Speedo Drive

[roy1944]

The speedo on my S1 has packed up and on investigation it seems to be at the gearbox end which seems dificult to get to and would mean removing the upholstry around the tunnel.
Has any one had a simular problem with the angled speedo gearbox entry. I have read about horendous problems inside the gearboxes which can cause the speedo to stop working
In the mean time before its fixed is there a chart that will give the cars speed going by the rev counter

[ChrisC]

I cant answer the question but you could always use a mobile GPS device (TomTom etc) to map speeds to your revs...

[daverawle]

Roy,

The right-angle drive sometimes fails, often due to an un-lubed cable or sticky speedo head. Replacements are available, if you are buying on ebay make sure to get the 1.25:1 ratio one. Taking the seats and upholstery out isn't a big deal, getting it back so the centre dash panel hinges is the hard part. You need to do this at service time anyway to get at the front uj.

Dave

[paulj]

Hi I also had it fail
changed the right angle drive, and all was good
a bit of a fiddle but changed from under the car,
hope you find it
Paul

[GSR 54D]

Regarding speeds from the rev counter: There are tables in the original car handbooks. If your car has original gear box and 3.07 diff. I will look them up on Friday if you wish.

John H

[chuffer]

Roy, mine hasn't packed up but the speedo needle is wavering about too much so I bought one off ebay for peanuts. It served one purpose in that it proved that the angle drive was indeed the cause of the needle wavering. However, the one I bought was 1:1 whereas I also need a 1:1.25, which is what is on the car now.

My parts book tells me that the item fitted to a 3.8 Series 1 is numbered C17087 but when I ask a vendor of these parts he says that part is 1:1.

Does anyone know if he is correct or misinformed? What's the part number for 1:1.25?

cheers
Ray

[Heuer]

Ray

The usual cause of a wavering speedometer needle is the cable rather than the gearbox. Worth starting with a new cable and being very circumspect in the routing to avoid tight curves. Some people fit the 2+2 cable as it is longer so allows a larger circumference curve. Easy enough to test as rolling the end of the inner cable between finger and thumb will make the needle jump if it is not right.

As regards the the speedometer drive gearbox itself there is only one type as far as I know. The speedo's were calibrated differently to match the various diff ratio's and types of tyre. Each speedometer will have a code number on the face which relates to the matching final drive, mph/kph and tyre size. If you buy a different one you will need to have it recalibrated by Speedograph Richfield or similar. Full list of speedometer codes is here: http://etypeuk.com/forum/viewtopic.php?t=951

[steve3.8]

Hi Ray,
angle drives are available here and they will know the ratio

http://www.speedograph-richfield.com/

although a little pricey at ?94 i would like to think they are engineered better than others,thus maybe also putting less load into the T5 [derived] gearbox-----talking of how is the conversion ? has all gone well?

regards Steve

[daverawle]

Roy, mine hasn't packed up but the speedo needle is wavering about too much so I bought one off ebay for peanuts. It served one purpose in that it proved that the angle drive was indeed the cause of the needle wavering. However, the one I bought was 1:1 whereas I also need a 1:1.25, which is what is on the car now.

My parts book tells me that the item fitted to a 3.8 Series 1 is numbered C17087 but when I ask a vendor of these parts he says that part is 1:1.

Does anyone know if he is correct or misinformed? What's the part number for 1:1.25?

cheers
Ray

Ray,

That is the correct number for a 3.8 car and the ratio should be 1.25:1. I don't know what works on a 4.2 car which has the number C25547, maybe that's 1:1. I suggest you get one from SNGB as they will change it or refund you if it's wrong.

I think the 1:1 ratio ones were used behind the dash on some other models to get the cable lined-up with the speedo, certainly those abound on ebay.

Dave

[chuffer]

Thanks to everyone for the feedback re the angle drive. Before I was able to determine which one to buy the old one packed in altogether! So, like Roy I had a speedo with the needle well and truly at rest. Fortunately I knew this was totally down to the angle drive because it had, in its previous life attached to my Getrag box, had its squared input shaft ground down to a metric size so it was only a question of time before it started slipping in my new T5, which has imperial dimensions.

So I?ve fitted a new drive and taken David?s advice and replaced a slightly-kinked cable as well. I?m pleased to be able to say that for the first time in 3 years I now have a speedo reading which is both accurate and stable.

However, on my way to this pleasing outcome I had to do a bit of digging about which angle drive to buy and daverawle helped greatly by providing the speedograph-richfield URL. From that I moved onto this one:

http://www.nisonger.com/smiths-parts.htm

and between them I think I can shed some light on Jaguar?s use of gearbox-connected (not speedo-connected) angle-drives and clarify their use. Firstly, it is clear that the angle drives are made by Smiths and that three were in use across most of the Jaguar range in the 60?s and early 70?s.

Probably the most popular was the drive with Smiths part number BG2402-07 and this has an input/output ratio of 1:1. It was used in most of the saloons of the era and probably gives rise to the assumption that Jaguar used a 1:1 angle drive predominantly but it is not true to extrapolate that they therefore used them in the E Type.

