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Hard shift - weird acceleration vibration

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Old 02-07-2009, 10:13 AM
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Default Hard shift - weird acceleration vibration

Ok, I'm brand new to Bonnevilles. I just bought a 2001 SE and have been driving it daily. I know I need to fix the clunk in the steering wheel but everything else seemed fine until about 2 days ago. Maybe its just me becoming more sensitive to the car, but I've noticed a weird problem. If I'm accelerating on a straight road the car drives perfectly smoothly. Likewise, as long as I am not accelerating, there is no problem (coasting at any speed on roads straight or bumpy is just fine). However, if I am on a hilly/bumpy road and accelerating, I feel what can only be described as a gear grinding. Its not too loud, but I feel it in the pedal and severity increased with how much the car is bouncing. The best way to describe it is the feeling that you get driving a truck where one is trying to accelerate in a gear that is too low. Its like the gears are working too hard and almost vibrating/grinding. Is this just the car or do I have a problem? Also, what could it be?

My other problem is that my bonneville seems to shift had into and out of park. Every other gear is smooth as silk but park/reverse are a little rough. Not terrible, but I'd like to fix it now if its going to cause problems.

And one last thing- can you save your LIM gaskets if you change to the "good green" antifreeze from DEXCOOL. I'm not leaking yet, but worried...


Thanks in advance.
Old 02-07-2009, 10:32 AM
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Check your trans mounts. The front drivers side is good for causing problems like you discribed.

DEX isn't bad coolant, but you do need to mantain it lik eanything else. If your going to flush then go green, it'* cheaper.
Old 02-07-2009, 01:04 PM
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ok, I'll be checking that out, thanks.

But... is there any way to avoid the LIM gasket replacement? Can I somehow preserve them? At 126*** miles I know its coming but I'd like to put it off...
Old 02-07-2009, 01:56 PM
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If it goes, it goes. Some do some don't.
Old 02-07-2009, 07:01 PM
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Checked the motor mounts for play by revving the engine in gear with brake on and sure enough- bad mount. But now I am wondering... should I just replace the front or all? How can I know which are bad. And is the front mount near the radiator the only fluid-filled one?

Also- all the links to the "hockey puck fix" are bad. Is there a DIY post about this anymore?
Old 02-07-2009, 07:07 PM
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Ya, the front is the only one like that.

Sorry, I have not done a write up on motor mounts and really didn't have any plans to do one. I might be able to do something next week but it wont have much detail.
Old 02-07-2009, 09:50 PM
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pm billboost37 about the hockey puck fix

he'* done this to his car
Old 02-21-2009, 04:33 PM
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so I did the motor mount replacement and went ahead with the hockey puck fix... helped a lot with throttle response and gear shift in/out of park, but I still have the problem described above. So what other things might cause that weird feeling on bumps? FYI- it only happens at 50-60+ mph... is this normal? It does seem to be a little better than before but I could be wrong.

Also- the puck mount gives weird vibration on acceleration.... I know this is a known problem but is there any solution?
Old 02-23-2009, 12:08 AM
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What you're describing - does it appear to be something in the engine, or something in the suspension? If in the engine, have the plugs and wires been done recently? Also, try cleaning up battery connections, both under the seat (paying close attention to cleaning the negative battery cable and bolt where it bolts to the floor pan) and under the hood.

If it appears to be suspension related, check your shocks and struts for any leaking oil.
Old 02-23-2009, 01:34 AM
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im inclined to say that neither one is the problem. It cant be the engine because it only happens at 45-70 mph going over hills (ie when the car lifts or lowers suddenly). If it was electrical it would be much more of a constant problem. Plus its feels to be in the drivetrain.


Also, it cant be suspension or else I would feel it under no acceleration. So I'm inclined to this its in the tranny... the mount would have made perfect sense but seems that cant be it. One thing to note- after the mount was changed it only happens when the car bounces up and not when it is compressed to the ground. Could this mean I have the new puck mount too low to the frame? Maybe the fix is just a few washers away...


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