3 replies to this topic

[jgripp81]

I just had a driver MOI "fitted" and I can tell its still not even close to feeling like the driver it was supossed to match (plus i saw the scale and I was over 100kg/cm2 less). Yesterday testing it out my adams adaptor broke in less than 20 swings. So now that I am going to have to get work done again I was curious how much weight and if needed, tipping ill need to have done to make up for the 100+ its off.
And one other question, what effects does having the grip on do to moi?

[TomWishon]

jgripp81, on 09 January 2013 - 11:08 AM, said:

I just had a driver MOI "fitted" and I can tell its still not even close to feeling like the driver it was supossed to match (plus i saw the scale and I was over 100kg/cm2 less). Yesterday testing it out my adams adaptor broke in less than 20 swings. So now that I am going to have to get work done again I was curious how much weight and if needed, tipping ill need to have done to make up for the 100+ its off.
And one other question, what effects does having the grip on do to moi?

Was the person doing the work using an Auditor brand MOI measurement machine or doing from a formula and winging it?  Did you see the MOI measurement of the driver being used as the benchmark for MOI matching?

We talk mostly in g/cm2 for MOI not kg/cm2, but the conversion is easy.  Without question, MOI is a very custom aspect of fitting.  For each golfer there is an MOI for their woods and then for their irons that matches best with their natural sense of tempo, timing, transition force, downswing aggressiveness so as to allow them to be a little more consistent in their swing timing and rhythm.  Most male golfers end up with a driver MOI somewhere between 2700 and 2850 g/cm2 - please understand that there are always exceptions above and below this basic range.

To miss an MOI by 1000 g/cm2 is a pretty big error.  I can't imagine a clubmaker who has the Auditor machine and has done even a handful of MOI match builds would miss a target MOI by this much.

Adding or removing weight in the grip end of the club has very little effect on the MOI of the club - yes it does change it but not at all by as much as weight increases/decreases in the weight in the head.  And not even close to how much the MOI is changed by changes in length.   But if you are talking about the MOI of the club with the grip on vs off, that's much more significant for sure because most grips weigh in the area of 50 grams or so.

The reason that weight change in the grip has the least effect on full club MOI is because the axis of rotation about which the Auditor MOI machine works is the wrist-c o c k release.  So that means the grip is the closest to this wrist-c o c k axis of rotation and as such weight changes that are closer to the axis of rotation for the MOI have the least effect on the MOI.  

Hope this helps a little,
TOM

[jgripp81]

Thanks Tom for the reply. I was hoping you would chime in.
He was using an Auditor so i guess it was g/cm2 not kg/cm2.
The reason i asked about the grip's effect is because when we first check my old driver it was 2900+ with a grip on. He said he could get a accurate reading with out the grip so i told him its ok to take the grip off and i remeber it going down but not by home much.
I guess the meat of my question is after i get my old driver (no grip) checked again and compare it to my new driver (with grip) and to make up the 100g/m2 difference, how much weight should be added and how much tipping is needed if i am adding a bunch of weight?
And here is my club specs (incase this helps) Adams fast 12 ls 202g, Matrix 6m3 at 44.75 272 cpm and a whiteout grip.

[TomWishon]

jgripp81, on 09 January 2013 - 03:27 PM, said:

Thanks Tom for the reply. I was hoping you would chime in.
He was using an Auditor so i guess it was g/cm2 not kg/cm2.
The reason i asked about the grip's effect is because when we first check my old driver it was 2900+ with a grip on. He said he could get a accurate reading with out the grip so i told him its ok to take the grip off and i remeber it going down but not by home much.
I guess the meat of my question is after i get my old driver (no grip) checked again and compare it to my new driver (with grip) and to make up the 100g/m2 difference, how much weight should be added and how much tipping is needed if i am adding a bunch of weight?
And here is my club specs (incase this helps) Adams fast 12 ls 202g, Matrix 6m3 at 44.75 272 cpm and a whiteout grip.

The very end of the Auditor MOI machine is made so you can measure the MOI of a club with and without a grip, but we never do this without a grip in our MOI work because we feel it is important to know the MOI for the whole club as it will be played, with the grip on.  The best way to get a proper measurement if the club has no grip is to take a grip of the same weight as the one you play, and cut it lengthwise so you can easily slide it on so as to make it much easier to do an MOI measurement.  The grip would be secure enough on the butt end of the shaft to allow an accurate MOI measurement of the club to be made.

Typically, if you're talking a more "normal" grip weight such as 48 to 52 grams in weight, the MOI of the club with the grip would be in the area of 35-40 g/cm2 higher than without the grip.  So you can see that while it does have an effect, it is not a huge effect and by no means nearly as much as weight changes in the head, way at the opposite end of the club's axis of rotation.

Typically with a driver, for each 1 gram of weight you add to the head, the MOI increases by around 30 g/cm2.  So you see the principle of MOI is very much related to weight changes that are farther away from the club's axis of rotation.  So if the new driver is 100 g/cm2 lower than the old one, adding about 3g to the head would bring it up to be around the same as the old driver.

TOM