Carby rubber spacers don't last long and front one split after 3 years. Is this common?
No, they usually split much more quickly than that! Both Sprint and 1850 aftermarket items suffer from splitting or part company from the metal plates relatively quickly, and in the case of 1850 ones even OE suffer from early splitting as the rubber element has a longer cantilever and thinner wall thickness. The Club aluminium versions are not cheap, but a worthy investment, as they are ‘fit and forget’; the original reason for using rubber as a vibration break doesn’t seem compromised despite many years successful use.
With regard flexiplates, these used to be hard to source, so I suspect current supply is now aftermarket. I’d try to source good second hand. An 1850 auto was broken recently and the engine was quoted as having been sold. As the owner is still hawking the gearbox, the chap who bought the engine may have a surplus flexiplate...
My son and I have run 1850 and Sprint autos for over 50,000 miles since 2003 without any issues with the flexplates or torque converter which is as it should be.
When you say the noise is on start up, is that just when the starter is engaged? If the starter motor cog isn’t engaging correctly with the ring gear on the flex plate, that may be causing damage to the flex plate. Before you install and potentially destroy another flex plate it would be worth measuring the fit (cog into ring gear) to ensure the positioning both line up. Some starters require a spacer to get the alignment correct (I use a couple of thick washers on each bolt to ensure mine was correct).
Only other thing might be, although I’ve never heard of it could be the torque converter out of balance. If that were the issue I would expect vibration to be permanently present. I did have to rebalance a prop shaft recently, but that was for vibration and wouldn’t impact on the flex plate.
I had the same with my wifes 2500. Eating flex plates and on those cars it's common as most used ones i was offered had little cracks also. Common issue when you drive like my wife. A lot of city traffic stop and go and trying to out accelerate everyone around you with that straight six one damper howl. Long distance drivers will have less issue's I guess but 80% of the used flexplates I had in my hands on autojumbles were useless.
I ended up fitting a repair plate extra inbetween the flexplate and converter. There was a spacer of around 2cm thick between the crankshaft and the flexplate. I did replace this one by a self made flanged type as the flexplates alway's crack just around the crankshaft end. This flanged type is spreading the load more.
There is now less flex in the flexplate but I have to say that my converter is reinforced. By earlier experiments with even more less flex "solutions" the converter did crack. When having that one repaired I asked for some reinforcements inside the converter where the mounting lugs are welded in.
I think spreading the load will be the answer but I can't remember if an 1850 auto has a spacer fitted.
I do have already a manual o/d for that car laying around...
