Monthly Archives: March 2006

Watts Linkage Bolts!

With the rear suspension going on a couple of weeks ago you’d expect reports of the Aston driving around by now. But I didn’t take the Watts linkage into account. The bolt won’t go in with the axle in place.

Turns out the assembly order is rear suspension first (including Watts linkages) then the differential, and then the brackets that hold the differential in. Maybe the answer is to split the differential from the differential rear carrier, fit the mounting brackets, then the carrier, then the differential. We’ll find out as Nigel’s car goes together.

Thanks Jacques for popping over to help with that.

Watts linkage bolts

Fitting the Rear Suspension and Axle

It was good to have Nigel around to help fit the rear suspension and differential – it’s definitely a 2 man job. Our first step was to connect up and bleed the rear brakes (using a long brake pipe as an extension) to make sure there were no leaks under pressure. The brakes aren’t accessible with the axle in the car.

The owners manual considered it perfectly reasonable to remove and replace the rear axle with the suspension in place, so we fitted the suspension first then wiggled the weighty axle into the remaining space. It wasn’t all that easy. The driveshafts foul the de Dion tube with the suspension on full droop, and there was only just enough clearance when the axle stands were moved from the jacking points to the suspension. A nice full (heavy) fuel tank would have helped enormously.

Rear suspension and axle

Sliding Halfshaft Joints

Owners of pre 1980’s cars will be used to sliding spline joints that allow propshaft and driveshafts to alter in length as the rear axle goes up and down. They are terrible things. The steel against steel movement ensures rapid wear, and they don’t work very well under torque (not ideal for a drivetrain part).

It seems the guys at Aston Martin put some thought into this problem. You can see the thinking: ” Why don’t we put 8 rows of roller bearings inside an extremely complicated housing machined and then ground to an exacting tolerance? I mean it’s not as if the rear axle is complicated enough already.”

It’s a wonderful solution. Metal rolls against metal so wear will be minimal, they’ll work under torque, and should last for ever. Must have cost a fortune to manufacture, but the Aston solution is by far the most effective I’ve seen prior to the introduction of plunging CV joints.

Halfshaft Joint

I’ve been replacing the rubber boots – they’ll slide over the bearing carrier with the aid of a cone made from an old oil can (much the same approach as you’d use for replacing CV joint boots).