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Wow... with stories like that I feel safe.. and I am happy i went with the lighter 10 bolt.. the whole reason i stayed 10 bolt was the mass weight and the rotational weight.. in that aspect the 10 bolt kicks the 12's ***.. and if it is built like you and I built mine, it seems good for upwards of 850hp i believe which is out of my range,,,, For me this means better lap times and 1/4 mile times.. cool... thx!!!
I have a Tom's 10bolt BOE and this 12 Bolt kit and I just don't think the mass is so much different to matter that much!
But I have still a lot of heavy old school stuff on my car! I have old 2-piece Lakewood scatter bellhousing, I still like 40lb flywheels, I have a 3" steel driveshaft, etc.
I have some Magnesium center Modular rims, and my crankshaft is knife edged, but super circular counterweighted, my 4340 rods are profiled, but my whole car is more vintage and raw! Ya I could probably take signifantly more weight off of it! I did cut out the entire mild tube steel cage and am going back with chromoly. The aluminum engine was bought to help that some! I was waiting on Tom's aluminum rear diff case, but that has been totally sidelined as per the Tom's differential Guy!
Last edited by TCracingCA; May 5, 2017 at 03:23 AM.
the only thing different that I probably will do, is bring my comfortable office chair home with all of the adjustments so I am not sitting on a crate and I would probably keep smashing my fingers balancing the posi cage Carrier on the bearing snout, so would probably drill a big hole through my work bench after shoving my bench clutter onto the ground!
Ps Beer!!!!!!!!!!!!!
Lastly I have never understood why most woman love little dinky pieces of jewelry, but generally show no excitement when they see a big beautifully shiny polished posi Carrier or a big billet part Holley, or new shiny freshly chromed bumpers!
Last edited by TCracingCA; May 4, 2017 at 09:16 PM.
I think what I wrote caused some confusion! Yes if you used conventional 12 Bolt stuff (no machining) you would have to use another non-Corvette 12 Bolt case! What I was trying to convey was I think these Tom's ring and pinions were made to minimize the case grinding and fitting!
But Unlike these great and knowledgeable shops that are on here sharing, I am not anywhere near their level! If I had one of them in my backyard where I could drop it all off, I would consider that just to get it done! Shipping stuff like this has always made me nervous! I don't trust the Post Office and UPS to get heavy boxes anywhere safely or not losing your package, unless you really pack things heavy duty and pray a lot! ! Plus these are rare parts and I feel strange having them go far far far from hom, into the care of strangers that I don't know! But I can tell Tracdogg is a really good guy and outfit! And I am warming up to the others on here! I am just beginning, and I am hoping locally that that Gear Shop still has an old employee who used to build these! Take the project as far as I can intelligently, because I do things pretty precisely and take my time go as far as I can to save some on the labor cost and to help the turn around time! Or maybe once I get to the point to pay someone, I would seriously consider tracdogg or supercharged and others that I am seeing as very knowledgeable guys!
Basically for grinding! I wasn't going to stick gears in and see where they hit and then grind caveman style! I was going to reference from a 10 Bolt case and together ring and pinion and measure that in comparison to the 12 Bolt posi and ring and pinion and approach the grinding by measurement and some patterning! I don't have a lathe but I do have some milling experience and equipment! No where near a professional! But they are my parts, so naturally no one will spend as much quality time with them, as I would!
Ps on my initial post, I was amazed by the sat in place distance the ring gear was sitting up on the posi case shoulder from the Bolt posi surface! Even if I refrigerated the posi case and heated the ring gear, it seemed no where close to slip down the posi case shoulder and onto the surface of where it should mate! It looks to me like you have to use quite a force to press that on and my initial thought without measurements was how is that gear going to handle that! It is a stout piece! I should measure and double check things, because It has been sitting around for years, but maybe someone plucked an unmachined one by accident, a long time ago! I bought this unit when I bought my full aluminum GM performance Small Block (Race Bow tie Wet sump unit) IMSA block basically capable of 800hp! I had the 10 Bolt built for the 500hp 355 cube long Rod engine I was running! I was planning on the highest normally aspirated small block in the history of my neighborhood!
We are good, I now see what you are saying. Nice to see all of this creativity going on.
12 bolt conversion.
The number one reason for doing this is the increased thickness of the carrier. There is some added gain in ring gear diameter also. Why do they cost so much?
Machining. I have seen many "bad" 12 bolt conversions. Because people just don't know what they are doing. The typical method of clearancing the housing for the ring gear is what I refer to as the "drop and gouge" method. Drop the carrier and ring gear assembly into the housing and wherever the teeth gouge the housing is where you start grinding. 6 hours later it eventually clears. But now the balance weights on the carrier are hitting the side of the housing. More grinding on an already thin area.
Next the left side cap is hitting the carrier. Start grinding on the carrier. Now the ring gear bolts are hitting the housing. If you are running a 3.73 gear the ring gear bolts are too long and bottom out in the gear. If you grind too much off the housing the bottom left cover bolt will crack the boss. All this plus everything I laid out in the previous post and you will have 30-40 hours invested. Is it worth it? OH YEAH!
