overdrive and pre-ignition

first of all overdriveproblem: I assembled 1 overdrive out of 2.Now there is a singing noise comming underneath the car (gearbox). The noise is there always when driving but only when driving in overdrive it is louder .I removed the overdrive and the noise is gone.I 'm talking about an overdrive fore a serie 3. Question: what is the normal amount of noise this overdrive is ment the produce or is this normal when you construct 1 out of 2 systems and what to do about it?

Next question : I 'm talking about the 6 cilinder 2600cc inlet over exhaustvalve engine. The car is equiptto drive on LPG as well on petrol. The normal adjustment of the static pre-ignition is 2° BTDC with octane 83. What is the setting for modern fuel (95 98 or LPG 110 octane). I set the static pre-ignition now on 5° BTDC.

Thanks at advance

Well I don't know what noise to expect, my landie sounds like a vintage bus negotiating the Burway when I am changing gears. (yes I have encounted vintage buses on the Burway)

How do I know what is right or wrong who has spent to long in luxury automatics ?

BTW thirsty buggers aren't they, landies and limos both.

On or around 10/10/03 7:21 pm, Larry using , in article ID bm6tv4$is48f$ snipped-for-privacy@ID-129032.news.uni-berlin.de, scribbled:

Nothing like a Tdi or a Td5 for fuel economy (40mpg on normal roads!)