Motor mounts
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Bill's GXP
- SE Member
- Posts: 24
- Joined: Thu Dec 13, 2012 9:56 pm
- Year and Trim: 2004 Bonneville GXP
- Location: My other car is a firetruck
Motor mounts
Hi everybody, new guy here. I have an '04 Bonne GXP. Original owner w/ 50k miles. I think my motor mount is going as I've heard on other "sites" that these are a problem. What syptoms should I look for. I did just put new tires on, but I'm getting a vibration starting at around 60 mph that's in the seat not wheel. I also noticed that if I manually downshift trans to 3rd, I'm getting a clunk that wasn't there before. The car is not really beat on, but I do some spirited driving at times. Any pointers will be appreciated.
2004 Bonneville GXP
One of 2,143 built and one of 300 in Liquid Silver.
One of 2,143 built and one of 300 in Liquid Silver.
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repinS
- Moderator
- Posts: 7391
- Joined: Mon May 19, 2008 9:51 pm
- Year and Trim: 09 G8 GT
- Location: Toronto, Canada
- Contact:
Re: Motor mounts
If you feel a clunk:
- getting on and off the throttle at speed (let's say 30-50mph), and the clunk is worse the more aggressively you do it
- clunk when you get back on the throttle at a rolling stop in 1st gear
- significant powertrain movement when you hold the brakes and goose the throttle when in gear
At 50k miles, if your front transmission mount is original, it likely is already broken, if not weak. Leaving it like this will blow out your other mounts too. Avoid cheap aftermarket mounts (specifically Anchor), they are too soft to begin with and also don't last very long. I have a polyurethane casting compound filled mount, it seems to be holding up but I'm pretty sure I'm experiencing weaker side and rear mounts since installing it.
- getting on and off the throttle at speed (let's say 30-50mph), and the clunk is worse the more aggressively you do it
- clunk when you get back on the throttle at a rolling stop in 1st gear
- significant powertrain movement when you hold the brakes and goose the throttle when in gear
At 50k miles, if your front transmission mount is original, it likely is already broken, if not weak. Leaving it like this will blow out your other mounts too. Avoid cheap aftermarket mounts (specifically Anchor), they are too soft to begin with and also don't last very long. I have a polyurethane casting compound filled mount, it seems to be holding up but I'm pretty sure I'm experiencing weaker side and rear mounts since installing it.
Jerry /// Past: 95 SSEi (June 2010 COTM) -- 04 GXP (July 2011 COTM)
91 Honda Civic Wagon DX 2WD (fuelly) -- 208,000km -- 92hp -- Autocross Warrior
09 Lexus LS460 AWD -- 94,000km -- Daily Driver
09 White Hot G8 GT -- 155,000km (fuelly) -- LS3 Cam -- GM LS3 CNC Ported Heads -- Kooks 1 3/4" Long Tube Headers -- Solo Catback Midsection -- Hooker Maxflow Mufflers -- Pat G Tune -- Rotofab Intake -- Tein S-Tech Springs -- GXP FE3 Dampers -- BMR Subframe Cradle Inserts -- BMR Subframe Connectors -- Forgestar F14 Gold 18x9 +40 -- Michelin Pilot Super Sport 245/45/18 -- Maverick Man Carbon Fiber Spoiler
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Bill's GXP
- SE Member
- Posts: 24
- Joined: Thu Dec 13, 2012 9:56 pm
- Year and Trim: 2004 Bonneville GXP
- Location: My other car is a firetruck
Re: Motor mounts
Thanks for the reply. I've been looking online for polyeurathane mounts, but can't find any. It's even hard to find stock mounts. Even looking up as a Cadoo with no success. Where did you get yours? My daughters friends father is an extrememly competant front end tech, ( does all my alignments ). He said as soon as he can he will check it out. I feel the clunk if I manually d/s like exiting a hwy. Doesn't do it all the time. Like I said, I don't beat this car, I live 1 exit away from my work. BTW, how do I get the GXP moniker under my name instaed of LE? Thanks, Bill
2004 Bonneville GXP
One of 2,143 built and one of 300 in Liquid Silver.
One of 2,143 built and one of 300 in Liquid Silver.
Re: Motor mounts
Where did you get that poly mount repinS?
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repinS
- Moderator
- Posts: 7391
- Joined: Mon May 19, 2008 9:51 pm
- Year and Trim: 09 G8 GT
- Location: Toronto, Canada
- Contact:
Re: Motor mounts
Jerry /// Past: 95 SSEi (June 2010 COTM) -- 04 GXP (July 2011 COTM)
91 Honda Civic Wagon DX 2WD (fuelly) -- 208,000km -- 92hp -- Autocross Warrior
09 Lexus LS460 AWD -- 94,000km -- Daily Driver
09 White Hot G8 GT -- 155,000km (fuelly) -- LS3 Cam -- GM LS3 CNC Ported Heads -- Kooks 1 3/4" Long Tube Headers -- Solo Catback Midsection -- Hooker Maxflow Mufflers -- Pat G Tune -- Rotofab Intake -- Tein S-Tech Springs -- GXP FE3 Dampers -- BMR Subframe Cradle Inserts -- BMR Subframe Connectors -- Forgestar F14 Gold 18x9 +40 -- Michelin Pilot Super Sport 245/45/18 -- Maverick Man Carbon Fiber Spoiler
Re: Motor mounts
very cool, thanks!