After seeing other people literally butcher these housings I built custom jigs and boring bars to do all this properly. No gouging, no guessing. My cap is custom made just for the 12 bolt.
Dave, you can see the radius on the cap for carrier clearance we were talking about. You can see how close the machining gets to the pinion race and the lower left cover bolt hole.
Thanks Mike!
Next time we talk I will incorporate it into the next set.
I am getting a good idea of what I want to do for billet aluminum cover. I may go for it after we discuss any possible options that you feel are necessary.
Last edited by 76strokervette; May 4, 2017 at 11:35 PM.
The more I think about clearancing these cases, and after the drop and gouge technic and troubles, thinking the better way to do the case clearancing would be to seat the posi carrier cage in with the bearings and no ring gear pressed on! Create something that can be laid on the ring gear flange (clamp it to it) that is the same thinkness and diameter. As you rotate it acting like a gauge mark and measure the track path! Find a way to measure from the ring gear surface to the case! Ya pressing on that ring gear and trying to do as tracdogg described (rough grinding the clearance) would not be a method that would net any precision and compromise the case! Heck once you have what you think is the clearance, you could then make or have made a foam or wood template slid on bolted up or attached that simulates the ring gear to check your work! Then if all looks good, take the posi carrier out and press the ring gear on and proceed!
It would though be nice to ship the case out and have it done! Jig and boring bars are professional level cool!
Last edited by TCracingCA; May 5, 2017 at 04:12 AM.
Mike is doing my HD 10 bolt right now. I went with everything to make the strongest 10 bolt possible. Along with Dave's caps, Mikes work and my 1480's back there, hope to test the limits often. Great thread here! Love the technical stuff.
Oh and did someone say billet aluminum cover lol?
Last edited by 69ttop502; May 5, 2017 at 07:09 AM.
Thanks Mike!
Next time we talk I will incorporate it into the next set.
I am getting a good idea of what I want to do for billet aluminum cover. I may go for it after we discuss any possible options that you feel are necessary.
Not billet and not corvette this is a cover I build for Dana 80 Rams sorry a little off subject. I am going to use a bat wing on mine.
I am not sure who all has these! But supposively they are made a little deeper to clear larger ring and pinions!
My steel cover is lightweight and strong, but I am going to get one of these, just to check it out. If I don't like it, I can sell it to one of you guys!!!!
This was from Ecklers and not sure who else sells one. And for you guys that like that ugly, but I guess functional Shark Bite suspension? They have another one for that thing!!!!
And I should go back and give the Corvette enthusiast credit for the idea! But here is a 1350 set up of telescoping halfshafts!
I am shooting for essentially vintage 1970's Formula One type suspension in the A$$ end of my Corvettes. Essentially multi-link using top rod to top of a Guldstrand or CVC-Apex (later Greenwood) suspensions that I have in my garage. So I am removing the halfshaft out of the suspension, by going to these floating units.
But I am building my halfshafts with the 1480 sizing, and those are the number earlier in the thread that I came up with that mimics this 1350, that this Corvette enthusiast shared.
The 1350 was built on 1.5 16-spline and the units for a 1480 set up, I think the best I could come up with was 1.562 16-spline, so a little for meat. The other thing that wasn't to my liking, but I couldn't find a unit was the yoke on the male spline unit is 3.5 tube, and .083 wall. I could not find a male spline with a .095 or .134 wall, but that section is tapered up from the splines and very short where the .083 wall is!
And Lastly duh!!!!!!
Because of my 3.73 planned ratio I was thinking 3-series case, but because of the posi carrier, I have to have a 4-series case! I had better plan to go visit my favorite Corvette Parts guy!
Last edited by TCracingCA; May 6, 2017 at 09:23 PM.
I am not sure who all has these! But supposively they are made a little deeper to clear larger ring and pinions!
My steel cover is lightweight and strong, but I am going to get one of these, just to check it out. If I don't like it, I can sell it to one of you guys!!!!
This was from Ecklers and not sure who else sells one. And for you guys that like that ugly, but I guess functional Shark Bite suspension? They have another one for that thing!!!!
I just bought one of those from Speed Direct........wanted the weight savings. They make them, so all vendors get them from them. I got a 10% Corvette Forum discount by calling and ordering from Speed Direct.
I just bought one of those from Speed Direct........wanted the weight savings. They make them, so all vendors get them from them. I got a 10% Corvette Forum discount by calling and ordering from Speed Direct.
And you have a real good fast car, so we will know very quickly if the darn things will hold up!
The current plan is I will pickup the differential and trailing arms at Carlisle. We would like anyone going to have a chance to see the build in person. I look forward to meeting any who are coming and as a bonus work on my corvette education.
No pressure Mike!
Dave
Or you can make your own 5 link . Added a whole year to my build.
No TOE OUT on acceleration . Eliminates the typical squirrely corvette squat. If I had to do it again ......
