In removing a posi carrier from the case, Eaton 1965, is a spreader needed? I have to rebuild the posi unit and replace a broken stub yoke. I'll reassemble using the same shim pack on both sides between the case and the side bearings. Also, is it necessary to polish the entire posi carrier or only the openings to eliminate stress risers?
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Re: Gary Ramadei: Diff Case Spreader Necessary?
Hi Joe
I never use a spreader on a 63-79 diff. Even with the 63 GS aluminum diff I didn't need one.
I have found the amount of "load" on a posi or open diff varies. There should be a fair amount of load on the case but I leverage a pry bar in posi window to pop it out. There is also the old trick of putting a box wrench on a RG bolt and turning the pinion to walk the ring gear off the pinion and remove it. The only one I ever had a problem with was the one I did for Jack Panzica last Spring. That one was imploded and wedged in so tight I had to burn it out. It was all junk so it didn't matter.
Now if you have a 65 Eaton then it will have the small window in it along with solid steel clutches and 10-18's. Check it very close for cracks. Look at the cross shaft holes, the radius of the windows and even inside just below the small window. I have found cracks in all those places. If you find a crack then replace the posi case,don't attempt to weld it or drill a hole in it. If you get to that point let me know.
Now if it's not cracked you may find the posi is sloppy and causing about 030-040" endplay. New rebuilt or New (imported) axles will not solve that endplay. Check them from the face to the snap ring- good originals will be about .195-.200. Rebuilts run about .180 and are ok but no where as good as an original 63-71/72. Many times I reuse them and have to face grind them 005-010" to work with a tuned posi.
Most likely the side shims are not going to be close enough. If you install new bearings you will want to have the preload correctly setup. The 63-66 housings are narrower then the 67-79's and use now obsolete thin steel shims. The vendors never tell you that one so you buy their kit and find the shims in it are for the 67-79's. Those wider housings used a ground cast iron shim. Attempting to hammer those back in, if correctly preloaded is very risky since they snap very easily. The steel shims in the kits work great for those. Your 65 will use 1 single steel in the 064 - 090 range.These were the same shims used in the 12 bolts. I still have stock on them but still have to grind them to size to set the final lash and preload.
If you are planning on reusing the gears be sure you note the lash and pattern on them before you take the diff apart. You can tell if they are GM by the stamping on the side of the RG, it will have a date and gear tooth count for each gear along with a GM stamping. If those aren't there they are not original GM gears.
The bearing hex bolts are 5 line and I always replace them with socket heads.
If you are going to Carlisle this week I will be holding a seminar on Friday at 1:00 in Building R. I will be going over questions like this along with boxes and TA's.
Gary -
Re: Gary Ramadei: Diff Case Spreader Necessary?
PS- polish the posi case as I show in my threads. Inside, outside, the windows and check the CS bolt pad most need to be milled deeper. It makes no sense to go to all that work and not blend and polish the case, it could prevent future cracks. What I have seen posted as polished cases by some rebuilders on places like CF are not what I would call polished - just an attempt to satisfy a customer.Comment
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Re: Gary Ramadei: Diff Case Spreader Necessary?
Gary,
Is all the above necessary since I am reusing all the old parts. Diff only has 13,000 miles on it since rebuild before and everything looks good, so far. I twisted/snapped the right side stub axle and can't think of a way to remove it without taking the carrier from the case. The distorted end won't get past the side bearing without beating it out. I can't get to the distorted end with a die grinder because it is behind the side gear and inaccessible. I feel that while I'm at it, I might as well polish the case since I have to flush everything clean as it stands now. I don't have a holding fixture either, so I hope I can find a way to clamp the diff in my vise. The rear has always worked well, is noise free, and the posi break-away torque was MORE THAN 70 foot pounds, since I set up the posi 15 years ago, and had a excellent mechanic/machinist assemble the diff at that time. I purposely set the break-away torque at close to 100 ft-lbs when I set the posi 15 years ago.Comment
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Re: Gary Ramadei: Diff Case Spreader Necessary?
