Type 9 speedo drive gear

[bingham]

I bought a Caterham late last year after it spent a few years off the road. It's all recommissioned now ( including a top end rebuild and remap courtesy of the excellent Northampton Motorsport ) but it still doesn't have a working speedo. It came with no cable angle drive or quill so I replaced them and turning the quill works the speedo but the quill doesn't turn with the wheels. I presume originally the angle drive or cable seized causing the nylon speedo drive gear to strip and the previous owner began taking the broken bits off. 

I've spent an hour under the car trying to get the drive cover off to no avail. Can I cut a hole through the cable drive side and use a drift to knock out the drive gear pushing out the cover or is it engine out gearbox out to do? Or speedo off to Caerbont to have the dial swapped into an electronic Hall effect type and put magnets on the prop shaft. I'm loathed to do this as it will spoil the originality of the car.

Opinions and suggestions would be welcome from the sages of Blatchat!

[Jonathan Kay]

Can be done in place. I think that you can create some lateral play to improve access if needed by loosening the gearbox mount. 

Previous discussions with hints: 1,2.

Jonathan

PS: We don't hate you! :-)

[ECR]

Another possibility is that the drive gear on the shaft in the gearbox has come loose which does happen as it's only a push fit on the shaft. If the car has ever been raced it's quite possible to have no drive gear in the box and no speedo.

Both of the above require the gearbox removed from the car to rectify so I hope they are not the problem you face

[bingham]

The drive gear is there I think as the quill engages the drive gear. I've been trying to get a jeweller's screwdriver under the cap but hadn't though of loosening the gearbox mount. I hope that will help. Probably easier with the car on a lift.

[Wrightpayne]

Would tapping the drive spindle knock the cap out?

[Nigel Riches]

I recall removing the cap which holds the speedo output gear in place, with the gearbox on the bench, and some substantial levers and drifts, it was not a jewelers screwdriver job ! There is probably the best part of 15mm engagement of that cap, and it's a mallet fit to reinstall it.

From what you describe it does sound like the "plastic" speedo gear has lost contact with the gear on the output shaft, and unfortunately the easiest way would be to put it on the bench, unless you're seriously into 7 masochism. it would also allow you to install a new seal where the shaft exits the 'box.

As you say, you could send it to Caerbont for a transplant, retain the original dial appearance, ok, the gubbins underneath ain't original, but outwardly you are going to save a lot of blood, sweat and tears Got to balance up the cost / benefit ratio, some time and muscle from you getting the engine out, not too bad a job, replace the drive gear, learn some stuff about your car, versus, send the dial to the wizards in Wales, and buy the bits to convert to electronicatrickery, probably not cheap. 

Your car, your wallet, your time.

Regards.

Nigel.

[bingham]

Thanks for the info Nigel, you've confirmed my suspicions. I'll try from underneath with the car on a lift for an hour and if that fails to do it properly will be engine out. 

[CharlesElliott]

I often wondered whether the Caerbont speedo already had an input for a hall effect sensor - generally their speeds have.

Having said that, I think the issue with the Caterham one would be the limited calibration, even if the sensor input was there.

If you find out, please let me know!

[bingham]

Mine won't ( 1998 car ) as it's got a mechanical odometer. I suppose later ones with an electronic odometer might.

[Terry Field]

Apologies, but I don't fully understand the problem.

However, I had a problem following a rebuild where the speedo worked with the wheels jacked up off the ground, but not when on the road.

I had numerous people try to fix it ( including the wonderful Redline) but to no avail.

I eventually worked out that there are two ways to assemble the drive; one is to push the quill into the angle drive and then mount the whole unit onto the gearbox. The other is to push the quill into the gearbox and then put the angle drone onto the quill and connect it to the gearbox.

Unfortunately I can't remember which one worked, and certainly never found out the reasoning behind it!

However, it might just be worth a try to see if either method works for you.

Cheers

Terry

 

 

[bingham]

Well after a couple of hours under the car I got the cap off and the 24 tooth drive gear out. Not an enjoyable job.Then I found there was no output shaft speedo drive gear fitted! The box was rebuild by Phil Jones before the car went into hibernation so I suppose it wasn't fitted then. The adaptor plate and drive gear may have been put back in to reduce any leaks from the speedo drive hole. So I just changed the seal and cap and put it back together.

I'll see if Caerbont can make a Hall effect one with the right colour face or can swap my face in. All in all slightly frustrating.

 

[Jonathan Kay]

I'll see if Caerbont can make a Hall effect one with the right colour face or can swap my face in.

There are three trusted speedo fettlers. Let us know if you can't find them in the archives.

Jonathan

[ECR]

Oh dear ! .......