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Woody
Woody MegaDork
11/16/19 6:47 a.m.

MG Midget or Spitfire: What is the best starting point?

Small and cheap are the target points.

Assume engine swap.

Go.

Streetwiseguy
Streetwiseguy MegaDork
11/16/19 7:03 a.m.

Starting point for what?  A bonfire?

I kid, I kid.

I think it boils down to whatever you like the looks of more.  None of the mechanical bits will survive much more abuse than the stock engines delivered, and they are all roughly the same size. There is an excellent built thread somewhere out on the cloud about a guy that put a Neon twincam in a Spridget.  Worth searching out, partly for the fab work, partly for the weak points he had to solve.  I remember the twincam and good tires had stock rear axle lifespan measured in hours.

I like the looks of the last Spitfire, but that's a matter of opinion.

You've been watching the S600 videos, haven't you?

Woody
Woody MegaDork
11/16/19 7:36 a.m.

Target lifespan for the rear axle would be approximately one weekend in Florida. 

pirate
pirate HalfDork
11/16/19 7:48 a.m.

I like the Spridgets and one with even a mild mannered rotary would be a real hoot.

alfadriver
alfadriver MegaDork
11/16/19 7:52 a.m.

Well.... I've not really seen a good Sprite/Midget swap.  Not to say they don't exist- I'm quite sure they do, but I've just not seen one.

But I have seen a pretty good start for a rotary Spitfire.   Where the entire powertrain was swapped over, live axle included.   The car was super quick, it just needed sorted.  Given that the car starts you in DM, then the "free tires" you get for that special weekend in Florida would be slicks.

I *think* there is space in the front to better layout the front suspension.  And for good ideas how to locate the rear, see loosecannon's MGB build.  Simple 3 trailing/panhard would be a really good and simple option (especially since the RX7 rear is already panhard.

Then the biggest technical challenge would be to stiffen the frame up.  And since you must have a roll bar, you can integrate that into the system and make it stiff enough.

I'm sure the same thing can be done with a Spridget, but i've just never seen it- the closest I've "seen" is NOCONE's DM car- which looks pretty sweet on my computer.

wheelsmithy
wheelsmithy SuperDork
11/16/19 8:03 a.m.

I'm going to ASSume you are not talking a tube frame monster that just looks like one or the other (then it's just down to looks). The big advantage to a spitfire is the separate frame. With a spridget, you're building a ship in a bottle. All that said, spridgets do have a surprising amount of room underhood once you ditch the heater. 

The spridget has a solid axle, and room for activities back there, wheras the swing axle spits are death, and the real IRS not strong. Maybe a wash between the two, depending on what you want out back.

The clamshell hood and removeable transmission tunnel are another spitfire advantage, as is being able to remove the body to fabricate whatever rear end, motor/transmission mounts, etc.you decide on.

Welghts are kind of a wash.

TLDR: As the owner of a long dormant spridget swap, objectively, I have to give the nod to Triumph.

NOHOME
NOHOME MegaDork
11/16/19 8:11 a.m.

I have owned a few Midget/Sprites. Once you have gone through the ENTIRE suspension they are Go-Karts that will leave you giggling after a hard drive. Expect any car you buy cheap to have clapped out front suspension.

I managed at the age of 19, with the budget of a beggar and the mechanical skills of a monkey, to swap a Fiat 1600 and 5 speed into the poor thing. I can tell you that an MG Midget at over 100 mph gets way too light in the front end. But going there was addicting.

 

Recall the budget bit? I kept the stock rear end. But recall that this was back in the early 80s when spare cars were $50 all day long. I kept a couple in reserve at all times. Went through 1 a year so not really horrible. Maybe a few extra axles during that period, but they are easy to swap.

The hot swap at the slaloms was the rotary. Use the engine AND the rear end. If memory serves, the downside was the exhaust on the rotary. Your passenger had to be ameanable to being medium rare. Something about rotary exhaust heat being from another thermal dimension. I just thought they looked ugly under the hood.

 

Of the modern engines out there, the only one that temps me is the 3 cyl Ford from the Fiesta or whatever, No idea how to control the fuel or the electrons, but size and weight are about right. Might poke through the hood,

Few Midgets running around with the GM 60 degree V6 from the camaro using a S10 T5 gearbox.  They fit under the bonnet and seem like they would be fun.

 

Pete

TurnerX19
TurnerX19 Dork
11/16/19 8:39 a.m.

I have seen a 6cylinder Jag engine in a Mk2 Midget. Very nicely done street car. It is documented in a mag somewhere, maybe CM or a competitor "H" branded. Not a challenge build! I have also seen rotary frogeye, and a poorly done aluminum Buick frogeye. Wheelsmithy understates the exhaust heat on the rotary. Pic is rotary car at NNJR-SCCA solo 1980.

Toyman01
Toyman01 MegaDork
11/16/19 8:41 a.m.

Spitfire. 

The entire front end comes off, hood and fenders. That makes engine swapping pretty easy. Abomination for reference. 

nimblemotorsports
nimblemotorsports Reader
11/16/19 9:56 a.m.

I have both.  My midget is called MGEO, it has a Geo Metro Suzuki 1.0 3-cyl and Samuri 5-speed. 

The midget has a shorter wheelbase, which might work better for autocross, but it isn't Lemons legal.

