Laverda
Cast Iron
- Joined
- Mar 24, 2014
- Location
- Riverside County, CA
About 1978 I had a 1963 Triumph TR4 with a 2200cc 4 cylinder motor and the center main bearing had spun. Being young and poor a low cost solution had to be found to get it running again. Making a boring bar that was turned by hand to machine the bearing bore oversize so a thick shim could be installed worked. Two dowl pins on each side held the shims in place. All including myself did not think it would last but as I was only making $2.60 an hour, I could not afford a better repair and had no choice as it was my daily transportation other than my motorcycle. Well it worked and when I sold the car years later as it was turning in to rust, the main bearing repair was still working fine and the car was run hard as I was a stupid 18 year old. I would measure the bore with the bearing cap on and torqued. If it is round and the correct size, I would run it.
Edit: I forgot to mention another main bearing story. My brother many years ago bought a 1970's BMW 530i car with a very noisy motor for basically free. The motor had been rebuilt but did not run well and had been driven thousands of miles like this while making a racket. The crank had been ground .01" under and they had installed standard size mail bearing shells so lots of clearance. Upon disassembly there was no damage to anything and the proper size main bearings fixed everything.
Edit: I forgot to mention another main bearing story. My brother many years ago bought a 1970's BMW 530i car with a very noisy motor for basically free. The motor had been rebuilt but did not run well and had been driven thousands of miles like this while making a racket. The crank had been ground .01" under and they had installed standard size mail bearing shells so lots of clearance. Upon disassembly there was no damage to anything and the proper size main bearings fixed everything.
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