So I've been happily tooling around with the B18/M40 from the parts car. Its been great, until today...

The M40 that was in the car had bad synchro's and the speedometer has never worked since I have owned the car. I now think I know why the speedo failed.

Car was originally an automatic and the conversion method caused the speedo cable to exit at a very sharp angle, real PIA to install. The parts car M40 had been working fine along with the speedometer since I got it going a couple weeks ago.

Yesterday I noticed a slight rubbing sound I couldn't identify. Sounded kind of like a brake pad when its getting worn. Intermittent with the speed of the car, but would stop when I released the clutch. Wasn't really loud or very menacing sounding so I thought I would try to track it down on the weekend.

Today I was driving about 40 miles an hour and heard a metallic "PING" and then the sound like something might be dragging on the ground. Pulled over and looked but could find nothing visibly wrong. Got back in and started driving but the "bad" sound was back so I stopped, checked again, found nothing. Started driving again to see if I could localize the sound and noticed the speedo was not working.

I then pulled over and called a tow. Probably drove a total of six blocks since the "ping". Thought something might be broken and loose in the M40 and didn't want it to get in the gears. Clutch engages fine and the car shifts fine but there are bad sounds coming from down there.

So is this the speedo drive gear failure? Any ideas?

I'll be pulling the transmission tomorrow and wanted to get ideas as far as diagnosis and remedy.

I still have the M41 I was planning on installing eventually but need to shorten a driveshaft and re-do the transmission crossmember arrangement of the PO. But at this point that might be the same amount of work as fixing the speedo drive.

Counseling will be appreciated. I'll be drinking English Bitter until I hear any suggestions.

Thanks,

-Mario E.
Lawrence, KS