Knocking from rear

[plasticsniffer]

My car is allergic to Sheffield roads!!!! I'm trying to track down the source of the knocking at the rear of my 1.7. I've had the ROS wheel off and been under it to investigate, but not sure what I'm looking for if it's the rear beam bushes. There's no tell tale pale rust around the mounts, and no obvious play. The knocking only starts as I cross into Sheffield from Derbyshire, and is only realy there on right hand corners. I've checked the exhaust and added a couple of cable ties, to move it away from the bumper, as it is not perfectly central in the cut out, but this failed. I've also put a piece of rubber tube around the bar that the spare wheel clamp fits and checked all is tight, but non of this seems to have made a differance. It feels like something is banging metal to metal to the shell, but I can't find any tell tale rust anywhere. Has anyone got any suggestions, please, as its off putting when pressing on!!!
Also, I've got an intermittant ABS fault. Sometimes the warning lights stay on when the car is started, and the TC and ABS don't work. Other times the lights go off but then the ABS unit opperates in fits and starts, even if the pedal is not touched. The lights then come on and the ABS goes quiet. I did change the front callipers back in Feb and wonder if the rear curcuit needs bleeding, but I've read that a special Ford tool needs to be pluged into the ABS unit to do this if air has got in. Has anyone got a work around for this yet? Is this likely to be the ABS unit or a sensor? I've checked the resistance of the rear ones at the plug above the rear beam, and both are showing a low resistance, ie not open or short circuit. When they fail which way do they go? Any suggestions will be welcome! Thanks in advance.

 

[yippeekiay]

Not sure about your knocking as it could be one of many things which is only diagnosed by trial and error or actually being in your car...sorry.

As for the ABS, you need approx 1.1 ohms resistance, much lower than that or zero means it's shot. If they're showing up ok then give them a clean and also try and clean the front tone rings as these accumulate rust/grit quite easily, also check they aren't bent as if you've changed the calipers recently you may have accidently knocked them as they're very thin.

The rears are in the drums so a bit more chew to get to than the fronts and are just a little cap with indentations all round that sits on the drum internal centre which can sometimes wear - think there's a few pictures on here somewhere. Make sure your connectors are clean and well seated.

I'd bleed your system anyway as I wouldn't have thought having air in the system would effect your abs too much - well, if it was that bad your actual braking would be affected more and I'd rather have decent braking in the first place then worry about the ABS. If there is air in the ABS unit then yes I think your right in thinking it needs to be sorted by Ford but I'd bleed the system first and see where you stand from there. k:

 

[YOG]

Disconnect the battery before starting work on changing brake components, keep the reservoir topped up, don't re-connect the battery until after you finish bleeding and you shouldn't have any problems with the ABS unit.

When we changed "The Arch Bishop"'s front flexible lines to HEL, some air remained (or was already there) in the system until we changed the rears the following week and bled the complete system in the recommended order.
Easier to bleed the system using something like a Gunson Eezibleed, as it keeps the brake reservoir topped up (still need to check the Gunson reservoir). The only small downside was that you need to remove a small amount of fluid from the brake/clutch reservoir after you finish, to bring the level down to Max:
http://www.ebay.co.uk/itm/NEW-GUNSONS-EEZIBLEED-BRAKE-AND-CLUTCH-BLEEDER-KIT-/200632185041?pt=UK_Hand_Tools_Equipment&hash=item2eb69c30d1" onclick="window.open(this.href);return false;

 

[deejames]

i had a really anoying knocking coming from the back that sounded like metal to metal contact. To start with it was only on some roads but then got worse. I got in the boot (with the seats down!) and got my wife to drive - in the end i traced it down to the plate that is rivited on where the spare wheel bolt is inside the boot. It turned out that one of the rivets had sheard off and was allowing the plate to vibrate on the boot floor. I hope that helps!

 

[jimmer69]

I have exactly the same issue only I only hear it on left handers!

Rear beam bushes reaplaced and rear top mounts replaced but to no avail!

Sounds like a knock I had from before I changed my shocks, could it be a nackered shock allowing the wheel to bounch up and down?

If so I'll have to get onto Spax as they're still under warranty.

Any other thoughts?

