Revvy 3h Gearbox...

[Rusty-Bretta]

Hi, my 3h gearbox seems to be a lot more revvy than the quoted figures... puzzled me for the past few years...
Westfalia Club Joker - was a JX lump
3000 rpm = 50 mph
3500 rpm = 60 mph
All rpm are taken from the Vans rev counter.
Did they do different spec 3h gearboxes or, is it possible someone has changed its internals. It was the original box from the van and I can't see why anyone would have changed the internals.

[Oldiebut goodie]

Maybe the alternator and pulley were changed?

[Rusty-Bretta]

Hadn't considered that... Any idea what should the original one be? Can I identify it... Suppose I could test the rpm with a separate tacho

[Bigjcc55]

On my aaz converted panel van the Rev counter showed way higher than a true reading.
I had the golf belt and alternator fitted. (Flat belt)
You can adjust the Rev counter by the little screw on the back.

[Rusty-Bretta]

Thanks for the replies, I suppose I could recalibrate it with available data on the gearbox, wheel size and GPS speed. Tickover sits around 1000rpm which I assume is correct. ..so that may indicate a gearbox related issue I suppose... Not straight forward on the converted diesel motor... it was a jx but us now 1y... not sure if any of the pulleys were changed... I'll check with the fitters...

[Oldiebut goodie]

Buy a cheapo rpm counter from ebay and check that indicated 1000 tickover first - sounds high for tickover to me. I would expect 750-800 area. ( I haven't one in the van so can't check mine without marking it and checking)

[pirate-pete]

Have not tried them myself but what about a tacho app for a smartphone?

The phone listens to the engine tone and from the frequency should be able to calculate the rpm. You'd at least have to tell it it is a four cylinder maybe other parameters.

I used to (and probably still have) hand held tachos that ran off the spark ignition but they would be no good for diesel.

[colinthefox]

You can check your tacho by using a neon indicator light connected to the mains. A diode in series makes it easier to read.

By the pulsing light of the neon, a mark on your engine crank pulley will appear stationary at 1500, 3000 and 6000(!) RPM precisely, accurate to better than 1%.

This is due to the nice people running the National Grid at a phenominally stable frequency of 50hz. In the last hour it has been 50hz +or- 0.2%

Be careful.

[Oldiebut goodie]

For the sake of £10! http://www.ebay.co.uk/itm/DT-2234C-Non- ... Sw0vBUacUW cheaper direct from that place in the Far East.

[Rusty-Bretta]

Fellas, great idea's.... the £10 fleabay deal looks good...my history with 240v is not good.... ... Ill purchase one and check out the current idle and work from there.. might get an app and compare the two... it'll be interesting to see what's going on here.... I love a mystery and solving it...

[Rusty-Bretta]

The laser rev counter did the job.... the dash rev counter wasn't far off... tick over was 934 and the dash rev counter was over the thousand mark... bigger difference at 2000 rpm with over 200 rpm difference. Adjusted the rev counter to closely match the laser reading. Still means I have a revvy 3h gearbox which is mad.... stil it's a positive negative if you know what I mean....
Thanks for all your contributions fellas....

[shepster]

Get some bigger tyres for the rear.

[Mr Bean]

Maybe the alternator and pulley were changed?

Alternator - surely not!
CS

[Oldiebut goodie]

What does that mean?

[Rusty-Bretta]

Still no idea what is going on with the gearbox...
The £10 rev counter was brilliant... good spot...