Ive got a Dax Rush MC frame. But I'm missing all other parts.
the frame is very light and of the looks of it its not buildt for anything else than a MC engine.

ive got a well buildt C20XE from an other project, QED cams etc. It would be a shame not to use it as it puts out a fresh 200hp.
Anyone tried to mount an engine as a part of the frame? 6-8 engine/gearbox mounts. 80-90 shore 20mm PU brushings with 12.9 8mm bolt through them.

Would it be a good solution to help the frame from twisting?

The XE is a heavy engine (130kg) and the gearbox R28, (35-40kg)
Will the torque make up for the extra kg vs a 65kg Yamaha YZF R1 with 150hp?

I put a 5L V8 in a Sylva Riot that was designed for a M/C engine and it was solidly bolted in with 2 points on the engine block, 4 points at the block/gearbox interface and 2 points at the rear of the gearbox.

It was not particularly easy and I'm not sure I'd do it again. Lengthened the chassis and added extra members to stiffen.

Worked quite well though apart from eating diffs.

Cheers

Personally wouldn't have thought poly mounting the engine / gearbox will take much flex out of the chassis, you'd need to hard mount it to make the engine / box a stressed member.

I've had cars with XE and R1 engines before - with the XE engine at 200bhp I am fairly certainly it will be slower than with the R1 engine at 150bhp.

[Edited on 11/6/20 by AdamR20]

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Originally posted by AdamR20
Personally wouldn't have thought poly mounting the engine / gearbox will take much flex out of the chassis, you'd need to hard mount it to make the engine / box a stressed member.

I've had cars with XE and R1 engines before - with the XE engine at 200bhp I am fairly certainly it will be slower than with the R1 engine at 150bhp.

[Edited on 11/6/20 by AdamR20]

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Originally posted by adithorp


Also, hard mounted the vibration would be pretty bad and could lead chassis failure anyway.

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As mentioned above I'm not sure poly bushing the engine and gearbox to the chassis will stiffen things much. My understanding is you need to rigidly mount them make the engine and gearbox stressed members to achieve what you're after.

On my Peugeot 205 GTI I've changed the rubber mountings between the monocoque body and the rear suspension subframe to solid Aluminium. You could tell the difference in the car's handling behaviour straight away. It didn't feel any harsher though, I'd expect to have to change the torsion springs and dampers to increase harshness (not what I wa after).

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Originally posted by v8kid

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Originally posted by adithorp


Also, hard mounted the vibration would be pretty bad and could lead chassis failure anyway.

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Well, it didn't with me have you had experience of this happening?

Cheers

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It might be worth observing that the engine can ultimately only transmit as much torque to the chassis as the rear tyres can react to the tarmac.

In other words: the engine has to have something to twist against

The tyres effectively act as a structural 'fuse'.

Although the more torque you have (after it's been multiplied by the gearbox) the more time your chassis is going to spend being stressed close to that limit.

I also have a Dax rush and I am thinking of using the style of mounting as used on the Ford world cop cross member,
My thinking is that if you use the block as an extra cross member as Ford did and also lots of American V8 engines are mounted,
It would give you extra stiffness closer to the front suspensions bottom wishbone connection as the usual angled soft rubber mount will induce
an outward force under braking for example, Quite often when braking hard on the entrance to a corner when you want you steering geometry to be at its best.
This is just my thoughts on the matter after reading quite a bit on chassis deflection.
Good luck with your build and have you been on the Dax forum yet, Whereabouts are you in the country.
Regards Allan

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Originally posted by ALLAN 14
I also have a Dax rush and I am thinking of using the style of mounting as used on the Ford world cop cross member,
My thinking is that if you use the block as an extra cross member as Ford did and also lots of American V8 engines are mounted,
It would give you extra stiffness closer to the front suspensions bottom wishbone connection as the usual angled soft rubber mount will induce
an outward force under braking for example, Quite often when braking hard on the entrance to a corner when you want you steering geometry to be at its best.
This is just my thoughts on the matter after reading quite a bit on chassis deflection.
Good luck with your build and have you been on the Dax forum yet, Whereabouts are you in the country.
Regards Allan

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Originally posted by TMB
Ive got a Dax Rush MC frame. But I'm missing all other parts.

the frame is very light and of the looks of it its not buildt for anything else than a MC engine.

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Solid mounting an engine, a certain Mr Chapman did this to try and stiffen his Austin 7 chassis for 750 racing, you couldn't modify the chassis, but it twisted the block and ran the bearings so I think he built a cage over the engine to give the same effect!

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Originally posted by mcerd1

and you'd be right - the Rush MC chassis is significantly lighter throughout using thinner tubes 1.6mm rather than 2.0mm on the main chassis rails (at least on the square tube version, round tubes are even lighter) and smaller diameter round tubes for the triangulation/bracing - which the designer of the chassis said he was concerned would lead to fatigue failure when converting these to heavier car engines when this was discussed back in the day


there were 2 types of 'Rush MC' chassis offered - Square tube or round tube (the round tube typically being with CC&AR suspension) - not sure which you have ?
but both were much lighter than the car engine chassis versions - being designed to handle much less weight and torque (not going to say less power cause I've seen some of the turbo busa cars in the flesh )

[Edited on 12/6/2020 by mcerd1]

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