Suspension Journey & review of Tractive Struts
05-25-2024, 06:26 PM
#46
I sent the Tractive struts in for service. They probably have 12-15 track days and 12-15,000 miles on them. https://www.inertialaboratory.com/ performed the rebuilt and observed a few things. One of the rear struts was internally leaking of bit of nitrogen into the oil. No external leaks were observed on any struts. The bushings on the rear strut pistons were worn on both sides of the car. Shafts on all 4 struts showed signs of hotspots but not abnormal wear.
Based on those notes, I would surmise that rebuilds are probably warranted every couple years. Fewer if you don't drive track events as often, and more frequently if you drive in lots of inclement weather. I see a bit of rain, but no salt or snow. Don't baby things but I don't melt if the car gets wet either.
The attached dyno charts are more interesting though. I requested a sweep be done of the Tractive DDA valve to help me establish how the struts perform at various settings. I casually noticed that sometimes making changes in the DSC had very little influence on how the car felt, and other changes had a large influence on how the car felt. The charts support my findings, as you can see there are times when changing the valve orifice size has little effect on the piston speed of the strut (1.8A - 1.4A for example).
One other weird finding is that there are still changes to the strut velocity between .2A and .6A . From Tractives notes, the valve is supposed to be closed at 600mA. If the valve is closed I don't understand why there would be changes to piston speed at lower amperages.
The speeds shown at 0A and .2A show what I expected for any amperage below .6A. I've written Tractive to ask why these behavior could have been recorded.
For reference, the top of the chart is Compression force over Velocity, and the bottom is Rebound force over Velocity. The graphs are smoothed and averaged over a series of motions at a given voltage. A raw pvp chart is somewhat noisy to read. The Tractive strut operation as reported to me is that the valve is fully closed at .6A or 600mA. And fully open at 2A or 2000mA. We only tested 0A through 1.8A in 200mA intervals. I'm very glad that Chris at Inertial Lab took it on himself to test values below 600mA.
Based on those notes, I would surmise that rebuilds are probably warranted every couple years. Fewer if you don't drive track events as often, and more frequently if you drive in lots of inclement weather. I see a bit of rain, but no salt or snow. Don't baby things but I don't melt if the car gets wet either.
The attached dyno charts are more interesting though. I requested a sweep be done of the Tractive DDA valve to help me establish how the struts perform at various settings. I casually noticed that sometimes making changes in the DSC had very little influence on how the car felt, and other changes had a large influence on how the car felt. The charts support my findings, as you can see there are times when changing the valve orifice size has little effect on the piston speed of the strut (1.8A - 1.4A for example).
One other weird finding is that there are still changes to the strut velocity between .2A and .6A . From Tractives notes, the valve is supposed to be closed at 600mA. If the valve is closed I don't understand why there would be changes to piston speed at lower amperages.
The speeds shown at 0A and .2A show what I expected for any amperage below .6A. I've written Tractive to ask why these behavior could have been recorded.
For reference, the top of the chart is Compression force over Velocity, and the bottom is Rebound force over Velocity. The graphs are smoothed and averaged over a series of motions at a given voltage. A raw pvp chart is somewhat noisy to read. The Tractive strut operation as reported to me is that the valve is fully closed at .6A or 600mA. And fully open at 2A or 2000mA. We only tested 0A through 1.8A in 200mA intervals. I'm very glad that Chris at Inertial Lab took it on himself to test values below 600mA.
No offense, but after following your journey with Tractive, I am glad I didn't go that route. Seems overly complicated and a lot of variables to consider.
I had a steep enough learning curve and trail/error with just the MCS 2-way remotes. I couldn't imagine all the added complexity with DSC settings and values.
I recently had mine rebuilt as well after 25K street miles, although it wasn't because performance dropped off, but more because 1 of them got damaged somehow when my car was in the shop, and since I was going to have to a un-install and a new alignment anyways, I figured I would just have them rebuilt to save labor costs down the road. I used the exact same setting so I could A/B test and when freshly rebuilt the exact same settings yielded a slightly stiffer ride (I'm assuming because the fluid was fresh), but they settled in now with about 3K miles on them to feel about the same as before the rebuild.
Last edited by TRZ06; 05-25-2024 at 06:33 PM.
05-25-2024, 06:49 PM
#47
No offense taken. I think they are pretty comparable as far as complexity goes - instead of dials to adjust at the 4 corners, you are just dialing in the settings to a suspension controller. You don't have to utilize all the dynamic abilities of the DSC. You could just build a suspension profile that is very similar to how a physical dial'd strut would work and tune the car the same way you'd tune a MCS car. The difference would be you'd use a laptop instead of moving dials at each corner of the car.
Where our respective kits differ is on your MCS setup you have nitrogen you can adjust the pressure of easily. In order to do that on this Tractive you'd have to remove the strut (I believe). There might be a pressure fill port that is serviceable with the strut on the car, but I don't know and haven't asked.
The added complexity exists if you want to use the DSC to make changes to the struts behavior based on inputs from the speed, brake pressure or gforces observed. So for example on back road driving, I increase the struts resistance for higher speeds because otherwise the car gets floaty. But at low speeds the softer strut helps reduce the shock of bumps.
You mentioned wanting to try 3 or 4 way struts, its the same variables at play with a DSC.
I didn't notice performance dropping off, but I have a off season here in the PNW and I was chasing a wobble in the car that I wanted to rule out the struts causing. The wobble is still there with the OEM struts. Not sure what it is related to or what is causing it but I continue to try to find the source of it.
Who did you use for your rebuild? Where there any notes the engineer provided about the struts condition?
I think too few people actually rebuild their struts so its cool to see you've taken the time to. Also, how did it get damaged in a shop?
