MOI-Weight Fitting and Matching OEM Clubs

Recently, I’ve had some readers inquire about MOI-weight fitting and matching non-Wishon clubs.

While that can be done, one of the reasons for my preference of the Wishon line of equipment is that it is designed to more easily MOI-weight fit and match the clubs.

What I mean by that is the clubhead weights for Wishon clubheads are lighter than the OEM companies. I have measured clubhead weights for companies like Adams, Mizuno and Titleist and each clubhead measured out heavier than the comparable Wishon heads. I’ve only found one set of clubs that measured out lighter, and that was some old Muirfield Lite clubheads which I will get to in a bit.


Other than that, GolfSmith makes clubs with the same clubhead weight in their Snake Eyes line. But, Tom Wishon headed up GolfSmiths club design department not too long ago and obviously left his footprint on the company. KZG offers a set of ZO Blades that are about 3 grams heavier, but the rest are more like 5 grams heavier. That’s actually pretty common for what I see from the OEM iron and wood heads. However, KZG’s drivers are slightly (2-3 grams) lighter than Wishon’s flagship driver model, the 919THI. But Wishon’s new driver model, the 739CCG, is actually much lighter, only weighing in at 188 grams.


But outside of the Snake Eyes and KZG lines, most of them weigh much more than the Wishon heads. From there, Wishon utilizes 7-gram increments in clubhead weight (so does GolfSmith and KZG). Here’s a look at the head weights of the Wishon 555C model irons:

2-iron: 232 grams
3-iron: 239 grams
4-iron: 246 grams
5-iron: 253 grams
6-iron: 260 grams
7-iron: 267 grams
8-iron: 274 grams
9-iron: 281 grams
PW: 288 grams

As you can see, right on 7-gram increments and the weight gets heavier as the club has more loft.

This is important because if you’re using a 1/2-inch or 3/8-inch club length increments that means the lower lofted clubs are longer than the higher lofted clubs. That means the mass of the club increases and you need to have sound weight increments in order to get that MOI-weight to properly match your golf swing.


Now, here’s a look at my set of Muirfield Light clubhead weights. Remember, these are the only iron heads I’ve found to be lighter than Wishon’s iron heads so far:

3-iron: 222 grams
4-iron: 228 grams
5-iron: 228 grams
6-iron: 233 grams
7-iron: 240 grams
8-iron: 246 grams
9-iron: 246 grams
PW: 260 grams

So, not only lighter, but MUCH lighter. However, look at the increments in weight. The 4-iron and 5-iron along with the 8-iron and 9-iron are the same exact weight. It’s no small wonder why Jack Nicklaus reportedly read MacGregor the Riot Act during this time when it came to their quality control.

However, I have seen this stuff with modern OEM lines as well. I won’t name the offenders, but I will say that it’s not nearly as bad as the Muirfield Light heads, but I’ve seen some that are way off and it affects the golfer’s performance.


So, why does this matter?

What I often see is that the MOI-weight for clubs are too heavy, particularly in the longer irons for people above a 5-handicap. And more in particular for those who don’t generate a clubhead speed of over 100 mph.

Recently, I helped fit the MOI-weight for a golfer using a Wishon 555C 6-iron and KBS Tour 90 shafts. The MOI-weight came out to 2,565 kg/cm2. In swingweight terms, his 5-iron came out to C-8.5 and his Pitching Wedge went up to D-2.0. Thus, the MOI-weight that fit his swing was rather light.

Here is the amount of weight I added to each of his irons in order to get the MOI-weight to match to 2,565 kg/cm2 throughout the entire set.

5-iron: ½-gram of lead tape
6-iron: no weight added
7-iron: no weight added
8-iron: 2-gram hosel weight
9-iron: 2-gram hosel weight
PW: no weight added

So, I wound up adding such a small amount of weight to 3 of the clubs and added no weight to the other 3 clubs in order to get the MOI-weight to match.

This golfer needs a light MOI-weight for their swing and swings under 100 mph with the driver. Now, if he had an OEM’s line of irons where the clubheads may be 6-grams heavier, there’s a good chance that every single iron in his bag is much heavier than the fitted MOI-weight of 2,565 kg/cm2. So, if he tried to fit himself with his OEM irons, he may be fitting himself for a weight that is too heavy for him to begin with.

And if he did happen to find the MOI-weight of 2,565 kg/cm2, he would then have to find a weight to reduce the MOI-weight of the clubs that are heavier than 2,565 kg/cm2.

How would we reduce the MOI-weight of a club?

A. Different, lighter shaft
B. Trim the club shorter
C. Grind the head

Not exactly appeasing options because they can dramatically change the key characteristics of the club. Lighter shaft may have a completely different shaft bend profile. Trimming the club shorter could make the club stiffer in the butt-section, change the kick point of the shaft (making it go lower) and may not suit the golfer’s setup. And grinding the head is something I simply would never do.


I’ve also found that MOI-weight is big for taller golfers.

It came as a surprise to me that when I trimmed off ¼-inch of a steel shaft from the butt end, it affected the MOI-weight by 60 kg/cm2. So, if you’re a golfer who is adding ½-inch or a full inch of shaft length to your clubs for your tall height, you may want the lighter clubheads so you can offset the extra MOI-weight that will come with the extra shaft length.

From my own personal experience, when I assembled my Wishon set of irons with ½-inch longer KBS Tour shafts which are fairly heavy (130 grams), every single iron came in lighter than my personal fitted MOI-weight of 2,725 kg/cm2 (for irons only).

The heaviest Wishon iron in my bag, pre-MOI fitting was the 4-iron at 2,702 kg/cm2. From there, I simply did a fitting and found my optimal weight of 2,725 kg/cm2 and then added the appropriate amount of weight to each club

On that note, I also had a set of Titleist 690MB’s with the same shaft and the same extra ½-inch shaft length. And the 3-iron thru 6-iron along with my 8-iron all came in above my fitted MOI-weight of 2,725 kg/cm2.

In the end, I have been able to MOI-weight fit and match OEM clubs for golfers. But, there’s no guarantee that one can reasonably do it without having to change the shaft. And in particular, if you are using longer shafts and/or have a driver swing speed under 95 mph, you may find some major issues with the MOI-weight of your OEM clubs.









3JACK