Motobecane 1978 50V Huret Speedo Rebuild

Bob Chesarek /

Nov 21, 2022 12:37AM

Tonight I disassembled my Huret speedometer from my 50V and ordered a new Bezel, glass and Gasket. What I can't find is the what looked like the white or lt. grey gasket the goes between the speedo and the black metal housing (speedo support). I believe it is shown as item #2 on the speedometer parts break down, part number 19573. Mine was completely dry rotted and had to be scraped out in pieces, a total loss.

So what do you guys do for that part? Make your own? Go without? Use Silicone sealant? I am open for suggestions.

Thank you for your input. Bob

Re: Motobecane 1978 50V Huret Speedo Rebuild

pat splat /

ggspeed

Nov 24, 2022 08:28AM

Hmm, document your rebuild for others. Cant help w parts

Re: Motobecane 1978 50V Huret Speedo Rebuild

Kelikaku קוטין /

kelikaku

Nov 24, 2022 09:00AM

I don't know but if a gasket can be cut from a suitable donor material.

It's easy to make a rubber gasket by using an old inner tube from a bicycle that's being thrown away by a bicycle shop. I also use them to make stretchable tie-down lines. The bicycle shops will usually give them away free.

Re: Motobecane 1978 50V Huret Speedo Rebuild

Bob Chesarek /

bob_ches OP

Nov 26, 2022 11:28AM

Thanks for the suggestions guys. I was thinking of making a gasket from thin rubber too but then I read that someone suggested using craft store 4 or 5mm foam so I am going to take a look at that option too.

After disassembling my Huret speedo, I have found out why the cable snapped. The drive gear in the speedo is frozen solid from hardened grease. Right now I am soaking the lower half in Acetone to try to dissolve the old grease and free up the mechanism. I have already purchased a new drive unit for the front wheel as the old one was frozen up and the arms that fit into the wheel were bent way out of shape. The foam gasket behind that drive unit was disintegrated also. The new drive unit came with a new foam gasket.

Re: Motobecane 1978 50V Huret Speedo Rebuild

pat splat /

ggspeed

Nov 29, 2022 09:03AM

Doesnt acetone melt plastic?

Re: Motobecane 1978 50V Huret Speedo Rebuild

P D /

pdcomm

Nov 29, 2022 11:49AM

> pat splat wrote:

> -------------------------------------------------------

> Doesnt acetone melt plastic?

Not all plastics .

Google says :

"There are all kinds of plastics. If a particular plastic bears a close enough similarity to acetone, the acetone will dissolve or at least affect its surface, softening, smearing or even dissolving the plastic. Other plastics, dissimilar to acetone, will remain unaffected by the solvent."

Re: Motobecane 1978 50V Huret Speedo Rebuild

Bob Chesarek /

bob_ches OP

Nov 29, 2022 11:25PM

I only soaked the lower half of the speedo right up to the plate the gears are on. I believe the gears are nylon which shouldn't be affected by Acetone. After 4 or 5 days of soaking, blowing out with compressed air, applying Breakfree CLP top middle and bottom of the drive shaft, letting that sit a day, then back into the Acetone and repeat. I am happy to report the the drive shaft is now spinning freely. Will be rebuilding the speedo with new bezel, glass and gasket as well as painting the housing.

MOPED ARMY

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