|Why would anyone spend $6,000 for an untitled old BMW that they had only seen in photos, with a motor that blew smoke out the breather tube, a transmission that would not shift, a head and a cylinder that had to be thrown away, a crankshaft whose rear bearing was held on by knurling the seat and coating it with locktite, a mis-aligned rear swingarm with weak front springs in it, and a mis-shimmed final drive that was growling and self-destructing? And then have this motorcycle shipped across the country? Read how it can happen.|
AD IN BMW OWNERS NEWS SEP 99
1966 R60/2 Complte restor, nothing missed. All new seals, headers, muffs, rubber pieces, rings, rims, tires, ss spokes, wiring harness, solo seat, new bearings in engine, frame, wheels. Matching #'s, Earls fork. Concourse cond. John 714-XXX-XXXX, firstname.lastname@example.org (CA)
The price quoted on the phone was $6,000 for the completed bike. The deal seemed to have many advantages:
EMAIL QUESTIONS AND ANSWERS
Atherton: Here's all the questions I can think of...
#17. General: Is there any thing that is not quite right ...
any weak point in he restoration?
11/12/99: Sent cashier's check to myescrow agent, who was Sales
Mgr at Irv Seaver BMW. While check in transit, Seller emailed that the
transmission was not working properly. I emailed Seller that I wanted
to discuss this before buying the bike.
SUSPICIONS OF MOTOR
Appearance: Motor did not have the usual restored look.
No beadblasting. Old valve cover gasket. Heavy dust inside the
front cover. Old clutch cable with cracks in sheath. Some bolts
rusty or rounded off. Some studs set in JB Weld epoxy. Controls
too stiff to use. Most significantly, the adjustment on one valve
was used up and the vavle could not be adjusted further.
Heads: One valve was so recessed that it could not
be adjusted, and its rocker arm was modified for clearance by
grinding. This was the initial tip-off that things were amiss
inside. Valve seats were found to be deeply worn (recessed),
and were re-ground deeper instead of replaced. The valves were
old and had been lapped to a thin sharp edge. One valve guide
fell out of the head, and another could be pulled out by hand.
Left head had a ring of peen marks around the exhaust valve's
seat to hold it in, and a crack in a fin.
Atherton: My spreadsheet shows a cost of about $3000
.... to make the bike right. This is not the restored bike I
hoped to get.
RE-RESTORATION OF MOTOR
The heads were sent to Bob's BMW for overhaul to include new valves, seats for unleaded gas, guides, and rotating keepers. Bob's reported that spark plug threads were after market repair inserts and should be repaired by removing the inserts, welding the holes closed with aluminum, and drilling and tapping new spark plug holes. Also, Bobs said it was cheaper for them to sell me another used left head to overhaul, than to deal with the peened exhaust seat and the cracked fin.
|Original head, showing circle of peen marks around valve seat||Another head was used for restoration, showing appearance without peening (valves are installed)|
|Original head, showing steel insert for spark plug threads, and crack in fin above it.||Head used for restoration, with spark plug hole rebuilt by welding in new aluminum and tapping new threads.|
My understanding of peening:
Valve seats are held by being pressed cold into a heated head, which then cools and squeezes the seats tightly. After the seats have been eroded and ground enough times, they lose so much material (become so recessed) that they don't stay in the head reliably.
If your seats need grinding again, but are already ground thin, and you don't want to pay for new seats, your old seats can still be ground again and then peened to hold them in. In peening, the head is heated up, and a hammer and punch are used to punch dimples in the softened head in a circle all around the seat. This deforms the alloy around the seat, swelling the alloy over the recessed lip of the seat, and locking the seat into the head.
The problem occurs when a complete proper valve job must be done. The seats cannot take any more grinding, and must be removed and replaced. It is hard to get the seats out of the peening, and the removal efforts may further hurt the head. After seats are removed, the stresses and deformation from the peening and the removal efforts have made the seat holes not perfectly round. It is then not safe to just heat up the heads and press in new seats - the new seats might come out. The seats holes must be re-machined. In my case, one exhaust seat had been peened. The shop said it was cheaper for them to sell me a used head that had not been peened, than to re-machine the peened seat hole.
Peening saves some money at first, but is semi-destructive of the head and costs more money in the end.
I was initially given two choices on the cylinders. The cheapest choice was to simply put oversize rings on the piston that was in the mis-bored left cylinder, and accept some piston slap. But both the pistons and the cylinders, although supposedly new and rebored with only 30 miles on them, were rather deeply scored as if they had been assembled with grit on them. So I decided to have the cylinders re-bored to the next size up, 2nd oversize, and bought new 2nd oversize pistons so that precise measurements could be made before boring. After measuring the new pistons, the cylinders were sent to a machinist for boring to fit them. The machinist bored one cylinder but stopped at boring the second cylinder because measurements on his boring equipment indicated that the 1st oversize boring job done by the previous owner was not perpendicular to the cylinder base. The machinist said this could be because the previous shop had bored the cylinder from the head side instead of the base side, or because the cylinder had been misaligned due to sand or shavings under it. So tthis cylinder had not only been bored conically, but was bored diagonally at an angle to the base. One alternative was to make the next bore big enough to ream out and swallow up both problems; it would take a 4th oversize re-bore to do this, and what is done to one cylinder must also be done to the other. However, the expensive new 2nd oversize pistons could not be used in a 4th oversize rebore, and the 4th oversize cylinders could never be re-bored again in the future. I decided on the other alternative: to discard the bad cylinder and order a good used cylinder from Bobs BMW, and bore it to 2nd oversize. For the price of another cylinder, I could continue to use the new 2nd oversize pistons, and the cylinders would have two future re-borings left in them.
