PHLEX Posted March 13, 2017 Author Share Posted March 13, 2017 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. 1 Quote Link to comment Share on other sites More sharing options...
fletch Posted March 14, 2017 Share Posted March 14, 2017 I just had my 2 piece drive shaft rebuilt and balanced. The rear shaft had a little side to side slop on the yoke. At low speed it would stay centered but as the rim got up it would slip hard one way and get stuck there from the g force. Balancer man showed me on the balancer. Interesting to see. Shows why my vibration got worse with speed and was not there below about 60k. 1 Quote Link to comment Share on other sites More sharing options...
RUNAMUCK Posted March 14, 2017 Share Posted March 14, 2017 I once made a driveshaft using two different halves of a yolk. One was inch, one was 25mm. Reamed the 25mm one to inch, and bought a universal cross to suit. Worked mint as, except the measurement inside the eyes where the caps sat was a bit wider on the 25mm, than the 25.4mm one. If id known that I could have shimmed the retaining clips to remove the movement. But I overlooked checking that measurement. Subsequently after a reasonable amount of high speed driving 180kph+ it developed a yuck vibration. Which slowly got worse. It flopped about so much it completely bell mouthed the tail bush in the gearbox. I think it started leaking quite ball too. Lesson learned. /lingpost 1 Quote Link to comment Share on other sites More sharing options...
Nominal Posted March 14, 2017 Share Posted March 14, 2017 2 hours ago, RUNAMUCK said: I once made a driveshaft using two different halves of a yolk. Eggcelent! /lingling post 8 Quote Link to comment Share on other sites More sharing options...
PHLEX Posted March 15, 2017 Author Share Posted March 15, 2017 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? Quote Link to comment Share on other sites More sharing options...
ajg193 Posted March 15, 2017 Share Posted March 15, 2017 How loose does your output shaft feel? Do these gearboxes have a bushing to keep the driveshaft located? Quote Link to comment Share on other sites More sharing options...
PHLEX Posted March 15, 2017 Author Share Posted March 15, 2017 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? Quote Link to comment Share on other sites More sharing options...
PHLEX Posted March 15, 2017 Author Share Posted March 15, 2017 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!! Quote Link to comment Share on other sites More sharing options...
morkster Posted March 16, 2017 Share Posted March 16, 2017 I said could be driveshaft too short wobbling on the gb output shaft on the first page. 3 Quote Link to comment Share on other sites More sharing options...
Kiwibirdman Posted March 16, 2017 Share Posted March 16, 2017 Funnily enough I have been wasting a lot of time around diff angles, drive shafts and the like.A couple of thoughts, your old lowered springs will probably insert the drive shaft further into your gearbox as long as the input of the diff is below the output of the gearbox. Severely lowered vehicles, think 30s chassis car with a Z in the chassis go the other way. The other thing is the diff angle will change as the suspension goes through its travel. My suggestion would be to refit the old springs, go for a drive and confirm that the vibration is still gone, check the distance the drive shaft is in the gear box and the diff angle. Put your new springs in with the lowering blocks, if you are going to use them, then make the diff angle the same. Because you have used the lowering blocks the drive shaft should be OK but check that it is in far enough. Most decent 4 wheel drive places should have the shims to change the diff angle. When I lowered my Silverado the kit came with 3 degree shims and putting them in made a world of difference to the vibration. 2 Quote Link to comment Share on other sites More sharing options...
RUNAMUCK Posted March 16, 2017 Share Posted March 16, 2017 Fitting 2 inch blocks will insert your shaft in deeper. I had to reshorten a d shaft when fitting blocks once. 1 Quote Link to comment Share on other sites More sharing options...
Valiant Posted March 16, 2017 Share Posted March 16, 2017 Pic of driveshaft installed in gearbox please. 3 Quote Link to comment Share on other sites More sharing options...
Mof Posted March 16, 2017 Share Posted March 16, 2017 I would think wheel alignment places would have tapered shims For front axle caster correction 1 Quote Link to comment Share on other sites More sharing options...
Unclejake Posted March 20, 2017 Share Posted March 20, 2017 ^ Caster adjustment can be done using big washers on these cars. One can cut a slot into a few washers and mess around with caster pretty swiftly as the McPherson struts basically hang down from the inner guard and are kept from spitting aft under braking by only the swaybar.... but having said that I suspect this vibration issue is more related to a rotating thing. WRT the gearbox to driveshaft: There's a soft metal sleeve in the gearbox that the driveshaft nose rotates in. That's the extent of the driveshaft bearing. The gearbox mainshaft itself has roller bearings which can wear and vibrate, but more than likely the gearbox would sometimes pop out of gear too (once those bearings are stuffed). The answer to this dilemma is most likely in the first few posts. I'll try to re-read them soon. Everyone wants this fixed! 2 Quote Link to comment Share on other sites More sharing options...
Mof Posted March 20, 2017 Share Posted March 20, 2017 Sorry, I think you misunderstand. I was only stating why wheel alignment places have them (for front beam axles with leaf springs) Quote Link to comment Share on other sites More sharing options...
PHLEX Posted March 20, 2017 Author Share Posted March 20, 2017 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. Quote Link to comment Share on other sites More sharing options...
Unclejake Posted March 20, 2017 Share Posted March 20, 2017 I don't understand why you're doing things to your driveshaft as you've already borrowed another shaft to no avail. If this problem genuinely wasn't present prior to taking the car off the road then it's most likely a result of something you have changed during the rebuild . Despite the problem being road speed related I'm still thinking the gearbox input shaft to pilot bearing could be worth checking. As you are feeling less vibration under acceleration it's possibly worth putting some weight in the very rear of the boot to simulate the change in suspension geometry under engine load . ... but I've never tried that so it could be a waste of time. What part of Wellington are you in? EDIT: I hadn't read that there was no vibration when towed without a driveshaft . That's awesome news 2 Quote Link to comment Share on other sites More sharing options...
PHLEX Posted March 21, 2017 Author Share Posted March 21, 2017 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 2 Quote Link to comment Share on other sites More sharing options...
PHLEX Posted April 3, 2017 Author Share Posted April 3, 2017 Just to give everybody an update. I splashed out and replaced the rear shocks and all the bushes with nolathanes, reinstalled the good set of springs with some 2" blocks. I thought the driveshaft didn't look as far in as the saggy springs let it go in but put it back on the ground and road tested. Vibration is back but not nearly as bad, probably 40% of the original intensity. It is also now only there between about 50mph and 60mph then goes away again completely. From here my plan is to get the driveshaft extended by 20-30mm and balanced and that should solve my problems once and for all. 1 Quote Link to comment Share on other sites More sharing options...
Adoom Posted April 4, 2017 Share Posted April 4, 2017 2 hours ago, PHLEX said: From here my plan is to get the driveshaft extended by 20-30mm and balanced and that should solve my problems once and for all. I had Howatt Engineering in Wingate, shorten and balance my propshaft, by 20mm last week. I just rocked up on my lunch break "hey, can you shorten this?", it was ready two days later. He also checks for play in the universal joints, in my case, they were still okay. Was $203 3 Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.