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How to make 10mm to 12mm spacers for a R200 ring gear without machine tools


LT1-280z

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Necessity being the mother of invention I wanted to share something I came up with. Since it’s nearly impossible to get small quantities of metric sized tubing in the US and I don’t have access to a lathe. I came up with an idea to make my own by resizing 1/2†OD tubing by forcing it through a die. I started with 1/2" OD x .035†wall DOM tubing I purchased from Fastenal. The OD / ID are too large to start but after shrinking its darn close to 12mm / 10mm. Using a scrap of 1/2" plate I had lying around I drilled a 31/64†hole with a bit from a standard 1/16†to 1/2†drill index set, I then slightly tapered the hole with a hand reamer about 1/4†deep to make the die. I then forced a 10†piece f the tubing though the die with my hydraulic press. The tubing diameter was reduced to very close to 10mm x 12mm. It did come out a little curved but with such short pieces it won’t matter. I cut the now reduced tubing using a tubing cutter to make sure the cuts were square, into 10.5mm pieces. I then used a counter sinking bit to remove the internal ridge left buy the cutter. The OD came out jut a little over 12mm making a nice press fit into the differential housing, with little effort I used a 10mm bolt and nut to draw the spacers into place.

 

DSCN0818.JPG DSCN0817.JPG DSCN0816.JPG DSCN0813.JPG DSCN0814.JPG

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Older R200's have 10mm ring gear bolts. Newer ones have 12mm (not sure of the cut off year). Most LSD units are 12mm, but the ratios tend to be 3.70:1 and numerically higher. In order to install a LSD unit in an older R200 or if you want the numerically lower ratios common in the older R200 (3.54:1 being most common). You use spacers to make up the difference. Although some have not used spacers and have not reported problems, IMO spacers should be used.

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LT1-280z,

I can't believe we practically live in the same town and I've never seen you around. I looked at your photo album and I am extremely impressed with your work. I didn't know what those photos were all about until now. Very crafty! Can't wait to meet up. I heard you might be coming to some of our future ZORB meets.

 

-Dave

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Everything I have read about bolts and their strength ratings would cause me to reconsider modifying a bolt in any way... other than to shorten it, drill it's head for retaining wires, or ball-milling the hex head.

 

The threads on high strength bolts are "rolled" onto the blank bolt shafts while they are hot and malleable. They use two large grooved plates to clamp the bolt blank, then the plates slide against one another to "roll the blank while the grooves in the plates create the threads. Then the bolts are heat treated to the required hardness and plated.

 

This process creates threads with a strong grain pattern at the root of the threads. Rolled threads are far superior to cut threads in many ways.

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Thank you all.

 

I agree with bjhines, I wouldn't mess with the bolts. I never heard of anyone shredding the 10mm bolts. So why tempt fate?

 

I did have a thought while dealing with this; what about re-tapping the ring gear to 12mm?

 

Ultimately I came to the conclusion that if a 10mm bolt isn't a failure point it didn't make sense to mess with it.

 

For me its not like I'm making 500hp and dumping the clutch at full throttle with slicks. (hmm... sounds like fun) There are probably better choices for rear ends if that's your thing. But then again I have heard of the R200 holding up to some serious abuse. (other stuff breaking first) :-)

 

Dave - yes I will definitely be at ZORB meets, zee you there!

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