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In this Discussion
- 51hornetA April 2006
- barrysweet52 April 2006
- Geoff C., N.Z. April 2006
- hudson8 April 2006
- hudsontech April 2006
Information Wanted
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Will someone kindly tell me the procedure for calculating the rear ratio of the differential when it is not stated on the housing? I know I have heard it before, but for the life of me I can not remember (old age). Thanks loads.---Cliff Minard.
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Let me see if I can remember.
Jack up the car with, I think, one tire off the ground - tho it may be both.
Place a mark on the tire at bottom-dead-center. Crawl under the car and place a mark on the driveshaft. You'll be counting how many times the driveshaft turns in this test, so place the mark at a convenient place that you can call "zero".
Have a friend turn the left wheel for 20 rotations. Have them count to themselves while you count driveshaft rotations. When they are completed, divide the number of driveshaft revolutions by 10. For instance, 30 turns is a 3.00 differential ratio. 37 and a third turns is a 3.73 ratio. If you know the factory-available ratios, this will put you close enough to quickly determine which ratio you have. If you don't know the factory options, then do a larger number of wheel rotations (say, 100) and divide by 50 for a little more accuracy on that last decimal place.
Hudsonly,
Alex B -
Hi Alex.---Thank you very much for your immediate reply. You are certainly a credit to this club. Hudsonly---Cliff Minard.
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hudson8 wrote:Hi Alex.---Thank you very much for your immediate reply. You are certainly a credit to this club. Hudsonly---Cliff Minard.
Actually, Cliff, I cheated - I looked it up on the internet just to make sure I was remembering it right. LOL
Hudsonly,
Alex B -
There's an easier way. Jack up one wheel, turn it one complete turn, and check how many times the drive shaft turns. You then double that figure. For instance, the shaft turns a whisker over 2 turns, you have a 4.1 ratio. A smidgen under 2 turns, your ratio is 3.9. Rough and ready, but good enough to get an indication. If you really want to get technical, cut a hole in a piece of cardboard, mark it in equal gradients 1 to 10, slit it to fit over the drive shaft, mark the shaft, and you have a dial indicator.
Geoff.If you're stuck in a hole, stop digging. -
I was going to explain how to do it using lasers, mirrors and focusing prism's but Geoff beat me to it with his cool dial indicator.....LOLwww.hudsonmotorcar.org
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Thanks Geof. Just to confirm, +.1 is a wisker and -.1 is a smidgen. Seriously I was wondering the same question. So thanks. I went for a drive thru the steep Adelaide hills recently and wasnt impressed with the slow speed going over the top. Was thinking about doing up a dif and changing the ratios. The diff cover on the back of my dif was welded up in the past. I guess it was because he couldnt stop the leaks.
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Hi Geoff--- Thanks for your answer to my post. It is a lot quicker. Hope you are feeling well & of course you are an asset to the club as well. Hudsonly---Cliff Minard.
