10 replies to this topic

[Tomm]

Hey,

Right well erm lastnight i found a thread on 16VMC of a lad who had modified a standard mini subframe to suit a C20XE engine, I was looking at the Box section tubing and it seemed to be 30mm x 30mm but i wanted to know what a suitable thickness of the metal will be. i have been having a look around and the most common seems to be 2mm which is way to thin i would have thought so if you have modified your subframe for a conversion what messurements did you use? have you had any trouble with it?

I didi have a look through loads of threads on 16VMC and i thought Matt might have advertised it on one of his adverts for one of his subframes but i couldnt find it anywhere So any help would be great!

Also where would i be able to get it from? I would need a fair old bit of it as i am more than likely to screw up some where down the line!

thanks, Tomm

[minivanman]

steel stock generally comes in 6m lengths. Find a steel supplier near you (dont know any down south) or find a local engineering/welding place and see if they can order some in for you. I wouldnt have thought 2mm would be beefy enough to make a subframe out of, I'd go for 4 mm or more if you can get it.

[Tomf]

Please could you post the link the the link showing the build. It might help people have a beter idea of what would be used.

[Jammy]

4m?!? Roll cage tubing is only 2.5mm! I would have thought 2.5mm-3mm should be fine.

[Tomm]

oh thanks for that jammy. I just really want to sure, when i thought of a C20XE supported by 2.5mm of box tubing it kind of concerned me a bit. didnt sound right in my head.

Thanks guys, i will have to have a look through the local directory and find some where local.

[Jammy]

Yea, go 3mm to be on the safe side, but you'd be surprised at what a well designed subframe can take! I mean standard mini subframe can't be more than 1.5mm thick! And thats been capable of taking 200bhp!!

[JoeBodge]

try "Parker Steel" mate, there the biggest stockists in kent. they are usual quite useful n will help you out. good luck with it

[minivanman]

Meh, if I was going to build something like that I'd use fairly thick wall section. Round tube is stronger than box section, and rollcage CDS is stronger than normal welded tube, which is why it doesnt need to be as thick. A normal mini frame is different because its made of pressed steel welded together.

[The Matt]

Yea, go 3mm to be on the safe side, but you'd be surprised at what a well designed subframe can take!............

to be honest I think that's the problem with home made subframes, they are not all designed and tested, they are made to fit an engine that wasn't originally meant to be in there. I would always tend to be overcautious with something like this and go for as thick walled material as is practical (without being stupidly heavy, or un-weldable). I mean, it not like you're going to be working out the second moment of area on the RHS and calculating any bending moments.

What part of the subframe will this be used to modify? I mean if it is just to make up engine mounts, then all you're doing is supporting the engine and stopping it from twisting itself out of the frame, but if you are chopping the front of the existing frame off then I'd be paying a lot more attention to detail, especially if you are using a flip front jobby! Tis harder to shape joints, but I'd rather see home made frames made from round tube rather than RHS!

As for 2mm seeming to thin, well, it's impossible to know without knowing what it is going to be used for and what loads it will be under, but you'd be surprised at how strong 2mm RHS can be

EDIT: RHS is Rectangular Hollow Section by the way!

by the way is By The Way (by the way)

Edited by mini mad me, 31 March 2007 - 06:39 AM.

[Woody]

My lotus 7 replica's spaceframe is made from 1.6mm wall RHS

[Tomm]

Thansk for that, I will have a look around. it just didnt seem right having a good old 200 brake strapped into some metal tubing 2 mil thick...

Thanks though, i think i will go for some thing between 2.0- 3.5mil