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#1 Mini_Mad_Manx_Man

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Posted 12 July 2018 - 08:18 PM

So I've just picked up a full FRA shell and know its home I'm looking for advice on strengthen high stress mounting points. After searching and searching I still can find any treads on FRA build or a guide or a video. Nothing!! Can anyone point me in the direction.  



#2 Retroman

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Posted 13 July 2018 - 07:48 AM

Welcome to TMF don't be scared of asking anything on here, someone will know

 

A full cage would be a good start, as it will be a custom build from there a standard 6 point would do.

 

Not one I have played with but you can start and triangulate and plate from there...I nearly said weld

 

16 gauge (1.6mm) box section and 2mm plate

 

Not sure what the use is but I assume it will not be grandma's shopping car

Make any add-ons as long as possible, and touch the shell at as many points as poss

Make use of seat belt holes too (assuming it has some)

You should be able to make it all bolt in

 

8oPFTD3.jpg

 

If you post some photos of the internal shell I can be more specific



#3 DomCr250

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Posted 13 July 2018 - 08:39 AM

I had a very early FRA shell and it was very solid with thick GRP in the most important places. 

 

The only weakish points I could see where the front mounts of the rear subframe (just did not look right), if I'd kept it (did not) I'd have put metal spreader plates in there for the bolts / nuts to sit on.

 

Front subframe looked like it bolted in to thick stuff, I think it's only supported on the towers and rear? 

 

Floors and roof were very thick on my one.

 

On my Mini Marcos (early Mk3) it flexed across the roof, seemed to be coming from stress loading's from the rear section, when I converted to a beam I put a hoop in that connected the L and R sills behind the driver with 'legs' at ran to the shock tower mounts and a crossbar between them.  Maybe that work looking at?



#4 Mini_Mad_Manx_Man

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Posted Today, 08:36 PM

Cheers for the reply's lads. 

 

I had a very early FRA shell and it was very solid with thick GRP in the most important places. 

 

The only weakish points I could see where the front mounts of the rear subframe (just did not look right), if I'd kept it (did not) I'd have put metal spreader plates in there for the bolts / nuts to sit on.

 

Front subframe looked like it bolted in to thick stuff, I think it's only supported on the towers and rear? 

 

Floors and roof were very thick on my one.

 

On my Mini Marcos (early Mk3) it flexed across the roof, seemed to be coming from stress loading's from the rear section, when I converted to a beam I put a hoop in that connected the L and R sills behind the driver with 'legs' at ran to the shock tower mounts and a crossbar between them.  Maybe that work looking at?

Mine doesn't feel that strong, I can push the roof in with my fingers I'd say (in the middle) and as you say its where the sub frames mount that scares me. Yes front subframe is mounted with tower bolts and rear mounts only. I would like to plate the points where the rear subframe mounts to the body but its know what thickness plate how big do the plates need to be to spread the force and how many layers of fibreglass is strong enough for a car body. I'd like to again plate the rear mounts of the front subframe and put box section in the inside of the hollow fibreglass crossmember to give the tower bolts support. Im I on the right lines?   



#5 Mini_Mad_Manx_Man

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Posted Today, 08:44 PM

Welcome to TMF don't be scared of asking anything on here, someone will know

 

A full cage would be a good start, as it will be a custom build from there a standard 6 point would do.

 

Not one I have played with but you can start and triangulate and plate from there...I nearly said weld

 

16 gauge (1.6mm) box section and 2mm plate

 

Not sure what the use is but I assume it will not be grandma's shopping car

Make any add-ons as long as possible, and touch the shell at as many points as poss

Make use of seat belt holes too (assuming it has some)

You should be able to make it all bolt in

 

8oPFTD3.jpg

 

If you post some photos of the internal shell I can be more specific

Thank you for the warm welcome, I don't understand why a full roll cage to start? My plan was to start by getting the subframes fitted and then anything that connects the subframes to the floor ect...... what are all the 16 gauge box section for? Thanks again I've never worked with fibreglass so it's all new.






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