The IRS in the triumph MUST be replaced.  The midget has leaf springs and an aluminum third member.

 The tilt front is great on the triumph, but I did that for my midget too.

I'd lean towards the midget.  If I were to do another one, I'd make it mid-engine with a transverse drivetrain, ala MR2,

and make the wheelbase longer.  And look at a Volvo T5 drivetrain.  :)

This is my MGEO custom front tilt bodywork. 

Woody
Woody MegaDork
11/16/19 9:57 a.m.

For me, it will probably come down to body condition.

Around here, a lot of Midgets seem to have been parked into the corner of the garage and used as shelves for many years. On the other hand, all the Spitfires look like they were filled with sea water and pushed into the woods back in the 80's

alfadriver
alfadriver MegaDork
11/16/19 10:10 a.m.

In reply to Woody :

LOL- so all things will not even be close to equal.  

Just make sure you have fun.

pres589 (djronnebaum)
pres589 (djronnebaum) PowerDork
11/16/19 10:11 a.m.

Maybe compare rear axle width of the stock car and find a solid rear that's stronger from some other application and swap over?  I know the list won't be that long as these cars are so narrow... Spitfire probably gets the nod here as well.

Streetwiseguy
Streetwiseguy MegaDork
11/16/19 10:25 a.m.

This is the Neon powered Midget build.  The guy is a pretty good fabricator.

https://forums.neons.org/viewtopic.php?t=369388

wspohn
wspohn Dork
11/17/19 12:57 p.m.

A Midget means no need for as much suspension work, and there are number of modern engines that can fit. The small turbo Ecotec from the Chev Cruze makes an interesting swap, as do the larger displacement naturally aspirated Ecotecs..

 

https://www.youtube.com/watch?v=cggUhD6NjZ4&feature=emb_logo

nimblemotorsports
nimblemotorsports Reader
11/17/19 1:12 p.m.

The plan for my Triumph is to use a RX8 suspension, both front and rear, they are modular and unbolt from the rx8,

and will attach them to the triumph frame.

Here is a pic, removed them already.   And the spitfire frame (not mine).   Being it has a frame, a rusted body is not so much a problem as it would be for a Midget.

I think it was someone on GRM that did a spitfire,

and said the front suspension geometry was not good, and had to lengthen the upper or lower arms and modify the rack.  Google should find it.

Brotus7
Brotus7 HalfDork
11/17/19 1:54 p.m.
Brotus7
Brotus7 HalfDork
11/17/19 2:02 p.m.

Aren't alot of comparable Spitfires in the area.. most would use up too much challenge budget.

https://www.facebook.com/marketplace/item/402481857355426/

Brotus7
Brotus7 HalfDork
11/17/19 2:05 p.m.

With links out of the way, I'd recommend the Spit with it's chassis.  I think fitting a better rear axle, and drivetrain mounts would be easier on the Spit since you can remove the body. S10 or exploder rear axle?

Woody
Woody MegaDork
11/17/19 2:48 p.m.

In reply to Brotus7 :

I'm having a hard time trying to envision how to adapt a live axle to to the Spitfire frame.

Toyman01
Toyman01 MegaDork
11/17/19 4:54 p.m.

In reply to Woody :

The Abomination uses a RX7 center section with Miata uprights and brakes. They are joined by shortened axles and home built A arms. It works very well.

nocones
nocones UltraDork
11/17/19 7:46 p.m.

I think everyone has covered the comparison pretty well. 

I chose a Midget because its what I Had though mine isn't really a great example of a effective Midget conversion.  I do think mine is an example that the "short wheelbase" doesn't really matter.  I have no issues at a road course with mine at 120mph. 

If I built another where the chassis was more "stock" I think I would still use an Midget because the chassis structure is a little more straightforward to modify for engine clearance.  Yes the tunnel provides strength but I believe you can fairly easily reinforce whatever you do to cut it away.   And as a percentage the sills take a lot of the load and those would never be modified by tunnel clearance.  

The spitfire if you need to cut the chassis it's a bit more of a loss of integrity that you need to patch in.  

That said weight balance probably can be inherently better with the spitfire as the front wheels are about a foot further forward of the firewall.

wspohn
wspohn Dork
11/18/19 11:56 a.m.

The Spitfire front suspension was just fine. It (well it really started with the Herald) was adopted for use in all sorts of sports racing cars including the TVR Grantura I used to race, but all or most of those race cars were bright enough to build a decent rear suspension that lived up to the ability of the Spitfire front. Trying to create a functional suspension for the rear of a Spit using the stock frame is a huge and potentially expensive job.  Not so much with the Spridget suspension which with the usual sort of race mods proved amazingly effective.

keithedwards
keithedwards Reader
11/19/19 6:57 a.m.

This $450 '59 Bugeye showed up this morning on Facebook Marketplace, in Sarasota, FL. https://www.facebook.com/marketplace/item/406996406598115/ I would think the hood would be worth that, assuming it is repairable. 

Ian F
Ian F MegaDork
11/19/19 7:13 a.m.

I would say a Midget - mostly due to the solid rear axle which should be much easier to upgrade than duplicating the Abomination RX7/Miata set-up in a Spitfire.  The uni-body construction of the Midget should be easier to stiffen with a cage than the central frame of a Spitfire as well as being easier to modify for engine clearance.

Here in the rust-belt, either of them will need rust remediation if purchased for Challenge money.

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