My 1973 TVR 2500M : Renew and Restomod

Very nice! Looking forward to seeing the fab work-

damen

Will the transmission only be removed from the top? With the mounting tabs living under the cross member, it certainly looks like it's vertical removal only.

That's a strange set of mounting points on the trans for sure.

In reply to Mezzanine :

Yes, I agree that the mounting locations are totally weird.  In the Miata, those attach to the big long sheet-metal connecting structure and run all the way back to the diff.  Not really a traditional trans mount, and doesn't lend easily to retrofit.  Hence why I've spent a month dithering on how to do this.

The mount will actually be installed from the back-side forward.  So it will be totally removed before I go to pull out the engine/trans.

Wouldn't it be simpler, and far easier, to just use a chunk of the ppf with a dogbone? Much like i did with the miata differential below:

I thought about doing that, Michael.  Definitely some advantages.

Though I'd have to track down a Miata in a junkyard and go saw out the part I need.  I've got steel tubing and plate waiting for me in the garage right now.

Did some work on the exhaust system.  Here's the start of the down-pipe.  It's 3" mandrel-bent stainless - big!

My plan is to split the exhaust into two 2" pipes.  The transition will happen basically as the exhaust comes horizontal.  This will give me a bit more ground clearance, and I'll be able to match the dual pipes that originally were on the car.

Here's the results of a couple hours hammering on a piece of steel:

That's pretty close to the size it needs to be.

How we feeling about mufflers???  I'm wondering what straight-pipes out the back end of this thing might sound like.  I've listened to Focus ST's with the "muffler delete", and they sound fine.  I know there's a muffler in the middle of the pipe too.  Maybe just 2 x 2" straights will be too loud.  Worth considering though.

Progress continues a little at a time.  Went out yesterday to the local Recycled/Surplus/New Aluminum Emporium to buy some tubing for intercooler piping.  I got 24 ft of 2-1/2" x 0.065 tube for the same price as I would have gotten about 6 ft online.  Score 1 for the local biz!

Otherwise I cut square steel tubing for the transmission mount, but didn't have time to fire up the mill.  Maybe today.

And I should be getting a big box of shiny toys in the mail today...

Nice work!  I confess that I am envious of how well organized youve got your workbench fastener stock.

I am envious of having a surplus aluminum shop handy to you.....

TurnerX19 said:

I am envious of having a surplus aluminum shop handy to you.....

It's super handy.  Interesting outfit - they have a lot of new stock, but then they also buy cut-offs and scrap, and weird surplus castings and extrusions.  So you can get almost anything there.  Mostly it's machine shops and builders buying there, but you get lots of artists and car guys too.  The owner is this old guy Bob, who runs everything out of a big garden shed.  Just has a note-pad (like paper, not android) and a hands-free cell phone.  Still won't take a credit card.  He said his business has been completely scrambled by the China tariffs - just doesn't know what anything is going to cost or when it might be delivered.

ManhattanM (fka NY535iManual) said:

Nice work!  I confess that I am envious of how well organized youve got your workbench fastener stock.

Some days it's messier than others - I'm no saint!  With as much stuff as I have packed in, I really try to keep things clean and tidy.  It can rapidly get too cluttered to accomplish anything.  Constant vigilance!

My father-in-law gave me the bolt bins along with a bunch of other tools and stuff.  About 15 years ago he decided it was time to return to his native Czech Republic to die.  Fast forward to modern times, and he's still alive and still a drama-queen.  But at least I got some cool tools out of the deal.

TVR Scott said:

How we feeling about mufflers???  I'm wondering what straight-pipes out the back end of this thing might sound like.  I've listened to Focus ST's with the "muffler delete", and they sound fine.  I know there's a muffler in the middle of the pipe too.  Maybe just 2 x 2" straights will be too loud.  Worth considering though.

Not exactly the same thing but I drove a straight piped turbo Volvo 740 for a bit. Turbos do cut down on noise a tad but it was still loud. The thing is that it's "loud" in a way that is pleasant in a way? Like a Hyundai with a rotted out flexpipe is both really loud and really unpleasant while a straight-piped turbo car is loud but also cool. I say do no mufflers to start with and then add to taste. 

I like the sound of a resonator or Cherry bomb earlier in line more than just a muffler at the end. Could be something to consider allowing for packaging now.