Hi Joe,
Short answer, no. You can put it back together as many would, it's just not the way I would do it.
ok so do you have an engine stand, even a cheap Chinese $40 stand will hold a diff so you can work on it. I highly recommend this to keep it from rolling around the bench top or in a vise. These weight 100lbs. The bracket holes are 3/8-16 and will hold the diff no problem- just be careful the bolts are not too long and blow out the casting inside. If you are referring to holding the posi all you need is your good axle in a vise.
If you are careful and don't bang up the case bearings while out then the preload and lash should be the same- just as if you final finished the build and then wanted to remove the case for something and replaced it again.
The fact you broke an axle is concerning. Was this a rebuilt axle or original when you last rebuild the diff? I have found some pretty bad rebuilt axles on the market. I show the pictures in my thread and will have one at Carlisle. Who ever "rebuilt" the axle didn't know what they were doing and left them hollow, hence the first heavy launch and they snapped in 1/2. The correctly rebuilt axles will have a seam in the snap ring groove, the type I mentioned clearly have a seam well below the groove. If you have those replace both of them for sure.
Check the axle bearing too. I have seen them damaged from broken axles. Heavy use, like in my son's 75 where he has 500hp at the wheels and
launches the car at 5K rpm with a stick shift, the bearings walk. When I built a diff, any level, I always Loctite the axle and case bearings on now.
Check the case real close, did the axle just break or were you hammering it? If hammering then those cases do crack as mentioned.
Since you are using the stock spring set up the break torque you have is good, did you have any hammering in corners? That tight is usually the reason, depending on how the lash was setup in the spiders. Use 2 bottles of the GM additive and 90 or 85-140 gear oil. I always use Lucas 85-140 with the GM additive but some like the 90 wt.
Feel free to call me if you have questions. I will be heading to Carlisle on Thursday.
GaryComment
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Re: Gary Ramadei: Diff Case Spreader Necessary?
Gary,
I used a piece of 1/4" steel plate which I bolted to the two lower holes in the diff carrier. I then clamped the plate in my vise so it appears that the diff is sitting atop the vise. Very comfortable working position. Yesterday I got the case out and carefully set the cast iron shims aside in their positions. There were two steel shims within the cast iron shims on the left bearing side, but they shouldn't present a problem when tapping them back in since they are sandwiched between two thick iron ones.
I found the old BBC yoke, cap and bolts (which I removed when I restored the car 15 years ago) in my attic and it looks very good, so I will swap it in. The snapped side yoke end will be removed when I take the case apart. I only got as far as removing the ring gear and the preload springs yesterday. The surprise is that the "good" side yoke is slightly mushroomed where it rubs on the "pin". The "pin" shows no sign of wear and the c clips are good as well. I think I'll buy a matching BBC side yoke to replace the mushroomed one, as well.
I'd like your thoughts on why it mushroomed the way it did, and whether or not I can dress the end and re-use it. Meanwhile I will look at my old receipts to see where I bought it. Splines on that yoke are straight and, surprisingly, the tip is flat and not scored very badly. Cheap steel?Comment
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Re: Gary Ramadei: Diff Case Spreader Necessary?
Hi Joe
I just got in from Carlisle and saw your questions. I was without 'net access since Thursday morning.
As mentioned earlier, the 63-66 housings are narrower and use only (1) steel shim, between 060-090". One of the things I mentioned to many guys over the weekend was the present master kits do not have the correct shims in them for the 63-66 housings. The 67-79 housings are wider and used the ground cast iron shims, about .250". The correct shim size was figured, as shown the overhaul manual, and used. The master kits have the stackable shims to replace the brittle iron ones that will break tapping in. Using the steel shims will allow the bearings to be correctly preloaded without using a spreader. The fact you found multiple shims tells me someone was in there before but also if they are in the .250" range you may not have a 65 housing but possibly a 75. The 65 bearing caps will not have a tab cast into them but the 75's will. If you can post some pictures I can take a look for you.
