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nderwater
nderwater UltimaDork
6/10/20 1:32 p.m.

I'm interested in starting a lightweight vintage roadster project, my favorite example of which is the Triumph Spitfire.  I'm much more of a rat-rod and resto-mod guy than a period-correct guy.  My biggest fear with adding power to a Spitfire is the real probability of overwhelming the primitive brake system and swing-axle rear end.

Are there any inexpensive brake and handling mods for this chassis?  My goal would be a fun car that can keep up with Miatas on the street and which (probably) won't kill me when I dive into corners.

Snowdoggie
Snowdoggie Reader
6/10/20 1:38 p.m.

I would look into a camber compensator for the rear. 

I have had both a Spitfire and a Miata, and the only Spitfires I know of that could run with Miatas on the street lived on trailers and wern't street legal, or had GT6 engines. 

nderwater
nderwater UltimaDork
6/10/20 1:40 p.m.

I'm thinking that an engine swap would be step 1, with a target of at least 150hp (10 lbs/hp).  That's more than double the stock output so I want the chassis to be able to cope.

Ian F (Forum Supporter)
Ian F (Forum Supporter) MegaDork
6/10/20 2:00 p.m.

Well.. the cheapest option is to basically take the entire drivetrain out of a Miata and graft it into the frame of a Spitfire. Massaging sheet metal as required.  All of the other options are less cheap.  Dherr's turbo Miata swapped Spit looks good. He used a R160 rear diff.  I don't remember what he did for brakes.

Bear in mind - you are not the first to have this idea. People have been trying this for the better part of 60 years. To date, an inexpensive solution to the minimalist suspension, brakes and differential components of a Spitfire has not been found.  When you take the smallest, lightest components available at the time and then wrap your chassis and body around those bits as tightly as possible, replacement options get limited.

Snowdoggie
Snowdoggie Reader
6/10/20 2:15 p.m.

I would just like to have my old 67 hp Spitfire back. That was a fun car. 

NOHOME
NOHOME MegaDork
6/10/20 2:30 p.m.

I would just go buy one and see if you bond wit it. They are more than fun-enough as made and you might find that you dont want to mess with the basic personality of the car.

Else, do like Ian said and stick this under the Triumph shell

 

nderwater
nderwater UltimaDork
6/10/20 2:33 p.m.

does even a single miata rollerskate hard-point mate up to a Spit body?

NOHOME
NOHOME MegaDork
6/10/20 2:41 p.m.

In reply to nderwater :

Does it matter at that point? It was yourself who used the term "Project" with no defined boundaries. I don't have any.  It would be a preposterous project. That is why you would do it. Maybe.

 

Now, knowing what I know now from doing the Molvo, I would go looking for a Suzuki Cappuccino and skin the chassis down to a sub-frame and graft the Triumph shell over that.

Snowdoggie
Snowdoggie Reader
6/10/20 2:43 p.m.

I remember my old Spitfire. The MG Midgets and MGBs I used to own. They were very much imperfect cars but they were a lot of fun. I loved those old cars. 

Old lever shocks. Less than 100 hp. "Negative Earth" electrical systems. Wire wheels. 

 

Ian F (Forum Supporter)
Ian F (Forum Supporter) MegaDork
6/10/20 2:44 p.m.
nderwater said:

does even a single miata rollerskate hard-point mate up to a Spit body?

Nope. Not even close.  Mainly because the upper shock mounts required for a Miata roller skate are located in air on a Spitfire.  There is nothing to mount the front cradle to. And the rear cradle will cut a fair amount into the passenger compartment and gas tank space. This is why I said, "take the entire drivetrain out of a Miata and graft it into the frame of a Spitfire" because then you can modify the suspension as required.  

In a way, think of it like building a Locost from a Miata and designing your frame to fit under a Spitfire body and using a Spit frame as your starting point (assuming very little of it will remain when you're done).

nimblemotorsports
nimblemotorsports HalfDork
6/10/20 2:57 p.m.

Or just buy a miata?  and graft the spitefire front bodywork to it for rat-rodness. 

I have a GT6 and it is getting a RX8 suspension swap, which are even cheaper than a miata, and heck use the rotary too. :)

I have a MG Midget too, that i would sell..in my ongoing downsizing effort.

 

93EXCivic
93EXCivic MegaDork
6/10/20 3:08 p.m.

The stock diff and axles are not going to live with 150hp. So you are going to have to swap something else in. The later rear suspensions are slightly better then early ones.

68TR250
68TR250 Reader
6/10/20 3:25 p.m.

I know the camber compensator is required on th swing axle Spits but later Spits ( with introduction of the MK IV) rear suspension 'fixed' the need for them.  I do recall a Spit in the early 70's having a kit which was basically a chain to limit how far the axle could tuck.

If you want mo' power (don't we all) look for or build a Spit 6.

