Wednesday, 10 March 2010

Tale of Two Shorrocks

During the restoration of the Coupe, the Shorrock unit was the only item that was not restored. I'd heard horrendous stories of people taking them apart to strip down and then having problems with the reassembly. So I opted to just give it a try and see if it still worked as well as I remembered when I had the Shorrock on my Herald 1200 saloon back in the mid 1990s.

Back in August/September last year I was still running in the engine, so didn't really give the Shorrock that many revs. However after a 1000 or so miles and increasingly higher engine revs it became apparent the Shorrock was not producing the levels of pressure I was expecting.

Fortunately, a friend of a friend had a Shorrock unit for sale that he claimed to be a rebuilt unit. It wasn't until October/November that I got round to swapping the Shorrocks over to see how well the rebuilt unit would fare. Removing and refitting the Shorrock installation isn't the simplest of tasks, but I can now do it around an hour. With the rebuilt Shorrock fitted I fired the engine up and took it for a test run. There was a noticeable improvement on the original unit. Fantastic I thought.

My joy did not last long. After less than a 100 miles the Shorrock seized solid while driving along the M4 doing about 70mph. Bugger. I was recovered home by the AA and the Coupe spent the winter under a cover in the garage.

In the last few weeks I have pulled the Coupe out of the garage and removed and stripped down the Shorrock. My worst fears haven't been realised however. The vanes and inner casing are still in fair condition having not made contact with each other. There was no sign of a lack of oil or lubrication. The metering pins on both units were identical. The seizure was caused by a poorly fitted bearing that should have been a press fit into the rear casing. Instead it appears that rather a lot of Loctite was used to secure the press fit bearing in place. When the Loctite let go, the back of the Shorrock wobbled and seized itself against the inside of the rear housing. Hmmm, not ideal.

So now, with the unit in bits I'm hoping to get the rear casing machined round ready to fit a new bearing dead centre without the aid of Loctite.

It would appear there are rebuilds and there are rebuilds...

1 comment:

Doug said...

LOL - just noticed your pic on the back of an AA truck. Giggling as I have just posted a stunningly similar picture over on

All the best