Talk Morgan Forums Morgan Sports Cars Morgan Three Wheeler & Super 3 M3W Chassis crack

Tony[/quote]
Hmmm... I'm no suspension expert, but I can't see how a spring would just compress more and more just because of poor rebound characteristics of a shock absorber! But I may be wrong - any examples of this behavior?
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It's called 'pumping down' and likely goes by other terms as well. If the damper compresses but the internal valving is too restrictive in rebound (i.e. slow), then it can occur the spring is unable to fully decompress before the next bump is encountered. A quick series of stutter bumps and the damper can be near fully compressed.

Thanks Steve - well something new to me. I’ve not heard of that happening in a M3W but indeed found some references on a quick Google search to this phenomena in kit cars. I would have thought it would be pretty noticeable to the driver?

Reminds me I had a huge thump going over a pothole (or more accurately, missing the wrong pothole) in Princes Risborough a year ago, and was convinced the chassis must have sheared a weld or 2! However no cracks found (yet!).

Another theory about chassis cracks: the original front spax shocks have exposed bump stops (exposed to light/heat etc) which tended to decompose into a fine yellow powder. I think later on spax shocks had a plastic sleeve fitting over the top portion of the shock protecting the stops. So maybe it is not the shocks that are bad, but the poor bump stops do not keep the shock from hitting at the top of the eye support thus allowing the full energy of the jolt transferring to chassis? just a theory. I replaced my old spax shocks with some 2019 used spax.....but still shopping for upgrades on the off chance that better shocks improves longevity of the chassis. ATR or Ohlins

Interesting thought...

I thought it was only the v early ones with Suplex shocks that had the yellow rubber bump stops - our situation. Our bump stops are still fine - we know this because we had to have one of the shocks rebuilt by the original specialist supplier earlier this year (broken rod). The Spax ones fitted from later in 2012(?) seemed to have been distinctive a) from the increased ride height and b) the absence of the yellow bump stop.

Well my M3 is 2012, and he shocks say "Spax." I am a little confused about the difference between suplex and spax (did early suplex made shocks that say Spax?). My shocks' stops turned to that distinctive yellow powder. I visited a vintage auto dealer in Chicago area that presently has a 2012 for sale. I checked out that car for it's level of rust/cleanliness etc relative to mine (he wants about 10 grand more for his than I paid for mine), and sure enough the bump stops are decomposed.

Has any body done a full chassis swap themselves? Looking, hoping, for a Mr Bleazey style how to do it instruction sheet.
Any info welcome

I have not heard of any owner doing a chassis change yet, or if MMC would sell you a chassis? Has anyone bought a new chassis? I think it would be an interesting diy task for a reasonably competent mechanic. It would certainly be worth taking plenty of stage photos for some info.

Would certainly be a good opportunity to sort all sorts of more/less inacessible detail...never sure that all of us who have had chassis changes will have add the ideal (re)build given the job was being done under time pressure at MMC cost....it was however good that they did it for most with no quibbling once the problem was fully apparent.

As MMC are no longer replacing the defective early chassis FOC. I have lodged a report with the government agency to look into a factory recall. Let’s see what happens.