I'm thinking right now I'l build the down-pipe, and the transition from 3" to 2" tubing from stainless, and then stop at two straight pipes.  I can then use some clamp-on couplers to try different straight-pipes, mufflers and/or resonators.  And once I'm happy I can do the final fab work and button everything up properly.  It probably pays to build in a little flexibility at this point.

Roughing in the intercooler piping: 

For some reason I'm finding a mental sticking point cutting the spare tire mount off. Don't know why.  Most of these cars don't have them anymore and it's not like this one is stock. Can't remember the last time I used a spare.

Another pic:

You know the real reason they put the spare up front was for crash resistance. Do not crash!

TurnerX19 said:

You know the real reason they put the spare up front was for crash resistance. Do not crash!

I've not heard that reason before for the location of the spare.  I thought it was that there was no room anywhere else.  And there is in fact no room anywhere else.

Since I prefer to not crash, I'll do it your way.

In reply to TVR Scott :

Earlier TVRs had it behind the seats. Just as hard to retrieve if you need it, and not get the interior tire marked. Excepting of course the handfull of cars with opening hatches. Probably just as hard on the tire, from UV instead of engine heat too.

Saw, machine, plasma-cut, grind, file, ream, tumble, weld, re-machine, weld a bit more:

And the trans mount is ready for a test fit.  It's a bit tight getting it thru the frame, but I figured out the correct sequence.  Hardware is rough for now and can probably be optimized.

And, it fits!

The engine and transmission are currently 100% supported by the chassis.  A fine milestone for a Tuesday night.

Now I get to rip it all back out to do the finish welding.

You can see my exhaust down-pipe peaking thru on the right-hand side too.

Woohoo!  Glad to see an update.  Nice work.  This is a great read.

Awesome! Think how much more you can enjoy that finish welding happy in the knowledge that it works...

Ransom said:

Awesome! Think how much more you can enjoy that finish welding happy in the knowledge that it works...

I like to think I learn a little as I age!  I was actually pretty happy with how the concept went together.  There were a few issues, but nothing insurmountable.

I want to get the shift lever properly installed and verify it's position.  And then it's time to work more on the exhaust.  I'm thinking the branch from 3" to 2" can happen next to the trans mount, and the smaller pipes will spread out and back from there.

Thanks guys, for the encouragement!

Ok, more stainless steel welding!

Let's talk about BACK GAS!  And not the kind you get from too many nachos while watching the Super Bowl.

When you TIG weld stainless tube/pipe, if you don't have an inert shielding gas on the inside then your weld will end up rough, brittle, and weak on the inside.  Old-school welders call this "sugar" and it's basically oxidation.  With the back-gas, the weld should look smooth and uniform, just like the outside surface of the weld.  Nowadays Argon is the back-gas of choice.  However Argon is expensive.

A side story - my grandfather was a union pipe-fitter in Colorado Springs for about 50 years.  He trained just about every apprentice to go thru the welding school, and he knew his way around a TIG torch better than just about anyone I've ever seen.  He was the go-to guy for sensitive stainless steel welding at hospitals and on the fountains at the Broadmoor Hotel.  He welded Titanium and Magnesium.  He'd done it all.  He taught me to TIG - overhead and the whole nine yards.

When he died in 2002 my grandma gave me a load of his welding gear.  Two gas bottles - one argon, one nitrogen.  Said me, "What's the nitrogen for???"

Fast-forward to now, I've still got the nitrogen, and argon is still expensive.  A bit of internet researching found a 1975 AWS paper on nitrogen back-purging.  They ran tests and found identical results with argon and nitrogen back-gas.

TO THE GARAGE!!

Here's my test set-up - 2" x 0.065" 304L stainless steel exhaust tube:

And here's the nitrogen bottle set up for back-gas duty:

Some places are selling fancy purge plugs and expanding hardware to seal off the ends of tubing.  I'm using foil tape with a hole popped in the middle:

The other end got a pin-prick from the filler rod.  I set the gas to flow and left it for 5 minutes of purging.

Here's the tube after welding and brushing with a ss-wire-cup:

Pretty spiffy looking on the outside.

And here's the inside:

Beautiful!  Thanks, Grandpa!

WOW!

That's awesome! Now I'll be up to three bottles not counting the kegerator, but that's really, really cool! That's gotta be way cheaper than argon...