Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/18/84; site mtu.UUCP Path: utzoo!linus!philabs!cmcl2!seismo!harvard!talcott!panda!genrad!decvax!decwrl!Glacier!mtu!steve From: steve@mtu.UUCP (Steve Seidel) Newsgroups: net.auto Subject: Re: Rattling odometer in 1984 Honda Accord Message-ID: <204@mtu.UUCP> Date: Mon, 22-Jul-85 10:51:23 EDT Article-I.D.: mtu.204 Posted: Mon Jul 22 10:51:23 1985 Date-Received: Thu, 25-Jul-85 02:21:00 EDT References: <6311@ucla-cs.ARPA> Reply-To: steve@mtu.UUCP (Steve Seidel) Distribution: net Organization: Michigan Tech, Houghton, MI Lines: 45 >The speedometer/odometer assembly in my 1984 Honda Accord LX hatchback >(over a year old -- hence out of warranty) seems to have developed an >objectionable rattling sound during the past few weeks. > >This sound is fairly slow (about one or two cycles per second); appears >to be directly proportional to the speed of the car; ... >-- >Rich Wales // UCLA Computer Science Department // +1 213-825-5683 > 3531 Boelter Hall // Los Angeles, California 90024 // USA > ARPA: wales@UCLA-LOCUS.ARPA -or- wales@LOCUS.UCLA.EDU > UUCP: ...!(ihnp4,ucbvax)!ucla-cs!wales I'll take a guess that the sound is that of the speedometer cable flopping over within the tube. This is a possibility if the tube is not properly routed or if the cable or tube has ever been bent. If there is too sharp a bend in the tube the cable will not rotate smoothly but tend to flop suddenly from one position to the next. This is also a possible explanation for the oft observed phenomenon of the erratic behavior of Smith's speedos (used in various British sports cars) at low speeds. (To the person with a hammer, the whole world looks like a nail. :-) ) At speeds in the range of 0 to 30 mph the needle will bounce wildly; the amplitude of the bouncing will decrease as speed increases. Part of the reason is surely the relatively taut suspension such cars tend to have, shaking the speedometer enough to cause the needle to oscillate. The needle is less affected by these vibrations at higher speeds, and thus stops oscillating, because the internal spring is more tightly wound and more effectively damps the vibrations (this is my own mechanical intuition and may bear no resemblance to actual physical laws!). But another cause of these oscillations may be that the cable is not rotating at a constant rate, varying its angular speed significantly during each single rotation. (I observed this phenomenon while recalibrating an 85 mph Jean Claybrook speedometer for 120 mph.) This rate variation is an obvious cause of erratic readings at low speeds. So if your needle wiggles, check out the condition of the cable, the tube, and their routing from the transmission to the speedo. But don't get me wrong. I didn't say that the wiggling needles of Smith's speedos can be remedied (they may be inherently too sensitive) but for ten years I've wondered why my MGB's does this and I think I finally figured it out, so I thought I'd pass it along. -- Steve Seidel Michigan Technological University uucp: {lanl, ihnp4, glacier}!mtu!steve arpa/csnet: steve%mtu@csnet-relay