jamesd Posted July 30, 2014 Share Posted July 30, 2014 I am rebuilding the centre diff on my WR8 flux but I can't find anything that says what oil/grease to use in the centre diff. In the manual it says to use Z164 grease on the front and rear diff's and silicone oil in the centre? It looks like there is grease in my centre diff rather than an oil. Should it be oil and not grease? Are there part numbers for the grease/oil? Quote Link to comment Share on other sites More sharing options...
Noj Posted July 30, 2014 Share Posted July 30, 2014 Silicone diff oil is what you need (once used, it turns black and grease like), of which there are many to choose from ie you don't have to buy hpi branded stuff. As for what weight to use, I'm a 100k upwards person for a center diff, which suits my applications. Perhaps check the wr8 thread and see what users recommend Quote Link to comment Share on other sites More sharing options...
jamesd Posted July 31, 2014 Author Share Posted July 31, 2014 Ah that explains it! I was beginning to think that my car had grease on the diff instead of the oil it should have had. So do I use the same oil on the rear diff or use the grease? Thanks for the help Quote Link to comment Share on other sites More sharing options...
Noj Posted July 31, 2014 Share Posted July 31, 2014 Diff oil all round, weighted accordingly for your RC. Currently, as an example, I'm rebuilding a Hyper ST Pro, fastrax oil weight for me is (Fr - CD - R) 60k - 100k - 30k, as she will be run on 5 and 6s. Now, that is possibly way too heavy for the WR8, so check the owners thread and glean info from there. You don't have to stick with the prescribed weights from the manufacturer, it comes down to how you drive and what suits you best....there can be some trial and error involved, be patient and all will come good.... Quote Link to comment Share on other sites More sharing options...
jamesd Posted July 31, 2014 Author Share Posted July 31, 2014 Ok thanks. I have looked at the WR8 thread and 100k is the stock oil so I think I will stick to that for the centre for just now. Is 100k the weight? If so will this oil be ok? http://www.modelsport.co.uk/traxxas-differential-oil-100k-weight/rc-car-products/32957 I cant find an HPI version I n the manual it says to use this http://www.modelsport.co.uk/hpi-heavy-weight-grease-30000-gear-diff-/rc-car-products/17526 in the front and rear diffs so should I just use diff oil instead? Quote Link to comment Share on other sites More sharing options...
Noj Posted July 31, 2014 Share Posted July 31, 2014 http://www.modelsport.co.uk/fastrax-cml-racing-pure-silicone-diff-oil-100-000-wt-/rc-car-products/37512 Cheaper And this: http://www.modelsport.co.uk/fastrax-cml-racing-pure-silicone-diff-oil-30-000-wt-/rc-car-products/367382 Avoid grease, oil is much better Quote Link to comment Share on other sites More sharing options...
jamesd Posted July 31, 2014 Author Share Posted July 31, 2014 Great thanks! I shall get some ordered up Quote Link to comment Share on other sites More sharing options...
Noj Posted July 31, 2014 Share Posted July 31, 2014 Welcome fella. Tip for filling (esp the 100k which is incredibly sticky), squeeze some in, leave to settle, then add a drop more, leave to settle etc. It is better to have to add some, than take it out Diffs want to be filled so the oil settles across the middle of the top cross pinpin on the bevel gears Quote Link to comment Share on other sites More sharing options...
jamesd Posted August 1, 2014 Author Share Posted August 1, 2014 Great thanks for the advise, the manual isn't really that detailed with its description and having never done this before I had a lot of blanks that needed filling in. Once I get the hang of the car I might experiment with different wt's but the only reason I am replacing it just now is because I have a problem with the ESC going into thermal shut down and some one suggested in another thread its probably my drive train. So far I have found a disintegrated bearing on the centre diff, two destroyed bearings in one rear hub and noisy bearings in the other rear. I am hoping that replacing them and changing the diff oil cures my problem. I assume the 30k wt diff oil you suggested is similar to the grease the manual said to use? Thanks again Quote Link to comment Share on other sites More sharing options...
Noj Posted August 1, 2014 Share Posted August 1, 2014 Ah, the old seized bearing maladies... Happens to us all fella, always keep spares of main bearings in stock....saabmania supplies excellent bearings at a good price. The oil will work better than the grease James, has a higher burning point, all important in a rapidly spinning diff. Let us know how you get on Quote Link to comment Share on other sites More sharing options...
jamesd Posted August 1, 2014 Author Share Posted August 1, 2014 Yeah to be honest I didn't think there was a problem with the bearings, but thought I had better check. I noticed that one of the wheels wasn't spinning a free as the others and when I took the bearing out all the grease had splattered out and it fell apart when I removed it. None of them were hard to turn really just when I spun them they would stop quicker than the others. I suppose its all extra resistance and makes the motor work harder which in turn creates more heat. That and the fact my ESC fan was noisy and the heat sink was full of grass, but I have ordered a new fan for the ESC. Fingers crossed once all this is complete and back together I won't get thermal cut out again. Thanks for the info its a wonder HPI don't use oil in the front and rear diffs as standard. How did you know that 30wt oil is equivalent to the HPI grease? Quote Link to comment Share on other sites More sharing options...
Noj Posted August 1, 2014 Share Posted August 1, 2014 going on the weight of the grease, which is 30k... I think you may need a slightly thicker oil up front, depends on how much the front diff unloads under power and balloons your tyres... You'll have to run it and see what you think Quote Link to comment Share on other sites More sharing options...
jamesd Posted August 1, 2014 Author Share Posted August 1, 2014 Ah right so the 30000 in the product code refers to the wt, I get it now. I didn't see any wt figure for the grease before and just wondered how you knew it was 30k. I actually see the tyres ballooning up lots when I hit full throttle and running on grass with off-road tyres, its usually the rear though and they balloon so much that they hit the body work. I haven't noticed the tarmac gymkhana tyres ballooning though. Quote Link to comment Share on other sites More sharing options...
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