Pete Lewis Posted June 10, 2021 Report Share Posted June 10, 2021 there has to be some failure of one of the following 1 diff sun and planet gears or their shaft 2 the output shafts 3 sheared crownwheel bolts this drive /no drive has to be identified it wont go away and is uncommon to be erratic in its presence Pete Link to comment Share on other sites More sharing options...
johny Posted June 10, 2021 Report Share Posted June 10, 2021 I would find the cause before moving the vehicle any more than absolutely necessary as theres a risk something locks up and finishes the diff off completely... Link to comment Share on other sites More sharing options...
chrisbladen Posted June 10, 2021 Author Report Share Posted June 10, 2021 Im guessing im gona have to take the diff out then as its only seems to have an issue under load and obviously its impossible to see whats going on while its being driven. Iv tried chocking the front wheels and with the handbrake on to imitate load, pull away but its got good drive and it wants to pull over the chocks! It feels like a kind of slipping sensation and with the teeth on the crown and pinion and planet gears being so big i thought maybe its on one of the splined joints either on either inner axle shafts or at the end of the pinion at the front of the diff. The splines that am visable from under the car on the drive shafts appear to be ok so to me it seems like its something inside the diff Link to comment Share on other sites More sharing options...
Colin Lindsay Posted June 10, 2021 Report Share Posted June 10, 2021 10 hours ago, chrisbladen said: Tried again today and now it seems i have full drive back. I have only drove it on the forecourt at the back of my garage so only up in to 2nd gear and its driving ok. If i go to pull away with some haste then i sometimes get that same crunching noise. But im unsure how iv gone from having drive to having no drive from the diff whatsoever to its driving again and i haven't done a thing? I could guess that something has jammed one of the gear teeth; you've dislodged it temporarily but there's a danger it's lying in the bottom of the diff ready to be swirled back up again and jam things - not pleasant at speed. I'd have the diff off and the casing opened for peace of mind. Link to comment Share on other sites More sharing options...
chrisbladen Posted June 10, 2021 Author Report Share Posted June 10, 2021 2 minutes ago, Colin Lindsay said: I could guess that something has jammed one of the gear teeth; you've dislodged it temporarily but there's a danger it's lying in the bottom of the diff ready to be swirled back up again and jam things - not pleasant at speed. I'd have the diff off and the casing opened for peace of mind. Sounds like thats something that could have happened colin, i just need to bite the bullet and take the diff off this weekend and see whats what i think Link to comment Share on other sites More sharing options...
Pete Lewis Posted June 10, 2021 Report Share Posted June 10, 2021 did you try the lift one wheel and turn it the prop should turn if you cant turn it the planets have suffered if the prop doesnt turn the planets have suffered or the short shafts which are easy to pull out and check before you drop the whole diff unit Pete Link to comment Share on other sites More sharing options...
Colin Lindsay Posted June 10, 2021 Report Share Posted June 10, 2021 Go ahead, it's a simple job and the worst part is trying to get it refitted again afterwards! It doesn't take much to jam the gear teeth, it might only be a small fragment but can do a lot of damage. Link to comment Share on other sites More sharing options...
chrisbladen Posted June 10, 2021 Author Report Share Posted June 10, 2021 10 minutes ago, Pete Lewis said: did you try the lift one wheel and turn it the prop should turn if you cant turn it the planets have suffered if the prop doesnt turn the planets have suffered or the short shafts which are easy to pull out and check before you drop the whole diff unit Pete Yes mate i did check, prop turns. Ok il pull the short shafts out first. I take it im checking the splines all look ok on them? Link to comment Share on other sites More sharing options...
Pete Lewis Posted June 10, 2021 Report Share Posted June 10, 2021 you may find the shaft has sheared and you get it in two parts theres a good few of them about over the years never seen a spline fail either on the short shaft or pinion coupling you have to remove both short shafts to enable a rear case removal dont drop the crownwheel /bearing caps out unless you can spread the cap mounts and have dial indicator to detemine crownwheel /pinion tooth backlash and the pre load shims for the diff case bearings Pete Link to comment Share on other sites More sharing options...
chrisbladen Posted June 17, 2021 Author Report Share Posted June 17, 2021 Took the diff off and took it to a specialist that my mate knows locally. They have stripped it and said the diff is perfect, no issues whatsoever. So now i really am baffled. Driveshafts appear to be in good working order so now i guess im gona have to just put it all back together and see how it goes. At least iv got peace of mind that theres not a rogue something lying there in the bottom of the diff waiting to fly up and cause carnage. Thanks for all the advice guys, il keep you posted how it feels when iv done a few miles in it Link to comment Share on other sites More sharing options...
