Home > 2019 snowmobiles > Tech 2019: Yamaha Engineers Explain The SRX Return

Tech 2019: Yamaha Engineers Explain The SRX Return

Snow Goer staff

The 2019 Yamaha SRX.

The SRX has a storied history that many sledheads are sure to remember. Yamaha first launched its consumer offering as a liquid-cooled trail sled aimed directly at speed freaks in 1976.

The SRX then returned in 1998, taking the form of two triple-piped sleds in either the 600 or 700 class. But the models soon disappeared as Yamaha shifted its focus toward four-stroke powerplants.

Good things come to those who wait, though, as Yamaha is unveiling the new Sidewinder SRX LE – a third-generation SRX serving as an ode to its speedy predecessors. In addition to the SRX making a proper return, the sled will also feature the new-for-2019 intelligent Quick Switch (iQS) interactive suspension system. The Fox iQS shocks allow a rider to change suspension settings instantly – from soft, to medium and firm – from a switch on the left handlebar for a completely customizable ride on the fly.

The history of the SRX lineage and rave reviews of its return weren’t lost on Jaret Smith, Yamaha’s snowmobile product and accessory planner the last two years. Smith took a moment to discuss the many details of why and how the SRX has finally made its return to Big Blue’s lineup.

SG: Who all was involved in the idea to bring back the SRX and how long has the decision been in the works?

Jaret Smith: “The original concept was from our past snowmobile product planning manager Chris Reid and it probably started around four years ago. His vision was a throwback before snowmobiles moved to big twins and big bump capabilities – back to when there were low and fast triples that ruled the trails. We expanded on the opportunities that were provided with the Sidewinder platform, and thought we could push the envelope even a little further with the SRX.”

SG: What were some of the motivating factors in the original design – were there certain goals in mind or did they evolve with the process?

SMITH: “The SRX project was really about taking a step back from the industry and really trying to improve certain attributes for the customer. The customer we were looking for was that lake racer and trail rider, and with that our initial goals were of course speed – not only top speed but acceleration – and overall handling; we wanted flat, confident handling going into the corner. Previously we looked back at the old SRXs, and when you ride the new sleds it really brings back the feeling from a lot of those old sleds where they sat low, and came into corners buttery smooth. This is the closest we’ve had to that old sled where the power comes on so smooth and linear. Those were the motivating factors and what took this from a Sidewinder to the next level.”

SG: Did you have specific goals such as track lug height, or ride height?

SMITH: “We had some fairly aggressive top speed goals, but we didn’t want to sacrifice handling. We wanted to make sure the sled was balanced not only for top speed and acceleration, but also the handling – that came into play quite a bit throughout the engineering process. We didn’t want to sacrifice overall handling in lieu of reaching that peak number – we could obtain it, but we could have to sacrifice other things.”

SG: Did you come across any obstacles, and how were you able to overcome them?

Click to enlarge.

SMITH: “There were a few things we came across. The 129 versus the 137 [inch track length] argument came up quite a bit. Previously, shorter tracks have always been the answer, but what we found was the 137 did a better job of getting the power to the snow. We needed the footprint of the 137 to achieve our acceleration and top speed targets. The 129 had some positives, but overall as we talk about balance the 137 gave us better corner-to-corner acceleration, while still retaining the top speed numbers that we were looking for.

“There were also certain limitations in regards to lowering snowmobiles with the center shock and the balance of how much you lower the front to the rear – you need to balance with the rear of the snowmobile to keep the balance overall. There’s a certain limitation on the center shock and we couldn’t go too low on ride travel with the center shock without significantly changing the handling and also ride compliance. The travel on the center shock absorber was an obstacle that would keep us from going too low.”

SG: Looking at ride height changes, did you have any original goals in mind? What was the reasoning behind lowering the drive axle one inch – was there a target market in mind?

SMITH: “With the target market being lake racers and trail riders, we knew we could sacrifice some of the big-bump compliance for those specific types of riding. We didn’t necessarily have a target of exactly how much we wanted to lower the unit, but we tried different heights and started seeing the positives and negatives of each incremental change we made. Once we came to the conclusion that the one inch was a balanced height, we wanted to make sure that we could control the set-in of the vehicle to one inch, and we could also balance the front to the rear so that the angle of the sled from front to rear does not change.

“The one inch was the best A-arm angle by lowering the entire machine equally. What that did is when we used the one-inch reduction we also changed the pre-load and used the dual-rate springs and at that height engineering felt they didn’t need to go any lower – the handling was there and we were hitting the top speed marks we wanted to hit in testing, so at that point we had reached the value we were looking for of handling and top speed performance at a one-inch value that was comfortable.”

