QUESTION - Should there be any end play on the pinion shaft after the ring nut is torqued down?
what you understand under ""end play"? so play axially or vertical? you mean the ring nut no. 16? if this is right torqued you don´t have any play or even so little that you may only meassure it, but not feel it by hands. if you have play then the preload of the two tapered roller bearings ( no. 19 und 23 ) is not correct
I have about .010" end play. @!#%!!!! That had to be there before!! WHY did my gearbox seem to work so well when it was completely WRONG from the factory??? Rhetorical question again.... Romano, I assume I can just add to the center shim to remove that end play and create preload? Is that right?
I'm just asking 'cuz I'm trying to learn this too. Also, I haven't studied the shop manual, but here's my observation, the bearings that support the pinion shaft are two (2) reverse facing tapered roller bearings, and these are supported in an aluminum case. As it heats, the case will expand ~ 11 - 13 uin/in-F as compared to the steel which is ~6 uin/in-F, so as the engine warms up, the case will grow more quickly than the shaft and take up float. AND since the pinion shaft is relatively long, this effect will be more pronounced. So---- isn't there a specification for pinion "Float"? I understand there must be a "recipie" for this assembly, and maybe zero float is what's specified ?? Like I said, "I'm learning too". I noticed a gear misalignment on a 308 that had me kind of freaked until, I did the math and discovered that a 150 + degree temperature delta would align the gears nicely. In the same line of thinking, there's a pre-load on the diff carrier in the housing because the case expands away from the carrier as it warms up. Your thoughts??? Whooaaaaa ---- I just re-read what Yurbo Joe said. Not feel, but measure! So .010 might be perfect. Gotta find a specification.
I'm navigating in uncharted waters here myself. I agree with you about aluminum expansion. It's kinda scary because if you have it too loose to begin with, the expansion is going to send it waaaaay out of spec and stuff will break! I'm sure that .010" is too much. Going to disassemble once again and add more shims.
You gotta find a value for that clearance. I thought, you didn't change anything with regard to those pieces? Or maybe I missed a post. So you brought it back to factory setup (right or wrong). Now assuming that was right, you need to know that value. When the case expands on warm up, it will shrink / diminish that .010 thou clearance, and then it starts reacting in a statically indeterminate way (more complex analysis where you take into account the Young's modulus and the convoluted geometry of the Al trans case). Best
until now I never thaught about the aluminum when warm. sure it will grow a little and the preload will get less. I`m no engineering to count this. to theoretically for me. but also the shaft will get warm and so will get longer a little. right scott, that is why I told you before first to adjust the preload of the pinion. when you now change the thickness of the center shim ( no. 8 ) you also change the preload.
This is how to assemble the shaft to test preload. Take all the extra non-driven parts out and assemble in order. This is a pic just before I put it in the case. Image Unavailable, Please Login
As Ramano said, there should be NO end play so no value for clearance. On the contrary, I have to put a "crush" on those 2 bearings. The mainshaft did not get changed. The layshaft or pinionshaft is what has to move. There is a shim behind the head of the pinion that has to be thinner and one in the center that has to get thicker by the same amount. The problem is that when I simply reduce the one and increase the other by the same amount, it's too loose. I'm going to have to add more to the center shim than I'm reducing the other. If you look at the pic above, you'll see the center bearing on the shaft you can see the shim to the left of it. You can also see the thin shims that I'm adding to that shim.
That's why there's got to be a value. Reverse tapered roller brgs are used on front wheel brgs - right, now in that mechanical assy, all components are steel. In this case, there's got to be a number (spec). Doesn't the WSM discuss this ? Bearing pre-loads are important. Best.
Oh, I see what you're saying now. Yes, there is a preload spec. There's a couple different ways to test but the manual says a XXX lbs. weight tied and wound around a pulley attached to the shaft should drop at a steady rate...can't remember the exact details. There are other ways a bit more simple.
