Originally Posted by Andysan

I am in dire need of help with my HPI Pr 4 please!

I have 2x Pro 4's, both running fine until about 2 months ago. When i race i hear a crunching from the front gearbox. The gears didn't look noticeably worn, but i replaced them anyhow. The same thing happeneed the next race.

Not having the time to spend on maintenance i switched to the spare car, but this is now doing the same thing. The sound is akin to human teeth rattling inside a box, but is only once every rotation of the wheels, particularly when the car leans around corners.

I am running one ways in both cars (i know they are bad for wear) and have so far replaced the one ways with new one ways and also regular diffs. I have replaced both gears numerous times with new ones (the revised type, meshed as instructed in the Hara ed manual), and also the bearings and layshaft. I have also altered the shimming but to no avail.

Tonight i rested the gears in another gearbox casing and turned them very slowly - they move fine up until an arbitrary point where they lock up very tight and wont budge, akin with he sound i hear once every turn. The lock appears random however, and i am not able to identify and mashed teeth on the gears or other parts that are misbehaving.

Could it be the gearbox casing sperhaps - i don't think it is because i have tried it on a different old casing that i had no problms with in the past.

I have made no changes to the cars - the only change is the introduction of rubber hosing at my track instead of plastic, but i don't think this is related (i don't crash allot).

Could somebody please ofer any help or advice to solve this problem, and general help in meshing my gears which i seem a bit crap at? I am only running a 27t, i don't think i should be getting these problems, especially to both cars at the same time.

Many thanks in advance!