Pete Lewis Posted June 17, 2021 Report Share Posted June 17, 2021 well dont quit yet if the car would not drive and the prop shaft was turning the loss has to be somewhere so was it actualy rotating at speed not just a bit of a judder movement but really round and round ???? this makes no sense so far Pete Link to comment Share on other sites More sharing options...
chrisbladen Posted June 17, 2021 Author Report Share Posted June 17, 2021 5 minutes ago, Pete Lewis said: well dont quit yet if the car would not drive and the prop shaft was turning the loss has to be somewhere so was it actualy rotating at speed not just a bit of a judder movement but really round and round ???? this makes no sense so far Pete Yes it was rotating at speed, the more revs i gave it the faster it span. I could go through the gears as though i was driving but not moving anywhere. It really doesnt make any sense thats whats baffling me. I have drive again now but i didnt do anything to sort it, i just came back after a few days of being sat there while i was at work. The only noise i had was a slight clunky noise from the rear when i tried to pull off fast. Hence why i wanted to get the diff checked just in case Link to comment Share on other sites More sharing options...
Pete Lewis Posted June 17, 2021 Report Share Posted June 17, 2021 you dont have wire wheels on splines and adaptors >??? or have you checked the hubs if a keyway has given up the shaft could spin in the hub flange even with a tight nut Link to comment Share on other sites More sharing options...
chrisbladen Posted June 17, 2021 Author Report Share Posted June 17, 2021 No i dont have wire wheels. Not chekced that 2 b honest but if a keyway had given up wouldnt that mean a loss of drive fully and not able to suddenly come back again? Link to comment Share on other sites More sharing options...
johny Posted June 17, 2021 Report Share Posted June 17, 2021 Chris, somebody must be missing something somewhere! Either theres something in the diff - a stripped spline thats only got enough grip when turning by hand, all the bolts sheared on the crownwheel but somehow it only slips under power, a bearing inner race thats holding a sheared shaft together, a flange thats broken free of its hub but is still sitting in place, so much play between crownwheel and pinion that they move apart underload so the teeth arent engaged.... or theres an optical illusion that makes it look like the propshaft is turning (vibrating?).... I thought everything down stream from the diff was discounted as the halfshafts dont turn? Link to comment Share on other sites More sharing options...
Pete Lewis Posted June 17, 2021 Report Share Posted June 17, 2021 well it may if spinning has seized and welded the two together thats a posible , no idea how you prove that the hub flanges are a swine to get off so normal or welded can be as bad as each other Pete Link to comment Share on other sites More sharing options...
chrisbladen Posted June 17, 2021 Author Report Share Posted June 17, 2021 17 minutes ago, johny said: or theres an optical illusion that makes it look like the propshaft is turning (vibrating?).... I thought everything down stream from the diff was discounted as the halfshafts dont turn? I will double check with the specialists but they have got the diff in pieces and assured me anything that would cause loss of drive is all good, they knew the issue so i would imagine they have thoroughly checked. I wish it was an optical illusion! I felt like i was going mad but my dad witnessed it aswell luckily otherwise i would have questioned if i actually was going mad. The issue iv got is that drive has come back so i cant say wether or not the half shafts were turning when id lost drive because i was in a rush i pushed it back in the garage and the next time i came down i had slight drive again so i didnt visually see if the half shafts were turning or not when i lost drive. But i think we can eliminate that because surely the side where the keyway was gone would just spin? I had my mate here holding the one wheel and the other wasnt just spinning in his hand so that clears that up, right? Link to comment Share on other sites More sharing options...
chrisbladen Posted June 17, 2021 Author Report Share Posted June 17, 2021 Spoke to the specialist again and they have 100% confirmed the diff is fine, with none of those issues mentioned Link to comment Share on other sites More sharing options...
johny Posted June 17, 2021 Report Share Posted June 17, 2021 yes the half shaft with resistance will not move and all the torque will go to the other. As Pete says the failure of a wheel hub key would explain loss or drive (just that halfshaft would spin) and even partial drive if the shaft to hub taper friction can still transmit some rotation.... Taking the hub off can be a pain as it needs the right tool but perhaps you can undo the hub nut and check the keyways in the hub and shaft are still aligned? Link to comment Share on other sites More sharing options...
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