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Discussion Starter #1
I thought I was starting to get the hang of Alfa fastening sizes and had stocked up on metric fine thread in a few sizes...but!

Yesterday refitting my Spider rear axle, after having it rebuilt, I managed to strip the tread on the nut securing the rear ARB to the trailing arm. The bolt is the stepped one which connects the axle to the rear end of the trailing arm, then has a smaller section and thread which goes through the roll bar bush. The bolt is fine, the nut is knackered. At first I thought it was a 10mm fine thread, but no...anyone know what thread size it is? So far tried 10mm x 1mm and standard 10mm x 1.25mm (I think).
 

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Sorry cant help you with threads but could you tell me if the ARB mounting bolt goes all the way through the diff casing - I want to replace the inner bush with poly but it means dismantling the suspension to get enough room to install it otherwise
thanks
 

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Can you measure the pitch? Rather than try to measure one thread, it's easier doing it over several & dividing to get the required figure - even better, use a thread pitch gauge.

It may be to some now-obsolete Italian standard or they may have used a non-standard thread to suit this particular application.
 

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Discussion Starter #4
Hi Joe, do you mean the "T" bar bush on top of the diff? Large pair of cone shaped bushes held by a castellated nut?
If so the fixing bolt is welded to the diff so does not come off. After taking off and replacing the axle I would do it by removing the rear trailing arm rear bolts, lower and remove springs and ARB (if fitted). This should leave the axle swinging on the rebound straps so will allow you to unbolt the T bar securing nut on the diff mounting, and carefully swing the axle over enough to slip the inner bush off and replace. Not too bad a job, but make sure you get the bush fitted both sides and the securing nut started as very tricky to do once the trailing arms are reconnected...don't ask how I found out!:thumbup: Also be careful taking that split pin out as it will be rusted. If it does snap and block the hole you might need to drill it out.
 

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I think the stepped one you mean is the thick one at the rear of the trailing arm (by the spring seat) going through the main rubber bush?

It has two threads on it? M16 x 1.5 on the inside against the trailing arm and the outer one is M10 x 1.25.

Yes - two different pitches not a typo.
 

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Discussion Starter #7
Thanks chaps, I'll have another go. That said lots of people mention taking the rear ARB off altogether.
 

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Sorry - I was barking up the wrong tree ... - I'd heard about removing the ARB and fitting a stiffer front ARB to improve things - easy enough to disconnect the rear ARB to try anyway
 
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