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12 bolt conversion

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Old 11-08-2017, 07:54 AM
  #141  
76strokervette
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Originally Posted by R6n350GT
How much are you selling these for and do you make for both 1330 and 1350 ? come with new bolts ?

Whats the weak will point, the cap, bolt or ujoint ? that is with street tyres and <350HP
Mike tested the 1330 clamp which is the 1st one shown in this thread.
He had to destroy the fastener to get the clamp to bend. The 1350 clamps are heavier so I would definitely say the fastener will break first.
I now have what is needed to make every corvette specific application.
The plan is to get all bases covered first and go from there.
Stock components in good shape usually hold up to 350 hp with street tires. Add sticky tires and that may change.
Old 11-08-2017, 07:08 PM
  #142  
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Originally Posted by 76strokervette
Mike tested the 1330 clamp which is the 1st one shown in this thread.
He had to destroy the fastener to get the clamp to bend. The 1350 clamps are heavier so I would definitely say the fastener will break first.
I now have what is needed to make every corvette specific application.
The plan is to get all bases covered first and go from there.
Stock components in good shape usually hold up to 350 hp with street tires. Add sticky tires and that may change.
Thanks for the reply. What do you mean by fastener ?

I think i will have 350-400 with pilot spot 4 tyres.
I have 1330 on the spindle ends and 1350 on the diff end.
the original unis that need replacing. One of the 1350 to 1330 ends have been replaced but you can only get them with grease fittings.
But they have the original straps and bolts... i went and got some new Allen key bolts to replace the bolts as some were starting to round.

What would you upgrade for my power ?
Old 11-08-2017, 07:31 PM
  #143  
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The fastener I was describing was a 5/16 bolt. The bolt was tightened to the point that it twisted in order to effect the part. I am guessing you have the dana 44 in an 80 to 82. I would upgrade as much as possible due to the carnage if something lets loose. What size bolt goes in your 1330 size axle?
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Old 11-08-2017, 07:53 PM
  #144  
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Originally Posted by 76strokervette
The fastener I was describing was a 5/16 bolt. The bolt was tightened to the point that it twisted in order to effect the part. I am guessing you have the dana 44 in an 80 to 82. I would upgrade as much as possible due to the carnage if something lets loose. What size bolt goes in your 1330 size axle?
1/4" bolt in the 1330 and 5/16" in the 1350-1330 conversion.

I can either upgrade to uni to 1330 spicer HD non greasable uni and upgrade the strap, drill and tap the flange to accept 5/16" or change out the flange to a manual 80-82. Drilling out would be cheaper...

I would then have 1350 straps and 5/16" bolts on the diff end. Will these be ok or do they need upgrading to ? Then the "weak" point may be the greasable conversion uni
Old 11-13-2017, 08:01 AM
  #145  
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Picture of pinion yoke and cap after black zinc plating.
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Old 11-13-2017, 10:57 AM
  #146  
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Originally Posted by 76strokervette
Picture of pinion yoke and cap after black zinc plating.
Nice.

Not sure if you answered this yet...the straps you are making...are they threaded to replace the u bolt type of u joint fasteners? If so, what is the thread size? I imagine the bolt comes in from the back side. So does that require drilling out the hole to a larger size? A nice hardened cap screw and lock washer or loctite would work. Right?

Good pics
Txs
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Old 11-13-2017, 03:41 PM
  #147  
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Latest part has 3/8-24 threads so you can use bolt or stud of your choice.
Old 11-13-2017, 04:04 PM
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Originally Posted by 76strokervette
Latest part has 3/8-24 threads so you can use bolt or stud of your choice.
Pretty hefty.

Thanks
Old 11-22-2017, 08:18 AM
  #149  
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Latest part is cap for hd inner stub axle.
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Old 11-22-2017, 08:19 AM
  #150  
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Another view.
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Old 11-24-2017, 09:33 AM
  #151  
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A little more technical information for all the big block guys.
The last part is heat treated 4150 and weighs 63.5 grams vs 72.5 grams for the factory cast piece. I will be checking out the ability of both parts today in respect to drive line angle. Not a 12 bolt part but I did get a request to make.
Old 11-24-2017, 09:40 AM
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Originally Posted by 76strokervette
Latest part is cap for hd inner stub axle.
I'm curious if there is a reason why there aren't "ears" on the cap like there are on the yoke part? I know they do not come from the factory with them as such. Having them on the cap would definitely make it harder for the u-joint to ride up over the ears causing a failure. Is there a way to machine a set that do have the "ears" incorporated?
Old 11-24-2017, 10:09 AM
  #153  
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It could be done but I do not believe is needed. The fit to the axle is the same as the pinion yoke and when you add the 3/8 bolts it should be pretty tough. Adding some loctite to the bolts would be cheap insurance.
Adding the tabs would just make the part more expensive with no real value IMO. Also with new part you have 180 degrees of clamping surface and the other side is fully supported by the axle.