Where our respective kits differ is on your MCS setup you have nitrogen you can adjust the pressure of easily. In order to do that on this Tractive you'd have to remove the strut (I believe). There might be a pressure fill port that is serviceable with the strut on the car, but I don't know and haven't asked.
The added complexity exists if you want to use the DSC to make changes to the struts behavior based on inputs from the speed, brake pressure or gforces observed. So for example on back road driving, I increase the struts resistance for higher speeds because otherwise the car gets floaty. But at low speeds the softer strut helps reduce the shock of bumps.
You mentioned wanting to try 3 or 4 way struts, its the same variables at play with a DSC.
I didn't notice performance dropping off, but I have a off season here in the PNW and I was chasing a wobble in the car that I wanted to rule out the struts causing. The wobble is still there with the OEM struts. Not sure what it is related to or what is causing it but I continue to try to find the source of it.
Who did you use for your rebuild? Where there any notes the engineer provided about the struts condition?
I think too few people actually rebuild their struts so its cool to see you've taken the time to. Also, how did it get damaged in a shop?
05-25-2024, 07:24 PM
#48
No offense taken. I think they are pretty comparable as far as complexity goes - instead of dials to adjust at the 4 corners, you are just dialing in the settings to a suspension controller. You don't have to utilize all the dynamic abilities of the DSC. You could just build a suspension profile that is very similar to how a physical dial'd strut would work and tune the car the same way you'd tune a MCS car. The difference would be you'd use a laptop instead of moving dials at each corner of the car.
Where our respective kits differ is on your MCS setup you have nitrogen you can adjust the pressure of easily. In order to do that on this Tractive you'd have to remove the strut (I believe). There might be a pressure fill port that is serviceable with the strut on the car, but I don't know and haven't asked.
The added complexity exists if you want to use the DSC to make changes to the struts behavior based on inputs from the speed, brake pressure or gforces observed. So for example on back road driving, I increase the struts resistance for higher speeds because otherwise the car gets floaty. But at low speeds the softer strut helps reduce the shock of bumps.
You mentioned wanting to try 3 or 4 way struts, its the same variables at play with a DSC.
I didn't notice performance dropping off, but I have a off season here in the PNW and I was chasing a wobble in the car that I wanted to rule out the struts causing. The wobble is still there with the OEM struts. Not sure what it is related to or what is causing it but I continue to try to find the source of it.
Who did you use for your rebuild? Where there any notes the engineer provided about the struts condition?
I think too few people actually rebuild their struts so its cool to see you've taken the time to. Also, how did it get damaged in a shop?
Where our respective kits differ is on your MCS setup you have nitrogen you can adjust the pressure of easily. In order to do that on this Tractive you'd have to remove the strut (I believe). There might be a pressure fill port that is serviceable with the strut on the car, but I don't know and haven't asked.
The added complexity exists if you want to use the DSC to make changes to the struts behavior based on inputs from the speed, brake pressure or gforces observed. So for example on back road driving, I increase the struts resistance for higher speeds because otherwise the car gets floaty. But at low speeds the softer strut helps reduce the shock of bumps.
You mentioned wanting to try 3 or 4 way struts, its the same variables at play with a DSC.
I didn't notice performance dropping off, but I have a off season here in the PNW and I was chasing a wobble in the car that I wanted to rule out the struts causing. The wobble is still there with the OEM struts. Not sure what it is related to or what is causing it but I continue to try to find the source of it.
Who did you use for your rebuild? Where there any notes the engineer provided about the struts condition?
I think too few people actually rebuild their struts so its cool to see you've taken the time to. Also, how did it get damaged in a shop?
Yeah, you are probably right. More of a different learning curve.
Yeah, the canister pressure adjustment is a very nice fine tuning tool. You can add platform to the car without having to change the springs. Although, not a 1:1 in behavior in how canister pressure VS a stiffer spring would work, for fine tuning and within a small margin range, it works great. It also allows you to add platform (aka added compression of sorts) without having to up the compression dial and change the damping curve.
I have ruled out upgrading to the 3-ways though, I just am at my limit of adding funds I want to use on the car. I will just drive into the ground over the next 7-8 years now, lol. Also, since I plan on keeping it long term, have to build the PCCB replacement fund (hopefully, not for a long time though)
Interesting about the wobble. Have you ruled out tire/balancing issues? Maybe a defective tire with a slightly misaligned steel belt can cause something like that. Good luck on that, that would drive me absolutely crazy.
MCS did the rebuild, they turned them around in about 10 business days and it was their busy season, so kudos to them. I did not have them dynoed pre rebuild, but they did dyne match them before sending them back to me. They said that they looked fine and didn't notice any leakage or seal issues. I can't say if anything was different on the dyno charts, but by feel (and I am pretty sensitive), I feel no difference in performance.
Yeah, I haven't heard or read of any before/after rebuilds either online. I prefer to not get into how one of them got damaged, it was just an accident of unknown nature, but was rectified and I was taken care of.
05-25-2024, 07:30 PM
#49
I suppose I could try new tires, I will be doing that pretty soon. Tires don't last too long here, 3-4 months during the track season. I think this issue has been around beyond then but it could also be wheel related, as I have not tried different wheels.
Of course the wobble is only at the track that I really notice it. I can't drive on the street at the speeds that create the condition. I keep hoping its just a bushing that is torn and a harmonic frequency is found that persists at certain speeds. It's weird for sure.
Of course the wobble is only at the track that I really notice it. I can't drive on the street at the speeds that create the condition. I keep hoping its just a bushing that is torn and a harmonic frequency is found that persists at certain speeds. It's weird for sure.