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06-16-2021, 11:14 PM | #1 |
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Bucking after new clutch install
I had a stage 2 SouthBend clutch installed a few months ago after the TOB failed. This is an Exedy clutch with 6 segments of their Feramic compound.
14 FRS at 87k manual trans car for reference. Put all new parts in down to a cerakoted bearing retainer, Verus fork and new subie TOB and flywheel. Only part I didn’t replace is the clutch pivot boss if I missed something. Since then I can get some nasty bucking if trying to launch hard. It gets worse when after spirited driving for a good session. It’s tamed a bit since installation, but still occasionally it gets obnoxious. I was thinking it was break in norms, but it it has not stopped yet. Also, I did have a Whiteline trans mount bushing installed. And lately, an HKS supercharger which has shown me how soft the bushing package really is making the issue more prevalent. Now, to the solution space. I’m not sure if this is the engine/trans mount set or the rear end suspension bits. Any comments appreciated as to where to start. Which might just be buying a GoPro to see the problem. My car is stock suspension wise other than the Whiteline trans bushing. I’d prefer an STI parts solution, but not sure if they address the rear end bushings with different parts like the STI grade engine and trans mounts. |
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06-17-2021, 12:18 AM | #2 | |
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Please describe "bucking" in reference to an automobile? |
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06-17-2021, 12:40 AM | #3 |
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Clutch chatter. Stock clutch is rated to let go before the transmission frags, and engages smoothly.
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06-17-2021, 03:53 PM | #4 | |
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It is a 350 ft-lb clutch. |
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06-18-2021, 09:45 PM | #5 |
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So on one drive I purposely gave it a lot of clutch slip a few times to wear it in a bit more. Not obnoxious, just a few slow engagements making it slip a lot. It is improving the 1st gear takeoffs.
This clutch doesn't make it easy. Feels the same weight wise to the leg, but engages like rock compared to stock. Learning curve on the break in, I think I'll be fine in another month or so of commuting. Last edited by jeepmor; 06-19-2021 at 11:48 PM. |
06-25-2021, 01:36 PM | #6 | |
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2013 Series 10 FRS #553
RCE T2's, SPC LCAs -4/2.6 camber JDL 4-2-1 EL, FP and OP, Tuned by Zach@CSG on e85 RR Wilwood Front/Rear Sport BBK, Motul 600 Fluid ARC-8 17x9 SX2 GTs 245s/Koing 17x8 v730's 225's |
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06-30-2021, 10:57 PM | #7 | |
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06-30-2021, 11:00 PM | #8 | |
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The Following User Says Thank You to jeepmor For This Useful Post: | jflogerzi (06-30-2021) |
06-30-2021, 11:06 PM | #9 | |
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2013 Series 10 FRS #553
RCE T2's, SPC LCAs -4/2.6 camber JDL 4-2-1 EL, FP and OP, Tuned by Zach@CSG on e85 RR Wilwood Front/Rear Sport BBK, Motul 600 Fluid ARC-8 17x9 SX2 GTs 245s/Koing 17x8 v730's 225's |
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07-01-2021, 12:36 PM | #10 |
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@jeepmor you might need the whiteline positive traction kit (subframe and differential bushing) to stiffen the rear. IMO it makes my car much easier to drive at low rpm, can lug the engine and the (stock) clutch doesn't make a peep on my 130k mile car. Though will make the car stiffer than coilovers and very loud and sometimes you'll get noisy vibrations from the rear.
I also notice that the clutch might act differently after some heat has gotten into the clutch or bushings. Maybe more deflection, compliance, etc. |
07-01-2021, 10:41 PM | #11 |
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Was thinking I was all alone with this issue. I'm getting used to it as well and it has greatly reduced. I definitely put a large bit of that on breaking in the clutch. 350 ftlb of holding power is a lot more than stock, and when it bites, there is zero slip. My new routine of slipping the clutch on purpose is in 6th gear going 60ish. Not tortuous, just making it slip a bit, run a few miles to let it coole, slip it again routine. This helped a lot more than trying to do it in lower gears.
That said, It hasn't disappeared just yet, but I'm adapting well and not as concerned about it now. Pretty new to sports car stuff like this, but an old hat in regards to my jeep. And, now that I've driven enough, it's very similar in nature to wheel hop on the jeep leaf springs. Thanks for the STI parts reference and Whiteline rear bushing suggestions. I've read the STI parts are stiffer, but still have low NVH. Not thrilled about the NVH feedback from radroach, but good to know it addresses a lot of this issue. It always felt like it was in the back end, not the clutch, but this type of issue can be difficult to pinpoint. As stated before, it really feels like leaf spring wheel hop. |
12-04-2022, 08:20 PM | #12 |
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I had the clutch opened back up recently, this root cause was the Verus fork with sloppy tolerances. The shop put in an OEM fork and all is well again, no more serious bucking.
Expensive mistake, but finally have this issue resolved. Also, the OEM throwout bearings still suck. At 30k, it's throwing rust dust out of it. Had the Exedy throwout bearing I saved from the Southbend clutch put in this time. |
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12-05-2022, 09:59 AM | #13 | |
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What in the tolerance was sloppy?
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12-05-2022, 12:17 PM | #14 |
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That is an extremely weird source for something like this...
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