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Speedo drive on new vehicles


BogMonster

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Since fitting the 265/75R16s the speedo on my 90 under-reads a bit (it was fitted with 205s when brand new, though the first owner swapped those immediately).

So I figured if I fit the speedo drive from a 110 shod with 7.50s, it should be OK, easy enough, off to look for part numbers.

...But...

No such thing, according to Microtwat :angry:

Micromuppet suggests that:

- All sender units on all 300Tdi and Td5 vehicles are YBE100530 irrespective of tyre size.

- The gears, which were selectable to give speedo calibration on older vehicles with mechanically driven speedos, don't fit the newer vehicles (according to Microclot these gears only do up to WA159806 which is the beginning of the Td5s, so wouldn't suit mine which is a 4A vin number). On older vehicles FRC3312 is a 22 tooth gear for 205R16 tyres and FRC3310 is a 20 tooth gear, which presumably does 7.50R16s, though it doesn't say that. There is also an FRC3311, 21 teeth, not clear what that is supposed to do (90s except a 50LE, don't understand the difference though). No gears at all listed for an XA > vin number, which is what I need :angry:

- The speedo head is the same on all vehicles, allegedly

So what changes the calibration from 205R16s to 7.50R16s??? The speedo on new 110s is accurate with 7.50s on, doesn't under-read like mine, so there must be something different somewhere but the ever useful Micro(&**^%&^(&^%*%^*&^ doesn't seem to give any hints

I have never had cause to pull out one of the new type electronic speedo drives and see what is inside, has anybody actually done this, or does anybody know what needs to be changed to correct the speedo please?

Or has anybody got a parts catalogue which is actually right :huh: maybe the old EPC (don't have that) -- I expect it needs the same sort of gears but not sure.....

Ta :)

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Stephen

My 2002 EPC tells me it's Transducer YBE100530 from VIN XA 159807 on the transfer box not main gearbox, doesn't show me a picture of it though :rolleyes:

just going to check another source :unsure:

right this should help

where the speed transducer fits [same place as the previous speedo drive gear] remove the cable/transducer, should be a allen screw holding it on, there's a 'o' ring seal, another seal & the speedo drive gear housing, another 'o' ring seal & the speedo drive gear, [similar to the type on older vehicles] I'll add pics shortly :D

diagram lt230t rear housing

File0014.jpg

key to diagram items 19 to 25

File0015.jpg

If thats no good then I suspect the original fiited tyre size is programmed into the ECU, as I can't find any other picture/part numbers for the drive gear shown in the above workshop manual pictures. :unsure:

Edited by western
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Thanks Ralph

That's the problem - I can't find anything on drive gears either! Nowt in RAVE about it apart from the LT230Q overhaul manual which shows a picture of a spiral gear similar to in the older T-boxes which suggests that the system for driving the sender is probably the same.

I suspect the gears are in fact the same and that Microcat is just wrong when it says they only fit earlier vehicles, but not sure. The LT230 transfer box is basically the same thing, albeit an LT230Q rather than LT230T. Allegedly the Q stands for Quiet, which mine isn't :angry: should be called an LT230HFGNILR (horrible F grindy noises in low range)!

I don't think there is any ECU programming, as on the 300Tdi's there is no ECU to program - just the speedo head which allegedly is the same on all vehicles. I think on a Td5 the speedo is driven by the engine ECU, but it must sense the speed signal directly off the sender on mine because there is no other hidden electrickery on the new 300Tdis, just a Td5 instrument pack.

I think somebody at work put a Td5 age transfer box (which would have had the leccy sender unit) in an older vehicle a while back, so I must find out if they remember changing anything in the speedo drive gears. If that fails then I will pull it out and have a look, and hopefully there won't be a "sproinnggggg" of bits falling into the bottom of the t-box :unsure:

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I'm thinking if the drive gear is indentical to older vehicles if the new transducer is made to fit the square end of the drive gear, similar to the square end of the normal speedo cable, :unsure: reckon your gonna have to get grubby & pull it apart, :o love the descripton moniker for your LT230. :lol::rolleyes:

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I think it must be. Will have to pull it out for a look at some stage, not getting under there this afternoon as it has been raining cats, dogs, elephants, whales and wildebeest so it's not worth an earful of muddy water for a look!

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Stephen, as I understand it, you still use the same gears in the speedo drive.

I've just fished this out of Martin L's very helpful reply when we were on the other forum -

"Will, the transducer is driven by the same speedo drive gear (as in older Defenders/90s/110s etc), so to alter the reading for different tyres still means changing the drive gear "

HTH

Mo

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Thanks Mo, that's what I needed to know :)

Now all I gotta do is find a 20 tooth gear <_<

I feel the urge coming on to liberate a part off one of the scrap t-boxes at work :)

I guess Microclot is wrong (again) when it says the later ones don't have them :huh:

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Thanks Mo, that's what I needed to know :)

Now all I gotta do is find a 20 tooth gear <_<

I feel the urge coming on to liberate a part off one of the scrap t-boxes at work :)

I guess Microclot is wrong (again) when it says the later ones don't have them :huh:

Did exactly this job recently when I stuck 235/85's on my 300tdi Disco - popped over to the local parts place and got the gear (I think it's the blue one) for a 110. Works a treat - HOWEVER...... I found that the square female end on the gear was a tad larger than the 'post' that sticks out of the transducer.

