16 replies to this topic

[blister]

i currently have group 2 narrow arches fitted i would love to keep them but i want to go lower!

what are the pros and cons or tubbing the rear arches?

hard job?

what arches have people used?

[mini_mad69]

It's not a small job, you need to cut out the current arches and a section of the rear quater, form a new arch section and weld it in. Then prep paint etc. pros are you can get the car lower with less scrubbing issues.

Cons are that its a permanent sort of modification, and when raising back up to standard height for any reason can make the car look a little silly.

[Bungle]

biggest con i can think of is if you would modify the monocoque beyond what VOSA/DVLA would call the original untouched shell and need a BIVA test and re register the car afterwards

they do say triming the front arches for bigger wheels is ok but this is a bit more than that mod

firing a email off to them might get you a answer

[blister]

has anyone ever got narrow group 2 arches over the tubbed rears?
i believe there was one person from surrey area with a blueish mini with a removable front but i cant seem to find any photos of his mini anywhere

i dont think it would be a problem with dvla/vosa but will have a quick read and if things are still a bit unclear i will send a email to them

[Bungle]

Q) Would the modification of wings to allow clearance for larger wheels fall foul of the regulations?
We presume not as the common fitment of sunroofs does not create issues as this is a non stressed item of the monococque, the same as wings?"

A) When considering a monocoque structure, it is necessary to consider what constitutes cosmetic panels that do not significantly add to the structural strength and which panels provide structural integrity. In general front wings modified in this way would not constitute a modification to the monocoque structure.
With reference to the further query, VOSA have advised that they would prefer the following statement:

What constitutes a monocoque is that of how an OEM manufacturer would view it. The chassis or `cage` assembly and all components that form it, less any cosmetic panels or infills that make no structural consideration to the monocoque or its component parts.
However, we must emphasis that this information is given for general guidance and each case will be judged on its merits.
Whilst none of this is definitive, and it contains the usual 'Judged on it's own merits' criteria, it does answer a lot of questions where the modifier has only been able to speculate in the past.
It means we are aware of what we can or cannot do and still retain the 5 points from the start of any modification process.

Monococques
It is NOT acceptable for the bulkhead, or transmission tunnel area, to be modified.
The specification for a monococque will vary with each manufacturer and the decision on what are acceptable modifications will be based on those criteria for each vehicle.
It is acceptable for additional seam welding to be carried out.


Should there be any further questions relating the above information on specific vehicles ACE would be willing to assist in further clarification on an individual basis.

http://www.the-ace.o...dification.html


worth asking as a lot of this is a big gray area

Edited by Bungle, 30 August 2011 - 07:24 PM.

[R1mini]

There is no need to IVA a vehicle for taking an inch or whatever from the arch.

If most zcar minis can drive around on there original registration with massive modifications to the monocoque, who is ever going to notice slightly modified rear arches.

Cheers
David

[retroracer1275]

i'll be fitting some group 2 arches to my tubbed mini soon! at the moment its got standard arches and looks fine

[Bungle]

There is no need to IVA a vehicle for taking an inch or whatever from the arch.

If most zcar minis can drive around on there original registration with massive modifications to the monocoque, who is ever going to notice slightly modified rear arches.

Cheers
David

Z cars do need to be BIVAed and i believe it even says this on their web site

it's also a bit more than trimming a inch on the rear arches as you also get involve in reforming the inner arch and the double skinned lip

[R1mini]

Z cars do need to be BIVAed and i believe it even says this on their web site

it's also a bit more than trimming a inch on the rear arches as you also get involve in reforming the inner arch and the double skinned lip

Even I agree things like the Zcars minis should be IVA'd but they are mostly not, so the reality is they continue to be driven on the road without the need to re registered.

I'm aware that trimming the rear arches is more involved than the front arches for instance, but the end result is barely noticable especially when hidden behind a group2 arch. It's a very minor modification, no one should be concerned about getting a Q reg and the costs associated with the test because they have a tubbed rear end. It ain't gonna happen and your not helping casting doubt on even minor modifications

David

[Bungle]

so what you are saying is it's ok to rob a bank as long as know one sees you doing it

i still think it's worth asking before you carry out a mod like this, otherwise if caught they are in for a BIVA test and possible Q plate all for something they might of lived with out if they knew the rules

it's such a big gray area the more info we can collect the better

[R1mini]

I personally think tubbing the arches is not necessary as the sump and exhaust will be scrapping the deck even if you moderately lower a mini

Bungle your not going to like my mini, if you think tubbing rear arches is a sin, 8" longer wheelbase, 6" wider track, 5" lower, flat floored, mostly spaceframed, ford sierra based suspension, probably bike engined, allthough I may switch to a turbo saab engine, all in a historic tax class mini

Cheers
David

[maggies_minder]

Bungle, im allowing you to post your "repost" pics but im banning you from posting IVA/BIVA stuff.

from........





now!

[Bungle]

I personally think tubbing the arches is not necessary as the sump and exhaust will be scrapping the deck even if you moderately lower a mini

Bungle your not going to like my mini, if you think tubbing rear arches is a sin, 8" longer wheelbase, 6" wider track, 5" lower, flat floored, mostly spaceframed, ford sierra based suspension, probably bike engined, allthough I may switch to a turbo saab engine, all in a historic tax class mini

Cheers
David

i love modified cars both my mini, camper and work van are modified (although not as much as your erm mini ?) it just people should know all the pros and cons of modifying their car and not the it's all right mate you wont get caught attitude we see so much on here

[Bungle]

Bungle, im allowing you to post your "repost" pics but im banning you from posting IVA/BIVA stuff.

from........





now!

and since when have you known me to stick to the rules ?

[maggies_minder]

Bungle, im allowing you to post your "repost" pics but im banning you from posting IVA/BIVA stuff.

from........





now!

and since when have you known me to stick to the rules ?

lol fairy enough, you may aswell continue before the slogan by my pic changes again.