Sounds like you have the diff to point of working on it in the vise. I like the engine stand because I can rotate it and work on it.
The fact your yokes mushroomed over is another flag you might have a 75. The 63-72? axles were hardened on the face and most I see can be reused. Yes some will wear but I have rebuilt those diff's with over 100k miles on them and reused the axles. In fact once used with a tuned posi I have to grind the face a few thousands. The 72-79 axles were soft and wore out to the point they would hit the ears on the housing. Those that attended my seminar at Carlisle on Friday saw a housing just like that, a mid 70's unit. I suspect your axles are soft. If they are flat faced they are replacements. The originals had center drilled holes in them. I have seen plenty of junk sold and rebuilt axles are part of that group. I also had and example of a sheared "rebuilt" axle at the seminar. Look for a seam where the new hardened tip was installed on the axle. It should be in the snap ring groove. If you see it below the groove I would not use them.Comment
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Re: Gary Ramadei: Diff Case Spreader Necessary?
Complications.........the case is cracked between one of the pinion shaft holes and the big window.
I have a line on a "nice" used 1969 case, but really should buy a new one.
My diff is out of a 72 Corvette. Carrier is dated 1-22-2 and the bearing caps have tabs.
The yoke that has started to mushroom is center drilled, as well as the one that snapped, as well as the BBC style one that I plan to swap in..
The BBC yoke that I found in the attic looks good and I am going to use it.
The question is whether to buy another "GM Restoration" part or buy a high quality one from Corvette International or Tom's Differentials. Also whether or not to use Tom's steel bearing cap on the left side.
Probably my best bet is to buy a new Eaton case (which I'll polish fully), a high quality BBC stub (not a GM Restoration part) and place it on the left side along with a steel cap/stronger bolts, and use my old BBC stub on the right side.Comment
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Re: Gary Ramadei: Diff Case Spreader Necessary?
Joe
Sorry to hear the posi case is cracked, less likely with the 69-79 cases but it does happen.
1969 was the first year to use the "tear-drop" window case over the earlier 1" square window Eaton cases. It is a much better design.
For replacing the posi case you have a couple of options.
1- find a good used one. Check it close and do not buy a 1" square window case, they just are not worth it. Used cases usually run in the $150-$200 range but make sure they're not cracked. Many who sell them don't know, although some DO and still sell them.
2-Buy a new loaded Eaton case. This is route many shops will take because they don't have to do anything to them and can still mark them up for a profit. These are now imported and come with fiber coated clutches and huge springs. The spiders are not the same as the old ones and in order to get those huge springs in place a set of clutches were removed per side. The castings are thinner inside the large windows. I personally wouldn't use one unless asked to.
3- Buy a NOS bare case and build it. This is what I do. Yes it will cost more but it is the best option in my opinion, especially if you plan on tuning it since the tolerances are better on the NOS cases then the old original ones. I would polish it inside, outside and in the windows. Mill the cross shaft pad to allow deeper engagement on the bolt, countersink the flange holes and use ARP Ring Gear bolts. Use solid steel clutches only, no springs or plates, tune the posi for a balanced operation, and you will have a posi built better then new or any other out there. If you want to beat it up some, then I cryo treat them but do it after the posi work is all done.
For the axles. The lone Star axles are typically what everyone sells and I use them as well. They are correctly rebuilt but you do have to check the part when you get it because QC isn't the best. I have not had any issue with these in service. The new reproduction ones are imported I believe and I had several, years ago, that were NOT hardened. I never attempted to use another "new" axle. I have used a lot of Tom's axles, typically the 30 spline HD ones for both the 10 bolt and 12 bolt conversions. These are the best out there but you have to find the 10-17 x 30 spline spiders and those are near gone now. I use those in the super 10 diff's and 12 bolts and still have stock on them but are used solely for full rebuilds.
