Setting differential pre-load

[Bikercmbc]

I was wondering if there was some kind of write up or instructions on determining proper bearing pre-load tension on the manual transmissions. I know I have incorrectly set the bearing pre-load years ago andmy car has a slight whine in coasting from the transmission, none on accl. I have the DMC specialty tool to adjust the bearing pre-load. is there a way to set it sithout dissassembly of the transmission to test it??

[Nicholas R]

I was wondering if there was some kind of write up or instructions on determining proper bearing pre-load tension on the manual transmissions. I know I have incorrectly set the bearing pre-load years ago andmy car has a slight whine in coasting from the transmission, none on accl. I have the DMC specialty tool to adjust the bearing pre-load. is there a way to set it sithout dissassembly of the transmission to test it??

If you have the BVI 645 tool, you could adjust it on the car but it would be all guess work/trial and error, which could ultimately cause more damage than actual help. You have to have the transmission out of the car and the bellhousing off to actually verify the preload with a force gauge.

Using a piece of string and a force gauge, you need to measure between 5-6.5kg/11.5-13.2lbf to rotate the differential, with the string wrapped around the differential housing.

[Bikercmbc]

Thanks nick, that's what I was expecting but just hoping there was an easier way. Well I might try one day when I have nothing better to work on or when I have to pull the transmission again.

[Nicholas R]

Well, if you did the math to convert the torque based on the difference in diameters, you could attempt to perform the same test at the wheel flanges (you probably need an extra pound or 2). The difficult part is that you'd need to remove the half shafts from the transmission, put the car in neutral, and tie the string to both half shafts. If you just tried it at one half shaft you'd just drive the spider gears inside the differential, and not actually turn the crown gear and differential housing. It wouldn't be as precise, but it may get you in the ball park. I could get you the diameter of the differential housing if you want that information; just need to go measure the one I have in the garage. Sounds like if you're getting noise, you do not have enough preload and you need to go in with the nut.

Did you have new bearings when you set it last time? Chances are if the preload was too low then, it's really too low now as the bearings have worn and become less packed.

[Bikercmbc]

Yeah, this will have to be a long term projects, just bought an Esprit, so spending a lot if time on it. I didn't put new bearings in, I was actually going to replace the seal but didn't mark it exactly, was one of the first things I did to my d when I bought it ten yrs ago. When I get around to it I'll pm you to get the diameter