The E Type seems to have used two drives throughout its life; Jaguar part numbers C17087 for the Moss box cars and C25547 for the rest. These drives equate to Smiths part numbers BG2402-02 and BG2402-08 respectively. It is important to note that both of these have an input/output ratio of 11/14, or 1:1.27. So the statement that the E Type used only one drive throughout its life is not strictly true, but it did have only one ratio and changes to the speedo head catered for the various diffs and the markets into which they were sold.

I now have all three drives and the photo below shows the differences.


The two E Type drives (extreme ends) differ only in the length of the input shaft; the early one being just over an inch long and the later one being approx 5/16?. The later one (C25547) is the only one available from Barratt?s and US suppliers now, along with the statement that it fits all cars. This is undoubtedly true and I have fitted it successfully to my T5 but from an engineering perspective, I would have preferred the longer shaft ? we?ll see how long it lasts.

Note that in all other respects, including the threaded connections, the drives are identical externally. The centre one is the BG2402-07, with a ratio of 1:1 and input shaft about 7/8? long.

Finally let me apologise to Roy for hijacking his thread but I hope this has perhaps helped him in his quest for a working speedo.

cheers
Ray

[PhilBell]

What's the best way to access and remove the speedo drive ? from the top by removing the trans tunnel or from below?

The speedo needle used to waver madly until it stopped moving completely.

The evidence points to the drive. I removed the speedo gauge then withdrew the cable from the sheath to find it undamaged. Sticking one end of it in the speedo and twirling the other end of the cable makes the speedo needle move ? I can achieve 20mph by hand ? suggesting the gauge is working.

I also reinserted the cable in the sheath and found it rotated freely in the sheath with no tight spots. I then pushed the cable fully home until it engaged with the speedo drive, at which point I couldn't rotate it. I was expecting it to turn in the speedo drive, showing that the drive was broken.

That still leaves the drive as needing further investigation so I'm planning to remove it and send it to a specialist for checking.

Any advice most welcome

[Heuer]

To remove the drive completely means removing the engine and gearbox. You can remove the speedo drive gearbox from below but it will mean removing the silencers and the gearbox support bracket. This will allow you to lever the gearbox sideways enough to get a small hand in there to undo the knurled collar. It will make the job easier if you also remove the seats, radio console, centre console and gear box cover so you can get the best purchase on the knurled sleeve.

I assume you have not got a T5 gearbox otherwise that is a completely different, and bigger, problem.

[christopher storey]

If your car still has the Moss box you should be able to gain access to the drive by pulling off the carpet on the left hand side of the gearbox tunnel and removing the rubber bung towards the rear end of the gearbox . If by any chance it now has a 4 synchro box the drive is on the opposite ( i.e. right hand ) side , and on a 3.8 you may need to cut a hole in the tunnel unless someone has already done it for you. To get the right angle gear off, it is often necessary to use a stout wooden lever to push the gearbox on its mountings to one side to give adequate clearance to withdraw the drive

[PhilBell]

Thanks chaps

Removed the seats and radio console last night but the handbrake is preventing me from lifting the trans tunnel off ? I don't want to force it because it looks like I will bend the aluminium covering. I assume the next job is to release the handbrake cable from the rear axle linkage so that I can pull the handbrake lever up more vertically, making it possible to lift the trans tunnel clear.

Mine still has the lovely Moss gearbox by the way.

[Heuer]

Easy to release the handbrake - just pull out the split pin and remove the cotter pin. On the 3.8 you can indeed access the side of the gearbox by removing the rubber bungs but although you can get your hand in there you will not have enough clearance to remove the speedo gearbox because it will foul the tunnel wall. When you do remove the box watch out for the rubber O ring which will more than likely fall out and needs to be there when you put the whole thing back together to avoid leaks.

[1954Etype]

Yes, releasing the handbrake helps. Try putting the car in third as well. Tape the thread on the gear stick to avoid damaging trim and replace the split pin on the handbrake clevis with an R clip when you put it back.

[PhilBell]

The quality and speed of response on here is truly outstanding.

With the trans tunnel out of the way, removing the speedo drive was easy and I was delighted to discover that the square drive where it engages in the gearbox had broken off, confirming the problem. Turning the speedo drive from the cable end using a match stick (kitchen matches are just the right size) also revealed that the drive is very stiff, suggesting the reason for the failure.

I also discovered that there was no sealant between the glassfibre gearbox cover and the trans tunnel ? no wonder I get a lot of fumes from the oil-onto-exhaust leak. I'll probably use Dum Dum for that so that it's easy to remove in the future.

[Heuer]

Gaffer tape is a good means of sealing - easier to remove and does not leave a mess! Save the Dum-Dum for other purposes as it is no longer available anywhere, unfortunately.

[richard btype]

Whilst on the speedometer discussion I too have experienced a failure! - I wonder however whether it is the meter itself rather than the drive? Just before the failure a noise was heard which sounded like a spring that was being wound tight and then let go before the noise was repeated.

After about 2 to 3 minutes of this noise which i had no idea where it was coming from apart from the speed side of the bulkhead the noise stopped as did the speedo reading.

I've contacted Speedograph for info on refurbishment which is a reasonable ?55.00 but having read this thread perhaps I'm looking at the wrong end?

[Heuer]

Sounds like the cable gave way.