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Stripping Yard Find: 3.7 Diff

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Steve-in-Florida Avatar
Steve-in-Florida Steve Hill
Orlando, FL, USA   USA
1974 MG Midget MkIII
1975 MG Midget 1500 "Good Lil' Car"
1976 MG Midget 1500
1978 MG Midget 1500    & more
As I've mentioned, i drove my newly acquired 1974 Midget home to Orlando from its previous owner in Georgia. Happy day!!!

Perusing the Midget forum, I came across this thread from Kurt: Diff trade thread

That got me thinking about how much i would like to adjust the rear end of my new car for highway driving.

In my research on the subject, someone posted a link to a site that lists parts in stripping yards www.car-part.com.

Lo and behold, there was a late model Midget, merely an hour's drive away. A phone call to the yard confirmed that the rear end was still there. Yes, I would have to buy the entire unit, as they would not sell me just the differential. The price seemed reasonable at $325.00 for all. (brake drums, housing, axles and pumpkin) A short motorcycle ride later, and I confirmed the jewel with my own eyes!

It's so very sad to see any MG in a stripping yard, by the way...

The car was a 1978 Midget in Blue. No engine or hood, transmission in the trunk, and a pile of rusting parts in the cockpit. But it still had the rear end!!! I paid for it, and they pulled it the next day.

Yesterday morning, my neighbor and I collected it with his pickup truck.

Once I got it home, I eagerly removed the axles and the diff, in order to confirm the tooth count of the ring and pinion. Yep, it's definitely an 11-tooth pinion and a 41-tooth ring gear, and 41/11=3.72...

Now I'm waiting for a package from Moss, with a new gasket for the diff and gaskets and O-rings for the axles. I'm hoping to install it in the `74 Midget at the end of next week.

Lastly, I would like to offer a sincere "Thank You" to the person who posted the link to the stripping yard search engine. It sure helped me with this whimsical endeavor!

Steve

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200mph Avatar
200mph Platinum Member Mike Joy
Winston-Salem, NC, USA   USA
Great find!

Suggest you mark the axle shaft end bells in both axles L and R so you can be sure they go back in the same side they came out of.

Your 3.90 pumpkin will make a good spare, or it has good resale value ($200+) to owners of earlier Spridgets with the 4.22.



"Have you ever thought... Everyone driving slower than your MG is a MORON, everyone driving faster must be a FREAKING IDIOT!". . . George Carlin

Steve-in-Florida Avatar
Steve-in-Florida Steve Hill
Orlando, FL, USA   USA
1974 MG Midget MkIII
1975 MG Midget 1500 "Good Lil' Car"
1976 MG Midget 1500
1978 MG Midget 1500    & more
Thank you for the suggestion, Mike. I was already aware of the importance of keeping tabs on the "handedness" of the axles, and will mark them accordingly.

I would also like to report that I was quoted 207.53 EURO for the 3.55:1 Ring and Pinon Set, with an additional 53.35 EURO for shipping to Orlando, FL. Being that I am NOT in the EU, the VAT charge of 39.43 EURO does NOT apply. The set is in-stock, and ready to ship.

With today's current exchange rate being 1.21 Dollars to the EURO, the quoted price with shipping is $315.66. That's better than HALF of what Moss is charging.

Here is the site that sells the ring and pinion set: shop.bastuck2.de

Thank you for reading. I hope this is useful to others, as well.

Steve

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S1 Elan Kurt. Appley
Akron, Ia., USA   USA
Lucky find Steve. Wanted to mention that the gaskets you will get from the usual suspects won't be right and that you are better off making them yourself from a grocery bag. Not difficult and there is probably something in the archives telling how to do it. Use a small ball peen hammer to cut the bolt holes.

Kurt.

taskadog Avatar
taskadog Phil Burke
Tequesta, FL, USA   USA
Nice find Steve!
Looking forward to seeing your new car at Meade Gardens
Is your '74 chrome or rubber bumpered?

Steve-in-Florida Avatar
Steve-in-Florida Steve Hill
Orlando, FL, USA   USA
1974 MG Midget MkIII
1975 MG Midget 1500 "Good Lil' Car"
1976 MG Midget 1500
1978 MG Midget 1500    & more
Phil,
I have happily entered the realm of the chrome-bumpered Midget! It still has the Sabrina overriders, so I guess I'm just getting my toe in the water, eh?

I've posted a handful of pictures in the "My Vehicles" section. It's a really nice car; one that I simply could not pass up.

See you in April, if not sooner.

Steve

GeorgeOhr Nonya Business
Yes, confused, USA   USA
Man that's cheap. I might buy another just to have. No gaskets or o-rings needed; 3M ultra black and you're done.





In reply to # 3660510 by Steve-in-Florida

With today's current exchange rate being 1.21 Dollars to the EURO, the quoted price with shipping is $315.66.

Steve

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S1 Elan Kurt. Appley
Akron, Ia., USA   USA
If you got the whole axle, maybe you ought to look at just swapping the whole axle. I imagine the salvage yard axle needs brake work though.

