This is topic Putting 4.3 in 1.8 NA in forum Garage 2002-2009 at Spec Miata Community.

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Posted by Todd Greene (Member # 16630) on :
What will be the most efficient (Cost v. Labor v. Difficulty) way to replace the 4.1 Torsen:
Replacing the ring and pinion?
Replacing the "pumpkin"?
Or the entire assembly?


Posted by trimless1 (Member # 2624) on :
If you can find a used 4.30 ring/pinon in a junk yard that is the cheapest solution. But you will still need to pay labor for the swap unless you have the expertise required.

Removing the pumpkin is fairly easy so removing it and taking the doner R/P to a local shop for the swap seems to be the way to go.

Good luck in finding a "cheap" 4.30 gear set, they were in very limited supply when I was searching last month.
Posted by Keith in WA (Member # 16099) on :
It depends what you can find in used parts. If you can get a good price on one, the entire assembly is definately the easiest but from what I've seen, the whole 4.3 torson assy is usually pretty spendy.

If you hunt around you can find some good deals on '99 open diffs...less than the cost of a new R&P. The labor will be close to if not the same to put your torson in the 4.3 or the 4.3 in your old pig.

Not sure what you mean by pumpkin vs. entire assy. Pumpkin with the aluminum carrier? If so, it's more expensive to ship that way and people usually sell the carrier for $150+ so it's probably going to cost you more.

There is a market in most of the leftover parts though since many non SMers also want to convert their 1.6 to a torson even if it's a 4.1.
Posted by Todd Greene (Member # 16630) on :
Thanks Keith,

Pumpkin = Pig