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broken thread in rear end housing

Posted: Sun Nov 10, 2013 4:51 pm
by peter2
Hi,

While changing sealings of the break pedal axle I noticed a leaking screw from the cover that holds the hydraulic pump. I tried to fasten it but it run very light, so I took it out.
The inner thread in the rear end housing is gone. Not the winding, the whole body of the winding (don't know to explain better) seems broken off.

I put it back with a lot of liquid sealing and fastened it by hand. I can feel the remaining thread holding the screw in place, so it will not drop out, but this screw no longer transports any mechanically forces to the cover. I hope it stops leaking when the sealing is dry tomorrow.

Is there a way to fix it properly?

Peter

Re: broken thread in rear end housing

Posted: Sun Nov 10, 2013 8:56 pm
by henk
Peter,
as I understand the threat in the hole is almost gone.

There are a few ways. One is to weld the hole and then drill it again and tap new threat in it.
Or you can use a repair set like in the picture.
Image
These sets are expensive, but a garage will have them. But you being in Germany I think it all will be metric.

You can use a helicoil. Se picture.
Image

The difference is that the first one is a bush, the helicoil is a sort of spring.

You can make one yourself on a turning machine (lathe). Take a bolt that's one or two sizes bigger. Drill a hole in it and tap the right threat in it. Shorten it to the right length.
Drill out the hole to the right size for the tap. Make a new threat in the hole. Turn in you self made helicoil and use some Loctide to fixate it. Job done.
Problem could be the size between the hole and the edge of the rear end. If it's to small it could crack while tightening the bold.

Hope you understand what I’m describing, but if not just Google and you find more.

Re: broken thread in rear end housing

Posted: Sun Nov 10, 2013 10:12 pm
by peter2
Hi Henk,
henk wrote:as I understand the threat in the hole is almost gone.
Sorry, no. The hole is gone, not only the threat. As far as I could see through the cover there's only 1/3 of the threat left. The rest is cracked off.
Helicoil would be easy, but there's nothing left to screw it in. :(

Peter

Re: broken thread in rear end housing

Posted: Sun Nov 10, 2013 10:25 pm
by scoobyjim
you get a tap with the heli coil kit that taps a bigger size hole. you then screw the coil in and it takes you back to the origonal size.

Re: broken thread in rear end housing

Posted: Sun Nov 10, 2013 11:07 pm
by henk
Please: :needpics:

Re: broken thread in rear end housing

Posted: Sun Nov 10, 2013 11:48 pm
by tmc
If it does start to leak again could you use a long bolt with a nut inside ? I guess it would mean taking the hyd. top off to see.

Re: broken thread in rear end housing

Posted: Mon Nov 11, 2013 8:12 am
by peter2
Hi Henk,
henk wrote:Please: :needpics:
I know, but taking pictures of the problem area didn't work. The inner hole is always dark. Maybe a photo editor can help, I'll try it later.
Peter

Re: broken thread in rear end housing

Posted: Mon Nov 11, 2013 10:07 am
by Bensdexta
As I understand it, the inside part of the casting around the hole has cracked off and presumably dropped down inside the back end... where's it gone...?

As suggested by tmc, fitting a bigger bolt from the inside, which you have drilled down the middle and tapped with the correct size thread sounds like a solution... But would the bolt head on inside of the casting cause a problem? If so it would have to be cut off, so you're left with a big threaded bush...

Re: broken thread in rear end housing

Posted: Mon Nov 11, 2013 10:39 am
by peter2
HI,
Bensdexta wrote:As I understand it, the inside part of the casting around the hole has cracked off and presumably dropped down inside the back end... where's it gone...?
exactly. I don't know where it's gone. I don't know if it's gone yesterday or at a repair in former times. If it's still in, I hope it follows gravity and goes to the filter.

Is there a picture of a rear end with the pump cover off? The screw is the rear one on the left side.

Peter

Re: broken thread in rear end housing

Posted: Mon Nov 11, 2013 6:09 pm
by peter2
Hi,

pictures: :-)

Overview:
Image

and thanks to iPhoto
Image
Here you can see the threat ending in the middle of the hole.

I think the easiest repair is drilling two holes in the housing right near the defect hole (from this view), screwing a thick (10mm min.) plate inside and drill a hole with the correct threat in. This avoids any difficult welding in the casting. If there is enough room inside ...

Peter

Re: broken thread in rear end housing

Posted: Tue Nov 12, 2013 12:15 pm
by AdrianNPMajor
I'd be thinking seriously about having the hydraulic lid off and dropping the pump pedestal to see exactly what is going on.

Best
Adrian :thumbs:

Re: broken thread in rear end housing

Posted: Tue Nov 12, 2013 1:20 pm
by henk
That would be the best thing to do. I think you will have to remove it to fix the problem.