cheekychimp
(Director of Housing and Urban Development, and carbon/kevlar balls)
11/26/15 04:27 AM
Talk to me about engine mounts.

I know there is a trade off between 'comfort' and durability, but I seem to remember that some of the mounts cause a LOT of vibration if replaced with harder compound inserts whilst others seem to be okay.

I need to do my passenger side mount (US driver's side) and I think I already have some mounts somewhere but I'd like to get some advice on which mounts if any I shouldn't replace with anything other than OEM.

This is for the daily, if that makes a difference.


jeverts
(Member +)
11/27/15 04:55 PM
Re: Talk to me about engine mounts.

The Durometer of the Urethane is going to determine how soft the insert is. Most aftermarket inserts run from 60-100 duro. The higher the number the stiffer the plastic. If your looking for something that is going to still hold and absorb some of the vibration go for the 60 duro side. Now its still going to have more vibration than the OEM mounts just for the fact that the OEM ones are hollow on the bottom. Hope this helps.

prove_it
(my racist jokes aren't actually funny)
11/27/15 05:07 PM
Re: Talk to me about engine mounts.

Fill them with window weld urethane if you want soft but firm

cheekychimp
(Director of Housing and Urban Development, and carbon/kevlar balls)
11/28/15 11:09 AM
Re: Talk to me about engine mounts.

I've never understood how this window weld works. Do you simply repair the torn rubber by putting window weld in the cracks, or do you mark the location of the center bushing, remove the entire rubber mount, pin the bushing in the correct position and then make a complete mount out of window weld?

How long does it take to cure and what is the life expectancy of it? I quite fancy having a go at this if it isn't going to fall apart within 12 months.

I have absolutely no idea on the durometer of whatever mounts I do have. Is it likely to be stamped on the insert anywhere because I am pretty sure there is no packaging with any of them them?


prove_it
(my racist jokes aren't actually funny)
11/28/15 01:12 PM
Re: Talk to me about engine mounts.

You just fill in the center of the mount, let it cure for 8 hrs, add some more urethane, let it cure 8 hrs, then fill it in smooth to the surface. let it cure a good 12hrs or so. You can't fill in the whole thing at once or the middle stuff won't cure.

Cheap poly mount that is softer than the kits, but harder than oem. Yes it will "fix" torn mounts as well.


fuel
("Just to be pedantic!")
11/29/15 05:01 PM
Re: Talk to me about engine mounts.

Quoting cheekychimp:

I've never understood how this window weld works. Do you simply repair the torn rubber by putting window weld in the cracks, or do you mark the location of the center bushing, remove the entire rubber mount, pin the bushing in the correct position and then make a complete mount out of window weld?

How long does it take to cure and what is the life expectancy of it? I quite fancy having a go at this if it isn't going to fall apart within 12 months.

I have absolutely no idea on the durometer of whatever mounts I do have. Is it likely to be stamped on the insert anywhere because I am pretty sure there is no packaging with any of them them?




I've just done the same with the rear diff mount bush on my RAV4 - it was so torn that the centre was completely free and the diff was just flopping around. I used Sikaflex 227 and just filled the gaps in one go and it was cured overnight. It's holding up fine so far - I'll have to post up the pics I took of the before and after.


GSXftw
(Member)
01/01/16 03:14 AM
Re: Talk to me about engine mounts.

Get a polyethylene cutting board, and cut inserts to fill the hollow parts. Put in as many as you want, its cheap, and non permanent if its too stiff for you.

Spyke169
(Member +)
01/01/16 04:47 PM
Re: Talk to me about engine mounts.

Haven't tried on a GVR4 so I'm not positive on the sizing, but I used two hockey pucks for the rear mount on my 1g automatic dsm, from what I could tell digging my fingernail into it the puck is softer than poly, but much more stiff than oem.

belize1334
(well bread and nobly conceived)
01/13/16 01:51 PM
Re: Talk to me about engine mounts.

I have the full prothane kit installed in mine. The keys rattle at idle but it's not intolerable compared to the other discomforts (decel growl, stiff coilovers, etc). I still have balance shafts so I'm sure the vibrations are not as bad in mine as for built motors.

Early versions of the prothane kits used an insert that worked with your factory rubber but the revised kit is a complete replacement. You have to press out the old rubber as well as the metal sleeves and then the new polyurethane slides right in. Some people argue that you should only replace a few of the mounts and leave a few of them at factory spec. Personally, I disagree. The primary load bearing mounts are the two sides. The factory mounts have built in "sag" so I wouldn't want to run one of each for these - they should either both be factory or both be poly. And since the torque on the driveshaft "can" twist the motor in the bay, I say go poly. Then there's the rear mount. Most argue that this is the one that contributes most to vibration, but it's also the main roll-stop, so I say go poly. The front mount has the easiest job, it helps with roll stop but it's attached to the cross member, which has a bit of flex through the subframe bushings, and the bushing inside the mount is oversized to allow for variations in geometry when assembling. You could get away with a factory mount here, but since this one contributes the least to vibration you aren't really saving anything. So I say, go full poly all the way around.

That being said, there are things you could do to soften those poly mounts up a bit. The big one for me is trimming. The two side mounts are way to wide as they come from prothane. The fit inside the mount cylinder just fine but you have to squeeze them to get them into the chassis mount. That defeats the purpose of the mount, which is supposed to joint the motor to the chassis through the bushing - the polyurethane should not make direct contact with the ears on the chassis mount. So, I used a really sharp knife and cut a few mm off of both sides for both mounts, incorporating a mild taper, until the polyurethane cleared the chassis brace and just barely touched both sides at the widest point, right where the bushing goes through the mount. The bushing is then squeezed between the chassis uprights when you tighten the mounting bolt, just as it should be. For the front and rear I didn't have to be as aggressive with the trimming but I still did a little if I recall correctly.

The second thing you can do is to soften the mounts up with some careful drilling. I haven't done this myself, but I probably will next time I pull the motor. I'd advocate using a 3/8" bit and putting anywhere from 4 to 10 evenly distributed holes, drilled all the way through and parallel to the axis of the center bushing. And, just because I'm super OCD about this kind of stuff, I'd use an odd number of holes just to make sure that there's no preferential direction that is stiffer than any other (there are fewer directions of symmetry with oddly distributed numbers).



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