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01-27-2005, 10:18 PM
What is the differance in IM-7 and IM-8.

01-27-2005, 11:12 PM
The IM# system is unique to the Hexcel Corp which manufactures rod blanks. It's the Hexcel company's own internal quality standard rating number system that is unique to the Hexcel Corp. I read that it pertains to the number of graphite fibers in the rod blanks somehow. The less fibers use the higher the modulus number rating. Lower numbers of graphite fibers used means the wall of the tublar blank are thinner. High Modulus means that each fiber is stiffer than a lower modulas rated fiber and less fibers are needed to make the rod as stiff as needed. Stain rating is another system that is use to rate the way the rod behaves I saw that either in a link that someone posted in here or in a magazine somewhere. I think it was an online article that someone posted the link to in the Bill Dance Fishing Talk Forums. I suspect that the G Loomis Rods that are rated IM-8 are better than the IM7 rated rods but I am not really sure.

Here is the link to the article in case you miss it in the other posts on this thread.

But the other companies have tried to copy Hexcel QA standard number rating system but I am not sure they use the very same standards that Hexcel Company uses. Hexcels QA system is more likely propriatory and specific to them and secrete as well. And not all rod builders buy blank material from Hexcel so these other companys would be using a rating system that is not really related to the Hexcel system. G. Loomis use the Hexcel rod blanks I suspect.

So company XYZ so called IM7 rod may not be the same as a G. Loomis IM7 rated rod. If that makes sense.

My guess is that the IM8 G. Loomis rods would be lighter than a IM7 G. Loomis Rods but may be easier to break if its strain rating is not high.
What is the differance in IM-7 and IM-8.

01-27-2005, 11:28 PM
Thanks for your input.

Crappie Attitude
01-27-2005, 11:57 PM
Denny. Not meaning to butt in here but thought I'd pass this along to you.

The IM# system is not unique to Loomis rods....there are at least a dozen other manufacturers that use the system.

IM stands for impressive modulus which is a stiffness to weight ratio. In other words, the higher the number, the lighter the weight of a particular stiffness of rod. It has nothing to do with sensitivity other than a lighter rod of a particular "power" might seem more sensitive. I don't believe there are any industry standards that dictate any sort of uniformity. Each manufacturer I am confident has their own "standards."

Hope this helps.

01-28-2005, 12:02 AM
My BPS rods are IM6 and they sell for 19.95 compared to the $200 you will pay for G Loomis

01-28-2005, 12:26 AM
(Googled up & copied from a fly fishing site) :

IM6 is a 'Grade' of Magnamite, a graphite product of Hercules Inc. BASF makes a similar product, as well as others. The important thing about IM6, IM7, IM8 ratings for fishing applications is the tensile modulus. Most dept. store rods that are graphite composites are around 30-35 million psi tensile modulus. The IM is a shorthand for that tensile rating. IM6 = 40 million IM7 = 41 million IM8 = 45 million. Tensile modulus briefly is: (Courtesy Owens-Corning) "When a bar is pulled in tension, it has to get longer. The tensile modulus is used to calculate how much longer it will get when a certain load is applied to it. Units are normally millions of pounds per square inch. Higher numbers indicate materials which will not elongate as much as others when they are being compared under equal tensile loading conditions." That elongation, or elasticity, is what allows the rod to spring and bend back.

So (grossly oversimpifying) a rod made of IM6 can be built with similar strength and flex characteristics to a rod that uses cheaper material, while making the tube wall thinner, which in theory makes the rod lighter and more sensitive. On the other hand, just because a rod is built using IM6 does not mean it's a great rod. Exactly how the material is laid up in the blank, whether any other material (other graphite composites, fiberglass, aramid and gel-spun polys for instance) the taper, length, all go towards making a good blank. These things also affect the action (fast or slow taper). Then to make a good rod, you have to worry about the seat and handle, and how it's connected, guide material and so on.
************************************************** *******

So what that tells me, and in answer to the question of the difference between an IM7 & IM8, is .......... an IM8 rod blank has 4 million psi more tensile modulus. And knowing that different brands have different standards and QA systems ......... it breaks down to almost meaning nothing, in the "overall" scheme of things. But, in laymans terms, it should indicate that the IM8 rod would be a little lighter, probably a little stiffer (in direct comparison), a little more sensitive (denser), and probably a little more expensive (lol). A IM7 rod would probably bend easier and over a greater percentage of the length of the rod, than would an IM8 (of the same brand/model/composition). .................cp :cool:

01-28-2005, 12:29 AM
I use the Richard Williams Crappie Wizzard Rods myself. They sell for about 30 bucks or less plus shipping cost. All my other rods I got at either Cabelas or Bass Pro Shops and I don't own a single G Loomis rod. They are way too expensive for my budget. Are G. Loomis rods better than the one's I use? I don't know and am very happy with my current rods.

I want a rod that is strong, light weight and sensitive in the sense that I can detect the light bites or taps and know when to set the hook. My rods do all that. I have only broken one rod in half that I know of and that was when I was up in Canada and hooked into either a big Northern Pike or a big Muskee and tried to set the hook too hard and snapped the rod in half. I was using big musky baits that are about 12" long and a 7ft long glass blank fishing rod. The fish hit the bait and took off and had covered about 50 ft before the rod broke. It was in shallow water along the bank on a grass weed covered cove and man I will never forget that day.

I have broken off a few rod tips when I was young and didn't always watch where the rod tips were going.

I need to find the article that I read and that was interviewing the owner of G Loomis rod company. He was the one telling the story about the IM# system.


01-28-2005, 01:08 AM
Here is a link to the G. Loomis web sites rod section. Note that G Loomis is changing the way they describe their rod blanks. Can you guess why? Since other's copied their system they are breaking new ground to change the way they describe thier rod blanks. They do this to try to distinguish themselves from the other rod manufactures I suspect.

http://products.gloomis.com/gl/products/blanks/category.jsp;jsessionid=B5WS2ui0nvcKzsEFdzdW1C6RMs m78QG1ZblW6G0dWeCVOSOvKfCx!48636424!-1062685675!7005!8005?FOLDER%3C%3Efolder_id=2534374 302032544&ASSORTMENT%3C%3East_id=1408474395181201&bmUID=1106892434910


note: G. Loomis company is really going out of thier way to not use the IM# system this year. I find this very funny myself. but then again I am not trying to sell fishing rods and they have to be feeling the heat or pressure coming from the many other rod maufactures out there that sell thier rods for much less money.

01-28-2005, 02:05 AM
took me a few hours but I found the link finally. man now I can go to sleep LOL


01-28-2005, 07:00 AM
Thanks to everyone.

Crappie Attitude
01-28-2005, 07:04 AM

That is a flippin awsome article!


01-29-2005, 10:13 PM
Great articles & posts, not sure I understand it all but very interesting. I just looked at my Sam Heaton rod by B'n'M. It is IM6, would an IM7 or IM8 be even lighter & more sensitive? Hard to believe, I can't see there would be enough difference for $150 or $200 more for G. Loomis, etc. I have a Quantum rod I bought at Wal-Mart (sorry about that Fatboy), it is also IM6 but in my opinion not near as good a rod as the B'n'M.