Lost all gear oil today, 1991 Testarossa

such a torque adapter you cannot use because as I have written already to start turning the diff needs more torque than when it once rotate to let it rotate.
also my description with a spring scale is not so good. better would be to put on this wire a weight with 0,2 kg and let the diff rotate. then it may not get faster turning during rotating. but this you only can do if the gearbox is out and you can put it vertical.

 

the easy version: use 2 assembly levers and try to push the diff left and right. the longer the levels are the better you feel if you have play or not

the better version: take a dial gauge on the diff and try to move it left and right. then you see at the gauge if it will show some or not

remember here 1/100 mm count

when all is adjusted use a complete shim for the right cover and test again before you adjust the backlash

will go to sleep now. here it is nearly 3:30 am

 

I will not clutter up this thread ..but in the manual a 2 kg starts the axle to turn .. that is a specific torque .. so not sure why in concept measuring rotation torque which would be a calculation of 2 kg divided by the radius of where you put wire of 2 kg .. like I said hate to step on pa2pilot ..just trying to get him a better way to measure it

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Assuming you got the preload correct how did you measure backlash?

 

Okay preload sounds fine as long as it didn't have the crown gear on it when you verified it.

I use a dial indicator on a flexible / adjustable arm for backlash.

 

If backlash is in spec then move on. The diff replacement wont affect pinion depth and in your case on the drive side (convex side of the tooth) the pinion is slightly deep. To change that you need to completely and I mean completely disassemble the gearbox and change the shim behind the rear pinion bearing steel sleeve.

 

This is what I kinda of was referring to .. and to get the measurement we would need the radius of the ferrari tool ..with that and the states amount of 2kg weight plus gear ratio since take from inner pinion gear it seems you can get the in lbs of torque as shown in video

I still in this cause not sure what I am missing and using feel by turning without grunting seems a little too loosey-goosey for me

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sorry, have written a mistake here:

it must say 1,8 to 2,0 kg

too much play, the crown has to go nearer to the pinion

this looks ok for me, but on the video I not can feel

yes

less the 5/100 mm

more than 5/10 mm, in the video it looks like about 4-5 mm, a half tooth

this belongs on the pattern, but between 2 and 3/10 mm is not bad. measured outside of the crown when rotating the diff. you feel when the crown want to start rotating the pinion. just now you only hear it, but you may turn more that you feel when the pinion also rotates. important is you may have a little play, of course not as much as in the video. and you are lucky not to have to adjust the pinion also

 

Jamie you actually need a 1.8 shim. It appears at first, the ring gear had no clearance with the pinion, So just to do some easy checking, I had Jamie installing pieces of paper between the right side cover and the differential housing, along with his original 1.5 shim. The prima donnas out their may think what are you doing using paper, but frankly it's quick and simple to just add paper as it's between .003 to .0035 thick. Three pieces of paper changed the feel of his gears. BUT moving the right side cover out, made him lose his bearing preload, which he felt was correct with a .118 thousanths shim. So the left side shim was changed, back to the supposedly TOO thick .138 thousanths shim, that I made for set up purposes. This WASn'T suppose to be the right thickness, but with it installed, his cover only protrudes from the case three thousanths of an inch, with no nuts tightening it. That's just about what it needs for a preload. I expected his cover to protrude at least ten thou.

So he's sending me his new 512M left side cover, so I can compare the bearing bore depth to flange dimension, to my 86 Testarossa side cover.Something is goofy, to require an abnormally thick left hand shim. Takes no time to compare depths of the two side covers. I was curious what the "upgraded" 512M cover has that the mundane Testarossa cover doesn't. Beside the obvious recess in the five o'clock bolt hole.

This wouldn't have been as hard, if he had simply done a comparison measurement between his original housing, and the new Newman housing, to figure out the distance between the ring gear mounting surface, and the taper roller bearing seat on the right side of the improved part. MUCH simpler to measure on a surface plate, than fiddle fart around in the car. Although his part had exploded on the left side, the right side is still a valuable part to measure.

 

when you go left side with more than 3,5 mm then the crown goes more away from the pinion and the "click click" in your video is getting even more. you have to move the diff more to the left side, so you need a thinner shim than 3,5 mm. original the thickest available shim is only 3,20 mm ( have a look at the spare parts catalog. https://www.eurospares.co.uk/parts/ferrari/testarossa-1990/transmission-pedals/differential-axle-shafts-35150 )

just do it as I suggested: loosen the crown from the diff, put shims all 90 ° same size and tighten again the crown ) only that it is tight, so not too much torque. this you can do all without removing the diff again. then see the play how it is going down. because of the shims between the crown and the diff you just know what shim you need for left and right side

brian, we get confused here a little when we talk metric and inch sizes at the same time

where do you see this? in the video it shows clearly how much play there is between the crown and the pinion

 

The preload is easy without the tool. Its like when you set preload on a wheel bearing on an old car or trailer hubs. You want to feel drag when you turn the diff but not like its binding and you strain to move it. I grab the diff itself and rotate it by grabbing it like holding a football not with my fingers on the gear flange. The bearings need to have pressure on them to work properly and not allow slop but not be squeezed to death either.

Backlash is the gap between the gear teeth. Call that clearance the slop. When you grab the crown gear and try to turn it you'll feel it move slightly before the tooth touches the tooth of the pinion gear and it'll make a metallic clack sound. When you rock the gear forward and backwards thats the clearance or backlash you're trying to establish. That amount should be around .006" or whatever the book says.

And yes it was set that way from the factory or someone else was in there in the past, Ive seen it often.

So with the trans in gear grab the crown gear firmly and try to rock it back and forth and listen for the sound I mentioned. If you have movement you then need to put a dial indicator on it to measure it. Read the movement from the edge of the tooth thats parallel to the ground and try to get the indicator as close to perpendicular to the gear as possible rather than on a steep angle because it affects accuracy.

 

Forgive the music but it shows what you need to know.

 

this is about 0,15 mm. so what I also nearly have written in my post no. 691

nice video, better than explaining with words