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MG Midget and Sprite Technical - Midget history (a list)

Hi midget world,

Just out of personal curiosity, I tried to list up for myself as many of the key structural changes as I could, by month.
There are already so many great books, and web sites that list up these things that my list many be redundant. But every time I went to look something up I was a little bit frustrated because: some books have the information buried in paragraphs of text, or only list the changes by vin number (probably the most accurate way, but difficult for me to use because most people know when their car was built, but not the number). Also, because the cars were built for many markets, authors have not always been so clear about whether they were saying it was the UK model, or the US model adopted 4-way flashers at a certain date, or whatever. Also, a lot of trim and moldings information doesn't interest me very much, so I left all of that out (that list would be many times longer than mine). Hopefully, this simple list will help me to answer folks questions more succinctly in the future.

Anyway, I made this list and thought I would share it to see if any one else would like a copy of it, or, more importantly, you can help add to it.

For source material, most of all, I used the "Original Sprite & Midget", by Terry Horler, 1994, and a little bit from a whole lot of other sources, including from you folks here (searching the archives, library and so on).

thanks for reading,

Midget history (key points).
Focus of this list = US destination.

Bugeye 948 cc, 43 hp, 1455 lbs
'58 ~ A-series engine, A-30 Suspension, Morris Minor steering rack. Fr drums, mech. tach

Mk1 (GAN1) 948 cc, 46 hp, 1400 lbs
3/'61 ~ Lockable boot, "MG" front end.

(GAN2) 1098 cc, 56 hp, 1466 lbs
10/'62 ~ Fr discs, RVI tach.

Mk II (GAN3) 1098 cc, 59 hp, 1490 lbs
3/'64 ~ Wind up windows, curved windscreen w/ center stay, quarter windows, O/Handle, key cylinder, crackle dash w/ gauges angled to driver, self-cancelling turn signal stalk, 1/2 elliptical Rr springs, electric fuel pump (1 breather tube). Fr spring increased +0.2" (9.4" -> 9.59" ).

Mk III (GAN4) 1275 cc, 65 hp, 1510 lbs (unladen), 1701 lbs (kerb = full fluids and all optional accessories).
10/'66 ~ Convertible top (velcro from 12/'68), separate brake / clutch master, seat belt shoulder nuts on rear wheel wells, 2nd breather tube added to SU fuel pump.

11/'67 ~ FMVSS: collapsable steering column, "safety" bonnet hinges, reversing lights, laminated windscreen, padded dash, 2-spd wiper motor (round body), dual circuit brakes, knock-off spinners become "octagon" nuts, PCV, air pump, cross-flow radiator. Negative earth.

10/'68 ~ Reclining seats, 3 wiper arms, toggle switches changed to rockers, side marker lights added, flat tail light lenses.

12/'68 ~ Differential change 4.22 -> 3.9.

10/'69 ~ "Facelift": Slim Fr bumper & Fr sidelights lowered 1", split Rr bumper, 2nd muffler added, Dr trim "vestigal pockets" eliminated, wire harness covering changed to blue PVC.

6/'70 ~ Interior courtesy lamp & boot lamp added. Boot and bonnet ratchet stays.

9/'70 ~ Heater becomes 1pc housing (butterfly at grille for '71 only). Fuel vapor recovery added (charcoal canister, sealed fuel & oil cap).

10/'71 ~ "RWA": fuel tank +1" (7.2 -> 8.4US gal, but 0.5 gal lost to internal air space). Radial tires, alternator adopted. Temp gauge changed from degrees to "C-N-H". Column lock/IG cylinder adopted.

12/'71 ~ Seat belt buzzer & ignition key buzzer adopted.

1/'72 ~ Triumph steering rack (mounting brackets changed from aluminum to steel, ratio reduced from 2 1/4 turns to 2 3/4 turns). Brake lines routed through inner wing panel.

7/'72 ~ Anti-burst locks adopted, quarter window frame material changed from chrome plated to stainless steel.

8/'72 ~ Fr spring increased +0.25" (9.59" -> 9.85" ). Panel lights switch changed to rheostat. Panel switches added backlighting, column stalks adopted. RVC tach. Bumper reinforcements increased, angled reinforcing beams in boot added.

8/'73 ~ Seatbelt interlock (1 year only).

9/'73 ~ Fr bumper irons lengthened rearward to the suspension structure.

12/'73 ~ Fat bumper over riders (1 year only).

10/'74 ~ 1500 cc Spitfire engine, Marina transmission. Rubber bumpers, square wheel arches. Boot reinforcement beams changed from angled -> straight
Differential ratio 3.9 -> 3.7 (late '78)

~ 11/'79 (end)

E/G mass model engine + transmission
948 1455 Bugeye 290lb
948 1400 GAN1
1098 1466 GAN2
1098 1490 GAN3
1275 1701* GAN4 305lb
1275 GAN5
1500 1850* GAN6 350lb (+45lbs of cast iron).

