Su­per­charger over­haul

Classics Monthly - - 1964 Singer Gazelle -

T his month has been a fo­cus on the old man’s Fro­g­eye, as it’s not far from com­ple­tion and it would be nice to get it done for the sum­mer. With this ob­jec­tive in mind the 3000 there­fore has taken a slight back seat this month. The dash and wiring are now in and the brake lines are all plumbed up, but the main ob­sta­cle to fin­ish­ing the Fro­g­eye has been the su­per­charger, which is tak­ing a huge amount of time to get right.

This Shor­rock unit is a lovely lit­tle piece of pre­ci­sion en­gi­neer­ing, so restor­ing at home can be a chal­lenge, but a bit of thought and me­thod­i­cal work­ing and any­thing is pos­si­ble! Last month I left off on the hunt for new bear­ings and thought this may prove to be a chal­lenge, but a friend rec­om­mended a gear­box/mo­tor spe­cial­ist with a trade counter. A very ex­pe­ri­enced chap with a vernier caliper and a clutch of bear­ing books made light work of the prob­lem. Twenty-four hours and £100 later I had a full set of su­per high qual­ity bear­ings and seals. Re­sult!

The next prob­lem was fit­ting them, as each blower vane is on a yoke that has a bear­ing run­ning on the main shaft. Press­ing the bear­ing out was there­fore not a sim­ple op­er­a­tion – if the yoke was not sup­ported it would bend – not ideal! To sove the prob­lem I bought a length of alu­minium bar from a lo­cal me­tal sup­plier and cracked open the lathe. I made a sim­ple sup­port to the out­side and in­side di­am­e­ter of the yoke and then a series of lengths of bar that suited the each yoke aper­ture.

This meant I could hap­pily press out the old and in with the new with­out fear of bend­ing any­thing. I thought this could be the hard­est job, but it was just time con­sum­ing. The chal­lenge was the bear­ing on the drive plate – it was stuck

fast and had very lit­tle ac­cess to the rear of the bear­ing. I ended up care­fully weld­ing the puller to the bear­ing in­ner, but even then the force was so high the bear­ing ma­te­rial/par­ent me­tal gave up rather than let go.

Dis­cre­tion is the bet­ter part of val­our ap­par­ently, so a cup of tea later and out came the oxy-acety­lene to lend a hand! I re-welded the puller, put some puller load on and heated up the old bear­ing. Af­ter a while you could hear it creak­ing then a ping as the puller load did its job. I had to re­peat this process be­cause as it briefly cooled it gripped again.

The outer race of the same bear­ing was also a bit of fun as it was pressed into a blind hole. I found a very large washer, turned it to the right di­am­e­ter and welded it into the bear­ing, which meant I could tap it out from be­hind.

In the mean­time I’ve been lin­ing up the an­cil­lary com­po­nents ready for the charger. I found an old oil sup­ply fit­ting and pipe in the stash of parts that came with the car. The braided hose was past it, but pro­vided a good tem­plate for a hose spe­cial­ist.

I have also been restor­ing the man­i­folds ready for a fin­ished blower, which in­volved a bit of parts wash­ing and blast­ing with a light me­dia. I am glad I tried to get ahead of the game here, as I have just dis­cov­ered the be­spoke Shor­rock man­i­fold fouls my tubu­lar man­i­fold. Easy... re-fit the orig­i­nal cast ex­haust man­i­fold, you say? But that fouls too! Looks like more fun ahead get­ting the su­per­charger fit­ted to the car.

The chal­lenge was the bear­ing on the drive plate – it was stuck fast

Su­per­charger mocked up on the en­gine.

The outer hous­ing in place.

Bear­ings and vanes in the ro­tor hous­ing.

Re­assem­bly is the re­v­erse of dis­as­sem­bly.

The lovely lit­tle badge.

My home-made press tools.

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