You may want to talk to Ted Schumacher at TS imported for details.  Ted is great wealth of info that he shares readily. He also raced Spits back in the day.

TS Imported Automotive, 108 South Jefferson St., Pandora, Ohio, 45877, USA
Tel 800.543.6648 (USA & Canada only) 419.384.3022 (Tech / General Information)
Fax 419.384.3272 (24 hours) tedtsimx@bright.net
Hours 8:30 - 5 p.m. Monday - Friday, 9 - 1 p.m. Saturday (unless attending an event)

Is that allowed to post a dealer info here?

 

The Abomination is a mixture of Miata, RX-7, and Spitfire.

The front is Spitfire A-arms modified to use Miata uprights, hubs and brakes. The shocks are rear shocks from a Yamaha R1 motorcycle. 

The rear is a custom subframe with custom upper and lower A-arms using Miata uprights, hubs and brakes. The diff is out of a second gen RX-7. The axles are custom built. It also uses the R1 shocks.

The engine and transmission came out of a FB RX-7

It works, but I would not street drive it. It would beat you to death and the 2" of ground clearance means it bottoms out fairly often even on autocross courses. It is a hoot to drive though.

This is a pretty old picture, but this is the front suspension. I don't have any rear suspension pictures. 

NOHOME
NOHOME MegaDork
6/10/20 4:27 p.m.

In reply to Toyman01 (Moderately Supportive Dude) :

proves my point....Cant let fear and common sense write the requirements specification document. You need a lunatic.

clshore
clshore Reader
6/11/20 4:54 p.m.

OK, here's my crack-pipe inspired Spitfire vision (I've owned and raced Spitfires since 1968, still have 5 or 6).

Results will be lighter than a stock Spitfire, but with about 360 HP, on pump gas, streetable and with friendly manners.

  1. Triumph Spitfire *
  2. Honda L15B7 turbo motor w/ECU, harness, intercooler, etc. from 2018 Civic (good for about 205 stock  HP out of the box)
  3. BMW 323i Getrag 5 speed transmission *
  4. Custom BMW shift lever mechanism
  5. Custom motor/trans adaptor plate
  6. Custom Honda friction disk with BMW center spline
  7. Custom throwout bearing adaptor, Honda T/O to BMW lever.
  8. Custom driveshaft
  9. R160 Subaru diff with NZ Spitfire conversion kit *
  10. PRL Motorsports 2016+ Honda Civic 1.5T Big Turbo Upgrade Kit
  11. Hondata or KTuner for configuring the ECU
  12. SAE modified Mopar swing axles* OR GT6+ Rotoflex conversion with MGF hub mod & custom CV axles

(* indicate the items I already have)

The Spitfire motor has a rear hump oilpan, and is not tall, so the front part of the motor sits above the frame crossmember,

but even so, the front pulley hangs over the rack tube.  The GT6 motor is longer, and hangs over the rack too, but there is

a low bulge in the hood to clear the front of the GT6 valve cover.

To fit the L15, the Spitfire chassis must be modified by relocating the front chassis crossmember in front of the steering rack.

Even so, to place the L15 pulley behind the rack tube, and fit the motor under the hood w/o surgery requires that the

motor/trans be located to the rear about 6" or so. Fortunately, the Getrag transmission is rather short.

Some Fangling may be required.

Of course, all the other bells and whistles, wheels, tires, brakes, etc. can be added later.

nderwater
nderwater UltimaDork
6/12/20 12:49 p.m.

Holy heck.  Sounds like it would be easier to fab up a tubular frame and fiberglass body for a rollerskate than to try to source then adapt all those off-the-shelf parts to fit.

clshore
clshore Reader
6/12/20 1:31 p.m.

In reply to nderwater :

Take away the motor&trans, and everything else is common Spitfire bolt-in stuff that's been done for years

Relocating the front cross member takes a sawzall, a disk grinder, and an arc welder, could be done in one day by one guy.

Compared to that, fabbing up a tubular frame & fiberglass body is like building a starship.

The Spitfire is a body on chassis car, the whole front end is easy to remove, heck, the whole BODY is easy to remove!

You will not find an easier car to swap into, once you've figured out the Tetris challenge of how to make things fit.

But if you are looking for a simpler upgrade, convert your car into a Spit-6, transplant the Spitfire tub onto a GT6 chassis.

The Spitfire & GT6 chassis are virtually identical, there are about 14 bolts securing the body to the chassis, all at the same locations.

You'll get the 2 L motor, closer ratio gearbox (and maybe an O/D), better rear ratio (Spit 4.11 vs 3.27 or 3.89 with O/D), bigger brakes,

and 4 link rear suspension if it's a GT6+.

Still a hoot to drive, the extra torque and better gearing let you squirt into traffic holes, but not as light and nimble as a Spitfire.

Apexcarver
Apexcarver UltimaDork
6/12/20 1:46 p.m.

