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#1
08-23-2009, 10:11 PM
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motor mount replacement
79 formula w/ 301
for a while i thought and still think that i have bad U-Joints in the rear end, when taking a turn very slowy and backing up slowly i feel a clunk that seems to be every one rotation. today i was explaining this to my dad so he took it for a drive to see what he felt, he did agree but then also said there was a knocking/banging coming from the front, so we popped the hood and power braked in reverse and drive to check the motor mounts...low and behold he was correct! when i shift into drive and rev it you can see the motor lift a good 2 or 3 inches on the drivers side, then right into reverse and rev her and she shifts back down and makes a wicked noise. anyhow now that i know they are bad i just want to know the easiest way to replace them....i have plenty of wood, 2 2-ton floor jacks, and an engine hoist. should i just jack up the motor with some wood and the floor jacks under the oil pan ? or should there be some bolt holes i can put some bolts into and lift the motor up with the hoist ? all the components are installed and didn't know can i put bolts through holes in the heads ? or find ones lower on the block ? thanks |
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#2
08-24-2009, 03:45 AM
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You can change out the mount pads with engine still in chassis.
It's a bit tricky but not that bad. I bent a 9/16th combination wrench at a 90 degree angle & it sure helped out with the nuts inside the crossmember. |
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#3
08-24-2009, 08:24 AM
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Usually you can use a hole in the back of the cylinder head or an exhaust manifold bolt to attach a chain to. You can also jack up the engine using a piece of wood on the balancer.
__________________
1971 Pontiac GT-37 Car is a junk yard dog and maybe one day will be restored. 
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#4
08-24-2009, 05:41 PM
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well i wont have to be bending any of my wrenches i have a nice set of adjustable ratcheting wrenches. just wasn't sure what approach would be easier...am thinking i'll jack up the front nice and high, put it on jack stands, then use a piece of wood and jack up the motor enough to give me enough clearance to get the old ones out and new ones in.....sounds nice and easy but i'm not gonna take any chances...i'll invite my buddy over and make sure to have a 6 pack in the fridge.
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#5
08-26-2009, 12:02 AM
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I've done this several times - jacking from below works well, but just be careful you don't damage your oil pan...you don't need much clearance.
__________________
78 White T/A, Carmine interior, Fisher T-tops, WS-6 package, 3.08 gears, a/c, rear discs. Original 403 with 300,000 miles replaced by new Pontiac 455 (roller everything, 6x-4 heads, Performer manifold, Hooker Headers, Hughes converter, Cliff's Q-jet) - I only get 12 mpg! |
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#6
08-26-2009, 04:15 PM
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ok well i was all ready to swap the mounts today...i jacked up the car, had the tools out next to me, was about to jack up the motor a little bit but first pulled out the mounts from the box and crap!, wrong mounts! he gave me 2367 instead of 2387* so i had ford/mercury mounts. anyhow i went back to switch em he's gonna get em in tomorrow morning but on the bright side they were about half the price as the others.
so just wanted to know exactly what i should take off.....do i just remove the 3 bolts that hold the mount into frame and the 1 long nut and bolt going through the mount ? |
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#7
08-26-2009, 10:24 PM
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If you have a problem getting the bolts and mounts to line up, you may have to loosen or remove the trans mount bolts so you can move it around a bit.
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#8
08-27-2009, 07:01 AM
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just out of curiosity, i saw on ebay a seller sold the motor mounts and trans mount together. do you usually change the trans mount at the same time ? how do you know if the trans mount is bad ?
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#9
08-27-2009, 08:56 AM
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Honestly it wouldn't hurt to change it out while you are under there and have all the tools already out. When I do work on one of my cars I'll get all the parts that might need replacing at the same time while I'm in the area I'm working on. Just saves time in the long run, don't have to keep jacking the car up and replacing stuff. Good bet is it hasn't been replaced and 30 year old rubber mounts aren't doing the job they should be. Not that a 301 is going to be straining the mounts with alot of torque but as you can see with your motor mount they do go bad. I'd just replace it now while the tools are under the car already, and the beer is still in the fridge lol.
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#10
08-28-2009, 02:05 PM
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tranny mount does look about 30 yrs old so i ordered one, only cost 12 bucks. anyhow was going to change them today but rains have delayed this task until sunday. anyhow getting to the bolts on top is fine but getting to the nuts inside the cross member is quite tricky. the one at the bottom can be gotten to with either an extension and a socket or a wrench and i can get to the nut on top facing the front of the car, but getting to the nut in the rear seems a bit more daunting. any tips or tricks to go about getting to it ?
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#11
08-28-2009, 02:56 PM
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Tight fits like, almost always call for a box speed wrench. They aren't cheap but they pay for themselves. I use mine everyday.
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#12
08-28-2009, 03:52 PM
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Quote:
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#13
08-28-2009, 05:44 PM
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yea you had posted earlier, like i said i have a set of flex head ratcheting wrenches and i was able to get on 2 of them.....i'll try again sunday after the rains pass maybe just a little more wiggling and stuff and can get it on.
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#14
08-29-2009, 08:42 PM
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well am gonna finish the mounts tomorrow, i got the drivers side done today. i thought the flex head would work well but i just couldn't get it locked the right way i ended up pulling out the torch and bending a crappy 9/16 wrench the same way and it worked wonders.
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#15
08-30-2009, 08:07 AM
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just thought i'd add a little more....soaking the nuts and bolts with some pb blaster helps a lot and def. an extra set of hands. i put the wrench in from underneath then clamped vice grips on it to lock it against the cross member but it has a tendency to fall out as it loosens so one person working below holding it and one person above removing the bolt seemed to work best for me.
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#16
09-18-2009, 08:21 PM
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Probably a little late for this tip, but if you have issues getting the long bolt back through the bracket and mount, it may be that you'll need to loosen all the bolts on the mount and the ones on the engine bracket as well...just enough so everything has some give in it. When the long bolts are fitted, tighten all other bolts up. Annoying, but sometimes its the only way.
__________________
Regards, Leigh Pontiacs I’ve owned…. 1960 Laurentian 283 1963 Laurentian 283 1976 Trans Am 400 1977 Trans Am 400 1951 Chieftain Flat head 6 1967 Firebird 400 convertible 1967 Firebird 400 coupe 1979 Trans Am 403 1971 Formula 455 (clone) 1969 Firebird 350 1968 Firebird 428 manual. Sydney, Australia |
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#17
09-19-2009, 12:09 AM
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LeighP Thanks for the advice anyhow.
when i put them back in the drivers side pretty much lined up perfect and the passenger was just slightly off and wouldn't budge. since the rubber was new and so tight though i took both bolts and lubed em up with some anti-seize then used the air powered ratchet wrench and sent 'em in. sometimes when you just use the noggin a little bit it makes for less physical work. |
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