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reinforced chassis?

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Fend-la-bise Avatar
Fend-la-bise Bruce W
Mazamet, Tarn, France   FRA
Hi everyone. I've just about finished sandblasting and checking the welds on the chassis. I have heard that some folks weld additional reinforcing plates in some places on the chassis. Is this a good/bad idea?

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Greg1835 Avatar
Greg1835 Greg S
Rudolph, WI, USA   USA
I'd be careful about welding additional gussets/reinforcing plates where it "looks like it would help". It's possible in doing so to redirect twisting forces to different areas of the frame not designed to take them and in the end to do more harm than good.

Fend-la-bise Avatar
Fend-la-bise Bruce W
Mazamet, Tarn, France   FRA
Thank you Greg. I rather thought that it was unnecessary, but your point about the forces would seem to be a valid one!

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Doug in Vegas Avatar
Doug in Vegas Douglas D
Las Vegas, NV, USA   USA
Haven't ever heard of a frame collapse on the Spitfire.

spitfire50 Avatar
spitfire50 Paul Mugford
Rochester, N.H., USA   USA
Bruce,
Somewhere lost in history there was a study of the Spitfire frame done that showed where adding plates would improve the torsional stiffness of the frame. It helped a lot, but since the frame is so weak torsionally and contributes relatively little to a low overall figure for the car it probably wouldn't be worth doing unless more extensive measures were also being taken to increase the strength of the body. A full roll cage does much more and easier.
All the best,
Paul

tightapex Avatar
tightapex Greg Bailey
Gilroy, CA, USA   USA
1974 Triumph Spitfire 1500 "The Toy"
A metal hardtop does wonders to stiffen the chassis. I'm not sure about the market for early Spitfire hardtops, but it's a quick way to achieve noticeable results. Alas, it is a trade off... convertible bliss or tight chassis, but it works.

Tonyfixit Avatar
Tonyfixit Tony M
Duncan, BC, Canada   CAN
When I was restoring my Spitfire the car was not fitted with the central 'H' brace or Radio support.
I did not think I would want one as I was afraid it would interfear with my leg room (as it happens it dosent ) and be a real pain if I needed to remove the transmission cover (it is).

The car did have a lot of cowl shake though and I wanted to try to address this.

My gut thought was, there was little I could do to stiffen the frame. But some extras attention to the front bulkhead, sills (heavier sill stiffener), dash support etc.did make a huge differance.
One long term Spitfire owner after driving my car soon after it's restoration remarked "it's the thightest Spitfire I have ever driven"

Now, I have no doubt they were mainly kind words to make me feel good (we all like our ego tickled )
But the car did feel good.

I have since fitted the 'H' bracket, mainly because a kind member here was offering one, but fitting it made little difference to the feel of the car.

I feel to go further the car would need a roll cage (as has been suggested) or some kind of 'T' arrangment like the Triumph Stag. If this were used, making the windshield a structural member would help a lot, but doing this is a whole new area of expertise.

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Manana Avatar
Manana Steve Wten
Thornhill, ON, Canada   CAN
Bruce, this is a great question, especially for anyone putting a few more ponies in their Spit.

I'd love to hear some more ideas too. I have a hardtop but prefer driving and autocrossing topless and a roll cage is not in the cards for me.

Any of you old racers or serious autocrossers have any suggestions?

Tony, do you have any further specifics for what you did?



Steve
http://stevew10.wix.com/spit16



Edited 1 time(s). Last edit at 2017-12-31 05:40 PM by Manana.

Tonyfixit Avatar
Tonyfixit Tony M
Duncan, BC, Canada   CAN
In reply to # 1505316 by Manana
Tony, do you have any further specifics for what you did?

Unfortunatly this was about 25 years ago, I had recently bought my first mig welder, and was probably high on Argon/CO2 ;-)

I needed to relpace/ repair floor pans, inner sill in the footwell to 'A' pillar area, inner sills and outter sills.

So with all that needing to be cut out, it seemed easier to build in some gussets in the floorpan -firewall- bulkhead area especally as I was still new to mig welding and perhaps had less confidence than just following factory welds (or plug welds in lieu of spots)
Some gussets were also added behind the dashboard in the firewall-cowl area, which was a pain to get at.

I did actually take one or two pics, but this was in an era pre didital photography, and as I remember they mainly the uglyness before the welding and grinding.

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clshore Carter Shore
Beverly Hills, FL, USA   USA
In reply to # 1505316 by Manana Bruce, this is a great question, especially for anyone putting a few more ponies in their Spit.

I'd love to hear some more ideas too. I have a hardtop but prefer driving and autocrossing topless and a roll cage is not in the cards for me.

Any of you old racers or serious autocrossers have any suggestions?

Tony, do you have any further specifics for what you did?

Yes, here's my advice based on nearly 50 years experience owning and driving and racing these cars:
Don't sweat it.
(Dumbo's Feather)
Just redo any welds that look dicey, and then just put it all back together.
The Spitfire gets most of it's torsional strength from the body, not the from the chassis.
BTW, the hardtop adds very little, but the H brace is MANDATORY.

hearditallbefore Avatar
Portsmouth, Hampshire, UK   GBR
These guys did Some reasearch - see page 3

http://www.stanceworks.com/forums/showthread.php?42151-Helicopter-Turbine-Powered-Roadster-(Not-a-turbo-miata!)

The weak area of all small chassis Triumphs is just in front of the diff. The bigger chassis Triumph cars have T shirt plates welded on there to syptiffen them up.



Swatting the yellow jackets away from the Triumph apple of truth…

Fend-la-bise Avatar
Fend-la-bise Bruce W
Mazamet, Tarn, France   FRA
Thanks to you all for your input. I'll stick with the standard chassis, having already checked and strengthened some of the welds. I'll keep you posted.

clshore Carter Shore
Beverly Hills, FL, USA   USA
In reply to # 1505394 by hearditallbefore These guys did Some reasearch - see page 3

http://www.stanceworks.com/forums/showthread.php?42151-Helicopter-Turbine-Powered-Roadster-(Not-a-turbo-miata!)

The weak area of all small chassis Triumphs is just in front of the diff. The bigger chassis Triumph cars have T shirt plates welded on there to syptiffen them up.

Mmm, yeah, except DUHH, they showed a STUNNING lack of understanding of how the car was designed and built.
They tested the bare frame WITHOUT the body bolted on.
You know, the bit that gives the car MOST of it's torsional stiffness?

Funny thing, after nearly 50 years, I have yet to find a Spitfire with chassis cracks, 'just in front of the diff' or anywhere else.

But then again, none of them had a Gas Turbine motor either.

Doug in Vegas Avatar
Doug in Vegas Douglas D
Las Vegas, NV, USA   USA
I have considered a single structural (aluminum angle?) beam running the whole length of the dash which would provide a mount for the steering wheel and support roll stress

Some of our racing enthusiasts have experience in gutting this area.

hearditallbefore Avatar
Portsmouth, Hampshire, UK   GBR
Top tip from a commercial restorer here in the UK.

Drill a hole at the lowest point of the chassis rails under the diff, the bit where they all rust, check inside chassis with a little cameraphone borescope, (€10 on eBay etc), if it’s only surface rust, alls well, just pour in some rust treatment if you feel it’s worth it and pop a bit of weld over the hole and grind flat.

Doesn’t take long, but settles a nagging doubt. Generally, they are either good or rotboxes inside.



Swatting the yellow jackets away from the Triumph apple of truth…

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