Gearbox on S1

[RichardF]

I was led to believe that with the standard 4 speed 'box at 70mph the revs would be around 4000rpm and that a 5 speed box gives better/more comfortable touring by, presumably, lowering the rpm's at cruising speeds. I have the 4 speed box and my rev counter reads 2,500rpm at 70 - could it be out?

[Heuer]

Depends on what rear axle you have: 3.54; 3.07, 2.93, 2.88 etc. If it is of any value I have a 2.88:1 rear axle with a T5 gearbox (0.8:1 in top) and shows 100 mph at about 3,000. If you have a standard box and diff I would expect your revs to be higher - the service manual has the exact details. Could be the speedo is wrong (see here: http://etypeuk.com/forum/viewtopic.php? ... ght=speedo) The rev counter works on pulses sent by the tach generator on the rear camshaft cover and is about 5 volts per 1,000 rpm if I recall correctly. The generators do fail and result in lower RPM but unfortunately the replacements are also error prone. Best way is to use the service manual to calculate what your RPM should be and work from there. Bottom line - I would expect 3k or higher at 70mph

[daverawle]

Hi Richard,

Before you start digging too deep; do not believe what the S1 rev-counter is telling you. It may be right'ish but is just as likely to be way out. Find an alternative method to measure engine revs before you spend any money or waste time.

Dave

[RichardF]

Thanks, it was only a point of interest. I did check the speedo against a moving modern car so I know that it is about right. Does a 5 speed box make for more comfotable touring?

[Heuer]

Richard

I use a portable Sat Nav to give me speed readings, especially useful abroad in Km/h. The 5 speed is a big improvement for touring as it gives you, in effect, an overdrive gear. The advantages are many:

1. Lower noise on long trips, especially on the continent
2. Better fuel consumption so less frequent stops - I get an average of 20mpg at 90 mph
3. Lower engine revs means lower temperature and vibration - an aid to reliability
4. Slicker gear change so you will not 'beat the synchro'

Having done 20,000 miles through Europe in our car the golden rules are safety and reliability. The former through less driver fatigue, the latter through keeping heat and vibration to a minimum. Ask Harry for a go in his new E-Type Fabs 5 speed demonstrator if you are interested.

[daverawle]

Thanks, it was only a point of interest. I did check the speedo against a moving modern car so I know that it is about right. Does a 5 speed box make for more comfotable touring?

Richard,

Not sure if you have a 3.8 or 4.2l engine and it could make a difference to your choice of box. It?s only subjective but this is what I experience with my 3.8l and a 5 speed box; my 5th gear ratio is 0.81and the diff is 3.31:1.

At 60 mph in 4th gear (1:1 in all boxes I think) I have 2500 rpm and the engine is very smooth ? just humming. If I then select 5th the revs drops to around 2000 rpm which is actually the noisiest part of my engines rev range so I generally remain in 4th until around 70 mph. So for me, with a 3.8l engine, 5th gear is purely for motorways and high speed touring, when I have the feeling that I?m conserving the engine and reducing the fuel consumption. A 4.2l may behave differently but if you have one then you?ll have the all syncro box and I wouldn?t bother to change it.

Dave