Endield Diesel engine Mounting Brackets

[Mahesh]

Hello guys...i have a Diesel bullet 325cc will be soon assembling a 435cc diesel too...but i am confused to as to which foundation beds to use....well my mechanic has a Plans to make the beds ( the sizes of the pieces needed to be cut and a frame to which he fixes those cut plates and welds them ) he is suggesting 10mm iron plates ..and everyone one knows steel is stronger than iron so i want to make the foundation beds from steel...it will be both lighter and also stronger...but he argues that the beds needs to be heavy so that they counter the engine vibration....and i think the lighter the foundation the better as we all know for performance a lighter bike is favorable....so i need your advice....with whal do you guys make your Foundation beds or mounting brackets or what ever they are called..

[mark_in_manchester]

I'd be surprised if he has a lump of 10mm cast-iron to suit. It will be brittle, and difficult to weld to the rest of the frame. 10mm mild steel plate is available everywhere, and easy to weld - I used it to make engine and gearbox plates on my bike. Depending on how thick / rigid your crankcases are, you may well get away with something thinner.

[tappy]

I totally agree with Mark, and frankly if your "mechanic" is such a poor engineer you should take your bike to someone better qualified and better able to make the conversion - unless you've misunderstood your mechanic's arguments then he really doesn't know what he's talking about.

Has he not seen a diesel engine powered "whacker plate"? Those have got several kilos of weight attached to the bottom and they go up and down like billy-oh. Just how much mass is he thinking of adding? As much as the weight of an engine and whacker plate?
No matter how rigid, the frame form a flexible connection to the rest of the bike, with very little damping. All you'll do by adding weight is reduce the resonant frequency slightly, reduce the amplitude a tiny, tiny bit, and the acceleration forces felt by the rest of the bike will be largely the same. Much better would be to strap the engine in very firmly to the frame, with good connections at many points (reducing degrees of freedom and helping spread the forces to reduce local stresses) and then modifying the vibration responses of other parts.

This is why bike designers over the last century have use rubber foot pegs, rubber hand grips, weighted mirrors, rubber mounted bars, tanks, electrical components etc.

[Mahesh]

well where i live 10mm iron plates are easily avaiable.....they cost like 55rs for a kilo and so a 10mm plate can be bought for like 500rs ... and rs means rupee...but steel is costlier..and here in india engine mounting plates are being made from 8mm iron plates from like way back 1980`s...and those bikes are running good...and my guy went ahead and made them of 10mm just in case and also for brag rights i guess.....but i want to get those mounting plates out of steel is because they will be lighter thus better at acceleration and less strain on gearbox, etc...but i am unable to understand if whether reducing the weight will increase the vibration..????

[pietenpol2002]

The failures of diesel-engine Enfields as reported on this board have been largely related to tubing, not with the conversion components. It would appear the conversion components have been sufficiently over-designed so as to transfer the failure mode into the tubing. I suspect your fears are unfounded.

[tappy]

If you have very thick, stiff pieces of metal that aren't flexing at all, and join those to relatively light bits of hollow tubing, then the hollow tubing will flex a great deal where it meets the big lumps of metal, and is more likely to fail there.

If you use less metal at the engine interface, designed with a little more thought, then the stiffness can be better matched where it meets the tubing. This way you will reduce weight, reduce stresses and reduce the problems associated with welding very thick bits of metal to much thinner bits. And hopefully also avoid having to use cast iron welded to steel. Cast iron is good in compression, but is really not good in tension. Hence why iron bridges were first developed using arches. Bending puts a piece of metal in both tension and compression, and vibration causes bending. So really you want to be using steel.

A 10mm deep x 50mm wide x 1.5mm wall box section of steel has 2/3 the stiffness of a solid 10 x 50 section, yet only 1/3 of the weight. Add in the use of steel (even nice, cheap, forgiving, mild steel) and it'll be stronger than a 10x50 section of cast iron.

I don't know what geometries & sections you're talking about etc, but it gives you the general idea - hollow steel sections with through-bosses at bolting points should be a better solution that solid cast iron.