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Reinforcing the front sub-frame
https://www.ausmini.com/forums/viewtopic.php?f=2&t=36787		 Page 1 of 2
Author:  Wombat [ Tue Oct 16, 2007 9:09 am ]
Post subject:  Reinforcing the front sub-frame
There has been some mentioned from time to time about strengthening the front sub-frame - it it just extra welding around the top of the towers or is there other steps involved?

Picked up a cheap ($15.50) sub-frame off ebay -only cause it was pickup only -not far from home and only one other bidder :? Figured I use it to practice sandblasting and spray painting and may as well beef it up while about it. If it comes up OK I'll think about swapping for the one in the car.
Author:  simon k [ Tue Oct 16, 2007 9:15 am ]
Post subject: 
around the tops of the towers tend to crack on dry ones, I've heard (but haven't seen) that you can reinforce the tie bar mounting ears... hopefully one of our old school gurus will pipe up :)
Author:  rampage101 [ Tue Oct 16, 2007 10:11 am ]
Post subject: 
From memory thats mainly it, its in the Modify Your Mini by Vizard.

The main thing was adding some gussets (I think??) and seam welding around the top of the towers.
Author:  britishvita [ Tue Oct 16, 2007 10:22 am ]
Post subject: 
skssgn wrote:
around the tops of the towers tend to crack on dry ones, I've heard (but haven't seen) that you can reinforce the tie bar mounting ears... hopefully one of our old school gurus will pipe up :)


Vizard covers this in his book, I think from memory it involves triangulating the tie bar mounts. Would be a good modification for a race/rally car as they bend easy and are low to the ground so are easily hit and bent if you run off the road.

Just out of interest, I think the blue cooper s for sale on ebay that someone mentioned the other day hit an embankment in classic adelaide last year and it bent the tie bar mounts pretty badly.
Author:  Wombat [ Tue Oct 16, 2007 10:30 am ]
Post subject: 
rampage101 wrote:
From memory thats mainly it, its in the Modify Your Mini by Vizard.

The main thing was adding some gussets (I think??) and seam welding around the top of the towers.


Probably where I read it :oops: I've decided old people don't get Alzheimer's - it's really information overload- so much crammed in there that the information gets separated from the source :lol:
Author:  sports850 [ Tue Oct 16, 2007 11:52 am ]
Post subject: 
I've seen them "seam welded" before , most of the welds are in short strips to allow a miniscule amount of flex but some rally cars were welded all the way on every join . The subframe was stronger and more rigid but prone to cracking after a lot of abuse .
Author:  Morris 1100 [ Tue Oct 16, 2007 6:02 pm ]
Post subject: 
The original Hydro subframe in my Cooper S was badly cracked around the top of the towers. It was a Series Production race car. :wink:
Author:  drmini in aust [ Tue Oct 16, 2007 7:21 pm ]
Post subject: 
When I did 13secmini's 4EFTE subby, I seam welded all around the top of the towers. it's an old rally trick, goes back to the 60s.
Some of the welding there on standard subbies is pretty suss. :wink:
Author:  Wombat [ Tue Oct 16, 2007 7:28 pm ]
Post subject: 
Thick enough for a stick or do I need a MIG?
Author:  drmini in aust [ Tue Oct 16, 2007 7:34 pm ]
Post subject: 
They were stick welded originally, MIG had hardly been invented in 1961. :lol:
Author:  Wombat [ Tue Oct 16, 2007 7:36 pm ]
Post subject: 
Duh :lol: :lol:
Author:  gafmo [ Tue Oct 16, 2007 8:02 pm ]
Post subject: 
this is wheere i found Marcia's Cracked
Image

Kev to the rescue :wink:
Author:  TheMiniMan [ Tue Oct 16, 2007 9:30 pm ]
Post subject: 
Yes, they tend to crack around the tops of the towers, they bend the bump stop area, & can rip the tie bar mounts backwards

The "Usual" or "Common" method is--->

Re-weld around the tops of the towers, but just "Stitch" weld them,,, (as in Sewing Stitch) as in-->inch weld, inch gap, inch weld, inch gap & so on...stiching helps stop them crack even further if/when they ever crack again (not that they will after you do all this tho)

brace those tower tops with 2 strips of metal that are placed along the front & another on the back of the tops of each tower,,, but long enough so that they can be bent down to meet the "upwards" part of each tower along the "INSIDE" sections,,, if you get my drift??? Doing That tends to stop "ANYTHING" happening to that part of the frames ever again.

it`s a leverage issue,,, the bump stop stops the wheel assy rising up & then the upper inner control arm """levers""" the inner pick up point down wards, pulling the tower down & away from the top caps that are mounted into the body. TRUE!!!

Also weld 2 triangular gussett braces into the tie bar mounts,,,one each side of each tie bar mount. Strong as an ox then & rally till the rest of the car is destroyed.

some people brace along the entire front crossmember too , but i don`t bother unless it`s had a bad whack there,,, &/or someone has been silly enough to hook a tow rope up from there & pull that forward. I`ve seen more than plenty of frames bent like that (doh!!!) :-)

i`ve also known the hard core rally guys fabricate a fairly thick steel plate & weld it to their bump stop areas to help stop it bending & cracking in there as the previous guys photo shows,,, but hey, that`s for pretty hard core off road stuff & not really an issue for road use or even much of a reliabilty for the "Average" rally mini, but still it`s an option if you have issues there.

I`ve seam welded rally frames & speedway frames--> That is to stitch weld all around where all the plates that make up the entire frame meets in all places all over the frame,,, but havn`t bothered doing it for any road or bitumen track car frames at all, no real need as long as there`s 2 diagonal braces fitted, one either side from above the towers (near the shock mounts is good) down to the ends of the front cross members, all that helps torsional rigidity enough for circuit racers. But still, differnt people have different ideas.

I`ve also done seam welding & bracing on rear frames, but mainly for rally minis. Most circuit minis have more metal taken out of them for lightweight-ness (swiss cheese) than added to them



Long live your subframes :-)
Author:  Blokeinamoke [ Tue Oct 16, 2007 9:45 pm ]
Post subject: 
drmini in aust wrote:
They were stick welded originally, MIG had hardly been invented in 1961. :lol:


Nar- Mig was invented in WW2. Jaguar used it from 1958 after the Browns Lane factoy fire was caused by an oxy explosion.
Author:  drmini in aust [ Tue Oct 16, 2007 9:50 pm ]
Post subject: 
Blokeinamoke wrote:
drmini in aust wrote:
They were stick welded originally, MIG had hardly been invented in 1961. :lol:


Nar- Mig was invented in WW2. Jaguar used it from 1958 after the Browns Lane factoy fire was caused by an oxy explosion.

What I meant to say was it was hardly in common use, here at least. :wink:

BTW oxygen doesn't explode, it's not flammable in itself. Sure does help things burn fast though! :lol:
It's an oxidising agent, not a fuel gas.
No I'm not joking- it was explained when I did oxy welding in my trade. :wink:


OTOH acetylene is pretty dangerous stuff- it has a very wide fuel air ratio ignition range. Also, free acetylene is unstable above about 15 psi. This is why it is dissolved in acetone, in acetylene cylinders.
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