| Author |
Message |
David Feinberg (Fastradio2)
Junior Member
Username: Fastradio2
Post Number: 81
Registered: 4-2002
| | Posted on Sunday, July 07, 2002 - 3:36 pm: | |
Henry,
Yes, I did solve the diff pre-load problem. After reafirming my suspicions with some old-time Ferrari techs...and confirming that the backlash changing after bearing replacement wasn't totally out of the norm...I went through the service procedures line by line to get some backlash (I was starting with a binding diff-no backlash...) and ordered the thickest shim available for the left side(sits behind the left cover). I had inquired about the other selective sized shims, but none were in the Country. There is also a shim behind the diff bearing (not cover) on the right side...No sure as to the availability, as after the adjustments, the pre-load was in specs.
Ferrari has a pretty narrow range their looking for in terms of backlash. No surprise that the shop had one made...
Regards,
David |
Henryk (Henryk)
Junior Member
Username: Henryk
Post Number: 51
Registered: 8-2001
| | Posted on Sunday, July 07, 2002 - 3:13 pm: | |
David,
Just curious as to whether you have solved your problem.
When I bought my 88TR, it was undergoing an installation of a 512TR differential buy the seller. It was for sale on consignment from the Ferrari dealership, which was also doing the work. I couldn't pick up the car till a "shim" came back from the machine shop. It had to be custom surface ground to the correct thickness.....??????? |
David Feinberg (Fastradio2)
Junior Member
Username: Fastradio2
Post Number: 69
Registered: 4-2002
| | Posted on Tuesday, June 25, 2002 - 5:38 pm: | |
Ric,
I'm at a loss here too, as why the diff carrier pre-load has changed. Seems that the measurement that they are looking for is the ring gear backlash. By loosening the LH diff cover, I can get that spec, and the shaft now turns freely. So, a .30-40mm thicker shim should do the trick.
Not sure if when you did your TR overhaul if you replaced the diff carrier bearings...I did, and possibly they are slightly different in specs then what I removed...Tough to believe, but all else checks out perfectly.
Thank you.
David
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Ric Rainbolt (Ricrain)
Junior Member
Username: Ricrain
Post Number: 160
Registered: 2-2002
| | Posted on Tuesday, June 25, 2002 - 1:52 pm: | |
Tough question. I rebuilt my TR's gearbox, and didn't have to change the shims. I remember some value being enscribed on the diff gear with an electric pencil. I forget the math, but I double-checked the numbers and it was in spec. I used a pull type weighing scale (a fish weighing scale, actually), to determine the amount of force required, as per the WSM.
I wonder why yours changed. (?)
Sorry, I can't help any more than that. |
David Feinberg (Fastradio2)
Junior Member
Username: Fastradio2
Post Number: 68
Registered: 4-2002
| | Posted on Monday, June 24, 2002 - 9:23 pm: | |
I'm just completing a BB transaxle overhaul...
All new bearings, synchros, etc...as well as new differential carrier bearings.
All clearances thus far have been in-specs. In that I did not replace the ring and pinion, nor the side case housings, I presumed that the factory selected pre-load shims would be correct. As it turns out, this is not the case as the differential now binds when the bearing carriers are completely tightened.
I have set the pre-load on several other exotics, primarily Lotus...but have never come across a situation like the Ferrari, as you cannot see the pinion gear once the ring gear/diff is installed in the case. The WSM states to check the gear engagement patern using red lead paint...Looks perfect. Further states to check the clearance between the ring and the pinion gear...Huh? Can't even see the pinion, nevermind measure the clearance. Do they mean measure the backlash? I know that there are other ways (shaft turning torque) to set the pre-load, but I'd prefer to understand what they're trying to check here.
Anyone been down this road before?
David |
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