SG: How did you find the balance between ride height and ride quality?

SMITH: “We actually made no changes to the arms and linkages – they are standard for a 137. The work was done in the suspension itself – engineering reduced the initial rate of the springs for the set-in, so we allowed the sled to set-in at one inch lower, and then we increased the final rate. Utilizing those dual-rate springs, adjusting the spring rate, we can then lower the sled on the initial set-in, but then when it reaches the end of its stroke, it has the same force of a standard single-rate spring, so we can control the ride comfort and how the sled goes through the stroke of the suspension. We looked at other avenues, but the best solution we found was changing the suspension itself and not the geometry of the sled and linkages and arms. We had a great chassis, but wanted to take it to another level.

“From there we also added the iQS system, which allowed us to add another layer of control. With that, we can make changes on the fly from soft to firm real quickly, which added to the overall sled package.”

SG: Was the iQS always going to be part of the SRX package? What went into that decision?

SMITH: “Being that the SRX is a flagship model for us we always wanted to make sure that it had the latest and greatest technology. Truth be told, this project began with QS3s – a lot of early development testing was done with QS3s. But then as iQS started to evolve and getting closer and closer, we ended up making the decision to move the sled over to iQS. We felt the SRX was a great starting point and a great sled to introduce the market to iQS. Being our flagship model, there was no question we were going to introduce it with iQS. The overall ability to change on the fly in the two target market terrains we felt was important to have and this was a great model for that.”

SG: How did you choose the 1-inch RipSaw track? What was the advantage, and did you try any others?

SMITH: “The 1-inch RipSaw provided the best overall top speed with no reduction in acceleration at 400 meters. One of the other big things that we talked about also was it was the best overall handling track with regards to how playful the rear end was on-and-off the throttle, braking performance and acceleration – this was the best overall track for the sled. We did test quite a few different tracks – a 1-inch RipSaw II, a 1.25-inch RipSaw II in a 14-inch width. Not only just on the lug height and pitch profile, but we also tested different widths and lengths to find the best overall package.”

SG: What were the exact changes made to the clutches to make them “optimized”?

SMITH: “It has a multi-angle secondary cam that allowed us to reduce the tip weight. This improved the force balance between primary and secondary clutches, which reduced the heat and gave it a little more performance overall.”

SG: Ergonomic changes included a new throttle, new brake lever, etc. Why were these changes made?

SMITH: “The throttle was a big one for us because a lot of customers transitioned from the Apex and Vector, so they will be really familiar with the throttle pull and shape. The new throttle is designed more closely to those older throttle models – it’s more comfortable for a longer run.

“The new brake master cylinder itself has much better modulation through braking, a lot more precise and a better feel. The kill switch isolated on the other side was more for less clutter on the overall handlebar set-up – it just cleans up the overall controls and where they fall on the handlebar.”

SG: What’s the ideal conditions (or the perfect day) on an SRX?

SMITH: “The ‘perfect day’ for an SRX would be blue sky, sun shining, -10 to -15 degrees Fahrenheit, with a trail that was groomed the night before that had time to set up and flat crunchy snow.”  

SG: Now that the project is complete, what about the finished product makes you the most proud?

SMITH: “The neat thing about the SRX is its ability to break the norm. With an industry pushing toward larger and larger track heights, suspension travel and bump capability, we often overlook what made some of those older triple sleds so special. I regret selling my 2000 SRX 700 – the sound of that triple-triple coming out of the corner, the slot car like handling. For anyone who owned one of those sleds in the past, the new SRX brings back all of those feelings without the sore back at the end of the day.”

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One comment

  1. Ive been riding Yamaha sleds for 33 yrs, I will admit I tried BRP, Polaris and cat, Before Yamaha amalglamated with Cat, Yamaha had the best finish out of all brands, Now you can see they have faalen down to Cats level, I’m not knocking Cat, but Yamaha was always the best finish. I currently have a 2017 sidewinder LTX with turbo dynamics ecu update and exhaust, the sled runs great and pulls hard. I’m looking at purchasing anew one for next year, I’d like to get the SRX, change the track to a 1.25 ripsaw, but when looking at the price, and than look at the Thundercat price and with the snowmageddon on, It hard to not buy a thundercat.
    With arctic cat building our sleds why is their so much of a price difference between the two brands, for the same sled other then colour and Make. Yamaha has always been number 1 in my eyes, and to do that change I’m not sure, but the bottom line is Loyal to your brand.

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