PHLEX

Managed to get a bit more done over the past week in between work and other projects.  On Saturday removed the old rubber spring bushes from the good leaf springs, replacing them with nolathane bushes since the whole front end has already been done in nolathane.  The rear bushes basically fell out but the fronts were in there so well they required fire so there's now a nice burnt rubber patch on the grass at the workshop!

Last night I got stuck back into removing the saggy old springs to install the good ones back in, replace the shackle bushes in the rear with nolathanes and swapping out the old tired rear shocks in favour of some Monroe replacements. Finished the passengers side and decided to leave the drivers for another night, All going well I should receive my lowering blocks today and can finish and road test when I get home!

Over a month between updates due to chasing my tail trying to find the source of the vibration coming through the driveline at anything above about 70KPH.  Fortunately due to a couple of mates who have cortinas and lots of assistance from my tech post here on OS we managed to figure out the issue was that when I replaced the modded rear leaf springs with some factory springs in much better condition it raised the car around 15mm which was enough to pull the driveshaft out of the gearbox that much too far to allow it to wobble at speed. We eventually removed the shaft and towed the car up to 90kph and it was smooth which pointed us to either the gearbox output shaft or the driveshaft itself. Having already replaced the UJs in my shaft and trying a friends one I decided to try the old springs back in before spending money and it solved the issue!!  Big thanks to everyone who assisted with that. 5 pages of good advice and the answer was actually on page one but it took me a while to try that.

here's a pic of the testing rig I set up to check the run out of the rear wheel axle flanges

Silver lining from this is I have now replaced every bush in the car (previously only the fronts had been done), brand new gearbox mount as the old one was soft and oil soaked, checked and replaced the rear axles to a pair with less wobble (wasn't the issue), replaced the universal joints in the driveshaft, spanner checked the entire car and found a few loose-ish bolts that needed a nip up and the long term fix for the driveshaft wobble is to lower the car at least an inch which was always my plan along with widened steelies.

I picked up some second hand front king springs which have dropped the front end 55mm giving 150mm ground clearance to anything structural on the stock wheels. I have ordered some 2" blocks for the back to match it to the fronts height.  The front shocks will need to be shortened to keep the springs captive but I'm going to do some driveway testing before I commit to the height as my driveway is a bit of a prick and as this will eventually be a daily driven car I don't want to be scraping!

Massive difference between stock and king springs. I see why they state you need shortened shocks!

Still got plenty of work ahead of me to get the Cortina where I want it. Few more interior touch ups, pillar trims and a stealth stereo install and then its time for an exhaust and a rejet to get the potential out of the engine!

Last night we swapped the good springs back out for the sagging modified missing leaf units that were in it when I got it. It lowered the car 10-15mm when parked although handles like running in jandals due to the missing leaf.  Also swapped my original driveshaft back in complete with new UJs at both ends and the vibration is 99% gone. Took it up to 70MPH on the way home and smooth as through the driveline. The only place I still feel a little bit of a wobble is for a split second through the transition of being on the gas to completely off the gas which I would guess is a change in suspension geometry. I feel if it was a driveshaft insertion issue then it should go away completely when I lower it, if it was a diff angle issue I can live with it as long as I can replicate the angles once the good springs and lowering blocks are in

Once lowered the plan is to get the driveshaft extended to ensure its smooth if I ever choose to raise it back to standard

All focus is being put onto the driveshaft currently.  Swapping back to the "low" leaf springs this evening to see if that gets rid of the issue. Will re check the UJs in the current shaft while i'm under there. Ill take some pics while im there to show the difference between the driveshaft distance inside the box and also have a good look at the output shaft for anything unusual

If that doesn't work I will bite the bullet and get the driveshaft extended and balanced

Thanks for all the suggestions! I feel like we are close to a resolution

I did a bit more googling and found nothing else but the best description is that it vibrates worse while coasting, under full acceleration it almost clears completely and under moderate acceleration it comes and goes.

Two things that have come to mind.

I removed the original leaf springs that were missing 2 of the leafs from the pack obviously to lower the car and replaced them with an unmolested factory set which raised the back of the car up about 2" and evened it out front to back.  Is it likely that raising the car has meant the driveshaft yolk is now not going into the gearbox as far and is now flopping around? Plan was always to lower the car 1.5-2" all round once it was driving properly anyway so im wondering if adding some 2" blocks might sort my issue?

Also I have done a bit more reading into gearbox and diff angles and might revisit this as I see they should be around 2-3 degrees different as dead straight can actually cause problems also. does anybody know of a supplier of the wedges that can be used to change the diff angle?  I was also wondering about shaving an angle into the top of a lowering block to changer the angle if needed. has anybody done this?

Thanks for all the help!!

There's definitely some play when the car is sitting at ride height. I noticed ages ago the driveshaft doesn't seem to be in the gearbox as far as I would have expected but wondered if that might have been to give it room to move in and out with the back axle moving up and down. Makes me wonder if it would be worth getting the shaft itself extended by an inch as approx. half the yolk is sticking out of the box when its at ride height so there's plenty of room for movement.  