*Note that I think the 1510 unladen weight reported (in 10/'66, with this 1701 curb weight) is comparable to the 1490 of the prior model, and the "curb" weight was defined by FMVSS to include fluids and optional accessories. In that case, the actual weight increase was less in the later models than at first it seems. 1275 = +20lbs, 1500 = +140lbs, more or less.
Norm Kerr

Well almost...

Hope you like being critzied, because a list like this is going raise some eye brows and get some comments ... its just to be expected

My 2 cents worth of corrections...
The round wheel arch came out (I think the end of ???) 72 not the early part of 71 the American midget did not come out with an alt till early/mid 72, and mid 73 in the UK the big thing about the 71 was the anneversry wheel

what makes the changes so hard to follow is how the car was built and designed...The car was a total OFF the shelve parts design car, in other words there was no real plan for when changes occured like in todays cars,, as the parts ran out, then the new upgrades where used regardless of date and time.



If it's 'US-centric' and excludes trim, and goes by month rather than chassis number then IMO it might only add to the confusion.
BTW the 3.7 diff came in from August '77 production, not 'late 78'.
David Smith

while I am sure that there will be conflicts, and Prop you are right that these cars "evolved", rather than following the more regimented cycle of modern cars... Terry Horler's book was based on the BMHT records, which would surely be about as accurate as any possible in the case of these cheap cars that were not real well documented during manufacture. Terry's introduction lists the number of experts who lent their hand to gathering as much accurate information as possible, as of 1993.

Mostly, I followed his book's information, and then added to it with some detail stuff that I found he did not state one way or the other.

My intention has been to have a decent reference, not a definitive "last word", or anything like that.

David, thanks for that detail on the diff change, I had struggled to find that month somewhere!

Norm "work in progress" Kerr

Norm Kerr

Terry is nearing completion of a new Spridget book, however I think that it may be more of a buyers guide than a reference like "Original Sprite & Midget". I will ask him if it contains any updated information along the lines of what you are compiling.
G Lazarus

Dennis is organising a full line up of Midgets for Midget50 next year - which will be really interesting - to see all the changes there and easy to compare :)

Norm, that's a pretty impressive list. I know that it took some time to research all that information, thanks. It would be neat if we can get an example of each major change lined up in order at next year's Midget 50 along with a poster showing the changes from your list.
Bill Young

Prop, I just reread your comments. From what I read Norm has the RWA beginning production (not sales) as of October 1971 which is certainly not "early in the year". Figure a month or two to reach US dealers and the first RWAs would probably have been sold over here in or around January of 1972 as '72 models.
By October of '71 the actual '71 model would have been out of production. That's not unusual for a model to end production several months before the new model is produced to allow time in the factory for tooling changes as necessary. I would certainly expect the change from SWA to RWA to take more time than usual because of the time required to change the stamping dies for the rear quarter panels and inner panels. Even a change in steering racks would take some time and not be "phased in" because the jigs needed to position the components on the chassis for welding would need to be modified and that was certainly a one time operation. Once the jigs were changed you couldn't produce any cars with the older style components. For components that didn't require tooling running changes were much more common, usually being nothing more than different suppliers of a similar part.
Bill Young

Thanks Bill, and I agree with you, that would be awesome if that worked out at Midget 50!

there are a few details that I had to take an educated guess at, and am hoping to uncover given more time:

- actually when did the second SU fuel pump breather tube start being used? (the advent of the larger pump for the 1275 sounded likely, but I couldn't find any information about this anywhere).

- actually when did the angled reinforcement beams get added to the boot? (few books bother to add glamor shots of the inside of the boot, so I had to assume the date for now - it would have been either for '74 with the big over riders, or in '73 in preparation for them).

Both of the above items are really tiny details, though. My goal was just to gather a list from the (excellent) available books that specialized in gathering this sort of information together, for my own easy reference of mechanical items over the years. For trim details (there are millions of things, like steering wheels), that are more than adequately covered in those existing books, so I left all of that out of this list.

Figuring that there is always some lag between "announcement in the press", "building at the factory", and "selling at the dealers", I expect that there will ALWAYS be a fudge factor necessary in all discussion about any of this stuff of at least a month or two either way.

I was really surprised when I looked into the differences between "unladen weight" and "kerb weight", because the more I studied the weight of each model, and the way that number was reported at the GAN4 launch, with both of those numbers side x side, it made me think that there are about 140 ~ 150 lbs normally attributed to the 1500's "anvil like weight" that might have always been there in the earlier models as well, once fluids and accessories were accounted for...

I would LOVE to learn what the weight is of a pair of 1500 rubber bumper assemblies, and compare that to my '74 bumper weight!

'73 (with reinforcing bars, but normally sized over riders) = 29 lbs
'74 (with those wonking big over riders) = 54 lbs
'75 (TBD, as soon as someone weighs a pair for me!)

Norm Kerr

Great point Bill,

I gladly concede, Mine must have been one of the LAST SWA as (I think ???) mine was made in oct of 71 or maybe it was May.

Now that you mention it, I seem to remember someone saying the rwa where being sold in feb of 72 freaken hot to work on my midget

This thread was discussed on 14/07/2010

MG Midget and Sprite Technical index

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