Fitted a diff!

[Grrrmachine]

After my touring developed an ominous rumble at the rear, the only solution was to replace the diff.

Having read the wiki, I was preparing myself for a killer job of frustration and exertion. But it was a piece of p!ss! Two drive-shaft bolts tested my patience a bit coming out, but once the old diff was lowered out on a trolley jack, the new one offered up and lined up with the bolt holes on the first go!

I just need to tighten up a few drive shaft bolts and I can lower the thing off its jack stands, but while I'm waiting for my cuppa to cool down, I must say, that was a lot easier than I thought it would be.

[SDM]

good lad, a lot of satisfaction gained from DIY work!

Fixed mine today in about 5 minutes and i was very happy!

[gareth]

I've had so many diffs on and off E30's now it's getting boring

Sometimes they can just be an utter arse to line up again. i think you got very lucky on the first hit

[dowot]

i've got mine to do this week...

[Grrrmachine]

It's more a comment that, for a lightweight like me, the task seemed daunting. But with the right tools (ratchet spanners and a trolley jack; no need for sockets or breaker bars or crow's feet) anyone can do it.

In terms of DIY jobs, it's made me feel a lot more confident in taking on heavy jobs, like a steering rack swap or a clutch change.

[gareth]

Don't get me wrong, it's a fair old job. One that's made a massive amount easier with an assistant for pulling the handbrake up and down while all the prop and output shaft bolts are removed.

another top tip is to clean the mounting threads out properly before bolting the new diff in. fresh paint stops them going in very well too

[Brianmoooore]

another top tip is to clean the mounting threads out properly before bolting the new diff in. fresh paint stops them going in very well too

Applies to all fastenings, anywhere. A set of thread cleaning nuts and taps, and spending a few minutes using them is a good investment of time, whatever work you're doing.

[gareth]

The trouble with these is that they're M12x1.5 iirc. Standard M12 is M12x1.75 so a standard tap will wreck the threads.

A handy hint here is to use a spare bolt of the right size. Grind a flat or groove on it then wind through and it'll scrape out/remove any muck

[Brianmoooore]

The trouble with these is that they're M12x1.5 iirc. Standard M12 is M12x1.75 so a standard tap will wreck the threads.

A handy hint here is to use a spare bolt of the right size. Grind a flat or groove on it then wind through and it'll scrape out/remove any muck

Good point! Always check the pitch on a bolt by measuring the pitch, or simply by holding it against a known 'standard' bolt before attacking a threaded hole in a casting with a tap.
I tried to clean up the threads in the output flanges of a 328 diff. yesterday, and had to dig out a rarely used tap for the job.

[skipunda]

Thanks for the tips

[gareth]

standard pitches for comparison, while i'm being unusually helpful

M6x1
M8x1.25
M10x1.5
M12x1.75
M16x2

These sizes are what you're likely to find in a tap/die set. After that, you're into finding taps from tool suppliers and at 6pm on a sunday, it's time to improvise with a grinder and spare bolt

[Grrrmachine]

I do wonder what it is with German cars and odd threads. The 80s Audi I had (and VW as a whole) are obsessed with M10x1.0 threaded nuts and bolts, which makes replacements, and taps and dies, depressingly hard to find, especially east of Berlin.

[gareth]

The idea behind a finer pitch thread is having the same overall thread diameter but obtaining a larger core size for more strength. This allso moved the effective diameter of the thread further out so it has a larger shear area. That and less stress raisers on the bolt itself. All good stuff

Peugeot are terrible for threads... took me a while to find a helecoil kit for my 205 GTi a few years back, with a M11x1.25 thread!!! and M7 threads on the strut tops!!! AAARRRGGGHHH!