Speed/Rev ratios & Speedo

[Nick C]

My speedo doesn't work at the moment, so I was wondering whether anyone had any rev/speed convertion tables? I.e. how many revs you should be doing in a given gear at each of 30/40/50/60 mph.

Also, how do you get the cable off at the Overdrive end? I've got the other end undone easily, but I can't get the bottom undone - it looks to me like a knurled collar I have to undo? I can't get it to budge however, and I can't see by looking at the new cable how it goes on, the new one (from Rimmers) looks different at both ends to the old one, yet I've double checked the part number against their website (It's a '77 1850 with Overdrive)

Cheers,

Nick

[Lewis]

I had a right kerfuffle with cables earlier this year....my donor was reputedly a '78, so I got the after 77 cable. This didn't fit. So I got the earlier one. That wasn't right earlier.

On eBay I saw one that looked the same as the one I tore off, so I bought that which worked. Think it was listed under Stag parts! Worked lovely mind...

My OD end had a small metal bracket that was screwed into the box, securing the cable end in place. May be what you have?

[2F45T4U]

My 77 1850 has a broken speedo too

It's a non O'D but in 4th gear if you drive at 1500rpm past 30mph speed cameras, 2500rpm past 50mph ones and 3500 on 70mph Mways you'll be ok

[Mad Mart]

Does yours look similar to this:-

http://cgi.ebay.co.uk/TRIUMPH-DOLOMITE- ... 0029073527

I know the Sprint ones have a small fork type bracket with a bolt in, as per Lewis's description. Not sure if the 1850 is the same.

[Neil907]

If you know the ratios you can use this to work it out.

http://www.kabamus.com/garage/gears.html


Neil

[Neil907]

for 1850

final drive 3.63

1st 2.65

2nd 1.78
2nd od 1.42

3rd 1.25
3rd od .996

4th 1.0
4th od 0.797

[2F45T4U]

46mph in 1st

64mph in 2nd

95mph in 3rd

and in mine 111mph in 4th

[1300dolly]

is that 111 on your speedo or with a speed check?
more likely to be nearer 105.

[2F45T4U]

well thats against the rev counter, that was accurate to the speedo (that was broken when the car was taken flat out along the autobahn ) and the speedo was accurate to a GPS.

Mines not quite a 91hp 1850 anyway

[1300dolly]

i wasn't having a dig at you but speedos are not normally accurate.

[Dollyboy]

usually up to 5mph out, most commonly reading faster than you're actually going

[xvivalve]

Unless its a Ford 1.6L Mundano which can show 135 on the clock coming back from Ben Nevis!!

[2F45T4U]

I know someone whos had a daewoo matiz (800cc) up to an indicated 105mph! Thats on the limiter in 5th gear, with the help of gravity of course

The speedo would over read by about 15mph at 70mph.

[Jon Tilson]

is about 19mph per 1000 in top. Overdrive should be 21.5 or 23.5 dependiong on the o/d fitted. Variations for 175/70 knock off about 1/2 mph, for 185/70 add 1/2 mph.

Near as dammit from memory. There is a calulator web site somewhere for Rove SD1's that lets you type in the axle ratio and tyres to get dead on.

Jonners

[tinweevil]

I use the Mintylamb click and select gear speed calculator. A very handy site that covers gearbox, diff and tyre variations. You can look up any Triumph gear ratio here.

tinweevil