Got four new tires mounted and balanced (Milestar P175/80R13, blackwall):
But while troubleshooting that left front brake problem, I discovered the previous owner had been unusually creative.
The left and right front wheels had completely different brake mechanisms. Left had a self-adjuster unit from a different model Mercedes; right had the correct manual adjuster unit. All four wheels are supposed to have the manual adjuster mechanism. In addition, the left front wheel had (1) incorrect brake shoes, (2) incorrect brake cylinders, and (3) an incorrect brake drum. Larger diameter cylinders on the left front caused left brake to pull, due to having “more force” on the shoes and drum.
Finding correct brake parts for a 50+ year old car isn’t exactly a piece of cake. Also discovered that the 3-arm flange between the transmission and driveshaft giubo is very worn and needs replacing. A giubo is a rubber damper (vibration absorbing) disc, invented by Antonio Boschi back around 1900. Giunto means joint. Giunto + Boschi = GiuBo. Here’s what a new one looks like:
And here’s the old one (note cracks and fraying, which cause vibration in the drive train):
When the mechanic removed the old giubo, he discovered the mounting flange at the transmission was so worn, the bolt holes were ovals, and the bolts flopped around in the holes. I ordered a replacement flange – but the wrong part was shipped. Ordered another, shipped overnight ($$$) – and the delivery company lost the package. On the third attempt, I finally got the correct part by driving to Norwich Connecticut on Saturday afternoon and bringing it home myself. Flange and giubo will be mounted today (Monday, September 9). Braking system will be in almost-new condition (new wheel cylinders, master cylinder, steel lines, brake hoses, shoes, matching drums, etc.), but work is now one week behind schedule.
September 16 update: Driving back from the shop, with completely rebuilt brake system, the engine started missing under load. Going uphill, there’s a random hesitation; going downhill, no hesitation. Got much worse the longer I drove; engine was actually “bucking”, like the ignition was rapidly going on and off. Need to fix that before setting out on the journey. Frustrating – but the brakes and driveshaft are working smoothly now.
September 21: Another week lost in search of the cause of the engine hesitation. I’ve removed carburetor, cleaned all the jets, checked fuel flow, distributor connections, coil, condenser, resistor, etc. At 5pm Friday, it turns out that one of the spark plug wires was barely making contact with the spark plug sleeve. The wire actually fell out of the sleeve when I was checking wire continuity.
Ignition wires are simply pressed down into terminals (“sleeves”). The sleeves have small threaded points which are supposed to screw into the wire. Looks like that didn’t happen on at least one plug wire.
Today I’ll pull all five ignition wires and make sure all connections are tight. Problem could have been (1) a poorly made connection at the factory, or (2) I pulled on a wire, weakening the connection, at some time since I got the set (six months ago). Vibration plus heat build up during driving, could make the weak connection finally fail, but could partially re-connect when engine cools. Verification after repairs will be a good long test drive on Sunday, after the rains stop.
September 22: cause verified and problem solved. Plug #1 wire wasn’t screwed down inside plug cover sleeve. Fixed that, checked all other plug wire connections, then went for a 20 mile drive with no problems. Looks like I’ll be heading toward the West tomorrow. Further updates will be on the Trip Details page.
(With all the mechanical improvements I’ve been making, I’m almost embarrassed about the exterior paint appearance. The car was cheaply re-painted many years ago; the newer paint is cracking and wearing through. Buffing helps a little, but in many areas makes it worse. I don’t have the funds for a new paint job, so I’ll have to live with it. Definitely a “20-footer”.)