Steel caps, I can either make them or buy them from Tom. I support Tom and buy his and fit them. To fit them you're going to need access to a surface grinder and Bridgeport mill. If you are not going to launch the car hard you don't need the cap. Also you do not need to fit one on the RH side, some guys say in a place in TX have sold guys that but it's not needed. If you go with the steel cap you will also have to drill and tap the LH pad holes for 1/2-13 bolts so you can torque them to 100 ft/lb and you have to fit them to 001" rock +/.0005".
Now if you are going to require the steel cap you might as well fit a solid sleeve in place of the crush sleeve. See how this all started to snow ball?
I get calls all the time asking what needs to be build to support a engine with 500-900hp in a C2 or C3. The answer is everything south of the engine as well as welding in frame gusset and supports.
If you are under 450hp, are not going to push the car hard, forget the steel cap and solid sleeve. Build a polished and tuned posi with 10-17's, use the ARP RG bolts, Tom's gears and tap a drain since it's not original anyway. Use the LS axles or Tom's and remember to break in the new gears correctly and change out the oil at 500 miles. Use the GM additive (2) bottles and Lucas or GM 90 or 85-145 gear oil.
Good luck.Comment
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Re: Gary Ramadei: Diff Case Spreader Necessary?
So Joe
Where are you with the rebuild?Comment
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Re: Gary Ramadei: Diff Case Spreader Necessary?
Hi Gary,
I'll be polishing the case and chamfering the pinion gear shaft holes later this week. I ordered two halfshaft safety loops from DragVette. I have decided to order one big block style stub shaft to match my spare. I'll order that from Tom's. I'll use the new stub on the left side and the used, good original "spare" on the right. I have decided to re-use all bearings and seals, as they are AOK. I will re-use my "snowflake" discs since they are in good condition, I don't use drag radials or wide rear rubber, and the posi always worked as it should. What I WILL do, however, is to build it without the cage and preload springs, and shim it per your instructions. There should be no need for all the turning of the case since my clutches have long ago worn in. Do I still need 2 full bottles of posi additive if I build it this way? I recall that I added 1 1/2 bottles when I built the thing in 2000. I will be needing more shims for the side gears. CAN I USE CASE BEARING SHIMS FOR THE POSI SHIMS? THEY ARE ABOUT 1" SMALLER IN DIAMETER AND I HAVE A LOT OF THEM. I'll use "The Right Stuff" to seal the diff to the rear cover, and then fill with 85W-140 dino gear oil. If I can find a suitable plug with the indented square hole, I'll drill and tap for a drain plug, as well. I have a 1/2" NPT tap.
I haven't found anybody around here who I trust to set up the ring and pinion. I am going to re-use the pinion bolts and set them in with red LokTite. Will not go with a steel bearing cap at this time, nor will I go with a solid crush sleeve. If I can't get the ring and pinion set up then I'll have to settle for having the car laid up until the spring. I might run it over to you this winter for setup, and reassemble the rear suspension in the early spring.Comment
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Re: Gary Ramadei: Diff Case Spreader Necessary?
Hi Joe
I just read your thread on CF as well. Couple of thoughts.
First I found it interesting Dave used my picture of the blown apart posi but didn't reference me, I believe I was the only one there who posted detailed pictures. Not unusual on that site though. Also the most important part of tuning is the correct seating and balancing of the clutches/spiders. Sky65 ( Tom ) called me a few times and I just don't think he got it correct because if it's as loose as he states it wasn't done correctly. Nothing against Tom at all, this is a challenge for the first time tuner and trying to coach someone on the phone is not an easy task. It takes me a good 5-6 hours alone to polish and tune a posi. Also on CF is a thread on a blown diff and a guy who said he has a Super 10, he does not and I doubt he realizes what he paid for. A tuned posi does NOT use the springs and plates. Point being- the info I see on CF is plain wrong.
