Jump to content


Photo

Stitch Welded Chassis


  • Please log in to reply
5 replies to this topic

#1 stuart bowes

stuart bowes

    Camshaft & Stage Two Head

  • TMF+ Member
  • PipPipPipPipPipPipPipPip
  • 1,502 posts
  • Location: Dagenham

Posted 11 June 2022 - 02:38 PM

Just something I've been thinking about but in no way committed to doing in this car at this point.  kind of a thought experiment

 

Often when my mates have stripped and rebuilt cars I've heard them talking about fully stitch welding the chassis which obviously has it's pro's and cons..

 

pro's

------

  • stiffen up shell and make suspension setup more effective (the main purpose probably)
  • strengthen up the shell which may be necessary due to age (noticeable sometimes when you jack up one corner and then can't open or close a door)
  • arguably slightly better crash protection

 

cons

------

  • unless you can get to the back side of the welds you're adding a new rust point
  • may affect the design of the car's crumple zones (although, in a mini really will that make any difference)
  • may make the ride a lot harsher which is fine for track but less so for the road
  • makes replacing panels in the future more awkward

 

and possibly some other stuff I've not thought of

 

my thoughts are, will stitch welding go some way to giving good rigidity for people who don't want the awkwardness of a full cage

 

and, if I maybe just stick to a few key areas where I can get to the other side and paint over welds then would that just force other parts of the car to flex worse and cause damage (i.e. maybe better to do either all or none)

 

I'm aware the vizard has some thoughts on welding up the cross member / tunnel / plating over bulkhead subframe mounts / welding up parts of the subframes and adding corner pieces etc / strengthening tie rod mounts, and I'm considering all of these things

 

 

so anyway has anyone ever fully stich welded a mini shell for fast road use and did it make a worthwhile difference

 

or it it really just a waste of time and gas


Edited by stuart bowes, 11 June 2022 - 02:40 PM.


#2 weef

weef

    Speeding Along Now

  • Members
  • PipPipPipPipPip
  • 412 posts
  • Location: D@G

Posted 11 June 2022 - 10:34 PM

I have not "seamed" up a Mini but a few years ago I was asked to do a similar task on a MK1 Ford Escort. In those days we had a local Ford RS dealer and they had a good storeman who was very helpful in supplying the parts required. 

The shell involved was a standard Escort and to convert it to an RS spec involved welding in a sackfull of plates, gussets and other parts along with "seaming" up some of the joints. The process involved a complex variety of welding and brazing, Ford RS giving an "approved system of work".

It is not just a process of going wild with a welder and stitching up everything you see and welding in plates "willy nilly", incorrect welding can have a detrimental effect rather than a benificial one.

What I am trying to say is that it is just not a case of "if it is seamed up " it must be stronger and indeed if you are jacking up a car on one corner and the door will not open I think it is beyond seam welding.

Take care if you are going down this road try and find out from others who have already tried, someone on the forum may have done this.

The Escort involved went on to rally for several seasons and never had any problems with the shell integrity, until it hit a tree, and that was the end of that.

The conversion was not a cheap operation, the Ford supplied parts were not inexpensive,  there were many hours work involved and if you intend just for road going it might not be worthwhile, the choice is yours.



#3 stuart bowes

stuart bowes

    Camshaft & Stage Two Head

  • TMF+ Member
  • PipPipPipPipPipPipPipPip
  • 1,502 posts
  • Location: Dagenham

Posted 11 June 2022 - 11:07 PM

That sounds like a somewhat more involved version of what I've seen before, I wasn't thinking of a real race spec thing, more just going around the car stitch welding the panels together (say, 3/4" welds every 6-8" or so) where panels were previously just spot welded 

 

I suppose primarily around the floorpan and bulkhead area, boot floor to side panels and wheel arches, probably around the door frames, and so on.  presumably taking time to cool and balancing it out side to side to try and reduce any warping (although we're not talking about seam welding the entire length of panels or anything here)

 

at least that was the general gist of it from what I understood when someone told me about a nova they souped up a few years back.  admitedly that was receiving a vaxhall LET engine so probably worth the effort / more necessary ?

 

it's just something I was thinking about when I saw a post the other day about reinforcing the front subframe mounts, and it made me think, well if I've got the shell all stripped back now, it's a good a time as any


Edited by stuart bowes, 11 June 2022 - 11:28 PM.


#4 PiG

PiG

    Mini Mad

  • Noobies
  • PipPipPipPip
  • 144 posts

Posted 12 June 2022 - 07:09 AM

I've done my subframes as per Vizard (seam welded strut tops, reinforced mounting tabs on front and triangular gussets in all the corners both front and rear) and will be doing reinforcement plates at the toe board. Not a great deal of effort while it's all out anyway.

Mine is a B road car not intended for track do don't see the need to go further.

#5 PiG

PiG

    Mini Mad

  • Noobies
  • PipPipPipPip
  • 144 posts

Posted 12 June 2022 - 07:25 AM

These were pretty rusty original frames, excuse my welding as was learning then!

They have been tidied up and now in black EM121 epoxy coating with wax over

Attached Files


Edited by PiG, 12 June 2022 - 07:31 AM.


#6 sonscar

sonscar

    Up Into Fourth

  • Members
  • PipPipPipPipPipPipPipPipPip
  • 2,709 posts
  • Location: crowle
  • Local Club: none

Posted 12 June 2022 - 08:06 AM

An often overlooked thing,spot welded flanges are welded close to the angle of the flange imparting rigidity.Seam welds are on the edges of the flange and can peel apart as the rigidity of the angle is lost.If the integrity of the original spot welds is beyond question then seam welding can give some increase in overall rigidity.As said if the shell already flexes then more attention is needed to address this first.Steve..




0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users