swept Posted January 9, 2014 Report Share Posted January 9, 2014 hello all, I have been having a lot of fun with my 1985 505 N9T 5 speed...engine in and out twice for various things (clutch and cylinder head), brakes and suspension bushings all done. New catalytic converter to get it through air care. The problem now is I have a rattle at 1500 rpm when the gearbox is engaged and I suspect it may be the centre bearing in the torque tube. The workshop manual doesn't detail the best way to remove the torque tube. Would the easiest way be to drop the rear cross member (bolted just under rear seat) and then undo the connection at the differential. Does the differential swing back far enough to allow for the tube removal? thanks for any advice, Ken Quote Link to comment Share on other sites More sharing options...
Bean Posted January 9, 2014 Report Share Posted January 9, 2014 Hi Ken, I'd be sceptical that it's the center bearing unless it was making the noise all the time when moving. The center shaft is rotating as long as the rear wheels are moving, so even if you put in the clutch at 100 KPH, that center shaft will be rotating at speed no matter if you are in gear or not... So if it was that center bearing it would be speed dependent and it wouldn't matter if it was in gear or not. I would also think it would rumble more than rattle if that makes sense. Can you tell us more details about the rattle? I had a rattle that would happen just at a specific rev range and only when accelerating. I suspected it was a heat shield, but had a heck of a time finding it. Turns out it was the heat shield over the turbo, a weld had come undone and it would rattle loudly but only at certain frequencies. I ended up drilling it out, and adding more rivets and that cured the rattle. More details on the specific noise, when it happens, when it stops, etc etc would be helpful to figure out what the issue is. (If it is the center bearing, diff can move far enough back to disengage the torque tube and shaft) Rabin Quote Link to comment Share on other sites More sharing options...
swept Posted January 9, 2014 Author Report Share Posted January 9, 2014 thanks for the quick reply Rabin. the rattling sound happens always at 1500 rpm, in any gear, and goes away below and above that rpm. The sound doesn't happen when the car is out of gear (clutch depressed or shifter in neutral) and the engine rpm is increased. When I hear the sound I can also feel vibration in the floor boards. It happens every time that rpm is crossed, and especially is noticeable if the rpm is increased or decreased slowly. I had the exhaust shop that did the catalytic converter check the exhaust clearances and it was all fine. I put the car on a scissor lift and ran it in gear but did not hear the rattling sound even when revved to 1500rpm. I will check the exhaust shield. otherwise I am looking for things related to the drive train. thanks for any ideas Quote Link to comment Share on other sites More sharing options...
swept Posted January 9, 2014 Author Report Share Posted January 9, 2014 rumbling might be a better word to describe the sound Quote Link to comment Share on other sites More sharing options...
Bean Posted January 9, 2014 Report Share Posted January 9, 2014 Check the clearance of the torque tube over the rear cross member, and if you can put it on a lift, you have to make sure the lift has jacks on it so that you can compress the rear swing arms so that they're not at full droop. (IE: Support the car on the rear swing arms - usually on the shock mount works well.) The rear cross member has rubber bushings in it, and when they are shot you can get a similar driveline vibration from them as the cross member can move much more. I still can't see it being the bearing with how you describe the onset of the noise, but agree that it's likely the driveline that is the source - but it's being amplified somewhat and that vibration due to contact is likely what you feel. That rumble you feel could likely rattle one of the under car shields as well which is where the rattle sound comes from. Rabin Quote Link to comment Share on other sites More sharing options...
swept Posted January 9, 2014 Author Report Share Posted January 9, 2014 I'll get it back up on the lift and check the torque tube clearance around the rear cross member and check the shields under the car. thanks very much for the advice, Ken. Quote Link to comment Share on other sites More sharing options...
tulaweb Posted January 9, 2014 Report Share Posted January 9, 2014 It seems to me that if it is RPM dependent and occurs in any gear at the same RPM, then it has to be forward of the transmission or in it. Everything aft of there would be road speed dependent not RPM dependent. Quote Link to comment Share on other sites More sharing options...
Bean Posted January 9, 2014 Report Share Posted January 9, 2014 No worries Ken - this sounds a LOT like the sound my first 505 Turbo made, and I was almost positive it was the cross member mounts that caused really tight clearance. So check for play of the cross member in the metal boxes on each side, as well as the rubber diff mounts. Diff mounts should be in good shape as well - as it could contribute to clearance issues as well. Rabin Quote Link to comment Share on other sites More sharing options...
Bean Posted January 9, 2014 Report Share Posted January 9, 2014 Engine, transmission, and diff are all rigidly mounted together, so it's possible that at 1500rpm the harmonics of the engine affect the whole drivetrain. That vibration contacting part of the body is what I thought was generating the sound in my car. Worth investigating at the very least. Rabin Quote Link to comment Share on other sites More sharing options...
swept Posted January 13, 2014 Author Report Share Posted January 13, 2014 it does look like the harmonics of the engine is the culprit....when the engine speed is increased to 1500rpm I can feel the increased vibration transmitted to the differential even when the drivetrain is not engaged. crossmember mounts and diff mounts seem to be okay. thanks for the input, Ken Quote Link to comment Share on other sites More sharing options...
