soo.. Poly-Urethane motor mounts?

[The Running Man]

So, my engine is shaking a lil, and my gear changes dont feel so hot. Nissan tend to charge the earth and an arm for these as the 2 horizontals are "liquid" filled, and have a tendancy to drop their liquid!

so im thinking, buy 4 new 2nd hand motor mounts, Poly-Urethane them and bang them in!

has anyone here tried this, know any results? im thinking 80a shore poly urethane!

 

[saitrix]

Poly mounts will last forever, well ages, and it will keep it nice a stiff in the engine bay. Worth the money if the car is planned on being kept. Much price difference?

 

[The Running Man]

for a set of 4 mounts;

Nissan = £400~ probably plus VAT
Scrappy £55 a set, £30 for the poly, and then sell off my old set back to scrappy or similar...

 

[SB118]

Poly them? You mean cut your own pieces?

 

[The Running Man]

no its a liquid, you cut out a bit of rubber from the old ones and fill them up with poly urethane over night and they dry into position and essentially then you have a filled mount with some movement as opposed to buying prothane solid mounts?

 

[Berger]

no its a liquid, you cut out a bit of rubber from the old ones and fill them up with poly urethane over night and they dry into position and essentially then you have a filled mount with some movement as opposed to buying prothane solid mounts?

I cant see that working myself, how are the two bits of rubber going to bond together, once theres a split it will just worsen.

Best bet is just to grab some decent mounts from a scrappy, i picked up two mounts and some other bits for £20.

 

[Lopéz]

As Berger said, I don't see how this will work. You can't just cut "a bit" of rubber out and fill the gap with polyeurethane, how will it bond to the rubber?

 

[Ev0]

Be careful with poly engine mounts, they can cause problems.

Firsty you'll most likely have increased vibrations through the car at idle. The virbrations that the flex in the original mounts would usually deal with will be transferred elsewhere.

Secondly, if not all the mounts are being done then the ones that aren't will wear quicker due to do the fact any movement that used to be spread over all of them will probably be transferred to these. As the poly ones will not really flex the movemnt has to go somewhere. If you are doing all the mounts then be careful as it can do nasty thigns to where the mounts bolt into.

I put a strengthened lower mount on my Clio, it lasted 2 days before I took it off. Vibrated more at idle and when giving it some where the engine used to be able to move a bit it now couldn't and the movement was transferred to the exhaust manifold causing it to hit the subframe and rattle.

Others who have had them on for longer have also had a shock when the thread the mount bolts onto breaks, as the mount itself can't flex the force was transferred to the thread itself. I'm now going to chuck a genuione new mount on when I can be bothered as the one thing the new mount did do was firm up the gear change a lot.

Saying that, this is just my experiances, other cars may react differently, but in principle it can stil cause problems

 

[BigglesPiP]

Do keep an eye on the oil pressure, more solid mounts can cause foaming.

 

[Jonnycoupe]

If its a donut design with a metal bush inside reacting engine movements then a poly liquid insert can be quite effective.

I used Silicone sealer on my old Rover, it was better than air obviously but not quite as stiff as poly so I have now real NVH issues. I can see that working to fix older mounts as it bonded very well to the rubber.

My Teg has poly inserts to support the existing rubber bushes, only on the front and rear ones to control torque, they are great for gearchanges and sharpen up car turn in as you dont have the engine shifting about. However there is more noise at idle and the bumper resonates and deceleration i find it has a lot more cabin noise. I dont mind too much as i dont use it everyday and its nice how it takes out a lot of clutch take up slack.

I did have the radiator endtank seeping alittle and Im pretty sure the extra chassis vibration caused that.

 

[Matt82]

youre engine is probably shaking due to something being wrong with it

 

[merlin]

I used poly inserts on the Integra. My god it felt good, changed the cars body language enormously.

However, NVH was a real issue at idle, so I had idle speed set at 1,000 to smooth it out, NVH on the motorway did my head in so I had to remove the baulkhead one, drill it a little and plonk it back in which did make it bearable.

 

[Jonnycoupe]

When I do my clutch I think Im going 'tune' my mounts. A couple of drilled holes should help give them more compliance.

 

[The Running Man]

youre engine is probably shaking due to something being wrong with it

what?! why? do you have prior with my car? how can you draw that conclusion without even seeing it?

the mounts are doughnuts with a bullet tube through the middle. the rubber goes around these, and the plan was to fill with liquid poly and then let harden etc.

hmm i will look into the drilling as 1 or 2 holes could help control NVH which is soemthing i am aware will increase when i put them on

 

[Dogbreath]

Do you know of a good source for the polyurethane casting compound? It seems to be quite expensive stuff.

 

[The Running Man]

dunno google not as hot as it once was it seems for this kind of product1

 

[Simon]

I had Roversport mounts on my Rover.

Engine didnt move, it was a lot better under power as engine wouldnt move and even going into a corner you could tell the difference as the engine was less of an undamped mass and more 'part of the car'

However they caused vibration at idle and increase cabin noise due to the vibrations going into the chassis. Theses were simply solid rubber ones too not even poly.

 

[The Running Man]

yea they can help to stiffen up the rigidity of yuor front end, with the engine effectively a solid lump holding the car together. increase gear change acceleration time and does reduce its torquing under *** etc.

 

[Matt82]

what?! why? do you have prior with my car? how can you draw that conclusion without even seeing it?

the mounts are doughnuts with a bullet tube through the middle. the rubber goes around these, and the plan was to fill with liquid poly and then let harden etc.

hmm i will look into the drilling as 1 or 2 holes could help control NVH which is soemthing i am aware will increase when i put them on

a normal engine thats running properly doesnt wobble when its idling. you should take a closer look

 

[The Running Man]

where did i say its wobbling at idle? the engine runs smooth and revs up just fine. However, there is engine movement when yuo handbrake+ open throttle, and over bumps and knotice gear change nastiness when midway through a corner!