. Leonard Hofstadter - The Big Bang Theory.

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LORENZO73
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Location: Tarxien Malta

Re: Flat Spot

Post by LORENZO73 » Thu May 21, 2020 2:55 pm

Speedo and reefs now ok , with the gear of 20 teeth that he send me chris, many thanks .She comes like an original 75kpm with 2500 rpm on the fourth gear.
So now the difference is camshaft for much power.

Renzo

david painter
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Joined: Sat Nov 24, 2012 3:52 pm

Re: Flat Spot

Post by david painter » Thu May 21, 2020 4:22 pm

Just run Calculations actual speed 46.60 MPH equivalent Calculated Speed on 3.63 diff with 155r13 tyres is 46.64 MPH so Speedo now reads Spot on you should be well happy now
Dave

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LORENZO73
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Location: Tarxien Malta

Re: Flat Spot

Post by LORENZO73 » Fri May 22, 2020 2:35 pm

Yes David, i am very happy , because i know that my marina have diff and gearbox for 1.8.

The difference that she have is camshaft, i would like to tell, you and chris, big thanks for help to change it.

Renzo

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