Bean Posted January 13, 2014 Report Share Posted January 13, 2014 How do you mean "seem to be OK"? Did you pry between the box at each end and the cross piece to check for deflection? Another factor not present will be the affects of torque being applied to the wheels which will load up the arms from the drive of the wheels, and the diff will be affected as well as it transmits the torque - so what you may have to do is use mirrors and such and look for evidence of parts touching each other. I would still be nice to find out what those harmonics are affecting to produce that noise - I know how annoying it can be and it drives me NUTS when my cars have squeaks and rattles. Rabin Quote Link to comment Share on other sites More sharing options...
swept Posted January 15, 2014 Author Report Share Posted January 15, 2014 it is driving me crazy....unfortunately in traffic a lot of time is spent around 1500 rpm! I did use a pry bar to check the box at each end of the cross member and from what I can see in the gap of the box the rubber looks okay. no where does the exhaust seem to be touching so the engine harmonics must be transmitting down the torque tube, or through the engine mounts to the body. I think my next step will be removing the torque tube and then running the engine to see if there is any rattling. (I am also starting a new thread on cold starting issues). Quote Link to comment Share on other sites More sharing options...
Bean Posted January 15, 2014 Report Share Posted January 15, 2014 Long shot - but have you banged on the rear muffler to see if it has a broken baffle inside it? I had a 505 Turbo that had a loose baffle and it would only rattle at certain revs as well - and its another system that's affected by harmonics. Rabin Quote Link to comment Share on other sites More sharing options...
swept Posted January 15, 2014 Author Report Share Posted January 15, 2014 definitely will check that first...I'll let you know what happens Quote Link to comment Share on other sites More sharing options...
andrethx Posted January 16, 2014 Report Share Posted January 16, 2014 rabin's comment about the muffler got me thinking....above the catalytic converter, there is a heat shield that is attached to the car using several "rubber studs" (according to the parts fiche). they look like this: since the cat was recently changed, maybe one or more of these got messed with and the heat shield is the source of the noise? it's another long shot, but easy enough to check while you are down there... andré Quote Link to comment Share on other sites More sharing options...
swept Posted January 17, 2014 Author Report Share Posted January 17, 2014 thanks for the suggestions, you all were right to focus on the exhaust system...I found the problem today. One of the exhaust mounts at the catalytic converter had the rubber buffer on the back side of the upper bolt so that it wasn't actually acting as a vibration buffer between the torque tube and the exhaust. embarrassing mistake on my part that was also missed by the muffler shop when they did the catalytic converter. anyhow I am so happy to have a smooth quiet ride again...many thanks to you all. Quote Link to comment Share on other sites More sharing options...
Bean Posted January 17, 2014 Report Share Posted January 17, 2014 Great to hear you got it sorted fairly easily Ken. Thanks for posting a picture, but I have to say I was surprised by the customization and the colour change! May I ask the story behind the colour and the mods? Early grill and headlights, painted bumpers, removed side mouldings, possibly newer style front seats? Anything else? And did you need a filler panel for the front bumper or did you remove it on purpose? Rabin Quote Link to comment Share on other sites More sharing options...
swept Posted January 18, 2014 Author Report Share Posted January 18, 2014 five years ago my sixteen year old daughter saw this bright green vehicle in a yard where it had languished for several years and said "Id love to drive that". I figured with that colour I would know where she is at any given time . At the time it was already modified including being lowered. I bought it, put it back up to stock height and it has been put to good use as a daily driver. so, in short, I don't know the history behind the customization, but I do like the round headlights and early grill. The seats are the original bluish leather. (Two years later I bought a grey 505 that is identical to this for my second daughter, so I have been accumulating parts to keep them going). I absolutely love how these cars handle! Quote Link to comment Share on other sites More sharing options...
Bean Posted January 18, 2014 Report Share Posted January 18, 2014 Ken - that just made my day. I've got two daughters myself (granted they're only 6 and 3), but I would TOTALLY do the same thing for my girls. They're already euro car snobs, knowing that Peugeot's are the best and daddy's favourite, and the Volvo's are our safe family cars. If you ever need any parts - I've horded an awful lot of 505 turbo parts and it'd be a pleasure to help keep your daughters cars going. Fully agree on how these cars handle and stop - when everything is top notch few cars can even come close. They're hugely under-rated cars, and with the right tires, are weapons on any surface including ice and snow. If you get a chance - more pics of the cars would be awesome. Rabin Quote Link to comment Share on other sites More sharing options...
swept Posted January 18, 2014 Author Report Share Posted January 18, 2014 Rabin, I'll try to get some pics up of both cars soon. It does take a bit of work to keep them on the road but you are right...they are hugely under-rated. sounds like your daughters are already on the right path. I may need to contact you in the future for parts, although I have managed to stockpile a bit myself. last year a local fire department had a turbo 505 given to them to cut up into pieces for practice, and I managed to convince them to let me strip off a lot of bits (radiator, cylinder head, starter, alternator, etc) before the demolition...wish I could have taken the whole car but they wouldn't let me. anyhow keep up the great work on this forum...it is much appreciated. Quote Link to comment Share on other sites More sharing options...
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