Now for your diff. You are the boss, you can build it anyway you want but is sounds like you are getting things mixed up a little. When I speak at seminars or directly to guys on diff building the first thing I ask is "how are you going to drive the car"? If you have under 400hp and will not beat up the car you can use a stock type build, meaning you are correct that you do not need a steel cap or solid sleeve. I never build a posi with the springs or without polishing them, just about everyone else does. They can pop a posi together in no time. You have a NOS case so you are starting with a solid base to build up. These cases are better then the new loaded cases sold in the aftermarket for several reasons. You are going to polish the case so that is good. You will find these cases are not as far off dimensions as the old 65-79 cases are.
I never use those snow flake clutches, again I have seen plenty like the ones in my picture on CF. Many are not broken but I always use a new solid steel clutch set. These went up 40% in price in January, maybe a sign they may not be around much longer?? You can mic them and reuse them but for the cost vs removing the diff in the future isn't worth it to me. If they are under 067" thick replace them.
Tuning a posi is going to take time as mentioned. I did plenty of them by hand as well, it's a good work out but I since built a machine to do it like Tom's video shows. I probably run in a posi 700 revs cw/ccw before I'm done. You will have to do the same with used clutches. Many times I grind shims to size to dial in the tune and balance it. There is more to this then just shimming. Look over Tom's video, look at the part where he shows the cross shaft sliding in smooth. This has to happen in any position. If the posi is on the axle in a vise and is smooth and the shaft is free, then you flip it over and it drags it is no good. It is not balanced and is not going to work as it should. Most guys fail at tuning because they don't understand this important step. Maybe this will be a demonstration for the next Carlisle seminar?
The posi additive I believe changed chemistry a few years ago. I never needed more then 1 bottle per diff until the part number change and I had 1 posi chatter. Once 2 bottles were added in total it was fine. I would stay with 2 bottles.
Side shims are not the same as posi shims, I would not mix them. I have posi shim sets if you need them. Be able to grind them to size really helps. Some times the kit shims are fine, but most require a tighter fit. The shims come in 005 increments which can be a "mile long" when tuning a posi, I like to work within 001"
1/2 loops, we destroyed one when a joint failed and they would not back it up. Prior to that we found a poor weld on one.
Went to Tom's as I should have in the first place and use his loops.
Axles. You can use rebuilt or originals but I stay away from the New axles unless they are Tom's or Internationals. The others all come from a place in TX and are reboxed by the vendors. I believe they are imported and the ones I used or bought to use were soft faced or the snap ring dimension was way off. Buyer beware. The rebuilt ones are good - as long as you check them when you get them QC is not good.
Bearings, again your call on reusing yours but I never would. I only use USA Timkens just another insurance part in my opinion.
Drain plug, 1/2 npt is way too big. 1/4 npt is what I use with a magnetic tip. Best mod you can do, oil changes are now a 15 minute deal.
When you mention Pinion bolts, are you referring to the cap bolts? If so you can reuse them but I never do. For $5 socket heads are a stronger bolt and easy mod. The important check is to be sure the cap has 001" rock in it.
So I guess that's it. A diff built with a correctly polished and tuned posi, 10-17 spiders, solid steels, ARP Ring Gear bolts, Rebuilt hardened ip axles, drain plug, socket heads fit in caps with 001 rock and USA Timken bearings should hold up to 400hp all day long. If you mix and match then who knows?
Proper pattern setup is critical along with preload. Used bearing preload is not the same a new bearing preload. Correct case bearing preload has to be applied as well.Comment
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Re: Gary Ramadei: Diff Case Spreader Necessary?
Since they are new stamped they range from 068-070. Most are in the 069 range. When the faces get real shiny they are worn. You could probably get away with 065 -067" but again I wouldn't use them under 067". Some times they are warped too. They have to sit flat once you lay them on the side gear. Assemble then with the deepest stamped side in one direction.Comment
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