 

[plasticsniffer]

Think I've found the cause of the knocking at the rear. :grin: In the process of dropping out the rear O/S shock, to check it, I needed to drop the jack from under the beam end, and let the car down onto an axle stand. Lo and behold, the beam dropped in the mount onto the shell, so it seems to be the dreaded beam bushes, after all! Don't fancy the pallava of fitting new OEM ones so have just ordered a set of Flo Flex bushes. I'll report back if this is the cure. Not got round to bleading the brakes, yet, though. Hopefully later this week. So watch this space for an update on the ABS issue. :arrow:

 

[plasticsniffer]

Just an update on the knocking. It was the rear beam bushes. I've replaced them with the Flow Flex ones, and in the process found the tell-tale mark on the OS mounting bracket, where the beam had been touching the bracket, causing the banging. Now the new bushes are fitted, the banging has gone, even on Sheffield roads!!! :grin: The job was easy enough, using a jig saw, and a hack saw to carefullycut through the old bush and knock it out with a drift. The new bushes went in a doddle, as they have no steel outer. I'm struggling to tell the differance in the ride quality, so sofar, it's a result.
As for the ABS, I've just blead the system in the Fiesta manual order, but checked the resistance of the front sensors on the way round. It seems the OSF is open circuit, and the NSF is about 1 ohm, implying a failed sensor on the NSF. When I get this replaced, I'll update again.

 

[yippeekiay]

No, OSF is the failed one. If they show a resistance of 1 ohm that's a good sign k:

 

[plasticsniffer]

Yes, I meant the OSF. Both rear ones were showing about 0.9 ohms, when I checked them the other week.
Looking on ebay, there seems to be a large variance in price for a new sensor. Anyone have any recomendations to a brand of aftermarket ones that can be trusted? I assume OEM ones are a fortune, and the budget is non-existant! I'm a bit nervous about paying £16 for one, when others are £60 or more.I kind of got caught out with a heater valve, just after I got the car, in Feb. I bought the cheapest I could find (new) but it only seems to do hot or cold, with little control in between, but at least it's water tight! I don't want an ABS sensor that only gives me other problems, I've enough of those as it is. :?

 

[plasticsniffer]

New ABS sensor now fitted to OSF at a grand cost of £15 from Ebay. Removing the old one was problematic, in that the bolt had rounded (as expected?). Sollution: Gently and carefully smash the old sensor out then use mole grips to loosen the old bolt, with a little bit of heat and some WD40. Some emery cloth to clean out the hole and a new cap head and the new sensor was in. The warning lights went out after driving a few yards up the road, then the fuel light came on. More expense! :lol: . Sorted! MOT now booked for next Wednesday, at last. I asked a mate in electronics what the difference might be between a £15 sensor off Ebay and one at £150. His answer? About £135. Now time to focus on the other electric gremlins, like the tailgate release. I've checked the micro switch and all seems OK, but there's no power to it or the release motor. All the fuses seemed OK when I looked the other day so now wondering if it is linked to the central locking failure. I need to find somewhere remote to put the fuse back into the alarm to try re-setting it after the lock problem. I'm hoping locking and unlocking it on the key will do the trick, but I'm open to suggestions.

 

[yippeekiay]

Yeah, nice cheap fix. Was wondering how well them cheap sensors would work so keep us informed as I think your the guinea pig for them as I don't think they've been on the market that long. Only paid £42 for my genuine one anyway so not as bad as £150 wherever that quote was from.

:thumbs:

 

[grantc]

Hi , just paid £30 for 2 front sensors also. Came yesterday. Got the 2 dashboard lights, TC and ABS. If it stays dry I'll fit them today! I'll keep you all posted with results.

 

[Scotty1.7]

were did ya get the rear bushes froma nd for how much?

 

[grantc]

Hi , just paid £30 for 2 front sensors also. Came yesterday. Got the 2 dashboard lights, TC and ABS. If it stays dry I'll fit them today! I'll keep you all posted with results.

OK this is on the wrong thread as it is about "knocking from the rear". I will raise a new thread for anyone interested under "cheap ABS Sensors. Hope this helps!

 

[plasticsniffer]

Hi, Scotty, as mentioned, the bushes are Flo Flex ones. I found them on Ebay at just under £40, including postage. They only seem to come in bright orange, though!

 

[Scotty1.7]

You don't happen to have a link do you?

 

[plasticsniffer]

Search:
puma rear beam bush*
and loads of alternatives come up. Pay your money and take your choice! I went for the cheapest and easiest to fit, which were the Flo flex ones, here:
http://www.ebay.co.uk/itm/Ford-Puma-Rear-Beam-Mount-Bushes-Polyurethane-/390346920468?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item5ae27d5214" onclick="window.open(this.href);return false;