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354 differential replacement

Moss Motors
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Htimsc Avatar
Htimsc Gold Member Chris Smith
Portola Valley, USA   USA
Hello all, I am researching the possibility of replacing the existing differential in my BJ8 with a 3:54 ratio unit. I've not been able to find any reliable information about the parts, or the process, or where to buy. I found an old 2010 string of exchanges on the topic on the UK forum, but not much else. I also found this:
http://www.pbase.com/mdlempert/gears
but it too referred to 2010.
I happened to ask British Car Specialists in Stockton when I was there on something else, and Dave had said they do it, and it would be approx. $4K (~ 50/50 parts and labor). He did not elaborate any more. Unfortunately it is a bit further than I would like to drive my car and transporting it there would just add to the expense.
So I am interested in more up to date information and experiences - is there anyone who has comments/specific information to offer?
Thanks.

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Jack T Avatar
Greensburg, PA, USA   USA
You can buy the ring and pinion (Moss, AH Spares) and have a local driveline shop set it up. If you can remove the carrier yourself you will save a lot of money.

Htimsc Avatar
Htimsc Gold Member Chris Smith
Portola Valley, USA   USA
Thanks Jack - I took a look a their information and the description and it says BJ7, BJ8 - non-o/d (which I assume means cars without overdrive). Am I missing something?
-Chris

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Dougie Avatar
Dougie Doug Escriva
Portland, OR, USA   USA
In reply to # 208890 by Htimsc Thanks Jack - I took a look a their information and the description and it says BJ7, BJ8 - non-o/d (which I assume means cars without overdrive). Am I missing something?
-Chris

The 3:54 was the stock gear set for non-overdrive cars. I installed a set about 15 years ago in my '65 BJ8. Great upgrade for long freeway runs and really not a problem around town as some have said. I had a local shop install the gear set iwith new bearings in the diff for abour $200.00 and R & R everything myself. I have no idea where David is getting 4K, it's an easy install. The biggest expense is the gears themself.

cpcooper Craig Cooper
Chico, CA, USA   USA
Moss has the gears for a little over $1000. AH spares, about GBP 450, though they are heavy so shipping could be rough. I am also in Northern California, occasionally order from them and am always amazed how quickly parts arrive. Doug is right, once the gears are installed in the carrier, it’s an easy install into the axle, but can be daunting if you haven’t done it before.

Being legendarily thrifty, I would first try posting a wanted ad in the buy-sell-trade forum here. I’d also watch eBay daily for a rebuildable differential. (There is one there now for about $85 shipped) Search “Austin Healey Differential core” it’s a 3.9, but you could have the 3.54 gears installed as Doug did, then you’d have your current diff as a spare or to sell. Lots of help available here on how to install, or, if you’re really stuck, bring it to Chico and we’ll do it on my lift.

Craig

Jack T Avatar
Greensburg, PA, USA   USA
In reply to # 208890 by Htimsc Thanks Jack - I took a look a their information and the description and it says BJ7, BJ8 - non-o/d (which I assume means cars without overdrive). Am I missing something?
-Chris

Chris, the 3.54:1 ratio was standard in the non o/d cars. The gears can be interchanged.

Erl Erling O
Jacksonville, FL, USA   USA
Htimsc Avatar
Htimsc Gold Member Chris Smith
Portola Valley, USA   USA
Price at Big Healey USD 788.00 (today's rate). Not including freight, customs, etc.

Prie at AH Spares USD 566.00. Same comment.

That's an almost 40% difference - does anyone know why that might be?

Moss Motors has an "Assembly" that seems like it might come with other parts at $1,049.00. I'm going to call them tomorrow to ask what or what is not included.

While on their site I checked the schematic. There are a lot of parts that may not be required to be replaced (my BJ8 is an ~ 4 year old restoration and appears to be in good condition with no leaks - yeah, I know - why do this in the first place...). What are the MUST replacements other than the large gasket between the two halves of the differential?

Thanks for all comments.

-Chris

cpcooper Craig Cooper
Chico, CA, USA   USA
Ahead 4 Healeys has it for $503.43. You might get away without replacing any gaskets, but as long as it's out... the one on the carrier, maybe pinion seal and paper gaskets on axles. Main thing is to get the gears set up correctly by someone who knows how to do it and has the right equipment. I almost said it's pretty conventional, but no too many rear wheel drive cars around these days.

Drone Dog Avatar
Drone Dog TL Wright
Seaford, DE, USA   USA
you may want to read info on those paper gaskets for the axles. i recently spun a bearing in one of mine. it was suggested that the spacing when using the paper gasket may be too much and the spacer does not keep enough pressure on the bearing. i just used RTV sealant on mine. the o-ring keeps the oil in.

Redbn4 Silver Member Jim Frakes
Noblesville, IN, USA   USA
My advise, have a professional gear company set your 3.54 gears. In addition, could be wise to magnaflux the carrier. Note the pictures of a catastrophic failure. Not my car, not my set-up, but happened at 50 MPH CruSing Speed.
Added carrier photo. Notice the crack. Gear set too tight?



Edited 1 time(s). Last edit at 2019-02-14 09:28 AM by Redbn4.


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