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Just Some Dude in Jersey
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Discussion Starter · #1 ·
Mschinelli called me about a teensy differential leak and we discussed options for regasketing and other easy procedures. Before long, it dawned on me that his rear axle assembly was my old Red Baron's original rear axle that I had cleaned up with new seals and paint. His slight drip sounded familiar. "Oh yeah, I remember I had a leak at the bottom cover bolt that you remove to drain the gear oil". I had put allen bolts in that diff cover and I had always suspected that they didn't have a large enough surface area to seal the cover well. The stock Opel bolts have a flange around the outside of the bolt head to increase the surface area. I told him I have the oem bolts in my basement and went down to find'em. I found them. Enough for two diff covers.

But one bolt looked funny. The silver paint on it meant that it came from my early c-clip style 3:18 rear axle. It only has 2-4 threads and the rest of the shank of the bolt is unthreaded:

Auto part Screw Fastener


I seemed to recall that the bottom bolt that drains the diff was special in some way. I presumed it was longer, but now that I've found this funny lookin' bolt I'm not sure.


Can anyone explain why my funny lookin' bolt is so funny lookin'?


:thinking:
 

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Just Some Dude in Jersey
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15,866 Posts
Discussion Starter · #3 ·
Bump!

Does anyone know more about this?

I'm missing the bolts for the diff cover on the rear axle I'm working on and since I put a chromed cover on it I figure that I should buy some nice shiny chromed or stainless flanged bolts to hold it on.

I'm guessing that the bolts are supposed to be 8mm(dia) x 15mm(long) or maybe 20mm. Does anyone know for sure?

Do I have to have one of those partially threaded, straight shank, bolts? I figure that, if so, it is for the bottom left bolt hole that drains the differential fluid. Will it leak if I don't use that type of bolt there?
 

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This is probably of no help to you Gordon But I don't remember there being any difference in the bolts in my rear end when I pulled it all apart and I cleaned and or sand blasted everything
 

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What length are those bolts?
I would nave to pull one out to measure
And Mercougary is right I forgot about the brake tee bolt.
If no one chimes in I'll pull it out and measure it
 

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Your Noble Friend ;-)
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The oil drain bolt is the same as the others. Only the brake Tee bold should be 5 mm longer.

Direct link for what you want:


Dieter
 
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I got 12 mm for the short ones and 21mm for the brake tee bolt
Now I just need to remember what I torqued them too RATS
 

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oh yea 22 ft lbs thank goodness for the fsm I didn't write that one in my opel bible lol
 

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Your Noble Friend ;-)
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German torque spec: "Good'n'tight"

For the ones that don't know it, if you pronounce it the right way it sounds like "Guten Tag" which is German for "Good day" :p :sneaky:

Dieter
 
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