SE5 Eng & Trans Mount

Scimitar SE5 AJ-V6 Conversion - Mounts

Mobirise

Engine Positioning

The engine needs to be positioned with enough clearance from the auxiliary belt route to the rear face of the front suspension towers to allow for movement but not too far back that it impinges too much on the bulkheads foot wells.

The engine is positioned as far forward as it will go to reduce the amount it impinges on the bulkhead as possible.

But it needs to be back far enough from the rear face of the suspension towers to give adequate clearance for the auxiliary drive belt and alternator pulley.

The clearance doesn't have to be huge...

Just enough to ensure that they cannot come into contact through normal engine movement on its rubber mounts and to allow the replacement of the auxiliary drive belt without having to removed the alternator.

Consideration also needs to be given to where the back of the gearbox ends up along with the gear selector mechanism.

Engine Mounts

The AJ-V6 engine is mounted via its original engine mounts, though the LH mount does require a fair bit of surgery as described in the AJ-V6 section of this website here.
The chassis mounts are actually very simple. The engines mounts are horizontal and line up almost perfectly with the main chassis rails. Simple box section mounts are added to the top surface of the main chassis rails and universal mounting rubbers (also often advertised as V8 Land Rover Defender engine mounts) are employed.

Simple box section chassis bracket to take universal engine mount.
I later cut the bottom face of the box section out so as not to introduce a festering rust trap between the face and the chassis rail.

Tack welded in place once happy with the positioning.

Engine removed and mount seam welded to the chassis rail. The overhang was also trimmed to give a better appearance.

Blown over with zinc-rich primer.

Disatance between mounting holes.

550mm

Distance from rear face of suspension tower (both sides the same).

255mm

Completed.

Gearbox Mount

The gearbox has a mounting foot at its rear edge. I have utilized this to attach to a simple frame employing two more universal mounting rubbers as used for the engine mounts. In this case they are angled so that the mounting bushes aren't all acting in the same plane.

The chassis was levelled with scissor jacks and a spirit level so that the relative engine and transmission assembly could be set. In this case, according to internet wisdom (not mine but I can't remember where I found it) to -3 degrees.

The mounting foot at the rear of the gearbox almost lines up with the original bolt-on gearbox cross-member, certainly enough for it to be useable.

Rear edge packed until the correct angle is achieved.

the bottom face of the mounting foot needs to be 40mm above the upper surface of the gearbox cross-member.

The gearboxes original mount fitting will be utilized as it incorporates a handy threaded hole.

But it needs the cylindrical portion removing to make it useable.

The gearbox bracket is made from 5mm steel plate. The ends need bending upwards to allow for the angle of the rubbers. This wasn't to any pre-determined angle, merely as far as I could angle it without fouling the gearbox casing.

Seam welded.

The other side was cut, heated and bent to match.

They are seam welded on both sides to reduce the risk of cracking from being work hardened.

The square ends were rounded to match the rubber mounts.

Small braces were also added.

Trial fit.

The rubber clears the chassis rails.

Both rubbers fitted and the assembly clamped to the original gearbox cross-member with packers (obscured from view) to simulate the 40mm distance from the cross-member upper face to the gearbox mounting foot. Angled mounting feet cut from suitable box section.

The whole assembly was trial fitted to the chassis with the gearbox iun place and the angled mounting feet tack welded in place. They were then removed and seam welded to the gearbox cross-member.

They just fit, their forward edge almost lining up with the forward edge of the gearbox cross-member.

Fitted giving torsional support in two planes, both separate to the horizontal engine mounts.

Job done.

Prop-shaft Hoop

If the custom prop-shaft I will need for this were to fail I don't hold out much hope in the fiberglass transmission tunnel containing the flailing prop-shaft. So in a bid to reduce the risk of such carnage and for peace of mind I have fabricated a prop-shaft catching hoop.

The hoop is going to double up as the anchor point for the rear mount of the gear selector mechanism so this has pretty much dictated it's position which fortunately is where it needs to be anyway.

The hoop is going to fixed to the main chassis rails with bolts. It will slot down between the chassis rails for maximum strength.

There is a lip running along the inboard faces of the chassis rails. This is already relieved on one side, possibly to clear the overdrive unit. The lip needs removing as the chosen location.

Removing this lip also removes the join between the two parts making up the chassis rail in this location so the edges need to be welded back together.

Cleaned up and blown over with zinc-rich primer.

A spare prop-shaft has been used to ensure adequate clearance is maintained whilst not allowing the prop-shaft too much freedom to maim.

The hoop is made from the same 5mm thick steel strip as the gearbox mount. The bolt holes in the chassis will later be opened up to accept rivnuts.

First sections cut, drilled and 'bolted' in position.

The angled chassis rails made it tricky to figure out the cut angles for the next two pieces, so I cheated!

The metal sheet (held in place with 90 degree magnets) has the final height and width of the top piece marked on it. The next two pieces were offered up to it and the join line where they contacted the first pieces was drawn on them. They were then tack welded in place and then the brackets removed and seam welded (both sides).

Finally the same technique was repeated for the top piece.

Seam welded and complete.

Gear Selector Mechanism

I didn't get the original selector mechanism with the engine, not that it would have fitted anyway. But with it being a Getrag gearbox any BMW manual selector assembly will fit to the gearbox. Though whichever one you end up it will need shortening.

BMW gear selector mechanism fresh from eBay.

This one from a late 90's 5 series.

As standard it is way too long.

Here you can see how further back it is from the original position which itself is still slightly further back than ideal to line up with where my hand naturally sits.

The assembly was detached from the gearbox and slid forwards to the optimum position and then the alloy bracket was marked where the gearbox attaching bolt holes lined up.

The selector mechanism was then stripped ready for the bracket to be shortened.

A suitable section was cut out of the middle of the bracket.

The two ends were then taken to a local fabrication shop and welded together.

The shortened assembly slaved in position to determine the height of the rear mount.

I jot a bit carried away here and chose to use a nylon spherical bearing (to reduce risk of binding on the brackets rear shaft and to allow for the variance in alignment) attached via vibration mounts.

Dry assembly.

In position with brackets welded to the prop-shaft hoop.

This certainly held the gear shift assembly in the correct position but those vibration mounts are too soft and I don't expect the nylon spherical bearing to last long. So I have decided to junk this in favour of the original rubber bush and a suitable bracket.

But for now it will do to locate the selector mechanism so that I can shorten the selector rod to suite.

The distance between the gear lever attachment hole and the gearbox selector hole was measured and a suitable section cut out of the selector rod to shorten it accordingly.

The removed section was cut and rolled to a tighter diameter sufficient to allow it to be slid into the cut ends.

The ends were drilled ready for spot/plug welding (after removing the plating) and the rolled section welded into one end. The mechanism was then reassembled and the other end slid into position. Once everything was aligned the shaft assembly was marked where it needed to be fixed.

It was then removed and the whole thing welded together.

Refitted and functioning fine (apart from that rear mount).

That concludes the engine and gearbox mounts and the gear selector mechanism.

Mobirise

The contents of this website are purely a reflection of my own experiences and knowledge gained whilst working on my various projects. Anything you do based on what you have read here is done so entirely at your own risk.
Personally I wouldn't trust someone like me with a lawn mower! You have been warned! Flapper-bat!

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