tyres..... also tachometer

[phatmendus]

hi,

please can somebody give me some simple info on tyres.

I have an elan plus 2 where I need to replace some very old tyres. At the moment they have 165 on the car, but I hear that 185's can be fitted.

Please can somebody give me a right tyre size to fit to the car, if buying a mid range tyre. I would prefer 185's but are they fesable and do they offer a better perfomance?

One more question. My elans tacho does not work. I have luminition and an alternator. It is the standard smiths dial one fitted. I have read some posts saying they wont work. Why? can I make it work and where does it get the current from?

Would be grateful if someone could help on both questions.


Many thanks

Simon

[rgh0]

Simon

On a plus 2 you can fit most tyres up to 175 section. 185 section tyres get close to the rear spring platform on the strut and may foul it depending on the exact tyre size and width. The platform can have a little taken off its outside lip with a grinder or be "formed" with careful hammering to fit tighter around the base of the spring and then most 185 section tyres can be made to fit also, if you fit smaller diameter rear springs and supports then no problem with 185 section tyres.

For a road car 165 or 175 x 70 is probably the best profile unless you have a 3.55 diff and a 5 speed box however no reall sticky rubber tyres made in this profile. 175 or 185 x 60 gives you the best choice of performance rubber but with a 4 speed box and normal 3.77 diff the overall gearing is low with the smaller diameter tyres and you use a lot of revs on the freeways.

The tacho should work fine with lumenition and an alternator ( it does on my plus 2). The wiring needs to be done right when the lumention was installed however.

In particular check that the original ignition positive supply to the coil goes only to the ignition coil still , the tacho senses the current pulses in this wire as it passes through the tacho first and will misread if this wire has any other loads on it. The power supply to the lumenition must not be taken off this wire but off an independent 12 v supply.

Rohan

[blueseamonkey]

There is some info on tachometers on this part of the site
http://www.lotuselan.net/publish/bouncing_tach.shtml
You may need to change over to the other type of tachometer if yours is the wrong kind
Rick

[surveyor]

Simon,
Have you thought about going up a rim size - I'm running 185/60 x 14 yokohamas on "two gates" alloys on my plus 2 without any problems, they do look really well and the increased rim size restores the rolling radius to about standard. Lots of dry grip - more fun than grip in the wet though.

I had the same tacho problem when I installed an Aldon electronic ignition system in the Elan. The RVI tacho pickup circuit is at best marginal for electronic systems. I ended up pulling out the innards of the tacho and built a new circuit in a plastic box behind the dash. about a fiver (?5) and a couple of hours work with a soldering iron. Later built the same circuit into the actual rev counter casing of my AH Sprite. Works perfectly in both cases. I can try to scan the circuit if it's any use to you.

dennis

[Hamish Coutts]

Dennis,

This sounds interesting. Any chance of a circuit diagram? My electrical knowledge is mostly electromechanical (I was a telephone engineer years ago) but I'm keen to give it a go. There is also a Maplin store near by - and I still have my soldering iron!

Hamish.

[Roy Gillett]

I am reliably informed that the spicky tyres to fit to standard five and a half inch rims are Michelein XAS FF (stands for Formula France) They are essentially road legal race tyres. Not great for mileage but great grip. Not cheap either. In UK Longstone Tyres keep them (www.longstonetyres.co.uk) I have gone the six x 14 inch Minilite route with Yokohamas but have to refit the standard steels for Trials and Rallies.

Roy

[steveww]

Falken do a good sticky 175 x 70 x 13 tyre. Not as sticky as the Michelin XAS FF but a lot cheaper.

[phatmendus]

Is the falken tyre you suggest the 'sincerna SN828?, as this seems a nicely cheap tyre at less than ?20 each. If this is the type you are recommending then I think I will go with it. Otherwise looks like I would go with the goodyear GT2 tyre at around ?25 each.

Thanks

Simon

[tonycharente]

RE THE TACH PROBLEM
I recently sorted the Tach on my '69 Elan S4. In my case the Tach had been "all over the place" because (I think) I have electronic ignition (Lumenition) fitted, so I took the Tach to pieces in order to be able to reduce the (internal) "loop" from two turns to one to reduce the sensitivity, as suggested on various sites.
I put it back together and then wired it up again and calibrated it against a digital multimeter. There is a little rubber plug on the rear of the unit, which I removed, and then a small flat blade screwdriver poked through this hole accesses the adjuster. This is much easier to do whilst the Tach is still out of the dash.
I set it dead on at 4000 rpm - it now slightly over reads at 2000 and slightly under reads at 6000 rpm but is pretty accurate thoughout. And it's no longer "all over the place".
Cost: Zero. Time: Two Hours.
Hope this helps. Tony.

[steveww]

No I was thinking about the Falken FK-07U