Last edited by 76strokervette; 11-24-2017 at 04:57 PM. Reason: spelling
Old 11-27-2017, 08:59 PM
  #154  
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The head of the bolt is what limits the angle on the stub axle. With a set of 12 point arp bolts the new part will allow a larger drive line angle.
Best case made for cast stock part is 60,000 psi tensile strength. The 4150 in new part is 140,000 psi tensile strength.
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Old 11-28-2017, 12:20 AM
  #155  
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Has anyone fitted up a Moroso 1350 cap to see how close they are for the yoke? I think some old school drag racers substituted those onto them!
Old 12-02-2017, 10:28 AM
  #156  
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Originally Posted by TCracingCA
Has anyone fitted up a Moroso 1350 cap to see how close they are for the yoke? I think some old school drag racers substituted those onto them!
I chose the spicer solid u-joint as the model for these parts due to the fact it is most often recommended. The quality control on the spicer parts is usually very good also. I am pretty sure the caps are ground which is why you can get a metal to metal seal. I looked for moroso u-joints and could not find them. Where are you getting them out of curiosity?
Old 12-02-2017, 09:44 PM
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Originally Posted by 76strokervette
I chose the spicer solid u-joint as the model for these parts due to the fact it is most often recommended. The quality control on the spicer parts is usually very good also. I am pretty sure the caps are ground which is why you can get a metal to metal seal. I looked for moroso u-joints and could not find them. Where are you getting them out of curiosity?
I wasn't talking about moroso U-joints, I use very expensive Mark Williams solids for the 1350 ones! I was talking and asking about these gold colored 1350 caps that Moroso sells! They were in the Summit catalog for years! Was just wondering if anyone had bought those, instead of making caps or straps? They look very boxy, and might need to balance parts with them!

Last edited by TCracingCA; 12-02-2017 at 09:45 PM.

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Old 12-02-2017, 10:27 PM
  #158  
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I transferred this over from the under the Christmas tree thread! You can see I had the Super 10 post on a lathe, but haven't started contouring the windows etc yet toward polishing!

On the 12 bolt set up, I was grinding to polish the old fashion way, but only started that! Some pieces aren't in the picture!

"""


And from the Garage are Current projects I have out that I would like to get finished for Christmas!

In the back is the 12-Bolt Conversion with the last set sold from Tom's of true 4340 steel 30 spline inner & outer Axles in 1480 u-joint size! Going in my C2 Racer!

The front unit is a Super 10-Bolt with 30 spline inner and outer Axles in 1350 u-joint size and I have the Billet bolt on u-joint plates, but forgot to show those here! Going in my C3 Autocross car!

Well actually I have one 1480 and a 1350 in the front and back on each in the picture!

I already have another Super 10 in the race car, but moving that into a 3rd C2 Slalom car I have!

Heat treated spiders, and special crossshafts, etc., All drilled for 1/2 inch long studs!

A Virgin never used 1972 4-series case for the 12-bolt!

The sign is the actual shop rate sign out of Guldstrands second to last shop!

Hope everyone else can add more cool stuff to your rides! """"
Old 12-02-2017, 10:41 PM
  #159  
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I believe the girdles you are talking about are made of billet aluminum.
My personal opinion is I would not use them on a street car due to fatigue strength.Surface prep on aluminum parts in a high stress environment is very important. An engineer friend and I had a conversation about this a few months ago. A stress fracture was caused by pits in the anodized surface which ended up bringing a helicopter down. The 1350 pinion yoke shown in this thread is a Mark Williams pc.
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Old 12-02-2017, 10:59 PM
  #160  
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Originally Posted by bence13_33
I'm curious if there is a reason why there aren't "ears" on the cap like there are on the yoke part? I know they do not come from the factory with them as such. Having them on the cap would definitely make it harder for the u-joint to ride up over the ears causing a failure. Is there a way to machine a set that do have the "ears" incorporated?
The stock axles hole patterns are not centered to the part very well.
In a completely machined part this could easily be done and make sense.


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