1/4" BBGM/BBTG iron difference

[Smokey227]

I've got 2 sets of irons that I want to play as similar as possible. They have the exact same shaft, grip, length and swingweight. The only difference is the bbgm is 1/4" less. I hit both side by side alternating at the range and the flex feels the same but club with the shorter bbgm feels heavier. I rechecked all the specs including lie when I got home and they are spot on. On a digital scale the club is a few grams heavier but only a little. Had anyone else ever noticed this or am I missing something? Or am I crazy?

[mogc60]

Probably headweights or grip wraps or tip weights?? 1/4” off the butt of the shaft is hardly any reduction in weight. You’re not crazy though...

[Smokey227]

I didn't weigh the heads. I always just dry fit using a swing weight scale. Both sets have tip weights. The grips are the same both with a single wrap of tape.

[mogc60]

Headweights or shaft differences. Same shafts can fluctuate a few grams.

[Socrates]

What make are the two sets? Be specific and which one feels heavier.

[Smokey227]

Ping i25 with modus 105 stiff no stepping. 1.25 bbgm. 7 iron plays 37" to the end of the grip. D2 swing weight. GPMC grip

 

Callaway cf16 with modus 105 stiff also no stepping. 1.0 bbgm. 7 iron plays 37", d2 with gpmc grip. Raw lengths of the modus in the cf16 are 1/4" longer so they play the same length. No extensions.

 

Cf16s feel heavier. I thought they may play a bit stiffer but I didn't notice a difference.

[mogc60]

Bore depth and headweight....if I’m reading that correctly.

[Howard_Jones]

Components is hardly ever on specs, grips can be plus minus 3.5 grams, so lets take the extreme example.

 

Your CF16 might have grips that can be up to 7 grams plus from your I25 and if we use 5 grams grip weight = 1 SWP we now have 7 / 5 = 1.4 SWP lower reading on the scale with the "heavy grips".

 

Now we equalize SW, and at 37.00 1 SWP is 2.16 grams so to get 1.4 SWP we need 1.4 x 2.16 = 3.03 grams.

 

SUM = 3.03 head weight added plus 7 grip weight difference = 10 grams difference to total weight, or the same as if we compare a DG S300 Constant weight with Descending weight for our #9 iron.

 

Put both clubs on the gram scale and check total weight, if the club that feels heavy has a higher total weight you found the reason, and its caused by components "off specs", because most never measure grip weight, so any differences to grip weight ends up as something we must compensate for at head side, and then we get a different total weight and ACTUAL SW value we are able to feel, even if we are not close to this extreme example of 10 grams.

 

Total weight is more important than balance, and thats why i always warn club makers about navigating by SW values since Total weight is a more important parameter.

 

From now on, ALWAYS measure each components, and when we have a set of grips that wary, always use the lightest grip for the longest club and the heaviest on the shortest, just like when we weight sort shafts, and you will reduce the risk of clubs that feels different when we try to make 2 clubs to be equal.

 

I also suggest that we Dry fit without grips, and simply subtract 9 SWP from return value. This way we want be fooled to add 1.4 SWP on one club vs the other like in the extreme example above.

[Smokey227]

I do all of my builds without the grips. Grips go on last. And it isn't one club. I used the 7 iron as reference but it is the whole set. I just put them on a digital scale and they are consistently 3 grams heavier throughout the set.

[Howard_Jones]

Did you check weight on shafts and grips before you made them? 3 grams as average higher indicates higher shaft weight, and on the paper thats possible with a tolerance of plus minus 1.5 grams when we include the weight of 0.25" "more shaft" in one set vs the other. (106.5 / 38 =2.80 pr inch / 4 = 0.7 grams , the rest 2.3 grams from "tolerances" in shafts , grips, ferrules and epoxy)

 

At least you know now that 3 grams matters for how it feels for you, most would think we cant but we do. If the "heavy set" feels good and the other a bit light, just add 3 grams to all shafts on the middle of it.

[Socrates]

The CF16's are a smaller head than the i25's. If you check where the CG is on each head, I bet you will find the CG on the i25's is .25" or more further toward the toe than the CF16's. Therefore, you will find that the CF16's are slightly heavier heads to get to the same swingweight as the i25's as the CG is closer to the fulcrum point. That might be where your 3 grams is coming from.

[Smokey227]

I really appreciate the input. I am glad I'm not crazy.