So I looked at doing something close to the drop a spit on a miata rollerskate suggestion, only I was going to go sportbike power. 

 

First part is that the spit is body on frame, so the frame is all the structure, whereas the miata is unibody, so the body is all structure. So, miata rollerskate has no structure and the spit body has none either.

 

Taking that into account, you are then looking at grafting miata subframes onto the spitfire frame. You also need to go this way because they have different wheelbases.  This is kina a blessing in disguise, makes it easier to fab and merge them and just cut the tub to clear.

 

Oh yeah, track width...  if you put a miata subframe with stock miata wheels (the narrow ones) they will still stick out something like 4 inches past the fenders on each side.  When I was looking at doing it, I was going to cut to clear the fenders and just let them poke, otherwise you might as well ditch the miata subframes to bring them in. 

 

 

You are right to worry about the stock rear, from my research, if you break it with too much power it has a good chance of tripping and rolling if its in a turn.   Also, the power limitation for stock is only something like 100hp. So, some solution is needed. 

 

Its a lot of work and I had a kid, so I sold the spit roller I got off to Andy Neuman, who I think, wants to sell it on.  I sold it to him for $40. 

clshore
clshore Reader
6/12/20 2:55 p.m.

Yeah, stock Spitfire swing axles are actually 2 piece, a wheel flange bolted onto the axle, with a taper to 'lock' them together.

They will of course fatigue over the years, made worse by stickier tires, more power, and high G turns, and have a nasty habit of

snapping off in hard turns when raced, sometimes with the car getting inverted as a result.

There's some in-car video of that happening, quite a ride, exciting for driver, nearby competitors, and observers.

Serious Spitfire racers upgrade the axles; I got my set, made by a company called SAE from modified Mopar axles, in 1976.

BTW, the suspension is good enough that Spitfires won several SCCA championships with those 'horrible' swing axles.

Swapping a Miata motor/trans into a Spitfire works out well, and the Subaru R160 with a kit is a near bolt-in.

Maybe someone should make a Spitfire fiberglass body kit for Miata?

tr8todd
tr8todd SuperDork
6/12/20 3:32 p.m.

Spitfires are fun because you don't have to keep up with anybody to have fun in them.  They feel fast even at lower speeds because of the way the body twists and the cowl and nose shake.  Even nice ones feel like they can fall apart at any moment.   Adding more than just a little extra power will quickly overwhelm the rear end.  Not a car you want to try to keep up with modern sportscars.  Enjoy it for what it is.  If you want a Triumph that will keep up, then you should be looking at a TR8.  There are modified versions out there that even at 40 years old will still stomp the piss out of modern cars.

frenchyd
frenchyd PowerDork
6/12/20 4:32 p.m.

In reply to nderwater :

Newer will beat older. I hate it since I love older and really don't care about owning the newest.  
 It's really about picking your fight.  If you want the latest greatest hammer jammer  you're going to have to go to silly lengths  to make a Spitfire fast.   Even if you do somehow manage to make it as fast, the next model will beat you or the one after that. 
 

We aren't that far from electric cars whooping our butts.  Some already are. Boring 4 door transportation modules like  the Teasla 3. 
 

So pick your fight. Do you want a Spitefire? Or do you want to race 4 door electric sedans. 
 

Think of it this way. Would you rather drive a Ford Model A convertible? Or a Chevy Volt?  The Volt will be fast,  cheap, and reliable.  The Model A will be fun,  different, and simple to work on.  
Driving the Model A 40 mph will seem fast and 50 scary. Yes you can still hot rod the Model A and  put juice brakes. Maybe better tires or double the power with a Ford Flathead.   You'll still be different.  

Or Drive the much faster cheaper to operate, more reliable  Chevy Volt? 
 
The argument is the same between a Spitfire  and a Miata. Blending them together gets you virtually nothing. 

Snowdoggie
Snowdoggie Reader
6/12/20 4:38 p.m.

In reply to frenchyd :

Back to my idea that a restored 67 hp Spitfire like the one I used to have would be a lot of fun. 

68TR250
68TR250 Reader
6/13/20 8:39 a.m.

I don't know Doug, nor do I know how it all panned out beyond what it shows on the web page, but, how about going turbo charging?

http://www.tiggersavage.com/overview_dk.htm

wspohn
wspohn Dork
6/13/20 11:27 a.m.

Always thought that it was ironic that the very good front suspension of the Spitfire (really Herald)  that was used on so many other cars including sports racers (and my old TVR race car) was mated with a pretty diabolical rear suspension.  It was like they awarded the job of designing to two different people, one of whom had failed engineering.

I like the GT6 shape and they are more rigid, so if you like coupes that would be a way to go. Lots of interesting engine choices, many of which require a significant amount of upgrading of suspension (e.g. remove, throw away, replace with something better).

How about a Spit with a modern 4 cylinder ike an Ecotec with maybe a supercharger on it.....

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