Unclejake Posted February 14, 2017 Share Posted February 14, 2017 PHLEX, you've given a great description of the symptoms and what you've tried. That always makes it easier to diagnose. Nice work. These are simple light cars that drive well. I have had my old 1500cc Mk1 Cortina at ~ 200kmph on several occasions with no vibrations. You've largely eliminated the rotating mass of the fan through to the clutch pressure plate as the cause... but if you didn't put the correct I/D pilot bearing in for the gearbox input shaft (there is more than one diameter and and at least two input shaft nose lengths) then 'perhaps' that could be the fault??? Normally that would be a problem at revs rather than speed though Otherwise; it sounds like your driveline isn't in straight. Perhaps run a tape measure between the front and rear wheels on both sides of the car, and then check that the gearbox and engine are located in the centreline of the chassis rails. Worn gearbox bearings (including the white metal bearing the driveshaft locates in) can cause your symptoms, as can a dodgy diff-head (which I believe you've replaced) or an out of balance (or out of phase) driveshaft. It couldn't hurt to rotate the driveshaft one bolt hole to see what happens (although most likely nothing will) One other thing that can catch folks out is wheels with a larger center bore than the hub location flange. That one is hard to detect Good luck! 1 Quote Link to comment Share on other sites More sharing options...
Hemi Posted February 14, 2017 Share Posted February 14, 2017 This is pretty far fetched and ive only come across it once but, Have you checked you rear wheel bearings? i know, i know they makes whines first etc. but ive had a truck do very similar youll be driving along happy as and then at 60kph this horrific vibration would come out of nowhere and it would feel like the truck was shaking itself to pieces , eye rattling stuff. We replaced driveshafts,wheels,tyres,diffs (three of) all nada. it wasnt till one day after checking the wheelbearings (which felt fine) that i thought 'fuck it" so i jacked up each drive one by one and sure enough at around 30kph that vibration happened the same horrific one the truck was trying to bounce of the jack spec. Anyway we pulled it apart and the odd ness was because the bearing was fine but the outer race had scallops missing every say second bearing space. never seen it since. 2 Quote Link to comment Share on other sites More sharing options...
PHLEX Posted February 14, 2017 Author Share Posted February 14, 2017 Thanks for the suggestions there team! I will do some measuring this evening and see what I come up with. As it is a 711M engine one mount had to be changed to a shorter one to allow for the engine to sit in the hole properly as it is 10-12mm winder than the original xflow. I definitely had it up to 100kph when I first put that engine in without fault but it has been sitting around 18 months since then. I never checked the pilot bearing but that is definitely possible as the engine was out of a mk2 Cortina and had been mated to a different gearbox so if I don't get any results from measuring and checking diff and gearbox angles I will certainly look at that. Diffhead has been ruled out Driveshaft has been ruled out (now sporting brand new UJs just out of maintenance All tyres have been swapped for known good ones with no change Rotating assy has been ruled out as far back as the clutch by turning the engine off at 100kph and holding the clutch pedal in Ill get the tape measure out and see what I can find out. If all looks well I will put my old saggy springs back in and see if that changes anything, otherwise next step will be to get all the wheels re balanced and an alignment to rule that all out Quote Link to comment Share on other sites More sharing options...
locost_bryan Posted February 14, 2017 Share Posted February 14, 2017 If it's been sitting for 18 months, has it affected the wheel bearings or brakes? Something gone out of round from sitting? Quote Link to comment Share on other sites More sharing options...
Mof Posted February 14, 2017 Share Posted February 14, 2017 A little moisture in a bearing can make pitting/scallops in the bearing if it's been sitting. Long shot- check tyres for lumps Quote Link to comment Share on other sites More sharing options...
JoKer Posted February 14, 2017 Share Posted February 14, 2017 how round / straight are your rims? (I might have skim read this too much) once had feedback via the steering wheel in my subaru from a tire on the rear with a bulge in it (My only real life experience with this sort of thing & well aware it hardly relates to this instance so I am following this thread to see what the cause / fix is too Quote Link to comment Share on other sites More sharing options...
PHLEX Posted February 15, 2017 Author Share Posted February 15, 2017 front tyres were balanced when they were put in a couple of weeks ago and balanced up fine. Rear tyres have never been balanced in my ownership but put a spare pair of tyres on off a mates mk1 with the exact same symptom. I had wondered about bearings, one of the fronts felt a little loose so I adjusted it and that's taken away the phantom knock I could hear occasionally but unfortunately wasn't the cause of the vibration. Putting my foot on the brakes doesn't change anything either so had ruled out brake wobble 1 Quote Link to comment Share on other sites More sharing options...
1963 AP5 Posted February 15, 2017 Share Posted February 15, 2017 Had a fairly similar problem with one of my cars and it turned out to be the engine mounts. The rubber had gone kind of soft and spongy, probably through years of being soaked in oil that somehow found its way out of the engine. The soft mounts allowed the engine to wobble at certain engine speeds particularly when accelerating through 55-60 Mph. Changed the mounts and the problem went away. Not sure if this would be the problem with your car but might be worth considering. I also agree with the post above and correct pinion angle is very important and changing the springs can upset things. I think you can fit wedges between the diff and leaf springs to correct these problems. 1 Quote Link to comment Share on other sites More sharing options...
