M6 G8 GXP

[SSlowBoat]

Finally worked up the energy to install the new carbon fiber spoiler. The fun thing about all G8 spoilers, is that if you want to remove them, they will either break off naturally and turn into a projectile on the highway, or you have to break them off by hand. Same with the two front nostril/plastics in the grill and the two hood vent covers - although both can be removed without absolute breakage.

Anyway, surprisingly easy to break them off lol. No Bruce Lee action required. The carbon spoiler fit ok at best, but could have been worse. I ended up using 3M VHB tape (same as I used on my CTS-V carbon pieces), two self tappers, and I clamped it down with two bar clamps for a few days.

Also, installed a different set of mufflers and welded on some nice tips. The car came with a Solo axleback, which I think I mentioned above. The issue was that it was insanely loud with the long tubes and cat delete. Probably on par with an SLP LM1 and LTs. Luckily, the car came with stock GXP mufflers, which I quickly put on. It sounded nice and tame.

I bought a pair of tips off of ebay, 2.5" inlet to dual 4" outlet. The GXP mufflers have two individual tail pipes/tips instead of GT mufflers, even though the mufflers themselves look almost identical otherwise. Anyway, scored some G8 GT mufflers on Marketplace for $40, hacked off the stock tips, and welded on the new tips. I also threw on a coat of black paint. Originally, I didn't like how they stuck out so far, but they are growing on me. The sound is even more quiet than GXP mufflers by a hair, or maybe it's the giant tips throwing the tone out the back further haha. I can't tell from outside the car. Inside is a bit different, though.

This setup is likely temporary, as the Speed Engineering X pipe setup is made to adapt to the stock 2.25" exhaust. The mufflers are set up for the 2.25" exhaust as well. I feel like a proper 3" catback is needed so I can sleep at night and gain 5hp at 6600rpm. I'm a bit concerned about drone and it seems most catbacks, aside from Solo, have lots of it. I've been eyeing up XForce since it has a cutout valve for noise control, but may just make something custom to be different.

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noice, and yea i agree the solo axleback with catless x and lt's is loud af. even the slp powerflow exhaust with mufflers was loud and droned REALLY bad, to the point i had to hit a meineke before going to ocmd and have them make solo style j pipes to kill the drone.

loookin goood

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[harner]

Right before we went to the OCMD cruise, I knocked out a few things on the car. First, I took the G8 GT mufflers with fancy tips off and put the stock GXP mufflers on. The car made zero noise with the GT mufflers, haha. I did a LOT of suspension work, since the car was bottoming out all the way down to OCMD last Fall. PPV struts all around, stock spring, front and rear Mevotech swaybar end links, and Superpro top strut mounts. I also removed the POS Aerpro stereo and picked up a used G8 Designs hvac panel/install kit.

The Caprice PPV struts are really the only OEM, bolt-in option for the G8 since everything is discontinued. The GXP has the FE3 suspension package (vs the base and GT), and the PPV struts supposedly resemble the FE3 struts more than anything. However, they look physically the same and are made by Monroe, but they are a little stiffer. I wanted an OEM ride and ride height, so it worked out. Not to mention, they are reasonably priced. They definitely solved the bottoming out issue, and the overall ride is nice. I think next time around, I will go with an aftermarket option like Pedders. The sway bar end links were a must, as well.

The stereo was replaced and wow, it just works! G8 Designs is awesome to work with. They had over 100 pages of documentation for the install, full of pictures and diagrams. The owner, Steve, is very cool and helpful - and very responsive. He went into a ridiculous amount of detail in the docs to utilize unused connectors under the dash for accessories (like the steering wheel control box, microbypass/ebrake bypass switch, etc. Everything just worked on the first try.

