hutchwilco Posted June 30, 2013 Share Posted June 30, 2013 Hey guys, hoping someone has some suggestions: Recently had to replace my 88 Econovan maxi box since a friend mashed something up and I lost 1st and 5th. The box I put in was second hand, slightly different but I was assured it would bolt right up by the wrecker. (I confirmed the spline count was the same). I installed the replacement box, no issues bolting it up, but I got a loud whirring noise when I engaged the clutch. It sounds like something (presume the throwout bearing on the clutch fingers) spinning down to a stable speed. If I disengage the clutch, as I release I hear a chirp, (sounds like the TO bearing coming off the fingers) I suspected the throwout bearing obviously, so removed the box, and swapped back in the OLD TO bearing (which was in much better condition). I also bled the hydraulic clutch as I suspect that was not throwing as far as it should. Still not dice - the sound is not as bad but still there. When I had the box out, I checked the differences between old and replacement, and the TO yoke and bearing all seem the same. The gearbox input shaft seems very similar but I did notice about 5 or 10 mm difference in the distance of end of the shaft to the box mating face (the replacement box is a tad shorter). Does any of this add up to anyone? Quote Link to comment Share on other sites More sharing options...
KKtrips Posted June 30, 2013 Share Posted June 30, 2013 So clutch out and there is a noise and clutch in the noise goes away? Does this noise change depending what gear you are in? Or just engaging and disengaging the clutch with the box in neutral? Quote Link to comment Share on other sites More sharing options...
hutchwilco Posted July 1, 2013 Author Share Posted July 1, 2013 So clutch out and there is a noise and clutch in the noise goes away? Does this noise change depending what gear you are in? Or just engaging and disengaging the clutch with the box in neutral? No noise clutch out, but clutching in causes a sound of something spinning down (or two things coming together to match speed) then a constant noise at a lower rev. This is in neutral. If I change into a gear, as I let out the clutch there is some minor drive to the wheels but mostly awful extension of the clutching noise. It has been suggested to me that a minor (5-10mm) difference in the input side of the gearbox shaft (which I observed compared to the removed gbox), would mean the TO bearing does not sit on the clutch fingers, so the sound I'm hearing is the bearing contacting and spinning on the fingers (perhaps not in perfect alignment either... ie slightly off axis ). Quote Link to comment Share on other sites More sharing options...
hutchwilco Posted July 2, 2013 Author Share Posted July 2, 2013 For anyone who cares, I've figured out that I needed to actually measure the gearbox input shaft diameter. Should have checked it first thing - Stupid. Apparently Mazda changed the input and output shafts willy nilly with no rhyme or reason. The noise was the large dia clutch plate splines spinning on the too small dia gbox input shaft. not nice, but no damage done. Solution has been to replace the clutch plate with one with a smaller diameter hole. Quote Link to comment Share on other sites More sharing options...
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