Sunday, March 11, 2012

The Herald's back!

Replacing the diff in a Herald is one of the most awkward jobs in Triumphdom. Which is why, as soon as Gerald's diff's started singing, my heart sank.

It lost its oil after the pinion seal failed. Replacing the oil quietened it down slightly, but its days were clearly numbered. So I ordered the various gears, seals and bearings, as well as an alloy case from Canley Classics, and took the diff to Greg Tunstall Mechanical for an overhaul. He had the new crown wheel and pinion lapped to ensure it ran quietly, and built it into the new case.

The rebuilt diff with new crown wheel and pinion, and a Bastück alloy case.

I've just spent an entire Sunday struggling to refit the damned thing. Removing it was easy -  just undo all the bolts and stand clear, gravity does the rest. But refitting means shoving it into position against stiff bushes, limited room and the same, suddenly unhelpful gravity. Grrrr! For future reference, don't fit bolts through the rear bushes before swinging the front up, as it won't fit in properly. I figured that out eventually...

Once it was in I found one difference between the old iron case and the new Bastück alloy case. It's not possible to fit the halfshaft bolts once the output flanges are done up, as the case is a different shape. So I had to fit the bolts the other way, and fit enough washers so that the bolts didn't hit the cap head bolts holding the flanges in. Some of them come damned close though - if an ant squeezes in there it'll get a haircut!

Refilling took an age. The 140-weight oil Greg gave me was too thick for my oil pump, so it was refilled with a hose and funnel. Slooooowly.

Bleeding the brakes. The rubber brake hose was replaced with a braided hose. The swing spring was stripped and repainted, the eye bushes were replaced with blue urethane and the centre pad with harder red urethane. 

I also replaced a brake line and bled the brakes. Then it could sit on its own wheels for the first time in six weeks. It didn't start though, not until I'd removed a condenser fitted across the points to keep the radio crackles down. The radio's inline fuse also fell apart while I was looking for loose wires, resulting in some sparky excitement and a little Lucas smoke. Sigh.

Once running, the clutch turned out to be seized on... but I've learned how to free it off, so we shot around the block for a test blat. No new noises, and the diff's quiet. Thank goodness!


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