Sometimes I feel really dumb... When decreasing the shim behind the pinion head, you must also DECREASE the center shim. I was increasing it. That's where the end play was coming from. Another Homer Simpson "DOH!" moment Now, I have to go have more shims cut...I'm going to completely replace that center shim with a stack of my shims to about 5.6mm. Ferrari doesn't offer them in THAT size either. Again, what a cluster.
this is exact what I have written in my post no. 243, not as nice as you have written it now but with the same sence I think??
On the subject of aluminum case expansion when hot. I worked on an aluminum case Borg-Warner T-5. Now I know it is not the same as a Ferrari gearbox. It has opposing tapered roller bearings, the backlash is .000 to .005 I had them where the backlash was a little more and it would make a horrendous noise sometimes when changing gears. It would cause no damage but ungainly. So the theory mentioned about the aluminum case expanding does not always hold true. Ago
Just for grins - here's a sample calc from: Thermal Expansion - Linear over a 18" length (guesstimate of your length) 70degF starting temp 220 degF final temp 0.0621 Aluminum expansion 0.0432 Steel expansion 0.0189 differential expansion When initially set at room temperature, the 0.0189" preload would go to zero at an operating temp of 220 DegF. The above numbers are a sample calc only and not intended for use. Rgds, Vincenzo
Metal expands in all directions - but the direction of importance is the distance between the two shim points. Rgds, Vincenzo
I'm not going to buy into the whole heated up gear box discussion. As far as I'm concerned Ferrari engineered that variance into the design. I am going to give a little update here: I spoke with the Ferrari God this morning, Dave Helms. Seriously, he is the most patient man in this industry. I don't know how he does everything he does and still has time to speak to lowly little old me. But he does, and I am always grateful to him. In a nutshell, his advice was this: If I can feel the wear pattern with my fingers on the R&P, set it up the same as the wear pattern shows. If I can't feel the wear pattern, glass bead the gears and see if I can see the wear pattern after that. (He said people on here would flip out if they heard that but I trust Dave) If there is no sign of a wear pattern after glass beading, assemble it correctly. This makes sense because changing the mesh on a gear set that has already made a wear pattern is going to be noisy. The only problem with this is the center shim. If I try to set it up correctly, it will require a thinner shim by about .5mm. The existing shim is 6.1 and the smallest available from F is 6.0. I have tried every machine shop in this "3rd world country" I live in and no one can machine it down for me. A few posts back I said I was going to replace this shim with a stack of my own cut shims but realized that won't work because one side of that shim has oil groves cut into it. I don't think I can eliminate those. The saga continues...
Scott, If the shim is steel, probably is. A machine shop with a surface grinder and magnetic chuck could grind off the .5 mm or .01968 of the side of the shim that doesn't have the oil grooves. Dave
Agreed - that is why Ferrari spec a preload in many bearing applications (especially tapered bearings). Rgds, Vincenzo
as david said: every machine shop with a magnetic chuck can grind you this shim from the now size to the size you need. if you will make a new shim those oil grooves are important. but only to adjust and to check you may take an other shim without those oil grooves. when you all finished then you may let grind your original shim to the size you need. not that you will say one time: three times grinded and still to small
You all forget I live on an island in the middle of the Pacific. It is, more or less, a 3rd world country. At least as far as machine shops go. Here's the most well known machine shop on Maui. This should give you an idea what I'm talking about. Image Unavailable, Please Login
Anyway, I'm headed to the other side of the island in search of the guy who takes care of Yachts. He is said to be much better than any machine shop. If he can't do it, I'm going to set it up on a belt sander or grinder and do it by hand (Yikes!) I hope I can keep it flat.
oh sorry please scott: I really have forgotten this with the island is there really no machione shop with a magnetic plate and a grinding machine? hard top beleive. so may be a good business there to open such a shop? but I think there is a shop grinding cylinder heads? those normaly can grind those shims also. doing this by hand I would say you may forget it. because it has to be to 1/100 of a mm equal. by hand this is hard to get, but not impossible. problem is only that you need for 1/100 of a mm the exact size. but only now for adjusting you may take normal shim that you know later what exact size you need. good luck on the 3rd world island . I´m often in the philippines and this wooden hut remembers me or is this "shop" made of metal?
