Speedo drive gear removal

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Speedo drive gear removal

Postby zak » 06 Jul 2018, 11:32

Speedo suddenly stopped on way home from SP. Guessing its the speedo gear in the diff as its not turning when I spin a front wheel. Any tips to removing/replacing it folks ?
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Re: Speedo drive gear removal

Postby silverbullet » 06 Jul 2018, 11:53

After unscrewing the speedo cable nut at the front diff, carefully drive out the rollpin that secures the speedo pinion bearing sleeve (where the cable attaches)
Then the fun bit: withdrawing the bearing sleeve and speedo pinion. They can corrode in place because the sleeve is alloy and so is the diff casing...
A common fault is that the speedo pinion shaft goes tight in the sleeve, due to corrosion squeezing the bearing sleeve down a tiny amount and the already miniscule running clearances go to zero.
Then the nylon gear strips as it overloads.
Always get the sleeve re-sized with a 10.0mm machine reamer before reassembling, after the gear has been repaired/renewed.ImageImage

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Re: Speedo drive gear removal

Postby zak » 06 Jul 2018, 12:48

Cheers Ian, it all looks fun as long as you have 5ft long skinny bendy arms !! :D
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Re: Speedo drive gear removal

Postby zak » 06 Jul 2018, 13:41

Don't suppose you know what diameter the roll pin is?, its not moving easily and I don't want to mash the pin end etc.
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Re: Speedo drive gear removal

Postby silverbullet » 06 Jul 2018, 17:52

No problem. Size? Er...no. Aidan will know that off the top of his head.

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Re: Speedo drive gear removal

Postby zak » 06 Jul 2018, 18:08

doh - end of pin successfully mashed, and it ain't moving !! Wish I'd realised there is a proper roll pin punch tool before. :oops:
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Re: Speedo drive gear removal

Postby Winchweight » 06 Jul 2018, 18:44

5mm I think?
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Re: Speedo drive gear removal

Postby silverbullet » 07 Jul 2018, 08:54

Can you get a pic of what's going on with the rollpin and the tools you are using?
You need a punch thats almost full-size to drive out this type of pin (c section) and they can need a "robust" approach to get them moving.

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Re: Speedo drive gear removal

Postby zak » 07 Jul 2018, 17:49

silverbullet wrote:You need a punch thats almost full-size to drive out this type of pin (c section) and they can need a "robust" approach to get them moving.


Yes I should have had more patience. I couldn't really make out the exact size and didn't want to damage the ally casing so took a a guess and started with the long smaller punch which is about 4mm. I thought it was a normal roll pin but I'm guessing its one of the spiral jobbies that I'd never seen before, they must be thinner steel and its folded in. I ground another punch down to under 5mm to just get it started but its not moving.

I'll order a roll pin from Brickwerks so I can get the exact size

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Re: Speedo drive gear removal

Postby silverbullet » 07 Jul 2018, 19:14

I would recommend warming up the diff by going for a good drive, then applying a hot air gun locally to the diff casing, before trying again to drift the rollpin out (with better tools) while working hot.
This will minimize thermal stress on the casing and give a better chance of success.
Its pretty hard to destroy either type of roll pun (spirol or split) when in-situ. My guess is that its rusted in place.

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Re: Speedo drive gear removal

Postby zak » 07 Jul 2018, 20:39

silverbullet wrote:I would recommend warming up the diff by going for a good drive, then applying a hot air gun locally to the diff casing, before trying again to drift the rollpin out (with better tools) while working hot.
This will minimize thermal stress on the casing and give a better chance of success.
Its pretty hard to destroy either type of roll pun (spirol or split) when in-situ. My guess is that its rusted in place.

Thanks Ian, I'll do that. The end of the pin is definitely mashed over a bit as I could see the hole up the middle before. The only other idea I had was trying to use a small G clamp etc. on a short bit of the right sized bar in the other end but I'd probably struggle to get enough pressure on a small clamp. Fingers crossed the heat will be enough. Cheers again.
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Re: Speedo drive gear removal

Postby zak » 08 Jul 2018, 20:11

Ok went to order the bits tonight. Didn't realise there were different options with the gears. Brickwerks are out of stock of the roll pin so cant try again until I definitely know the pin diameter. Any one else who might stock them ?
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Re: Speedo drive gear removal

Postby Winchweight » 08 Jul 2018, 20:18

Give Aidan a call. He usually has stuff like that.
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Re: Speedo drive gear removal

Postby zak » 08 Jul 2018, 20:29

Winchweight wrote:Give Aidan a call. He usually has stuff like that.


Tks Shaun
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Re: Speedo drive gear removal

Postby silverbullet » 09 Jul 2018, 07:13

zak wrote:Ok went to order the bits tonight. Didn't realise there were different options with the gears. Brickwerks are out of stock of the roll pin so cant try again until I definitely know the pin diameter. Any one else who might stock them ?
Yes it's a minefield. Knowing your van's original build spec and diff code/final drive ratio is essential.
The original speedo drive gears are colour coded plastic, so best to get it removed first and do the cross-referencing before ordering.
I know this because I developed the bronze replacement pinion gears ;)

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