Speedo not working after 4AGZE swap

[BIGBOBO]

I had to move my car yesterday (moved) and took it out on the road for the first time after swapping in a SC engine.

Now I noticed the speedo isn't working but the tach does. Anyone knows what's up?

I'm using the SC gearbox and brought the SC cable from the parts car when pulling the engine but I can't remember if I swapped it over. Is there any difference in speedo cables?

[kaiowas]

The speedo drive at the gearbox end is a common failure point on SC gearboxes, it's only a plastic gear and tends to come apart. Assuming you've already checked that you attached the cable during the swap (these sort of thing are easily missed!) then it's the next thing I'd be checking

[BIGBOBO]

Don't the tach and speedo work using the same cable?

[elbon50]

Don't the tach and speedo work using the same cable?

The tacho is electrically operated

Doesn't use a mechanical drive

Mechanical speedo drives are a bit archaic these days

[BIGBOBO]

So can this gear be replaced without pulling the gearbox out?

[kaiowas]

Yes, although I believe there is a knack to it. Not done it myself so I can't really add much more so I'll try and send an expert this way.

[SySanguinary]

So can this gear be replaced without pulling the gearbox out?

Yes it can, although it's a right faff though.

Before all that though, check your cable works. Take out the end out of the gearbox and spin it with your fingers whilst looking at the dashboard. If you have movement then the cable is good. Next jack the car up at the back end and spin the wheel (both if you don't have an lsd. Have a look at the gearbox cable mount. Can you see the inside of it turning? If so that's working fine too, so the cable may not have been fastened in fully.

If it's not turning, then the speedo drive in the gearbox may be knackered. You can remove it by undoing the 10mm nut on the back of the housing, just below where the cable attaches. It will just about come out of the box before you run out of room on the rear firewall... and I mean just.

[BIGBOBO]

Ok thanks for all the information, Ill check it when I find some time .

[Kateg28]

I just wanted to say that it happened to me twice....

First time we (I say we, I sat and watched whilst someone else kindly did it for me, but I was very supportive! ) changed the plastice gear but very quickly it happened again so we realised the housing was chewing the white plastic gear (sorry for the overuse of technical terms) so we replaced some metal that had the white plastic in it (note use of 'we' again along with technical terms ).

You might want to consider replacing the metal housing thingy.

Glad to have been of help.

[SySanguinary]

[coanda]

You can still get the gears new. They are the same as the ones in early 3sgte cars.

TCB Parts still list the three key parts (key, drive and housing) on their website - that's where I got mine.

[BIGBOBO]

Finally found some time to check what's wrong.

Turns out the gear is still good but the key is just completely missing. No idea where it went. It might have dropped on the floor while taking it appart but I couldn't find it and didn't hear it drop.

Also, if you got a mk1a chassis with a swapped E51 trans you need to loosen the front and rear engine mounts so you can turn the engine enough to get the housing out.

[BMR2L]

You can still get the gears new. They are the same as the ones in early 3sgte cars..

Thinking I should get a spare whilst they are still available but the 3SGTE part is listed as 30 teeth and the Mk 1 one as 31 teeth. So that'll be 1mph out at 30, 2 at 60, 3 at 90...

Did you notice any difference? Is it a reduction gear? My mph speedo is under reading so less reduction would help me.

-AL

[jimi]

the 3SGTE part is listed as 30 teeth and the Mk 1 one as 31 teeth. So that'll be 1mph out at 30, 2 at 60, 3 at 90...

I'm curious, how did you work that out ?

[jimi]

They are the same as the ones in early 3sgte cars.

Even more curious where that info came from ? They are not the same part number according to my copy of the EPC and the ratios are different
AW11 = 31/35
3SGTE = 30/35

[ulysess1966]

I had to replace the key on mine. Apparently it was designed as a fail point if the right-angle drive seized, which is very common. Mine had seized up with gunge and old oil, but I got it free with a can of WD-40 and an afternoon turning it by hand in front of the TV. Mind you, that was nearly 10 years ago and it has been fine since.

[BIGBOBO]

I had to replace the key on mine. Apparently it was designed as a fail point if the right-angle drive seized, which is very common. Mine had seized up with gunge and old oil, but I got it free with a can of WD-40 and an afternoon turning it by hand in front of the TV. Mind you, that was nearly 10 years ago and it has been fine since.

I submerged mine in diesel for a day or two. Would turn again afterwards.