Hi guys, over the last few rides I’ve noticed a knocking sensation and traced it back to the lower bushing on my rear shock. I’ve undone the hardware and the reducers (I think these are also called top-hats) easily come off the DU bushing. So, do I just replace the DU bushing or do I need to replace the reducers as well?

Any advice on where to purchase the bits would be much appreciated.

Many thanks

So, do I just replace the DU bushing

yes, usually

Generally just the DU bushes. Easy enough if you have a tool to do it, impossible without.
Check out eBay as a couple of engineering bods have made some for sale. I’ve not used them but the principle is easy enough provided the fit is correct. Note diff shock makes use diff size bushes and thus need different tool. You can pick up bushes on eBay too.
Worth checking your top hat spacers, if you’ve left it too long (like I did) they could be shot.
Ps I mailed a guy on eBay csgeo or something similar. Works for British aerospace so I’d expect the tool to be good, circa £8 ish.

As you’re still running top hats, I would also recommend a Heavy Duty Reducer kit that TF Tuned and a few other places sells. They last a lot longer than top hats, and once the hats start to wear down at all you’ll start going through bushes pretty quickly

BETD Strong bush is worth looking at with their Hula Hoop bushes

http://www.tftunedshox.com/info/mount_kits_bushings.aspx

Just the tool for sale in the classifieds over there…. 😉

Fox [1/2″ DU] bushes are a generic size and should be available from most bearing suppliers for around £1 each
The part number is 08DU08

Not sure what the number for 12mm ones is

or try eBay before parting with silly money from bicycle parts vendors
http://www.ebay.co.uk/sch/i.html?_trksid=p4069.m570.l1313&_nkw=fox+du+bushes&_sacat=0

Fox is getting rid of the DU bushing and going to a polymer one for 2013.

The latest Mountain Bike Action (US) magazine had an article on how to replace your old ones with the new polymer ones. There is a video on their site here.

There is also a thread on MTBR here.