Ernie's diff....iculties

Hey Ernie, Are you going to use valve lapping compound on the inner diameter of the synchros as well as on the outer diameter of the gear tapers in order to improve your shifts and reduce your tranny break-in time?

 

Okay, so today I went over to Billybob's to finish putting together my transmission, and Plugzit came over to heckle us, I mean for support . Well I decided to stagger the plates and abrasive disks like I said I would. But before I did, I checked the abrasiveness of the disks, and wouldn't you know it they were worn on the sides facing the cross plates. The abrasive sides facing each other were pretty much like new. Anyway I staggered the plates and disks and then checked the preload. Again came up with ZILCH, no preload.

So the only way to get the preload would be to either, put in thicker cross plates or, put in thinker index'd washers, because as suspected stagering the plates does nothing. Though I did double the grabbing suface of my diff by staggering things. So once it locks up it should hold better.

Since my plates were worn I'm suspecting that the others that checked their preload also have worn plates. However the up side is that, if you take your diff apart all you have to do is flip the plates over and presto new abrasive material. Speeking of taking the diff apart, I previously said that you needed to remove the passenger/right side axle bearing before you could remove the diff. Well I want to correct this. You do not need to remove the axle bearings, it is possible to remove the diff with the bearings still attached. I pulled the diff twice today with the bearings in place. Just keep in mind that the

The pics of the ramp angles of the cups, and what it looks like when the spider gear retainer travels up the ramp in the cup, is so that you guys have a visual to relate to what we have been discussing.

 

Okay I really need to hit the sack. Good night kids.

 

Cheers for posting ernie. I wonder how much new plates are worth.....

 

Yeah I was sleepy alright. I didn't even finish my thought.

I think what I was gonna say was, just keep in mind that the.... differential will only come out just right. If it isn't manuvered just so it will not come out. If you are facing the front of the opened transmission, you rotate the diff out to the left/counter clock wise, so that the large side goes back into the case and the big ring gear comes out first. You sort of have to rotate it and then adjust it out a little, rotate it some more and adjust it a little more, until you have it all the way out. I think was able to get it out in about 3-4 adjustments. The key is to have one hand inside the case through the hole for the differential side cover, the part that holds the internal axle bearings, and then one hand holding the big ring gear on the diff from the front.

 

Now for the pictures. The first pic on post #151 is before, with the plates arranged the way the diff comes set up from the factory. The second pic is after with the plates and rings staggered, and the order in which they get staggered.

The pictures of the cups are pretty much self explaining. First with the spider gears sitting all the way in the ramps in the cup, and then with the spider gear retainers slid up the ramps.

 

FBB, as per FFs link
http://icpcitation.com/variloc_theory.htm

This is a great visual explanation.

 

in the http://icpcitation.com/variloc_tuning.htm, is the following a mistake?
Shouldn't that read, for less locking you need to increase ramp angle

"For oval track cars, a good starting point for stagger is to reduce it to one-half of that needed for a spool or Locker. If the car pushes all the time, less locking is needed (ramp angles reduced), "

 

I wanted to give you guys an update on how the diff is working. As some of you know my 348 has decided to take a dump AGAIN, but before it did I had two days to check it out.

The stagered plates in the diff are working and giving me more lock. I went out to and industrial park and tried it driving in a circle. I can get the back end to break loose alot easier, and it seems to have a bit more grip, not as much push.

When just driving normally there was no chirpping of the tires going around corners. It worked the same as when the abrasive discs were together. If I get on the gas I can hear the tires chirp when going around a corner. So it does seem to have more back end bite.

All in all I'm happy with the new setup in the differential.

Now if I can just get the damn thing running again.

 

Well fellas I have another report on the state of the diff.

I was getting a chattering that sounded like it was the clutch. I thought that it could have been the parking break, because I hadn't adjusted it since I put the transmission back in. So instead of adjusting the parking break I decided to eliminate it all together. Yesterday I completely removed the parking break guts out of both side of the rear wheels. Well it didn't do anything, I still have the chattering.

I'm convinced that it is the stagered plates inside the diff slipping, because it does it only when I'm going around a corner, and boy does it make a rattling. If I'm driving straight there isn't a problem, but If I drive at aat sort of angle it chatters pretty good. You can actually feel it shaking as the discs and plates are trying to hold together much more. As you know, I didn't add any more preload to the diff, the only thing I did was stager the plates. So I can tell you guys for sure that it is trying to hold the lock longer.

I don't like it though. because it makes such a racket when going around a corner. I don't know why it didn't do it the first day? Maybe because of the type of gear oil I have in it. I just put some cheap 75w-90 in it, just to get things sort of flushed out. I didn't wanna waste money on good oil that I'm just gonna dump anyway. So the next step is to drain the cheap oil and then put in some good stuff. I'm gonna use Mobile1 75w-90 and see how it likes that.

 

Consider red line synthetic. That'll help. Then you'll probably even want to add some of the LSD additive (either kind of LSD will do).

 

Will do.

 

Good ol Redline oils.....

 

...maybe it's the sounds from the ghosts of pellet-shot pigeons past.

 

Oh, hardy, har, har. LOL!

Well I was correct in my diagnosis, so THERE!

Yesterday I called all over the place looking for Redline. Almost all the places I called didn't carry Redline, and the one that did didn't have what I needed in the amount I needed. They told me that it would have to be ordere by the case and it would take about a week to get it. Screw that noise, I didn't need a case, and I didn't wanna wait so I bought some Mobile1. I have used it in the past and was pleased with the results.

Yesterday I had to change the front breaks on my truck. My wife drives it most of the time, and tells me "there is a metal sound coming from the wheel when I drive, can you look at it for me?" Well you know what that means, the break pads were metal to metal. Anyway while I was at the parts store buying the stuff to change the breaks I bought 4 quarts of the Mobil1, I think it was about $10 a quart, or something like that.

After I took care of the breaks on the truck I had lunch, and a nice nap, then got started on changing the gearbox oil. Dumped out the crap oil, cleaned off the chia-pet magnetic drain plug, and then filled it up with the Mobil1 75w-90, that has a GL-5 rating.

When I was done I took the car out for a good shake down run of about 40 miles. For the first block, or two, the diff chattered a little bit, but not as bad as before. I jumped on the freeway to get the new oil good and spread around the gearbox. I then took some back roads home. Well all I can say is, what a difference the proper gear oil makes. Mobile1 was just the ticket. No more chattering, plus I don't have any problem getting into 2nd gear when the gear box is cold. Mobile1 is good stuff, and easy to find.

So if you can't find Redline try some Mobile1.

 

Well I know it's NOT the ground strap. Hahahahaaa.

 

Ferrari gearboxes seem somewhat sensitive to the type of gear oil used, not that I know why.

Anyway, glad to read that you've got your 348 pretty well sorted out!

Now the challenge is to get the 3 Stooges together with all 3 348's for an Fchat photo-op.


(I bet that takes 6 months or more, any takers?!)

 

I'm game.

 

The odds of having all 3 of our cars running at the same time are astronomical. No bet.

 

Yeah, Baby! Video would be great!