Powerflex Dogbone Bush - fitting

[cloverleaf]

A few thoughts on what I did at the weekend – namely changing the engine dogbone bushes.

With the original mounts having done 110k (05 plate vRS) I thought it was about time to replace the rubber parts of the dogbone engine support. They’d actually failed about a year ago but between not actually having the time to do it myself, knowing it wasn’t a massively crucial part (other than hideous clunking and abrupt on/off throttle responses and potentially increased engine mount wear) and also thinking of selling the car I just didn’t get around to it. But now that I plan to keep it for another year or two before scrapping it I thought it was time to do something. Following this guide (Link), I found it a real piece of p*ss to sort and took about half an hour tops, including finding the socket set!

Basically, two 13mm bolts and two 16mm bolts take care of it all and really aren’t that difficult to remove – put it this way, if you’re capable of removing a sump plug then you’re capable of removing these.

Upon pulling the mount apart I noticed a lot of congealed rubber on the metal parts which I cleaned off with some petrol (the cheapest degreaser out there) before lubing up the two yellow Powerflex bushes with a little Fairy liquid as it’s less messy than grease and fulfils the same job. I also put some threadlock on the bolt that holds the assembly in place as you can’t torque this up massively or you will end up with a solid mount that is too harsh thanks to overly preloaded bushes. Some people have struggled to settle all this in place enough to do the bolt up but if you put the nut in properly and then push down on the socket as you do it up and it should go in perfectly.

So, things learned:

They’re not harsh as such but there’s definitely more engine drone coming through as well as a buzz/light vibration on idle. Thanks to the rough and ready nature of the 1.8T this isn’t surprising. It also made me glad that I didn’t bother to replace the vertical support bush which was actually in ok condition. Throttle response is now significantly quicker and without the harsh edge that was accompanying it – a result of the engine being able to spool up and rotate on the mounts before being constrained in its movement by the dogbone. Worth the increase in harshness? I’ll decide in a months time once I’ve done some longer journeys and they’ve had time to bed in. On a back road blast; yes. On a longer drive? Less sure…

Changes? I’d be tempted to cut 5mm or so off one of the blocks so that it could be assembled with zero preload and then fill in the resultant gaps with polyurethane adhesive. I'd do this as the Powerflex parts are thicker than OEM and cutting them down like this will prevent any slack and ensure that the bushes are able to absorb the low frequency vibrations better. It was noticeable that not only were the original bushes more like a hard foam in consistency but also had significant cut outs to soften their effect still further. So not only are the replacements maybe three times harder in terms of the material used but there are also no pockets to allow for increased movement. This’ll mean that the final product is more like five times harder (guessing here, but you get the idea) and hence the increased vibration.

The positives are a much slicker gear change with no jerking, much cleaner response when rolling on and off the throttle and no wheel hop. Ok, there’s still wheel hop but massively reduced both in the frequency of occurrence and the severity of it when it does occur. For the effort it’s definitely worth it but I think that unless you like to drive something that vibrates like mad and call it ‘racy’ to all your mates I think the average owner will want to keep some rubber in there to mix with the polyurethane bushes., regardless of the manufacturer.

Edited 15 August, 2011 by cloverleaf

[Lew_VRS]

Hiya mate, I bought the superpro one instead of the powerflex as I had read the powerflex was a lot less compliant. mine was fairly harsh for the first 1000 miles and had completely settled after 2000 miles. if the idle fluctuates a bit (i.e with no air blowers on) then there is still a tiny 'shudder' through the cabin/gear shifter. I think the good outweighs the bad imo.. just depends how you want the car to perform i suppose. the octavia's are versatile tools with a lot of compromise which means that they can go either way. I just think its great having a gearbox that doesn't feel like a coal stirrer lol!

Edited 15 August, 2011 by Lew_VRS

[STSKODA]

powerflex now do a red one that is even more complaint than the diesel superpro!

[RobClubley]

Nice write up

[cloverleaf]

Cheers, I try to give a bit of detail where I can. I think it's already beginning to settle down, there's still vibration and a jolt when the engine fires that can be felt through the car but it's not the end of the world. I think in terms of trying to sell it down the line it would probably put people off realistically as it certainly reduces the isolation from things. Does that bother me? Not really, the car's worthless now anyway so losing a hundred quid off the value doesn't really make much difference. The only concern I have is that these'll contribute to an early demise of the vertical bush although hopefully that won't be the case as I'll have to look into manufacturing a soft PU bush myself if that happens. The next stage is to sort out the various chassis bushes although these are more likely to be uprated rubber items rather than polyurethane - the main reason for the PU bushes on the engine stabiliser was the inability to just buy the actual rubber parts from VW!

[Silver Bullet]

I fitted a Powerflex one,

when I backed it out of the garage, as you say, there was droning and vibration. Thousands of miles later

much better, gear change much less clonky and very little wheel hop. You have done a worthwhile mod and wont regret it, good write up by the way.

In the days of the good old BMC Mini you could buy a engine stabalising kit comprisinig 2 anti-torsion bars that went underneath

from g/box casing to sub frame and a mini shock absorber that bolted on the side of the block then onto the bulkhead by the master cylinder, very un-ncap !!!.

[cloverleaf]

Ok, so 3000 miles down the line and the front vertical motion bush has now died too, as expected, so time to replace. It'll be interesting to see how this impacts on the vibrations in the car as the additional vibration from fitting just the rear parts has already created some irritating resonating rattles...

[Bigphil33]

would fitting new oem ones not be the best of both worlds.

[DBP]

powerflex now do a red one that is even more complaint than the diesel superpro!

I was looking for that one but I couldn't find it on awesome. Wish I went superpro now! Think I may send it back.

[IulianE]

so...why not fitting the red powerflex for diesel on the petrol engines,the material is softer.

Are they the same shape,is a direct fit?

[cloverleaf]

Thought I'd update this a little - it took me until now to finally change the circular bush after it started to die at the tail end of last year.

It was an easy swap with the aid of an oxy torch - heat the thing up for a few minutes on a high flame, stick it in a vice and then smack it with a BFH. One strike and it popped out in one piece. A spray of WD40 and the new bush pressed in easily with the vice - although a tip, if it starts to go in squint, is to push down on the bit that's not going in with a large file/screwdriver etc and continue to wind up the vice. It'll just slide right in. A quick opening of the bracket hole with a round file and it's all ready to bolt back on. Maybe fifteen minutes all told?

Back in the car there's not really any more shudder at idle than before and I think this is in anycase down to it needing new plugs/coilpacks than the mount massively as once at 850rpm it's smooth and silent. Clutch action is once again smooth as a result of the engine no longer rocking around and vibrating every time you pull away or re-engage it after a change. Possibly a little more under engine braking from 3.5k rpm and above but nothing massive, and it's more of an audible sound a couple of octaves deeper than it used to be. I reckon in retrospect the best option is to either replace neither bush and go OEM, or do both at the same time as it seems smoother now with both fitted than it did when I just replaced one - probably because just replacing one puts too much stress on the original bush and just leaves it to flap about and get out of its depth. If you can't be arsed with the oxy torch you could always just go for the superpro two piece bush that drops into the cavities on the existing one - this would probably be a good compromise.

[IulianE]

I have a RED powerflex dogbone bush since february....and is still perfect.I expect the small round bush to get worn,but I'm prepared anytime to change it.

I won't go back OEM for anything...this setup is perfect for me.