beefertoo Posted June 21, 2015 Share Posted June 21, 2015 just finally got my herald back on the road but now its got a noisy diff or gearbox,i cant decide which.basically there is a high pitched whine from it when either accelerating or cruising that gos completely when I let off the power. it does seem to be coming from the rear but I've just changed the diff with still the same noise.its a 3 rail o/d box and standard diff, could it be the box? if it is would it be worth converting to 5 speed?thanks craig Quote Link to comment Share on other sites More sharing options...
Pete Lewis Posted June 22, 2015 Share Posted June 22, 2015 in general bearings whine,if its on drive but disapears on coast/overun then its likely to be the pinion thrust bearing in the diff.or this would loose pre load and incorrect pinion mounting distance so the mesh is upset.Pete Quote Link to comment Share on other sites More sharing options...
beefertoo Posted July 20, 2015 Author Share Posted July 20, 2015 thanks pete, stripped and rebuilt the diff with new bearings and seals paying particular care over the preload/ clearances etc but its still just as noisy......looks like i'm needing a new crownwheel and pinion set (one side of the c/w teeth have a 'mottled' look to them), something is grinding itself to bits as there is metal chips in the oil when I split the case.currently its a 4.11 but would it be better with a 3.89 or even a 3.63 set? has an o/d box with a standard engine but I do a lot of motorway drivingcraig Quote Link to comment Share on other sites More sharing options...
Nick Jones Posted July 20, 2015 Share Posted July 20, 2015 When setting diffs with used gears the meshing pattern is more important than backlash. I have fallen into this trap myself and it was incredibly noisy!If the CW/P gears are at all pitted or have sharp edges then there is zero chance of quiet running anyway. Metal chips are a bad sign......I would have thought that a good 13/60 would pull a 3.89 diff, even with overdrive, but a 3.63 is probably pushing it (would be ready for a 1500!). 3.89 will mean changing propshaft and driveshaft flanges.Nick Quote Link to comment Share on other sites More sharing options...
beefertoo Posted July 20, 2015 Author Share Posted July 20, 2015 thanks nick, there are sharp edges on the c/w. I did wonder if a 3.63 might be pushing it and i'm not wanting to be putting a 1500 in,i'm quite happy with the 1300.will the 3.89 c/w replace my 4.11 c/w meaning I can use my original carrier etc? or will I have to get a diff that was 3.89 to start with?sorry for the q's but its an expensive mistake to make....craigp.s if any one has a spare 3.89 diff for sale please???? Quote Link to comment Share on other sites More sharing options...
Nick Jones Posted July 20, 2015 Share Posted July 20, 2015 I don't think much, if anything is interchangeable between 4.11 and 3.89. More than one version of the 4.11 too. CW/P are matched to each other - not to be swapped even between two of same ratio.Suggest getting a complete diff. Vitesse 2L, GT6 with OD and Spit Mk4 1300 had them as standard though the latter will only have 4 spring bolt holes.Nick Quote Link to comment Share on other sites More sharing options...
beefertoo Posted July 21, 2015 Author Share Posted July 21, 2015 thanks nick, will be on the look out for a 3.89 then. just have to keep the car local till i find one..craig Quote Link to comment Share on other sites More sharing options...
Clive Posted July 21, 2015 Share Posted July 21, 2015 re flanges and such....Some 4.11 diffs, certainly fitted to mk3 spit and I think late heralds, had a large output shaft that will swap into the 3.89/3.63 diff. Not sure on the changeover numbers, but I have done it a couple of times.As to prop, you could swap the prop flange, or redrill the fill input flange to suit what you have. Not difficult, especially if you have a spare uj flange kicking about to use as a template, drill holes offset to existing. (have owned a car that had previously had the prop flange bodged nastily, so we won't go there) Quote Link to comment Share on other sites More sharing options...
RobPearce Posted July 21, 2015 Share Posted July 21, 2015 Quoted from cliftyhanger Some 4.11 diffs, certainly fitted to mk3 spit and I think late heralds, had a large output shaft that will swap into the 3.89/3.63 diff. Not sure on the changeover numbers, but I have done it a couple of times. Yes, we did that with a 13/60 that we uprated to 1500 - the original Herald output shafts went in the Spitfire diff so that we only had to swap one UJ (on the prop) Quote Link to comment Share on other sites More sharing options...
Steve P Posted July 21, 2015 Share Posted July 21, 2015 On my 13/60 albeit with a large bearing 1300 engine,i have a single rail o/d box and a 3.63 diff.It will pull fine normally, just not up hills in o/d top.It completed the last RBRR and the o/d makes a big difference to cruising.The only mods are a four branch manifold and twin carbs.I am building a 1500 for it though.Steve Quote Link to comment Share on other sites More sharing options...
beefertoo Posted July 26, 2015 Author Share Posted July 26, 2015 well i'm now sorted out, nearly. got a rebuilt 3.89 from GT6 M on here at a good price(he has others)thanks for everyones help,now to find the time to fit and trial..... looking forward to a quiet drive (well as quiet as a herald gets)craig Quote Link to comment Share on other sites More sharing options...
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