The car made it to OCMD without issue. Once I was down there, I felt some clunking in the front end, on both driver and passenger side. Nothing felt loose/dangerous, just odd. While down there and contemplating if I should drive the car into the ocean, I went on Rockauto and ordered Mevotech front lower control arms (2 on each front corner). After we got back home, I installed the LCAs. During the process, I found the driver side swaybar end link was loose and the passenger side on a bad ball joint on the rear facing LCA. Everything is replaced and has greaseable fittings.

The car is going for an alignment tomorrow. What is in store for it this year? Who knows lol. I do have some LEDs to install and may do aftermarket headlights and tail lights. Not sure if I want to do heads/cam and keep it N/A (shooting for 500whp) or a mild cam and blower (keep it around 650whp).

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[harner]

Welp, find another PO gremlin with this thing. Anyone with a G8 will tell you the cars are notorious for a few things - premature strut/strut mount blowouts, tire sensors, A/C belt tensioning issues, harmonic balancers taking flight mid-drive to name a few lol. No difference on the G8 LS3 cars. The previous owner told me that the harmonic balancer came off the car and was replaced with an ATI damper. ~1 month ago, I lost A/C. I don't drive the car much, but found the belt to be laying there off the pulleys. I tried to reinstall, but it was chewed up. I did notice the pulleys didn't line up, which caused the belt to jump in the first place. Then noticed the serpentine belt in a weird spot on the damper. Doh!

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So drank a few beers with a buddy and we yanked out the crank bolt, which seemed to come out with minimal effort. No thread sealant on the threads, just RTV everywhere. We scraped out the RTV, reseated the damper, threw some fresh RTV on the ARP bolt washer, applied loctite and torqued that thing down to a hulking 240ft lbs lol. It's been rocking ever since. My suspicion is that the PO had his local lube shop slap the damper on and they didn't torque it properly.

Also, I got scammed on a set of used aftermarket headlights on one of the G8 forums. I won the Paypal case, but when I went to buy new, they are all sold out.

The car was briefly used for daily status when I sold my Escalade and was truck shopping. I bought a truck last week, so it's been parked ever since. It made a GREAT daily and blew cold air even on some of the hottest days of the year. Such a good car and the M6 is a blast. I'd have next to no interest in the car if it were an auto.

[SSlowBoat]

Welp, find another PO gremlin with this thing. Anyone with a G8 will tell you the cars are notorious for a few things - premature strut/strut mount blowouts, tire sensors, A/C belt tensioning issues, harmonic balancers taking flight mid-drive to name a few lol. No difference on the G8 LS3 cars. The previous owner told me that the harmonic balancer came off the car and was replaced with an ATI damper. ~1 month ago, I lost A/C. I don't drive the car much, but found the belt to be laying there off the pulleys. I tried to reinstall, but it was chewed up. I did notice the pulleys didn't line up, which caused the belt to jump in the first place. Then noticed the serpentine belt in a weird spot on the damper. Doh!

20240627_195402.jpg

20240627_195346.jpg

So drank a few beers with a buddy and we yanked out the crank bolt, which seemed to come out with minimal effort. No thread sealant on the threads, just RTV everywhere. We scraped out the RTV, reseated the damper, threw some fresh RTV on the ARP bolt washer, applied loctite and torqued that thing down to a hulking 240ft lbs lol. It's been rocking ever since. My suspicion is that the PO had his local lube shop slap the damper on and they didn't torque it properly.

Also, I got scammed on a set of used aftermarket headlights on one of the G8 forums. I won the Paypal case, but when I went to buy new, they are all sold out.

The car was briefly used for daily status when I sold my Escalade and was truck shopping. I bought a truck last week, so it's been parked ever since. It made a GREAT daily and blew cold air even on some of the hottest days of the year. Such a good car and the M6 is a blast. I'd have next to no interest in the car if it were an auto.

the ls3 balancer lyfe I had to do that too, that torque spec was fun to achieve on an auto.

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[Z28pr0jekt]

ATI's underdriven dampener for LS7s doesn't have enough of a "lip" and allows belts to get thrown. Tony Mamo had ATI make a run of custom sized dampeners for us because ATI refused to fix the issue. I'm wondering if that's the same issue happening here, for the LS7s, it's only the underdriven dampener that does this, that standard size has normal sized edges.

