Killer1734 Posted May 12, 2008 Share Posted May 12, 2008 Hi i brought my mates savage of him today as it was sitting there broken for almost a year. The problem i have is the truck will not move when it is reved up. I have checked the gear box and spur and when i turn the spur gear by hand and hold the truck still it does try to pull forwards and when it becomes almost too hard to turn the spur gear whilst holding truck firm and not letting it move forwards it juders as if it is slipping teeth somewhere and looses its taughtness on wheels. I have also noticed that if i hold 3 wheels tight and try to turn the forth it holds a slight bit of tention then it slips on the diff teath and i can do this with any of the wheels.I thought that holding 3 wheels and turning the forth that it would just not let you turn it much. It looks like both front and back difs have gone. Its not an engine fault as i have owned nitro planes and traxas trucks so i know how to set up mixtures etc. I cant see it being the gear box as the spur gear stays tight and tries to move truck forwards. But when on ground and throttle applied it will not move forwards even though if spur turned manually on cog it does want to move. The clutch bell is gripping and you can see it turning and also the spur when reving engine. Can someone look at there savage and hold 3 wheels tight so they cant turn and then try and turn the forth and let me know if they manage to get it to turn much or does it hold tight and not turn under preasure. This would let me know if it is my diffs for shore. I would realy appriciate any feedback And please no answers like check rods etc as i know enough about dog links etc to be able to check the trucks drives and break is off and not holding on. Thanks for any help again. Quote Link to comment Share on other sites More sharing options...
Spoonmeister Posted May 14, 2008 Share Posted May 14, 2008 Did you mate ever take the diffs out? I found out the hard way that if one of the diffs is in backwards then one set of wheels tries to go forwards and the other set tries to go backwards with the engine revving. This will kill your engine eventually (I didn't find that bit out ). Try running the truck with the wheels off the ground - if one set goes forwards & the others go backwards then problem solved Hop this helps. Quote Link to comment Share on other sites More sharing options...
snowbl!nd Posted May 14, 2008 Share Posted May 14, 2008 The pinion gears on the diffs inputs are probably shot... Lock up the transmission using the brake and grip one of the wheels - if you can turn the opposite one in either direction there is a problem in that diff. Do this for both front and rear and it'll indicate which (or both) diffs need sorting Quote Link to comment Share on other sites More sharing options...
Killer1734 Posted May 14, 2008 Author Share Posted May 14, 2008 Hi. I took the front diff out of truck whilst waiting for replies and found that the 2 big cogs inside diff that one had worn teath and the other big one was still like new. I have a feeling that both diffs are the same so have ordered new cogs for both. they both have the 4 bevel type so the guy that owned it must have been pulling high jumps and not letting off throttle when landing putting strain on the drives. I also have a reverse module that im going to fit.Might as well fit it whilst im doing the diffs. Anyway thanks for the replies.Will let you know how it goes. Quote Link to comment Share on other sites More sharing options...
Killer1734 Posted May 16, 2008 Author Share Posted May 16, 2008 (edited) Hi again. Checked both diffs and both were worn out. I did notice that it was the big cog on both diffs that is on the plastic side of barrel that had worn out teeth and not the other side. Im wondering if this is because there is movement in the plastic casing. Has anyone else expirienced this when changing diff cogs. Fitted the reverse module and wasnt as hard as the drawings looked. Still have to test truck tonight because was a bit late to start it last night but wheels dont slip on diffs now so should run ok. Edited May 16, 2008 by Killer1734 Quote Link to comment Share on other sites More sharing options...
Danny-B- Posted May 16, 2008 Share Posted May 16, 2008 When i had my savage i stripped my diffs, do yourself a fave and buy the metal diff cups a bit better than the plastic crap. http://www.jespares.com/radio-controlled-m...ersion-set.html http://www.jespares.com/radio-controlled-m...f-case-1pc.html Im sure i used 30k wt oil too Quote Link to comment Share on other sites More sharing options...
Mel Posted May 16, 2008 Share Posted May 16, 2008 If you want solid diffs make sure you shim them and they will last for ages http://www.madmanluke.co.uk/DB2DAAEB-5F54-...0DD4D9C3C6.html also if you want to go 1 step further get some alloy diff cups like Danny B said (i have got the nova ones) and they will hold everything together better Quote Link to comment Share on other sites More sharing options...
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