Unsure if theres some sort of bush that locates the shaft. I don't think ive ever replaced the output seal so maybe that helps to locate it?

Right so removed the shaft from the diff and got towed down the motorway up to just under 100. Vibration totally gone, smooth as shit.....   I have heard a theory the output shaft can get worn and cause a wobble.. what next? 

I've swapped out the driveshaft to a spare off a friends mk1 that seemed nice and tight but had been sitting for a few years. I have now put brand new universals in my original driveshaft so will swap that back in this evening and see if that sorts it out.

I've tried another pair of rear wheels to ensure its not those and it made no difference either so I believe the tyres aren't the issue.

Ok went for a drive yesterday morning. Vibration has definitely reduced but is still there above 70kph just doesn't feel like the cars shaking itself completely apart now but still a noticeable shake. I notice when I let my foot right off the gas and then press it on and off slightly I get a clonk clonk noise from the back end, I have had this previously in a Ute and it was the diff starting to go but in this instance I have replaced the diff with a good spare and it didn't make a difference.

I will swap springs over and see if that does anything otherwise its off with the driveshaft!

SO picked up a spare pair of axles, chucked them in this evening and re measured. Drivers side has gone from 0.50mm to 0.10mm and the passengers from 0.40mm to 0.10mm hopefully that's going to help.  I was 5 beers deep at the time i finished so decided to test drive tomorrow. I will report back!

About to jump in the car and go to pick up a pair of good spare axles to rule those out. I will test drive and if it hasn't fixed it I'll swap the springs over back to the crappy old ones and if it's still no better then I'll disconnect the driveshaft and get towed down the motorway 

I only measured the very outer edge of the hub flange so will have a look at the inner before I pull them out so I have a reference point 

Thanks ajg193 that makes some sense. Hoping to get some more time to diagnose tomorrow. If the vibration is still there I will focus my attention on the axles and bearings, if its gone ill pull the gearbox out and get it to somebody who can figure out what's going on.

Ok thanks for the info guys!  Since its up in the air I might drain the box, take the driveshaft out and get somebody to tow me up to motorway speeds to see if it still does it without the gearbox attached to the spinny bits. Thinking about it now .5mm and .4mm doesn't seem like much compared to how buckled some wheels i've had in the past have been that haven't been nearly as bad!

And as for being a mechanic I have seriously considered it. I've got enough tools and diagnostic gear to make most apprentices jealous

Ok managed to rig up a dial gauge and sure enough both hub faces are wobbly. Drivers side is definitely worse but both of them are out of whack

Drivers is out by .5mm and passengers is out by .4mm

is machining my best option now or are they too far out? 

will do!  Thanks!

Planning to remove the axles this evening and see how bad they are. Have been holding off making it un-drivable as my daily has a coolant leak i've been waiting on parts to fix and my race car is in pieces preparing for a new engine so that's slowed me down a bit as my 50cc scooter cant take me everywhere!

Should have an update by the end of the week

Thank you to all who have offered advice / suggestions / support so far!

Update:  Spanner checked the entire underside of the car, found a couple of bellhousing bolts not as tight as I would usually do them so cranked those up, checked subframe, steering, balljoints, engine mounts (one was slightly loose other was tight) rear suspension was all tight.

Thought for sure the slightly loose engine mount was the culprit but went for a drive and no change.  Got the car parked back up on stands, took the rear wheels off and watched the brake drums whils the car was in gear, both were a bit wobbly but the passengers side was a lot worse than the drivers. I haven't gone as far as pulling the drum off to watch the hub flange by itself but plan to so that this evening.

My question is,  how likely is it that I have somehow bent the hub flanges? I did blow the diff doing a burnout around 18 months ago so the axles have been pulled out about 6 times now using a slide hammer. I cant remember how hard it was to get them out the very first time but the last few times when I swapped a spare diff in and back out they came out with a couple of quick bangs.  Splines looked OK when I had them out the first time but I haven't had a thorough look as I was more focussed on replacing the diff

I'm going to try and pull the axles out over the next couple of evenings to see if they are visually bent, if so does anybody locally have some spare mk2 axles kicking around they are willing to sell?

Shocks passed wof and cant see any signs of leaks but they have been in the car for quire a few years as they have overspray from 2 different paint colours... definitely on the list of parts to replace anyway, ive ordered bushes for the back half of the car just now so will check shocks for rebound while they are out

Planning to do a full spanner check and chuck the old leaf springs back in this evening and go for a drive. If it still vibrates I will record the sound so we can analyse  

Ive been looking at those trademe units for a while and that's definitely the cheapest ive seen, sure the last one was more like $300.  Might be time to snap one up for the ford!

you all raise fine points...

Front suspension bushes are all brand new nolathane / super pro done around 18 months ago when I first painted the engine bay.  Rear springs have nolathane at one end and standard but good condition bushes at the other.  Hanger bushes have never been done, looked OK when I changed the springs but didn't take heaps of notice. Will check all bushes and order replacements for anything that's soft urgently with the end goal to have replaced them all over the next few months anyway, just balancing funds between this, racecar and general living!

