Insane Diff prices!

[Andy W]

Well I'm stunned!
It's freaking insane money....

A 3.9 diff sold on eBay last evening for £395....yes really...three hundred & ninety five quid!

Given the going rate seems to be an already very high £250'ish I don't get what happened there but one thing is for sure...my plans to by & fit one have have bitten the dust!

[philthehill]

I am afraid the trend over the last few years is for the price to go up especially as there are no new ones being made.
Most on 'e' bay go for more than £300 plus so £395 does not surprise me.
Here are couple for less and come complete:-

http://www.ebay.co.uk/itm/Mg-Midget-Aus ... Swc-tY3r~n

http://www.ebay.co.uk/itm/Austin-Healey ... SwbApZcQXj
The ratio is not quoted as far as I can see.

Or you can go for this diff.

http://www.ebay.co.uk/itm/MG-MIDGET-150 ... SwWdZZa10Y

I have only ever seen one of these 3.5 diffs - so they do exist and it is rare so will command the asking price.

[Declan_Burns]

Phil,
There are new CWP's being made and I have one in my car. They are actually quite reasonable and I have procured one for someone on this board earlier in the year and sent it to the UK. They are being sold for 246,96€
The company that has had the batch commissioned is called Bastuck and the CWP's are made in Turkey-according to the wrapping. Quite a lot of Automotive parts are made in Turkey. The CWP's you get in the UK all comes from Bastuck.
I found the tolerances were not quite right and I had to remove all the shims on the carrier side to get it to fit and it was a tight fit. I would have liked more backlash and I should have turned it down a few thou as I can hear it at certain speeds but I will live with it.
Here's a link to the source:
http://www.bastuck.de/shop/index.php?&c ... =1&lang=en
They also have the rare 3.55 listed

Regards
Declan

[philthehill]

Declan
Many thanks for the link.
Whilst you may be able to get the crown wheel & pinion for the 3.5, 3.7 & 3.9 diffs the BTA carrier will still be needed as the 3.7 & 3.9 MG/Sprite diff will not work with the Minor 948cc/1098cc ATA diff carrier.
Only the Riley 1.5 and Wolseley 1500 use the same BTA diff assys (see list below).

[Andy W]

I asked these folk to tell me the ratio of the diff. They spun it & replied that it's 3.5 - 1....can this be correct? They have now edited their listing to say as much....This ratio is not on the list...now I'm even more confused....

http://www.ebay.co.uk/itm/Austin-Healey ... SwbApZcQXj

[greendefender123]

Really you need to know the number of teeth on the pinion and Crown wheel but you obviously can't get that. We've been caught out before. At those prices think il be sticking to 50 mph.

[StillGotMy1stCar]

There should be two numbers stamped into outside casing to give the number of teeth, divide the large number by the small to get the ratio. That’s assuming it has the original crown wheel and pinion.
Just looked at axle you're talking about, a bit mucky, would need some cleaning to see any numbers.
Regards John

[philthehill]

The 3.5 ratio is not on the list posted above because the list was prepared by BMC Special Tuning before the 1500cc Midget came into production.
The list was mainly posted to show that the ATA & BTA diffs components are not interchangeable.
Whilst I can add the 3.5 to the list I do not have any BL parts numbers to complete.
I do not know how many 1500cc Midgets were produced with the 3.5 diff but the diffs very rarely appear for sale.
From the MOSS parts list it appears that the 3.5 diff was offered as an alternative ratio for the Midget (1964 on) under part number STR520 (MOSS).
I would suggest that you discount fitting a 3.5 diff to your Minor as it is too high a ratio and the performance of the car will be severely curtailed as it is not suited/matched to the power band of the Minor engine.
Unless you have at least a 1275cc engine or modified 1098cc engine I would advise also against fitting a 3.7 or 3.9 diff as again they are not suited to the Minor engine power band.
BMC Special Tuning produced several one off ratios that do not appear on any listings and rarely do they come up for sale.

[greendefender123]

Hes got the 1275cc engine fitted.

[Andy W]

Interesting, sounds like a good diff for a very uprated Minor!

I do indeed have the 1275 Marina engine, Metro HIF44 carb & DMG 1.5" exhaust so I am hunting around for a 3.9 diff in good working order but at a sensible price!

[StillGotMy1stCar]

Photos to help identify diff ratio. From my 3.9 diff, sorry not for sale.
Might be worth them scraping and wire brushing that area of the diff your interested in, may not be a 3.5 and could save them a lot of hassle if miss described!!
Regards John

[philthehill]

What ever diff you have fitted it needs to be suited to the engine power band.
Hewland gearboxes have easily changeable final ratios to suit the engine power band and road/track.
Just putting a higher gear ration diff is not always the answer.
This chart may be of interest:-
http://gerardsgarage.com/Garage/Tech/diffRatiosWS2.htm
Phil

[Smithy1961]

Anyone know what this diff might be ?
No other numbers on the crown wheel.

diff.jpeg (105.89 KiB) Viewed 4587 times

[RobThomas]

Have you counted the number of teeth. That's all you need to do. About 40 and about 10.

[StillGotMy1stCar]

As Rob says count the teeth or it is marked after the MOWOG in your photo, I can see 8 and 4 can’t see the next number.
Most likely 8-43 so a ratio of 5.375 : 1
Regards John

[RobThomas]

Yup. Looking at the chart above and adding 1 to each number gives you the part number for the crown wheel.

[Smithy1961]

yes counted 8x43

thanks guys