I tried a couple of solutions - don't try to squeeze the flat sides of the socket, you'll just crack the metal ;) In the end I packed it out with some thin strips of sheet (an old baked beans tin will do the trick).

Works fine now. :D

Dunk

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  • 7 months later...

After a slight pause (ok 9 months!) I have located a suitable "donor" for the parts required for this ;)

Can somebody (Disco_Dunk?) please confirm exactly how much you have to do to get the gear out to change it - does it just come out through the hole that the speedo transducer plugs in to on the outside of the t/box, or does it require pulling the t/box to bits?? :unsure:

Rave has no mention of the drive gear in either the WSM or the LT230Q overhaul manual so I don't know whether you can access it easily (in which case probably a 5 minute job) or whether half the friggin transfer box has to be pulled to bits... in which case I probably won't bother! Also a bit wary of trying to dig it out through the hole and finding "sproinngggggg" bits disappear inside the t/box....

For anybody else interested the parts are:

FRC3310 gear 20 teeth Blue for:

- 90 except 205x16 tyre

- Except 90

(This is LandRoverSpeak for "anything with 7.50s on" which would have been much clearer <_< )

FRC 3311 gear 21 teeth Green for:

- 90 except 50LE (no idea what the difference is)

FRC3312 gear 22 teeth Yellow for:

- 90" on 205x16 tyres

FRC3313 gear 24 teeth Red for:

- 90" 29D V8 Petrol Twin Carb (no idea why this is different either)

I'm assuming mine will have the yellow gear fitted and with 265/75R16 on it will require the blue 20 tooth gear to get the speedo back on track. Handily, I know where there is a t/box out of a crashed 110 which should have the blue gear in :)

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using the diagram above swapping the gear should be fairly easy.

found a bit in RAVE -- LT230Q trabsfer box overhaul ---- transfer box dismantling --- shows a drawing of the transducer & fixing bolt --items 7 & 8,

then go to Component dismantling --- rear output housing --- another drawing of the speedo drive gear & housing lifted above the casing --items 5,6 & 7.

that should get you sorted :)

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Just been and "liberated" the speedo drive out of the gash t/box, as easy as Ralph said, take out the single small bolt holding the electronic transducer in, wiggle that out, then a small flat blade screwdriver under each side and the whole thing slides out with a bit of a tweak, the mini housing with the plastic drive gear fitted in to it. Just got to put it in the 90 but that will be a job for tomorrow.

Thanks :)

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Just to confirm - I just fitted a later electronic sensor (part number you quoted) to a '93 LT230 that had a cable previously. It just drops in, so i would assume that the gears are also the same. I've not had a chance to check the speed against a GPS yet.

p.s when i say it just 'drops in' be careful to get the sqare spigot of the sensor inside the drive gear centre hole. Its possible to miss & then u get not drive & the gear starts to wear the sid eof the sensor spigot. took me 3 attempts.

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Just to confirm - I just fitted a later electronic sensor (part number you quoted) to a '93 LT230 that had a cable previously. It just drops in, so i would assume that the gears are also the same. I've not had a chance to check the speed against a GPS yet.

p.s when i say it just 'drops in' be careful to get the sqare spigot of the sensor inside the drive gear centre hole. Its possible to miss & then u get not drive & the gear starts to wear the sid eof the sensor spigot. took me 3 attempts.

youe assumption of the gears being the same is correct :)

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Job done.

Forgot to take the camera down to work :rolleyes: but not much to show anyway.... it is just as described. Here is the one that came out, the thing as removed:

Dscf0235.jpg

and when you pull the drive gear out of the little housing:

Dscf0236.jpg

Speedo reading before/after using GPS on 265/75R16 BFG MT's (fairly well worn)

Steady 25mph on speedo was 26.5mph true road speed now 24.5mph true

Steady 40mph on speedo was 43.4mph true road speed now 38.6mph true

which is much better when somebody is pointing a speed gun at you, now I know I am not speeding. On the 33x12.50R15 the speedo reading ought to be just about dead on I reckon :)

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Bear in mind that the tolerance allowed on speedo reading is IIRC +0/-10%

So most cars you check against GPS will read a fair bit under, cos they are meant to.

If fitting the other tyres pushes you over again, i dont know how that would fair in an MOT...

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Bear in mind that the tolerance allowed on speedo reading is IIRC +0/-10%

So most cars you check against GPS will read a fair bit under, cos they are meant to.

If fitting the other tyres pushes you over again, i dont know how that would fair in an MOT...

I know, but there are no MOT's or any equivalent here - I just want it to read the way it should do because I am a fussy bugger and I like things to be right ;)

The Discovery speedo would read slightly under too, except it has slightly oversize 255/70R16 tyres on (should be 235/70R16) so it is also just about spot on, reads about 0.5% low.

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Glad you got it sorted (sorry I didn't get a chance to help - mental weekend)

Dunk

I know, but there are no MOT's or any equivalent here - I just want it to read the way it should do because I am a fussy bugger and I like things to be right ;)

The Discovery speedo would read slightly under too, except it has slightly oversize 255/70R16 tyres on (should be 235/70R16) so it is also just about spot on, reads about 0.5% low.

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