This is the cylinder that was misbored by the previous owner's shop going to 1st oversize, so that the hole was both conical and diagonal. The machine shop doing my re-restoration was told to leave it alone, that another cylinder would be obtained for boring to 2nd oversize.
The machine shop misunderstood, and proceeded to give it a bore big enough to cure its problems. Maybe someone on eBay will be able to use 73.49 mm which is 4th oversize.
Crankshaft: The crankshaft was sent to Ed Korn's Cycle Works to have both bearing seats built up with chrome and ground to tolerances.
Timing Gears: The motor had a gear on the front of the crank that drove a camshaft gear above it and an oil pump gear below it. The fit of these gears is critical - too tight and they run quietly but shed metal flakes into the oil supply, too loose and they make a whining noise. The factory stamped motor with the gears that it needed, and stamped the gears that were installed. My motor was stamped -3, meaning it should have had all -3 gears in it. However, the camshaft gear was a -3, but the crankshaft gear was a 0. Evidently something had happened to the original -3 crankshaft gear and someone had found a 0 gear to replace it. It was impossible to find a used -3 crankshaft gear in the US, and a new gearset was almost $600. Also, I was told that in a motor this old, the original measurements might no longer be the same and a -3 gear might not be the best fit. In the end, the 0 gear on the crankshaft was re-used because it seemed to give the gearset the right amount of backlash play - at least it was not too tight. Later when the motor was running, I could not hear the gears, although the restoration mechanic said he could.
Gear Cover: Located a good used gear cover, inexpensive, too. This is the aluminum casting that encloses the timing gears, sandwiched between the motor block and the front generator cover. Then I bought and installed new stainless steel studs in the gear cover to hold the generator cover.
Transmission: Disassembly of the transmission revealed no internal wear or damage to account for its shifting problem. The most likely reason is that the seller installed the shift lever bolt with its head up, which makes the threaded part of the bolt protrude far enough downward to hit the frame and interfere with shifting. This bolt must be installed from below, with the nut on top of the shifter, and this must be done with the transmission out of the bike. If one waits until the transmission is in the bike before installing the shift lever, then the bolt can only be inserted from the top, which causes the shifting problem.
|The rebuilt transmission and motor, waiting on the work bench for installation in the rolling chassis.|
|Motor and transmission are in the bike.|
|View of completed motor and transmission installation. The new (used) timing cover is the section between the front generator cover and the main block.|
OTHER PROBLEMS DURING BREAK-IN
Rear Drive: On the first test ride after the re-restoration, the rear brakes were ineffective, and the rear drive made a growling noise. The seller had said that the head mechanic at Irv Seaver BMW had worked on the rear drive. Removing the rear wheel revealed oil soaked brake shoes and splines that could not be turned by hand. This indicated that the ring and pinion gears could be jammed together too tightly. Disassembly of the rear drive showed that the gears were indeed self-destructing. Evidently, the seals had been replaced to stop the oil leaks, but the drive had been poorly shimmed on re-assembly. Under the ring gear were two brass shims that were too thin and did not even fit tightly on the gear shaft. The thin shimming had forced the ring and pinion gears into tight contract, causing noise and wear. The rear drive was rebuilt again with proper shims to allow the right amount of backlash between the gears, and the brake shoes were renewed.
Suspension: The first rides indicated a possible problem with the suspension. The front end seemed hard, with the wheel bobbing very little riding over a bumpy lawn compared to my R27, while the rear end bounced easily and sank too low. The front swing arm was taken apart to see if it was seized - it was alright and swung free, although it did not have any grease in it. Then recently came an opportunity to compare this bike against another /2, and measure the compression of the front and rear suspension units on both bikes with a person sitting on the bikes. The front end of my suspension compressed the same as the other bike, indicating the springs were OK. But the rear end compressed 1-1/2 inches more than the other bike, so that the entire polished aluminum lower spring cover was hidden up inside the black shock tower. The rear springs were too weak, so I ordered new rear springs. When the new rear springs came, I removed and compared the front and rear springs both to each other, and to the new proper rear springs. This comparison showed that the longer and weaker front springs had been installed in the rear, instead of the proper shorter and stiffer rear springs:
When the stiff rear springs were installed, the back end of the bike rose up, the polished lower spring covers came down out of the shock towers, and the rear tire stopped rubbing against the fender.
Rear Swingarm: Before changing the rear springs, the rear tire was so far up into the fender, and so close to the fender on the left side that it whirred against the swing-up fender bolt. The rear swing arm seemed to be installed too far to the left, so that it was very close to the frame both at the pivot and at the bottom of the shock. I thought thi might be because the left pivot pin was screwed in so far that only a few threads remained to put the cap nut on. On the other side of the bike, the right pivot pin stuck out too far, but could not be moved in because the right bearing seal was sticking out of the swingarm. All this made me wonder if the bearings were installed properly. Over a year later, I finally got around to removing the swingarm to check the situation, and found that ball bearings had been used instead of roller bearings. Ball bearings might have held up OK for solo riding, but would not lat very long if a sidecar was attached.
Rear Wheel Bearings: Since the fat 4.00 tire was too close the left side of the fender, I replaced it with the original size tire, a 3.50. This thinner tire gave more clearance against the fender, but another problem surfaced. I began to balance the new tire by giving a spin on the free axle, and the wheel bearings were so graunchy that the wheel would not spin freely. New wheel bearings and seals and shims were installed to correct this.
|COST OF BIKE WITH BASIC
Allan S. Atherton
Louisville, KY, USA
Fredricksburg, IN, USA
Mark Huggett GmbH
Holderbank (Zurich), Switzerland