Speedometer Needle Bouncing

For all those wiring gremlins we love, this is the place to discuss them.

Moderator: Board Moderators

Post Reply
rogbmw
Junior Poster
Posts: 61
Joined: Tue Mar 28, 2023 17:23
Model: Lotus Excel SE
Colour: White
Year: 1987

Speedometer Needle Bouncing

Post by rogbmw »

Any suggestions on what would cause the speedometer needle to quickly bounce up and down between 0 and around 20 kph until the speed has passed that?

John
Regular Poster
Posts: 140
Joined: Tue Aug 06, 2013 13:16

Re: Speedometer Needle Bouncing

Post by John »

Could be the speedo cable is binding at low speed, also check that it's secure at both ends. There's also a speedo drive off the gearbox, I think it's mentioned in the service schedule as something to oil or grease periodically. If cable and drive are good it may be an early sign that the speedo is going to need attention. Mine needed a rebuild a few years back after similar symptoms to what you are seeing, but it could just be a cable/drive issue so worth checking that first.

Cheers John

User avatar
rbgosling
Senior Poster
Posts: 1720
Joined: Sun Jul 04, 2010 22:55
Model: Lotus Excel SE
Colour: Midnight Blue
Year: 1990
Location: Rugby

Re: Speedometer Needle Bouncing

Post by rbgosling »

Like John says, primary culprit is binding speedo cable - get some oil in there, if the inner cable can be withdrawn from the sheath (can't remember if this can be done, but it may be possible) you can lube it much better. Also check the cable routing, should be as smooth as possible with no kinks or tight bends.
"Farmer" Richard

1990 Lotus Excel SE (Lilith)
2022 MG MG5 EV (not due to be a classic for quite a few years...)
2011 Nissan Leaf (Ragly - EV pioneer, must be due to be a classic one day)

rogbmw
Junior Poster
Posts: 61
Joined: Tue Mar 28, 2023 17:23
Model: Lotus Excel SE
Colour: White
Year: 1987

Re: Speedometer Needle Bouncing

Post by rogbmw »

Thanks for the suggestions. The speedo is fairly new, and was replaced shortly before I purchased the car. I will give lubing a try.

Zag
Regular Poster
Posts: 100
Joined: Mon Aug 28, 2017 04:35
Model: Excel SE
Colour: Ice Blue
Year: 1986
Location: East Yorkshire

Re: Speedometer Needle Bouncing

Post by Zag »

As it's a replacement then I'd reckon something not quite right with the routing. As above check for tight bends / kinks etc. That said while it's apart no harm in a bit of lube.

Does it tick as this is often a sign of too tight a bend?

supraholic
Junior Poster
Posts: 61
Joined: Sun May 29, 2022 21:47
Model: Excel
Colour: Blue
Year: 1986
Location: Fort Worth, TX

Re: Speedometer Needle Bouncing

Post by supraholic »

At least for the Toyota Supras, the common culprit is an elbow off the transmission speedo gear drive. Haven't looked yet to see how the Excel's speedo cable is connected and routed. The Supra w58's got a sharp, almost 90 degree elbow while the a43d's got a less problematic smooth arc elbow. Both work the same way tho, just a flexible cable that runs through them and eventually wears out at least in part because the old soap grease inside it dries out.
Phil - 86 Excel SE

KevW
Senior Poster
Posts: 1689
Joined: Sat Jun 16, 2007 23:20
Model: Excel SE
Year: 1992
Location: Newcastle Upon Tyne, England

Re: Speedometer Needle Bouncing

Post by KevW »

My car also does this every now and then. This is despite having my speedo reconditioned and fitting another speedo cable. I took care to well lubricate the cable before fitting and have tried re fitting the cable at least four times at both the speedo and gearbox end to no avail.
Kev W no.282

Post Reply