mpshizzle
Well-Known Member
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I recently got my Gen 2 R1S back from service for this issue - and honestly, it has me questioning what I thought I knew about Rivian drive train feel. After getting the fix, it feels smoother than it did on delivery day, fresh from the factory. Like it was never right to begin with. So I did a deep dive into the topic to find out exactly what the issue is, what the fix is, and if it's at all related to a similar issue the OG Quads are known for. Admittedly I'm not a professional in this area but I'll do my best to share my findings.
I apologize, this is not as well researched/put together as my content typically is - and there's no video to go with this one. But I just wanted to get this out there. But don't worry, more testing is coming. I'm currently working on testing how Highway Assist affects efficiency. Watch here or subscribe on YouTube to see that, when it comes out.
The OG Quad Issue
I'm sure many of you have heard of the infamous clunk on the OG quad's half shafts. Some call it a clunk, a tock, or a click. It's most noticeable at low speed, especially when transitioning from acceleration to regen and vice versa (a torque reversal). A telltale sign of play developing in the axles. Rivian narrowed it down to the point where the half shafts connect to the wheel hub. From my understranding (correct me if I'm wrong) the root cause of this is manufacturing tolerances that were just ever so slightly too loose, combined with the crazy amount of power and weight these vehicles have. Over time play would develop and the components would wear down and it would get worse.
The OG Quad Fix
Early attempts to fix this issue was just replacing half shafts, adding grease, and torquing down the bolts tighter. This proved to be a band-aid solution though. Inevitably the problem seemd to come back. So then they started adding "Ting Washers". I don't know about you but I'd never heard of a ting washer in my life! So I had to look that one up. Basically a ting washer is just a fancy, well manufactured spacer. It's a very thin washer (just a few mm thick) that is meant to take up space and remove the opporunity for play to occur in the first place. The ting washer is orange in this diagram:
This solution seemed to have better success than the grease and half shaft replacement method, but it still seemed that the problem would eventually return.
Dual Motor Enduro is Immune - Or So We Thought
Enduro (the dual motor system) has a slighty different design that is supposed to prevent this issue from happening. I don't know the specifics of what is different so maybe someone who knows can fill in here? But what I DO know is the manufacturing tolerances were tightened up. Additionally it appears ting washers were installed from the start. This does appear to have solved the problem on the rear end, but it looks like there may still be an issue on the front half shafts and hubs.
The Problem and Fix for Dual Motor Enduro
For me - I started to notice the issue after.. uhmm.. enjoying sport mode too much. Unfortunately my factory Pirellis are near death at this point (about 25k miles in) and they just don't grip like they used to. I think the wheel hop and then sudden grip that can happen when you do a hard acceleration with worn tires was just too much for the front end and I started to hear the noise. When I took it into the service center they told me that they JUST gotten a customer satisfaciton program for this issue a few days ago:
Much to my surprise it covers both Gen 1 and early build Gen 2 dual motor enduro vehicles (manufactured up to August 2024). Interestingly the program says nothing about any kind of drive train noise, but rather the fact that play in the system can damage the wheel speed sensor and cause a fualt. Fortunately that was not a symptom I experienced, but the 2 issues seem to be related. So the remedy is to upgrade the ting washers to a new, updated part. (There were no specifics I could find on WHAT exactly was changed with the ting washer) I'm assuming vehicles manufactured after August 2024 have this updated part from the factory.
Better Than From the Factory?
I've just had Baymax back for a couple of days and let me tell you - I started questioning what I thought I knew about Rivian drive train feel. It is noticeably smoother than before. I've always said that Rivian drive train tuning is 90% as smooth as Tesla (and they are known for extremely smooth drive train tuning). It turns out that the last 10% I was missing was updated ting washers. Not a HUGE difference (it is only 10% in my entirely subjective and made up measurement, after all) but it is noticeable. The signs were there all along, but I just didn't know what they were. There were two things I felt and I'll try my best to describe:
1 - When coming to a stop, sometimes just RIGHT at the point where the physical brakes engage I could hear just the tiniest little moan/creak. It was such a small, barely noticeable thing, that I thought nothing of it. I just assumed it was fluid moving around in the hydraulics for the suspension system or something like that.
2 - When taking off from a stop at low speed there was a feeling like for just the tiniest little fraction of a second the motors were starting to push forward while the brakes were still engaged. Then the brakes would let go. At least that's what it felt like. I figured it was just a tuning thing (again that 10% of "smoothness")
But it turns out I was wrong on both counts. Both of those sensations are entirely gone now. It really was just the ting washers from day 1, and it just didn't get bad enough for me to notice until my worn out tires (and heavy foot) pushed them over the edge.
Will the Fix Last?
I sure hope so! That has been an issue that plagued OG quad - and it seems the fixes are more temporary than permanent. At least based on anecdotal evidence from some owners. That said, I do think there's a chance the fix will stick for a couple of reasons:
1 - While the symptoms are similar, enduro motors, half shafts, and hubs do have tighter manufacturing tolerances. And whatever changes they made seem to be holding just fine on the rear end. The satisfaction program specifically calls out the front drive unit, and based on my own experience, the rear end has remained solid. I'm guessing they're attemptint to do something similar for the front as they did with the back.
2 - I have seen TONS of mentions of this issue for Gen 1 Quad but I don't recall seeing more than a few mentions from owners of dual motors doing the same thing. So I'm guessing that means the issue must not be as wide spread.
3 - I haven't seen much of any mention from owners of more recent builds (After August 2024) - and this includes tri-motor owners, since they have the same enduro front drive unit. So for now, it seems that the revised part is
There is, of course, no guarantee - only time will tell. But I remain hopefull that it's a permanent fix.