Kurt

Steve-in-Florida Avatar
Steve-in-Florida Steve Hill
Orlando, FL, USA   USA
1974 MG Midget MkIII
1975 MG Midget 1500 "Good Lil' Car"
1976 MG Midget 1500
1978 MG Midget 1500    & more
Well, today was 3.7 differential installation day. Replaced the pinion seal, and put her in the `74 Midget. The gaskets I ordered happened to fit, and so far, everything is fine.

I also took the opportunity to install a urethane bushing set to the rear end of the car. the front will have to wait for another day.

We have a local MG club drive to JB's Fish Camp in New Smyrna Beach tomorrow, for lunch. I'm excited to see how the new diff ratio works out.

Additionally, I ordered the 3.55 ring and pinion from Germany, and am eagerly awaiting its arrival. I'll swap it into the gear carrier that I just removed, and have the local drive line shop set it up for me.

As for the other rear end, it had a leaking wheel cylinder in a past life, so it would not have been an easy direct replacement, without cleaning and replacing some key components.. The emergency brake set-up is markedly different between the 1974 and 1978 models, also. Rods and a central pivot point vs. a cable with a rigid housing. They have different mounts.

Nice to have a hot spare, though!

Steve

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Jon62midget Avatar
Jon62midget Silver Member Jonathan Brown
Savannah, GA, USA   USA
Hey Steve in Florida,
I've been through this process with the 3.7 diff too on my 1275 engined 62 MK1. Got a 3.7 at an autojumble in england, brought it back and installed it. Like you, I found it to be an easy swap and the gaskets and o rings from Moss all fit fine. Well, the paper mating gasket between the axle and the pumpkin was a little tight, but a bit of razor knife work around the inner edge of the gasket sorted it.

FYI, I'm getting 36mph at 2000rpm, 48mph at 2700 rpm, 58mph at 3500rpm, all GPS speeds.

The 3.7 was a noticeable improvement over the 3.9 I had before, but unfortunately there is a nasty noise and some fine metal in the diff oil, so I'm taking it back out. I've got the 3.55 gearset from Moss (damn, bought it just before your post with the info on the 200 euro set!) so I'm going to have that installed along with new bearings and seals.

I liked the 3.7, but I think the 3.55 is going to be even better for flat Savannah Georgia! I'd like to hear about how your local drive line shop does setting up yours, I'm looking for a shop to set up mine and florida isn't too far. Won't get to it till late spring though....

Good luck!

Steve-in-Florida Avatar
Steve-in-Florida Steve Hill
Orlando, FL, USA   USA
1974 MG Midget MkIII
1975 MG Midget 1500 "Good Lil' Car"
1976 MG Midget 1500
1978 MG Midget 1500    & more
I've been running the 3.7 diff for a couple of weeks now, and like it a LOT! it really does make a big difference out on the road. the 1275 engine has no problems with it.

I haven't seen what my top speed is yet, as I still have a couple of bushings and tie rod ends to address on the front end. The car wants to lurch one way or the other when I go over large bumps or hit a pot hole. This is probably today's project.

The 3.5 ring and pinion arrived from Germany yesterday, so the next project is to get it installed in a spare gear carrier housing. I have a couple of spare 3.9's, and will pick the one that needs a rebuild. No sense tearing into a good, serviceable unit, unless there's no other choice.

Steve

Jon62midget Avatar
Jon62midget Silver Member Jonathan Brown
Savannah, GA, USA   USA
I'm looking forward to hearing how it goes with the 1275 / 3.55 combo. I'm going to do the same, hopefully this June it will be all together. Some have said the 3.55 will be good, though obviously slower on acceleration. Others (some midget specialists in England) have said the 3.55 will be too tall for the 1275. I think that may be the case in hilly england, but I think in southern georgia and florida it will be just right.

Anyway, please report your progress! And if you could let me know who is doing the gear swap for you and if you are happy with them, that would be much appreciated.

Best, Jon

Mustangsix Avatar
Mustangsix Gold Member Jack Collins
Orlando, FL, USA   USA
Steve,

We're going to meet up at the shop and drive over to Black Hammock for lunch this Saturday. Details on our events page and Facebook.

Brian and I would like to see what you've done to the Midget. We have to repair the diff in our Bugeye but it has an early carrier and I don't think those gears will fit.


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GeorgeOhr Nonya Business
Yes, confused, USA   USA
In reply to # 3675077 by Jon62midget (some midget specialists in England) have said the 3.55 will be too tall for the 1275.

Quite possible. With the 1500 engine and trans it works great on flat but 4th and hilly it'll hold but won't pull.

refisk Avatar
refisk Rick Fisk
Frankenmuth, MI, USA   USA
That's what 3rd gear is for. smileys with beer

In reply to # 3676383 by GeorgeOhr
In reply to # 3675077 by Jon62midget (some midget specialists in England) have said the 3.55 will be too tall for the 1275.

Quite possible. With the 1500 engine and trans it works great on flat but 4th and hilly it'll hold but won't pull.

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