Thread: Sitec's 101..

The old red one was capable of 100mph... and the only thing that used to worry me was the thought of the windscreens imploding!!!! I have a 1.222:1 transfer case in stock (SWIMBO's Ser2), and I have the 1.003:1 coming from Taz. Either would suit the Ser 2, so my options are open. As normal, I've found the bits then thought about it.... Have two 4.7:1 R&P's here, but have one complete 3.5 Salisbury here too.... Still got a little while to think about it as its still not on the road yet!

Das... With the 1.003:1 box, you talk about the gear not fitting from behind.... Does that mean that it has to go in from the bottom, then gets poked out thru the rear, the intermediate gear is fitted, then the input gear is positioned and tightened? Or will it fit thru the rear hole, but won't pass the intermediate gear? Might have to be 1.222:1 yet.....

Originally Posted by Sitec

--- With the 1.003:1 box, you talk about the gear not fitting from behind.... Does that mean that it has to go in from the bottom, then gets poked out thru the rear, the intermediate gear is fitted, then the input gear is positioned and tightened? Or will it fit thru the rear hole, but won't pass the intermediate gear? Might have to be 1.222:1 yet.....

Well it's ( the 1.003:1 ) still sitting out in the shed waiting for Cate in her shinning armour to arrive in her Discovery stead,
Don't suppose I could have a quick stickybeak to see if that top gear comes out the back.
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Feel free if you want to Arthur. Either way, the box will be used. If it does not go behind the Cummins, it'll go behind the Tdi and LT77 in the wife's Series. Being a ragtop shorty it'll pull 1.003:1, and prob be good on fuel too!

Originally Posted by Sitec

Das... With the 1.003:1 box, you talk about the gear not fitting from behind.... Does that mean that it has to go in from the bottom, then gets poked out thru the rear, the intermediate gear is fitted, then the input gear is positioned and tightened? Or will it fit thru the rear hole, but won't pass the intermediate gear? Might have to be 1.222:1 yet.....

That I can't give a 100% accurate answer to, I know it's something with them, but I'm not sure quite where the interference comes in.

As you've asked, I shall phone ashcrofts and ask them today.

Just been on the phone to Ashcrofts, they tell me the input gear is physically too large to fit through the pto hole in the back of the box, so to remove you need to take the transfer box out of the car, pull the intermediate gears and then you can get the input gear out.

Mmmmm, so for my little exercise it might be a case of not being able to get my modified gear in.... To be honest, the 1.222:1 Transfer Box and 3.54:1 diffs option is looking favourable at the moment.. 2000 engine RPM gives me 98.8 km/h... and 2500 engine RPM gives me 124 km/h.. So, with that in mind.... I have 2 very good 4.7:1 Salisbury R & P's that I need to sell, and I'm after 1 3.54:1 Salisbury R & P complete with center as the offset is different!

Somewhere in our house is a one hundred year old book on mechanics and motor vehicle, in it is a description on how an engineer determines the final drive ratio using the engine size.

But those engines certainly were not high speed diesels.
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It took me a while to remember how to do it... Engine speed of 2500rpm. Rotated crank once and watched tail shaft.. It did 1.25 turns... 2500rpm x1.25 = 3125rpm at tail shaft. Divide that by the transfer box ratio 1.222:1. 3125 div by 1.22 = 2561 prop shaft rpm.. Divide that by diff ratio. 2561 div by 3.54 = 723. This is axle shaft speed. The wheel radius is approx 2850. Times the axle shaft speed by the wheel radius which gives you a distance covered in mm within a minute... 2850 x 723 = 2060mm in a minute. Then x that by 60 to hive you the distance in an hour... 2060mm x 60min = 123 kmh... (at 2500rpm). That's how I've been doing it... A mate checked it and arrived at the same figures with the different ratios...