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Speedo drive coming out - Gearchange/Gearbox/Clutch - The Lotus Forums Jump to content
Andyww

Speedo drive coming out

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I seem to have a problem with my speedo drive coming loose and the speedo stops working. I tried winding plumbers tape around it and pushing it back in hard but still vibrated out.

 

I thought that the drive was located in the housing by the long bolt which runs through close to it but it isnt.

 

In fact only the nylon part of the drive seems to be retained. The right angle drive itself is not retained as the bolt does not encroach far enough into the hole.

 

See picture, the brass part does have a groove but the long bolt does not seem to run into this groove.

 

I am thinking of removing the whole thing and pinning the brass bush into the nylon bush. But is this normal, has anyone else had this problem?

 

 

post-16906-0-61286100-1426975820.jpg

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I haven't pulled one of these apart before but wouldn't that be an o-ring groove? Have you looked at the workshop manual?

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Took mine apart recently. The long bolt does hold the whole lot together. I know as I had to take off my exhaust silencer to get it out. There should indeed be a stupidly thin oring around the plastic part. I had a bit of trouble getting my to work as the small gear fell out when I tried to reassemble. A good dollop of grease held it in place until it was pushed in. 

 

I am wondering if you are not getting it correctly in before inserting your bolt...unless someone has replaced your bolt with a smaller dia. bolt as the original is a stupid size. Either M7 or M9 which are a right royal pain to get hold of if you lose one?

 

Buddsy

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On  mine its definitely necessary to remove the silencer and long bolt to get the nylon part out.

 

But the inner part can be fully pushed right home, or removed, with the bolt present.

 

The bolt has the correct threads as it fits properly. One possibility I can think of is the proper bolt might be a special one with a thicker shank?

 

If the inner part is definitely supposed to be retained (which seems the case as thats what the groove is for) then the bolt must be wrong I guess.

 

I might have to take off the silencer (again!) and investigate further. I could get the damn thing off and on blindfold now :)

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HI, if fitted correcty it is impossible to get it out. Bolt is M9 x 65 mm and will fit in both grooves, nylon bushing and speedo drive.

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I checked again. Didnt remove the silencer but looking into the hole with both parts removed, the bolt only protrudes into the hole by 2mm or so. This is not enough to lock the brass part. So I dont know why mine is different.

 

Just to make sure I am not going crazy, this is the bolt? Its the only M9 bolt on the rear, and has a 13mm head.

 

Even looking at the casing from the outside, this bolt is not very close to the centre of the speedo drive hole.

 

 

post-16906-0-00897300-1427145578.png

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This might be the problem. M9 bolt has hex 14 mm. 

13 mm means it is M8. 

 

You need an M9 bolt 65 mm long.

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If it's screwed into the thread in the casting and tightens up, and it's an M8 bolt, then an M9 isn't going to fit. I wonder if the casting has been helicoiled to M8 instead of M9....and that has resulted in the too thin M8 bolt not retaining the speedo drive. Easy answer would be to fit some 9 mm od, 8mm id steel tubing over the existing M8 bolt. That ought to hold the speedo drive without the drilling and tapping needed to helicoil the casting back to 9mm. Just supposition, of course....but the existing bolt would come out easily enough so you can measure it!!

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I just dived under and got a vernier onto the head and it is actually 14mm. Sorry for the confusion.

 

So the mystery remains.

 

I am not going to take everything apart again unless it comes out again. I have managed to get it to be a very tight fit by judicious use of PTFE tape and it has been OK and does not leak at all and hopefully will stay put.

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Must be them Gremlins again.......(!)

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