After many months of delays and distractions, I have finally finished the subframe (with the exception of minor items like welding on tabs for things like brake lines). I will also get my engineer to inspect the subframe to determine that everything is okay. The engineer will looks for things like :
So what I have done to complete the design is add some brace bars (27mm OD tube with 2.5mm wall thickness used) that run under the engine/gearbox to tie the whole subframe together at the bottom. This is to prevent any potential compression or tension while under load between the front and rear of the subframe that would normally occur without these bars.
Firstly I used the tie-rod mount templates (made previously) to ensure that any tube used for the lower braces will pass close to the mounts.
The lower end of the brace bars will be welded to the bottom of the towers so I strengthened that area will some 5mm steel plate and some flat bar across the width of the subframe.
I tack welded some steel onto the subframe to replicate the position of the tie-rod mounts.
The tube was tacked into place. This photo shows the one that runs around the side of the sump. You can't see it from this photo, but the bar is just slightly lower than the sump so if I drive over anything high, it should hit the bar and not the sump.
The other end of the bar was welded to the bottom of the tower
Various other conversions I've seen have the tie-rod mounts cut off the original subframe and then welded onto the new subframe, but left dangling on a piece of flat steel with no bracing. You are putting a LOT of forward force through this mount under heavy braking so it needs to be strong. The new tie-rod mounts were made from 5mm steel and have another 5mm thick triangulated gusset bracing it. This will ensure it will be damn strong and all forces will be transferred to the front subframe mount.
So this is the final product :
A standard task to reinforce any Mini subframe is to weld the top of the towers so this was done, but I also ran a weld across EVERY seam where any two panels or pieces overlapped.
- Is the design at least as rigid/stiff as the original?
- Do the new engine mounts correctly transfer the new loads to the structure and then on to the mounts between the frame and the body?
- Are the frame and mounts designed and constructed to minimise fatigue cracking?
- Will the engine move excessively in the frame?
- Does the frame compromise the integrity of other systems like the suspension, steering, brakes and other nearby items?
- Does the frame contain members likely to break free and penetrate into the cabin in the event of a collision?
- Are the welds full penetration and of sufficient area and quality for the task each performs?
So what I have done to complete the design is add some brace bars (27mm OD tube with 2.5mm wall thickness used) that run under the engine/gearbox to tie the whole subframe together at the bottom. This is to prevent any potential compression or tension while under load between the front and rear of the subframe that would normally occur without these bars.
Firstly I used the tie-rod mount templates (made previously) to ensure that any tube used for the lower braces will pass close to the mounts.
The lower end of the brace bars will be welded to the bottom of the towers so I strengthened that area will some 5mm steel plate and some flat bar across the width of the subframe.
I tack welded some steel onto the subframe to replicate the position of the tie-rod mounts.
The tube was tacked into place. This photo shows the one that runs around the side of the sump. You can't see it from this photo, but the bar is just slightly lower than the sump so if I drive over anything high, it should hit the bar and not the sump.
The other end of the bar was welded to the bottom of the tower
Various other conversions I've seen have the tie-rod mounts cut off the original subframe and then welded onto the new subframe, but left dangling on a piece of flat steel with no bracing. You are putting a LOT of forward force through this mount under heavy braking so it needs to be strong. The new tie-rod mounts were made from 5mm steel and have another 5mm thick triangulated gusset bracing it. This will ensure it will be damn strong and all forces will be transferred to the front subframe mount.
So this is the final product :
A standard task to reinforce any Mini subframe is to weld the top of the towers so this was done, but I also ran a weld across EVERY seam where any two panels or pieces overlapped.
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