Speedo cable not working 1985 360 GLT

Will360

Hey there guys I'm working on an 85 360 and have recently replaced the speedo cable however it still doesn't seem to be working. Both the dash and cable themselves are in working so I'm wondering if it's something to do with the wheel itself but don't quite understand how it works. Any help would be greatly appreciated!

Thanks,

Will.

Forg

This is a general comment since I know zero about 360’s … but are you dead sure the spinny-bit inside the cable’s turning?

I’m not sure how easy it’d be to do, but are you able to disconnect the cable & either get someone to spin the rear wheels and see that the cable is actually turning? IMHO it’s most likely the electronics in the speedo itself at fault, but it’d be good to be totally sure that the drive in the gearbox is working.

How does the cable clip into the back of the speedo? The 240 has a round plastic clip attached to the end of the cable, you push the cable into the back of the speedo then turn the clip about 180-degrees to properly attach the cable BUT it can seem like the cable’s in properly if that plastic clip is totally missing & you didn’t realise that it should be there in the first place.
Short version - are you sure the cable’s attached properly/positively to the back of the speedo?

Major Ledfoot

Forg I’m not sure how easy it’d be to do, but are you able to disconnect the cable & either get someone to spin the rear wheels and see that the cable is actually turning?

That won't work, since the speedo drive is on the LH front wheel, I believe. 🙂 It's mechanically driven by a bowden cable attached to the wheel with a tiny C style circlip, according to 300mania.com.

Forg

Major Ledfoot That won't work, since the speedo drive is on the LH front wheel, I believe. 🙂 It's mechanically driven by a bowden cable attached to the wheel with a tiny C style circlip, according to 300mania.com.

That's even better news, sounds like it's easier than needing to spin the rear due to not needing to worry about diff behaviour etc. 🙂

An interesting combination of speed-sensor setups, though! Front wheels have been pretty common as a secondary sensor for RWD cars with traction-control ... if the "speed" at the rear is much greater than the front, cut back the power &/or apportion drive left/right if there's an electronically-controlled diff (that part's rare outside of top-end AWD cars mind you). I know 360's were entered by Volvo in rally, until the time when Volvo said "nah no more motorsport involvement for us", wonder if the speed sensor at the front wheel was in order to get a more accurate speed when (as just one example) doing Rally Dorifto?

Major Ledfoot

^ Nah, I reckon it was done that way because it was cheap. 🙂 Also, it made the speedo setup the same for CVT and manual vehicles the same by doing it this way.

IIIRC, the M47R used in the 360s didn't have any speedo drive.

I see what you mean about using such things for controlling traction control - although IIRC the latter-day Commodores used the ABS wheel sensors to do this.

Forg

Yeah the ECU in Big Red has front & rear speedo inputs so it can do some form of traction control via power limitation, and I think it’s pretty common for OEM to use the same wheel-speed inputs for ABS and traction/stability control.
The US 240’s with the ABS would use wheel speed sensors at the front?

Did all 300-series cars use a torque-tube? Possibly yet another variation which a front wheel speed sensor would standardise for.

Major Ledfoot

Forg Yeah, the US 240s with ABS had toothed wheels on the front hubs.
The 940s with ABS also have this, plus one sensor for the rear.

AFAIK, all 300s had a torque tube, although the B19 / B200 versions had bearings in the tube too.
Never owned a 360 because drum brakes are against my religion.