PHLEX Posted February 16, 2017 Author Share Posted February 16, 2017 Thanks! I will check the mounts this evening also. Makes sense they could cause an issue, ill be checking the engine is centered in the bay this evening and also angles and if everything looks straight I will put my old springs back in and go for a drive Quote Link to comment Share on other sites More sharing options...
datlow Posted February 16, 2017 Share Posted February 16, 2017 On 15 February 2017 at 00:37, Hemi said: This is pretty far fetched and ive only come across it once but, Have you checked you rear wheel bearings? i know, i know they makes whines first etc. but ive had a truck do very similar youll be driving along happy as and then at 60kph this horrific vibration would come out of nowhere and it would feel like the truck was shaking itself to pieces , eye rattling stuff. We replaced driveshafts,wheels,tyres,diffs (three of) all nada. it wasnt till one day after checking the wheelbearings (which felt fine) that i thought 'fuck it" so i jacked up each drive one by one and sure enough at around 30kph that vibration happened the same horrific one the truck was trying to bounce of the jack spec. Anyway we pulled it apart and the odd ness was because the bearing was fine but the outer race had scallops missing every say second bearing space. never seen it since. My maxima makes weird vibrations, replaced wheels and tyres(found some cheap 350z ones as apparently USA maximas had problems with standard alloys), still there figured I'll wait till wof time nothing found then a mate said sounds/feels like a airplane so googled maxima airplane and low and behold all these threads came up saying it's what they do when the wheel bearings are worn! shall investigate further on the weekend 1 Quote Link to comment Share on other sites More sharing options...
JoKer Posted February 16, 2017 Share Posted February 16, 2017 wanna borrow the set of rims you got in your Avatar? should make it well worse Quote Link to comment Share on other sites More sharing options...
JoKer Posted February 16, 2017 Share Posted February 16, 2017 even if I take my office phone out of them 1 Quote Link to comment Share on other sites More sharing options...
datlow Posted February 16, 2017 Share Posted February 16, 2017 2 hours ago, JoKer said: even if I take my office phone out of them Prob needs the phone to balance out the vibrations 2 Quote Link to comment Share on other sites More sharing options...
PHLEX Posted February 16, 2017 Author Share Posted February 16, 2017 Ok so had a roll around under the cortina with a tape measure. Distance between front and rear wheels is identical. Distance between front of back wheel and the sill is identical on both sides so that tells me the back axle is straight. Gearbox is within mm of exactly centered between the chassis rails. Diff is offset about 40mm but cant do much about that. Driveshaft yolk has a slight angle down when it comes out of box and slightly up when it goes into diff but the angles look about even between the diff and box, hard to tell exactly but theres not an excessive angle on either. Noticed the gearbox mount has turned to an oily jelly. Is this likely to be the cause? Both engine mounts are dry and good condition and the engine is centered in the engine bay. Im going to order a new gearbox mount just in case but some insight would be good so I know if thats likely the issue or if im still looking! Thanks everyone! Quote Link to comment Share on other sites More sharing options...
Hemi Posted February 16, 2017 Share Posted February 16, 2017 Yes replace that mount asap. When they got soft they can go way to elastic and do gross things. Dunno if it's 100% the issue but def yuck it off the list. 3 Quote Link to comment Share on other sites More sharing options...
JoKer Posted February 16, 2017 Share Posted February 16, 2017 40mm out is only 20mm in one direction to correct it, unless its meant to be there? Quote Link to comment Share on other sites More sharing options...
PHLEX Posted February 16, 2017 Author Share Posted February 16, 2017 JoKer I mean the diff is cast into the rear axle on a very slight offset. Checked left to right diff mounting into the body and looks nice and even 1 Quote Link to comment Share on other sites More sharing options...
locost_bryan Posted February 16, 2017 Share Posted February 16, 2017 11 hours ago, PHLEX said: Ok so had a roll around under the cortina with a tape measure. Distance between front and rear wheels is identical. Distance between front of back wheel and the sill is identical on both sides so that tells me the back axle is straight. Gearbox is within mm of exactly centered between the chassis rails. Diff is offset about 40mm but cant do much about that. Driveshaft yolk has a slight angle down when it comes out of box and slightly up when it goes into diff but the angles look about even between the diff and box, hard to tell exactly but theres not an excessive angle on either. Noticed the gearbox mount has turned to an oily jelly. Is this likely to be the cause? Both engine mounts are dry and good condition and the engine is centered in the engine bay. Im going to order a new gearbox mount just in case but some insight would be good so I know if thats likely the issue or if im still looking! Thanks everyone! Soft mount will allow the whole power unit to move, so it could be the cause. Marina's are prone to doing the same thing. 1 Quote Link to comment Share on other sites More sharing options...
JoKer Posted February 16, 2017 Share Posted February 16, 2017 hah no worries thought that might be the "case" ps mates still hunting engine mounts for his Marina seeing as you mentioned it too Quote Link to comment Share on other sites More sharing options...
locost_bryan Posted February 16, 2017 Share Posted February 16, 2017 I think I've got a couple of engine mounts in my Marina part's boxes. Which engine has he got? Quote Link to comment Share on other sites More sharing options...
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