Springs are definitely going to be the next thing I will swap out, I will also check one isn't in round the wrong way or anything stupid. I put the nolathane bushes to the front but didn't check they went randomly in different ends or anything. Makes sense to whip them out and put the old ones back in for a road test while i'm checking bushes anyway.

I didn't even think about working out the speed of the vibrations, as crazy as that sounds it is definitely a good point. Surely there's an app for that sort of thing!

Hoping to find some time tomorrow evening to test some more bits out - will keep reporting back!

Thanks 8Ball that's an awesome list to work from!  

I have managed to hit about 75 in 3rd and the vibration was still there although not as bad as it gets much worse at 80/90/100/110.  I have also run up to 100, taken it out of gear, put my foot on the clutch and turned the engine off and it shook itself down to 70 odd and then smoothed out so had ruled out the engine / flyhwheel. Shake doesn't change if I put my foot on the brakes lightly.  I have tried a known good driveshaft and absolutely no change  (Could somebody please explain phase in the universal joints?)  Thinking I might take the driveshaft out and get somebody to tow me up to 90k so I can rule out the engine/box/driveshaft completely.

I haven't tried changing back to the old springs I pulled out yet as they were pretty saggy so was hoping that wasn't the cause. I was also considering getting another wheel alignment and getting the wheels re balanced (although already tried a different set with no change)

I did briefly run it up on stands but not to anywhere near fast enough to make it shake and did notice the back wheels danced round a little bit so switched to another set and no different. Axles have been pulled out a couple of times to change the diff, is it likely using a slide hammer on them could bend the mounting face enough to cause a problem?

installed the new mount, perfect fit and much tighter but hasn't fixed it  

New mount has arrived today so will be chucking that in after work and going for a drive. Hopefully that's the end of it!!

The minor touch ups here and there have continued when I find the time.

I had replaced the dented Mk2 tank with a tidy Mk1 tank temporarally while I kept an eye out for a Mk2 tank in better condition, it fits the hole but you cant connect up the filler properly as its on the wrong angle and also a different size so I left a mk1 filler attached but just had it in the boot for now. First time I filled it up I found pretty quickly it had a hole in the top, fixed that with some knead it only to find fuel slop every time I moved the car, eventually getting frustrated and removing it to find 3 more holes on the very edge of the tank so the Mk2 tank is now back in and ill put up with the dent until I find a good condition one!

Got the "F" and "O" installed on the boot, didn't have any of the clips so wrapped a bit of electrical tape around the pins and used some foam tape to hold them in place. You'd never know!

Ok I've dragged the chain long enough!  

Monday evening after work I jumped in the Cortina and went for a drive round the block. brakes felt significantly better than before but I still wasn't happy. I got all 4 corners back up in the air and gave them another thorough bleed and it was night and day difference on the next test drive.  I drove to the bottom of the hill, turned around and came back up and had no issues. Absolute relief!

I was lucky to get booked in for a wof just before 5 on Tuesday so I snuck out of work early and took the car there, it drove without fault other than the very rotten front tyres but the replacements were sitting in the boot waiting to be fitted.  Once on the hoist it came back with only a few minor issues, one bulb out in the rear, bit of play in a bottom ball joint and one inner tie rod needing urgent replacement. Got the tyres fitted and went home to sort out the repairs and was back on Wednesday lunchtime for a recheck and all passed. Chucked on some rego online and headed home.

At this point I hadn't taken the Cortina on the motorway as its 50/70 the whole way from home to the workshop who did the wof so it was on the way home with a fresh wof I noticed a bit of a vibration at anything above 75ish km that gets worse and worse as you get closer to 100k... That's a totally different subject tho, back to the build..

I placed an order with an Australian company for some window rubbers so I could continue with the restoration. I have used this company twice before and their stuff seems quite good. ordered front and rear quarter window seals and also a set of channel seals for the winding windows. Once they arrived I got stuck into pulling the windows out one by one, tinting them and reinstalling with new rubbers,  LR went well but then got to the LF to find they had sent me coupe front seals instead of sedan so I sent them an email (Australia day by this point so wasn't expecting a reply) and moved onto the RR door since I had parts for that. I now notice they have only sent me enough of the channel rubber to do 2 doors, not the 4 I had asked for. Another email and finished what I was doing and then back into the garage as I was trying to avoid putting the LF door back together with the old seals.  3 unanswered emails later I get a response from the Australian company saying "Yea we don't stock them for 4 doors. send them back for a refund" which completely ignored the issue about the $60 freight I paid to send the wrong parts, the fact I was short changed 2 channel seals and the worse bit was that I bought the Rear quarter seals and asked them to do me a combo of the fronts and channel seals for my "4 door Mk2 Cortina" so it was totally their balls up!  After another week of not being replied to I did some googling and found another place based in Blenheim that was able to do the bailey channel rubbers by the meter so I put in an order for some of that and some external weather strips to finish the job but unfortunately had to re use the old front seals, fortunately both still in OK condition.