ZX5 Drive Problem

[Dazzieboy]

So I did my first regional at the weekend and in morning practice the car was flying and I was really happy with it. Then as the grip reduced during the day the car got worse and worse. The problem was that it appeared to be sending all of the power to the rear wheels out of corners meaning I was just spinning out and generally doughnutting. I'd never experienced this with the car before so didn't really know what to do. I've managed to strip the car down tonight hoping to find something obvious. I've rebuilt the slipper and both diffs then put on some really low grip tyres and went on the back garden to test it trying to simulate low grip conditions. Well the car is still the same when I put my foot in front of it and blip the throttle all 4 wheels spin so I know there is power going to the front but when powering out of a bend all the power seems to be going to the rear. This is an original kit ZX5 BTW and I have a white slipper pad at the front and red at the rear.

Please help!

[adam_u]

Whenever I've had any symptoms like you are describing it has been down to the diffs, check that the diffs aren't slipping, particularly the front one in your case, you should usually run the front diff a little tighter than the rear to prevent it pushing in the corners. Hold three wheels steady and then quickly spin the fourth wheel with your hand to see if it 'barks' at all, if it does then tighten a little and try again, you want the slipper to slip before the diffs... Let us know how you get on

[Duncan]

what set up are you using, did the track conditions change and have you tried putting the pin in the slipper

[Dazzieboy]

Adam - I'm thinking front diff also, I might try swapping them over and see if it alters anything.

Duncan - I don't believe there is the option of a pin on the standard ZX5 only the FS?

I have always noticed in the past that on low grip surfaces if the car was out of shape I could apply the power and it would pull straight ie front drive biased which I liked, this is just drifting everywhere I might as well be driving 2WD

[Dazzieboy]

Wanted to post a bit of an update to get some feedback. I rebuilt both diffs with new plates and ceramic balls, bedded them in then gave the car a run on wet Tarmac with rubbish tyres to simulate the low grip I had at the race meeting. I found that turning right on power I had understeer and turning left oversteer so I took the front diff out and replaced the spring and rebuilt it again. This time it seemed much more consistent though by this time it was properly peeing down so I came in. After running the diffs seem looser so I've ordered some new nyloc nuts as I suspect they are coming undone. I need to do a proper run at the track to see if I've cured it but noticed that with the ceramic balls the diffs don't seem to or need to be so tight?

Any hints and tips greatly received

[SamRCRacing]

After running in diffs they tend to come a bit loose. Tighten them up a tad and that should do the trick.


Sam

[Duncan]

what servo are you using

[bretts]

Are you using a one way on the prop shaft?

If so, have you checked it's in the right way round?

[Dazzieboy]

I'm using a savox servo can't remember the exact one 0242? Not sure if I have a one way on the prop but I certainly haven't messed with the prop at all and it was working fine before

[dpackster1980]

Are your hub bearings ok? If you were racing in the wet then a bearing may have started to seize. I always renew hub bearings once a season on the front and twice on the rear irrelevant of what car I run. They take the most pounding and can cause havoc if you don't check them regularly.

[Duncan]

If you have the small Savox servo this can be 1 or 2 degrees short in one direction I am told , if you have this servo it may be contributing to your problem. I had this problem and changed to the full size savox and now I have equal travel in both directions and the car turns the same left or right. Check your drive shafts if they are badly worn this might cause a problem on full lock, I have this problem now and I am looking at a bill of £88 to put it right.

[Dazzieboy]

That's quite interesting Duncan but I'm not convinced this is my problem for two reasons. Firstly my servo is full sized not the short one and secondly there is no problem turning in, it's on the power on corner exit where I got the understeer right and oversteer left. I'm off to the track tomorrow for a practice if the weathers good so I'll report back