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2 steps forward, one step back

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Westfield_XI

Westfield_XI

Jedi Warrior
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It looks like I will be running a 3.9 instead of a 4.2 due to part compatibility issues. Between the 3 complete diffs and the 2 extra spider housings I have enough parts to build up a complete diff with NO cracked parts. However, the 4.2 gearset is not compatible with all the rest of the parts. It seems that the older 4.2 crownwheel is significantly thinner than the later part by approximately 1/4" and the pinion is different by that amount also. The thickness is made up by having more metal on the housing to make up the difference, unfortunately that part was badly cracked and was unusable.

So while I source another 4.2 crown and pinion, I am having him buIld up the diff as a 3.9 for now. As you know it will only mean a change of at most 300 RPM at cruise which I can live with. Actually 5th was a bit long anyway and this way I will be running by the time the rain leaves the area so I can drive again.
 
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Westfield_XI

Westfield_XI

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racingenglishcars said:
I may have mentioned that previously:
https://www.britishcarforum.com/bcforum/u...ater#Post806723
However I'll bet you could make a spacer.
Click to expand...

Good call!! We could make a spacer, that was the first thing that came to mind. However the words laser cut and Blanchard ground came up in the conversation during which I learned that these diffs are machined to very high tolerances: this one has only 13 thousandths of shims total as opposed to 100 to 150 thou in a US diff and that the spacer thickness would need to be accurate to 5 thou to allow adjustiment of clearances with the limited space available. This will only add to the expense since the spacer will need to go iin and out of the diff a couple of times to get it right, each time being sent out for grinding.

If I am going to go to anymore expense and trouble, I might as well buy a Quaife or Tran-X, get a NEW pinion and Crown wheel and be done with it forever. This way I only am into this for the used parts I acquired the past few weeks and the shop labor that I was planning to pay anyhow. For all I know, I might prefer the way the 3.9 performs more than the 4.2 after a few thousand miles. It will also buy time to put away the funds for a change if needed.
 
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Westfield_XI

Westfield_XI

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racingenglishcars said:
Ah! Thus the wisdom of a junkyard diff. Temporarily of course. :smile:
Click to expand...

No, not really a "junkyard diff", it's the same crack checked parts from 5 different junkyard diffs just as before. Same diff I would have ended up with in the first place, just not in the ratio I would prefer and that I had in the first place. I will just keep my eyes open for a 4.2 with the thick crownwheel with all it's teeth to rob the gears. Meanwhile I will keep driving and tuning the chassis and engine.
 
racingenglishcars

racingenglishcars

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Westfield_XI

Westfield_XI

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The crown and pinion for $75 looks interesting, esp since a new set from the UK costs 190 quid! My problem is that I have had such bad luck with eBay the past few years that I am reluctant to do business through them anymore. In the course of obtaining parts for this project, a 24' boat restoration and others, eBay has let me down nearly every time. It is getting to the point that I have returned to the old method of asking friends and friends of friends for what I need.
 
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Guest

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Really? Ebay is now geared towards the buyer. So much so fella could screw a seller over if he wanted to.

I'm reluctatnt to sell there now.
 
jlaird

jlaird

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Have never had an eBay prob. either seller or buyer.
 
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Billm

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If you are looking for 4.22 gears- I have a BRAND NEW in the box 4.22 ring and pinion set (that I got from Paul Asgeirsson's stuff) that I would be happy to sell you for $50 (including shipping) if you want.
BillM
 
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Westfield_XI

Westfield_XI

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Bill, I would like that very much. PM sent. Thanks
 
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Westfield_XI

Westfield_XI

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Just wanted to say thanks again to BillM for the gearset. I got the new unit installed with his Brand New gears and took a short test drive before sundown today and everything is working great. The rebuilt diff is totally silent, unlike the previous one with the three broken teeth!!

I took advantage of the downtime to catch up on a lot of little jobs that I had been putting off, so the time waiting for uncracked parts was well spent from my point of view.
 
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Billm

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Glad that they worked (and well!)
Maybe someday I'll have your guy shim one for me!
Bill
 
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