jackmac Posted April 6, 2015 Share Posted April 6, 2015 Hi all, Just finished fitting a pair of diffs into my 90 with HD 4.11 ring and pinion, new HD front shafts, new ashcroft CVs, new HD drive flanges. When I was looking at the diffs, I noticed that there was a tiny bit of burring on some of the crownwheel teeth from the manufacturing process. Now it's all fitted and back on the road she's playing a tune! Constant whistling noise, but definitely not tyre drone, that seems worse under engine braking. It's not loud, but certainly noticeable and wasn't there before. The ring and pinion are new, in diffs that were built up (professionally I think) a year and a half ago with new bearings etc but never fitted. The front diff in particular seemed very tight. Front prop is new (under 1k miles), rear prop has a touch of play in one UJ but I think the noise sounds like it's coming from the front - it's one of those ones that's very hard to tell :/ My castor angle on the front is pretty terrible, but never had a problem with pinion bearings before so I'm assuming it's not that. Would it be reasonable to assume that this might just be high points etc on the gears making the noise? Quote Link to comment Share on other sites More sharing options...
Ex Member Posted April 6, 2015 Share Posted April 6, 2015 Who's R&Ps and who set them up. Step one is to ensure they are setup correctly. Step 2 is talk to the manufacturer. Nobody is solving anything across the internet. Quote Link to comment Share on other sites More sharing options...
jackmac Posted April 6, 2015 Author Share Posted April 6, 2015 Who's R&Ps and who set them up. Step one is to ensure they are setup correctly. Step 2 is talk to the manufacturer. Nobody is solving anything across the internet. Well even Nige couldn't answer that one, we think they might be from across the pond. If it were just the cut of the gears, would you expect the noise to decrease over time? Speaking to manufacturer / builder is not an option, as I don't know who they are! Quote Link to comment Share on other sites More sharing options...
Ex Member Posted April 6, 2015 Share Posted April 6, 2015 Well, IMO, you need to pull them and check the backlash and tooth contact first. Possibly not the best option to install unknown sourced diff assemblies that look to have problems without check out the setup... Quote Link to comment Share on other sites More sharing options...
Ex Member Posted April 6, 2015 Share Posted April 6, 2015 If you think it might just be the front, pull the front propshaft first to check. Saves pulling both. Quote Link to comment Share on other sites More sharing options...
jackmac Posted April 6, 2015 Author Share Posted April 6, 2015 Well, IMO, you need to pull them and check the backlash and tooth contact first. Possibly not the best option to install unknown sourced diff assemblies that look to have problems without check out the setup... They have the backlash written on the crownwheels, and have been checked with engineers blue by the builder. Since the blue was still on there I know they are making proper contact I'll pull the front prop and give that a go Quote Link to comment Share on other sites More sharing options...
Hybrid_From_Hell Posted April 6, 2015 Share Posted April 6, 2015 I'd say that the bigger gearsets can be "noisier " than a std 3.54 cwp set up but if they are that noisey then j would suspect set up wrong. whilst Backlash is one thing. And very importsnt... pinion height is a key essential. We find swapping from std 3.54 to ashcrofts or other after market hd gears often sees pinion height needing reseting. If pinion height is wrong Backlash is irrelevant the diff setup is wrong and ....The pinion being wrong will cause big problems Cheap bearing can also cause probs as tolerances are poor. Running it like it is for too long will cause abnormal wear which will make thdm incapable of them thdn being reset properly To do pinion height correctly you have to use special tools Is it both if one ? Quote Link to comment Share on other sites More sharing options...
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