Ratio maths.

Hat · May 8th, 2015, 18:04

As I don't have a tachometer in my Amazon I wonder what revs I am pulling on the motorway, I'm guessing there are some mathematicians amongst the classic Volvo community...
Mine is a 67 with overdrive and a 4:10 rear axle and has standard wheels and tires, what sort of revs would I be at when driving at 70mph in OD do you recon?

Volvo_133 · May 8th, 2015, 19:05

I have similar set up, 1970 B20, 4.1 axle, d type o/drive.
My rev counter will be 3000 ish at 70 mph.
Chris.

Hat · May 8th, 2015, 19:38

Ah thank you.
What rev limit do you set yourself?

Volvo_133 · May 8th, 2015, 20:02

Hi,
I live at Sheffield which has many steep hills. I find once i hit 4000 revs ( in any gear ) it is time to change up, as the car pulls as well in the next gear up..
40 mph is also my minimum speed with the overdrive on.

Hat · May 8th, 2015, 20:20

Oh yes I know the challenge of hills, I go to Dorset often, the high final drive is good on the motorway, but I have once run out of gears to change down to on a particularly steep hill..

Volvo_133 · May 8th, 2015, 20:33

I once tackled the uphill climb at Porlock in a 1961 Austin Westminster towing a caravan. I ran out of momentum in first gear. I had to slip the clutch in first gear to eventually reach the level road. The stench from the clutch!!!! Happy days.

ChasesDragons · May 9th, 2015, 11:13

Hope this helps all in some way.

GEAR RATIO CALCULATOR and more

Derek UK · May 9th, 2015, 11:32

More specific.........

jamie · May 9th, 2015, 15:40

Derek, thanks for that. I never realised that the D and J type had different ratios, I thought the only difference was the J was more robust and smoother, probably just subjective.

May 8th, 2015, 18:04	#1
Hat Senior Member Last Online: Feb 18th, 2017 15:16 Join Date: Mar 2014 Location: essex	Ratio maths. As I don't have a tachometer in my Amazon I wonder what revs I am pulling on the motorway, I'm guessing there are some mathematicians amongst the classic Volvo community... Mine is a 67 with overdrive and a 4:10 rear axle and has standard wheels and tires, what sort of revs would I be at when driving at 70mph in OD do you recon?

May 8th, 2015, 19:05	#2
Volvo_133 VOC member Last Online: Apr 22nd, 2024 18:48 Join Date: Jan 2008 Location: Sheffield	revs I have similar set up, 1970 B20, 4.1 axle, d type o/drive. My rev counter will be 3000 ish at 70 mph. Chris.

May 8th, 2015, 20:02	#4
Volvo_133 VOC member Last Online: Apr 22nd, 2024 18:48 Join Date: Jan 2008 Location: Sheffield	rev limit Hi, I live at Sheffield which has many steep hills. I find once i hit 4000 revs ( in any gear ) it is time to change up, as the car pulls as well in the next gear up.. 40 mph is also my minimum speed with the overdrive on.

May 8th, 2015, 20:33	#6
Volvo_133 VOC member Last Online: Apr 22nd, 2024 18:48 Join Date: Jan 2008 Location: Sheffield	steep hills I once tackled the uphill climb at Porlock in a 1961 Austin Westminster towing a caravan. I ran out of momentum in first gear. I had to slip the clutch in first gear to eventually reach the level road. The stench from the clutch!!!! Happy days.

May 8th, 2015, 19:38	#3
Hat Senior Member Last Online: Feb 18th, 2017 15:16 Join Date: Mar 2014 Location: essex	Ah thank you. What rev limit do you set yourself?

May 8th, 2015, 20:20	#5
Hat Senior Member Last Online: Feb 18th, 2017 15:16 Join Date: Mar 2014 Location: essex	Oh yes I know the challenge of hills, I go to Dorset often, the high final drive is good on the motorway, but I have once run out of gears to change down to on a particularly steep hill..

May 9th, 2015, 11:13	#7
ChasesDragons Member Last Online: Apr 12th, 2024 10:39 Join Date: Oct 2011 Location: NW	Hope this helps all in some way. GEAR RATIO CALCULATOR and more

May 9th, 2015, 11:32	#8
Derek UK VOC Member Last Online: Yesterday 14:24 Join Date: Jul 2006 Location: Chatham	More specific.........

May 9th, 2015, 15:40	#9
jamie amazon1954 Last Online: Mar 10th, 2021 20:19 Join Date: Dec 2002 Location: Bath	Derek, thanks for that. I never realised that the D and J type had different ratios, I thought the only difference was the J was more robust and smoother, probably just subjective.

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