So, we've been working on the suspension for a customers bike here today. We are fitting up a JRi shock as well as some machine work on the lathe for R6 shock and fork suspensions orders for two other customers. Part of that was fabricating up some bushing spacers for the lower shock mount for the two R6 shock orders... well, while fitting up the JRi shock on the customers bike, as we were pulling the stock shock, I noticed something... odd. It seemed looser than expected based on my prior experience when I pulled the shock (so so many times) on the Formula390 test mule. So, I did the unfathomable and actually measured the customers swingarm mount space for the lower shock mount... Then I measured the Formula390 Test Mule swingarm. Son Of A ******!!!! Turns out, the machinist over at Bajaja are ************!!!
So the difference in the bottom swingarm shock mount between the two bikes is 1.8mm!!! Really! OK, that's just the thickness of a few pieces of paper to most folks, but to a machinist, where anything over 0.001" is a mile, that's just NOT ******** ACCEPTABLE! If I'd turned in a part where from one to the next I had 1.8mm deviations (That' 0.070"!!!) I'd be handed my walking papers! I just can't wrap my head around some of the corner cutting KTM is doing on the RC390. When we were seeing bearings without grease, that was one thing. That's assembly Q&A. Somebody in a rush might miss it. It's not great, but I can see that happening in India. But... for the MACHINIST to be making THAT much of a tolerance???! No. No way. That's just NOT right! Only having the Formula390 test mule on hand when I was doing the various testing with the R6 shock swap development, I had only ever had that one bike. I had measured the factory OEM shock, and used that as a basis for swap candidates. Anything at or under that measurement was going to be acceptable. What never occurred to me however, was that the swingarm machining would have such WILDLY varying tolerances on it's machining. I knew that folks fitting the R6 shock would need bushing spacers. I just never figured those spacers would need to be different based on their actual bikes machined swingarm. I'm baffled, horrified, frustrated, and much to my amazement shocked to see such deplorable tolerances. I shouldn't be, based on what we've seen on the bike in the way of Q&A and various other screwups by Bajaja but I have MUCH higher standards for my fellow machinists. ESPECIALLY considering they have to be cranking these things out on a CNC! That means the button pushers operating the machines aren't even practicing the most elementary of practices of cutter compensation. I'm shaking my head here, in frustration and abject bewilderment.
Anyway, end result was I ended up fabricating up extra spacer bushings for the two customers with the R6 shocks, so that they can fit the shock on their bikes based on what their specific swingarm clearances are. KTM doesn't have any actual spec on what the clearance SHOULD be, but based on standard engineering fit spec it's looking like a target of .5mm / .25mm per side, or 0.018" / 0.009" puts things in the middle of the spec for "Close Running" and "Free Running" fitment, and seems like a reasonable fitment should be.
I'd also advise others that when you are fitting a shock to your bike, measure what clearances you are getting on your lower shock mount between the shock and the swingarm. If you don't have feeler guages, you can use a piece of paper as a guide. In general, printer paper is usually around 0.003" and 0.004" thick. So, you can fold it over and measure with two pieces (you can spray some WD-40 or light oil to get the pieces to hold to one another) to get a measurement of 0.006" and 0.008"... "ish". It's not the BEST way to test for clearance, but it's better than the ol' Calibrated Mark One Eyeball test for distances that small at an angle you can't directly see anyway. Or... spend $10 and go get yourself a set of feeler gauges. Yer gonna need them for when you go to adjust your valves anyway!
A******S!!!!1
So the difference in the bottom swingarm shock mount between the two bikes is 1.8mm!!! Really! OK, that's just the thickness of a few pieces of paper to most folks, but to a machinist, where anything over 0.001" is a mile, that's just NOT ******** ACCEPTABLE! If I'd turned in a part where from one to the next I had 1.8mm deviations (That' 0.070"!!!) I'd be handed my walking papers! I just can't wrap my head around some of the corner cutting KTM is doing on the RC390. When we were seeing bearings without grease, that was one thing. That's assembly Q&A. Somebody in a rush might miss it. It's not great, but I can see that happening in India. But... for the MACHINIST to be making THAT much of a tolerance???! No. No way. That's just NOT right! Only having the Formula390 test mule on hand when I was doing the various testing with the R6 shock swap development, I had only ever had that one bike. I had measured the factory OEM shock, and used that as a basis for swap candidates. Anything at or under that measurement was going to be acceptable. What never occurred to me however, was that the swingarm machining would have such WILDLY varying tolerances on it's machining. I knew that folks fitting the R6 shock would need bushing spacers. I just never figured those spacers would need to be different based on their actual bikes machined swingarm. I'm baffled, horrified, frustrated, and much to my amazement shocked to see such deplorable tolerances. I shouldn't be, based on what we've seen on the bike in the way of Q&A and various other screwups by Bajaja but I have MUCH higher standards for my fellow machinists. ESPECIALLY considering they have to be cranking these things out on a CNC! That means the button pushers operating the machines aren't even practicing the most elementary of practices of cutter compensation. I'm shaking my head here, in frustration and abject bewilderment.
Anyway, end result was I ended up fabricating up extra spacer bushings for the two customers with the R6 shocks, so that they can fit the shock on their bikes based on what their specific swingarm clearances are. KTM doesn't have any actual spec on what the clearance SHOULD be, but based on standard engineering fit spec it's looking like a target of .5mm / .25mm per side, or 0.018" / 0.009" puts things in the middle of the spec for "Close Running" and "Free Running" fitment, and seems like a reasonable fitment should be.
I'd also advise others that when you are fitting a shock to your bike, measure what clearances you are getting on your lower shock mount between the shock and the swingarm. If you don't have feeler guages, you can use a piece of paper as a guide. In general, printer paper is usually around 0.003" and 0.004" thick. So, you can fold it over and measure with two pieces (you can spray some WD-40 or light oil to get the pieces to hold to one another) to get a measurement of 0.006" and 0.008"... "ish". It's not the BEST way to test for clearance, but it's better than the ol' Calibrated Mark One Eyeball test for distances that small at an angle you can't directly see anyway. Or... spend $10 and go get yourself a set of feeler gauges. Yer gonna need them for when you go to adjust your valves anyway!
A******S!!!!1