[SSlowBoat]

ATI's underdriven dampener for LS7s doesn't have enough of a "lip" and allows belts to get thrown. Tony Mamo had ATI make a run of custom sized dampeners for us because ATI refused to fix the issue. I'm wondering if that's the same issue happening here, for the LS7s, it's only the underdriven dampener that does this, that standard size has normal sized edges.

it most likely loosened on the ls3 it's common people do not loctite or get enough torque on it. my 2015 1LE camaro had a ati installed that came loose shortly after purchasing and did the same thing his is doing.

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[JOATMON]

Harner, Good save on the harmonic balancer. That could have been catastrophic if it tore up the crank snout or otherwise.
I still see quite of few of the G8's and some Chevy SS's around. The compact sedan V8 cars always catch me by surprise because of the exhaust note.
They look like they should have 4 cyl. engines, then you hear them and realize they are sleepers.
Nolan

[harner]

Q4 2024 Update

The car is about to get an oil change and get tucked away for the winter. It's been a fun few months as the car has been ranging between daily driver-duty on nice days and just being parked for weeks at a time. The OCMD cruise was an event that took place earlier this month, so I checked fluids, catch can, and belts. The main serpentine belt was perfect so the balancer hasn't moved! However, the A/C belt was ready to take flight lol. The OCMD event was awesome and I put like 500+ miles on the car without a single problem. Lots of spirited driving and it didn't skip a beat.

Another G8 gremlin is that the AC belts are known to come off due to the crappy balancer design. Some guys just muscle a super tight belt on, others pony up for the Aussie kit that includes a new condenser bracket, tensioner redesign setup, and belt. I'm not sure what I want to do, yet.

Normally I'd be planning a cam swap or some major work to be done, but the car is happy where it's at. It's been super reliable and I can't complain. Outside of switching to aftermarket headlights and tails, and maybe a better exhaust setup (currently a cobbled together 3" catless X, to stock 2.25" piping, to stock GXP mufflers) - I'm not sure how far I want to go with it. Seems opening up the engine will devalue the car substantially. Oh the perks of having a low mile rare car. No plans to get rid of it just yet, though.

[SSlowBoat]

Q4 2024 Update

The car is about to get an oil change and get tucked away for the winter. It's been a fun few months as the car has been ranging between daily driver-duty on nice days and just being parked for weeks at a time. The OCMD cruise was an event that took place earlier this month, so I checked fluids, catch can, and belts. The main serpentine belt was perfect so the balancer hasn't moved! However, the A/C belt was ready to take flight lol. The OCMD event was awesome and I put like 500+ miles on the car without a single problem. Lots of spirited driving and it didn't skip a beat.

Another G8 gremlin is that the AC belts are known to come off due to the crappy balancer design. Some guys just muscle a super tight belt on, others pony up for the Aussie kit that includes a new condenser bracket, tensioner redesign setup, and belt. I'm not sure what I want to do, yet.

Normally I'd be planning a cam swap or some major work to be done, but the car is happy where it's at. It's been super reliable and I can't complain. Outside of switching to aftermarket headlights and tails, and maybe a better exhaust setup (currently a cobbled together 3" catless X, to stock 2.25" piping, to stock GXP mufflers) - I'm not sure how far I want to go with it. Seems opening up the engine will devalue the car substantially. Oh the perks of having a low mile rare car. No plans to get rid of it just yet, though.

nice!

For the ac belt, I did the ati balancer and it stopped throwing the stretch to fit LS3 ac belts

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[harner]

While this car already has an ATI balancer, I will admit that the new Gates belt was not stretched enough to go on, so I threw the old one on in a hurry. The tensioner is also a pile of crap, so I see why it fails. I had to fix the belt and it has stayed on for the 500ish miles during the cruise. Not that I needed AC much that weekend, anyway.