I apologize, this is not as well researched/put together as my content typically is - and there's no video to go with this one. But I just wanted to get this out there. But don't worry, more testing is coming. I'm currently working on testing how Highway Assist affects efficiency. Watch here or subscribe on YouTube to see that, when it comes out.
The OG Quad Issue
I'm sure many of you have heard of the infamous clunk on the OG quad's half shafts. Some call it a clunk, a tock, or a click. It's most noticeable at low speed, especially when transitioning from acceleration to regen and vice versa (a torque reversal). A telltale sign of play developing in the axles. Rivian narrowed it down to the point where the half shafts connect to the wheel hub. From my understranding (correct me if I'm wrong) the root cause of this is manufacturing tolerances that were just ever so slightly too loose, combined with the crazy amount of power and weight these vehicles have. Over time play would develop and the components would wear down and it would get worse.
The OG Quad Fix
Early attempts to fix this issue was just replacing half shafts, adding grease, and torquing down the bolts tighter. This proved to be a band-aid solution though. Inevitably the problem seemd to come back. So then they started adding "Ting Washers". I don't know about you but I'd never heard of a ting washer in my life! So I had to look that one up. Basically a ting washer is just a fancy, well manufactured spacer. It's a very thin washer (just a few mm thick) that is meant to take up space and remove the opporunity for play to occur in the first place. The ting washer is orange in this diagram:
This solution seemed to have better success than the grease and half shaft replacement method, but it still seemed that the problem would eventually return.
Dual Motor Enduro is Immune - Or So We Thought
Enduro (the dual motor system) has a slighty different design that is supposed to prevent this issue from happening. I don't know the specifics of what is different so maybe someone who knows can fill in here? But what I DO know is the manufacturing tolerances were tightened up. Additionally it appears ting washers were installed from the start. This does appear to have solved the problem on the rear end, but it looks like there may still be an issue on the front half shafts and hubs.
The Problem and Fix for Dual Motor Enduro
For me - I started to notice the issue after.. uhmm.. enjoying sport mode too much. Unfortunately my factory Pirellis are near death at this point (about 25k miles in) and they just don't grip like they used to. I think the wheel hop and then sudden grip that can happen when you do a hard acceleration with worn tires was just too much for the front end and I started to hear the noise. When I took it into the service center they told me that they JUST gotten a customer satisfaciton program for this issue a few days ago:
Much to my surprise it covers both Gen 1 and early build Gen 2 dual motor enduro vehicles (manufactured up to August 2024). Interestingly the program says nothing about any kind of drive train noise, but rather the fact that play in the system can damage the wheel speed sensor and cause a fualt. Fortunately that was not a symptom I experienced, but the 2 issues seem to be related. So the remedy is to upgrade the ting washers to a new, updated part. (There were no specifics I could find on WHAT exactly was changed with the ting washer) I'm assuming vehicles manufactured after August 2024 have this updated part from the factory.
Better Than From the Factory?
I've just had Baymax back for a couple of days and let me tell you - I started questioning what I thought I knew about Rivian drive train feel. It is noticeably smoother than before. I've always said that Rivian drive train tuning is 90% as smooth as Tesla (and they are known for extremely smooth drive train tuning). It turns out that the last 10% I was missing was updated ting washers. Not a HUGE difference (it is only 10% in my entirely subjective and made up measurement, after all) but it is noticeable. The signs were there all along, but I just didn't know what they were. There were two things I felt and I'll try my best to describe:
1 - When coming to a stop, sometimes just RIGHT at the point where the physical brakes engage I could hear just the tiniest little moan/creak. It was such a small, barely noticeable thing, that I thought nothing of it. I just assumed it was fluid moving around in the hydraulics for the suspension system or something like that.
2 - When taking off from a stop at low speed there was a feeling like for just the tiniest little fraction of a second the motors were starting to push forward while the brakes were still engaged. Then the brakes would let go. At least that's what it felt like. I figured it was just a tuning thing (again that 10% of "smoothness")
But it turns out I was wrong on both counts. Both of those sensations are entirely gone now. It really was just the ting washers from day 1, and it just didn't get bad enough for me to notice until my worn out tires (and heavy foot) pushed them over the edge.
Will the Fix Last?
I sure hope so! That has been an issue that plagued OG quad - and it seems the fixes are more temporary than permanent. At least based on anecdotal evidence from some owners. That said, I do think there's a chance the fix will stick for a couple of reasons:
1 - While the symptoms are similar, enduro motors, half shafts, and hubs do have tighter manufacturing tolerances. And whatever changes they made seem to be holding just fine on the rear end. The satisfaction program specifically calls out the front drive unit, and based on my own experience, the rear end has remained solid. I'm guessing they're attemptint to do something similar for the front as they did with the back.
2 - I have seen TONS of mentions of this issue for Gen 1 Quad but I don't recall seeing more than a few mentions from owners of dual motors doing the same thing. So I'm guessing that means the issue must not be as wide spread.
3 - I haven't seen much of any mention from owners of more recent builds (After August 2024) - and this includes tri-motor owners, since they have the same enduro front drive unit. So for now, it seems that the revised part is
There is, of course, no guarantee - only time will tell. But I remain hopefull that it's a permanent fix.
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) free for the year we had it, whist a friends was constantly getting looked at for this. Reminds me so much of the issues with bicycle bottom bracket designs (which in the case of sram use a wave washer in much the same way) at a much larger scale - cost/endurance/slop all coming together to prove that getting a few bits of metal to rotate in unison is surprisingly hard without bonding permanently.
- fortunately it's not AS bad as before. I'm guessing that the monster will be awoken again next spring after going through a wet winter and getting in the heat. That's what seemed to trigger mine. I keep hearing that they're going to release a new part but they just haven't yet. I am hesitent to just keep replacing them with the same part over and over
