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Drill and tap ring gear?


wheelman

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I just bought a Power Brute LSD with the 12mm bolt holes. I haven't actually pulled my open carrier yet to verify it has 10mm bolts but I'm pretty sure it does.

I checked with a local transmission shop to see what they would charge to swap the carriers for me as I don't have the tools to check the lash and was given a quote of almost $500.00.

So now I'm thinking "I can buy a dial guage, new bearings and have them pressed on for less than that."

I mentioned the 10mm, 12mm thing to the guy and he said they'd drill and tap the ring gear, how hard is this to do? I have a full size drill press at home and access to carbide bits from work, is this something I could do myself?

I know it's been argued here that it isn't really worth worrying about but I want to do this right. If it's a major job to drill and tap the ring gear then I'll either use spacers or buy some shoulder bolts.

 

Wheelman

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I'd buy a $20 dial indicator and make some spacers for the ring gear bolts (12mm OD 10mm ID tubing cut to fit). My backlash changed .0005" when I installed the LSD. I don't think it usually changes enough to worry about it. Once the diff is out installation takes maybe an hour and a half. Really easy. The hardest part should be pressing the new bearings onto the carrier.

 

If for some reason yours is different and the backlash does change to a degree that needs adjusting, then it's a bit tougher because you'll have to find a shim size close enough to work. But I haven't ever seen or heard of that being an issue.

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Mine was exactly the same before and after. I bought a 3.54 R200 from an 85 turbo car that had 12mm bolts. Gave $50 for it. I have a Yukon side gear puller so pulled the OEM bearings and re-used them. Drilling the ring gear is an exercise in futility IMO. Get some 12mm OD 10mm ID tube and cut spacers from it as John mentioned.

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Most of us got them from one member here who was nice enough to make a whole bunch of them. He used stainless 12mm OD 10mm ID tubing, and I'm not sure what he used to cut them to length. I would say that it is important not to cut them too long. Too short is not a problem, but too long prevents the ring gear from being tightened down all the way...

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I had a machinist use some K-monel material. It was handy and had the proper ID. Any steel material would work. Don't use an alloy such as aluminum or copper as these are too soft and would probably allow the ring gear to loosen over time. As Jon states, these bushings MUST NOT extend beyond the mating surfaces of the diff. The ring gear MUST seat tightly to the diff flange. Things would go bad quickly otherwise.

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Wheelman,

 

The ring gear bolt spacer issue has been discussed in depth previously however, when I purchased my LSD from Precision Gear I asked them what they recommend and what they do....Precision Gear has been building LSD diff's for on and off-road racing successfully for many years. What they told me was......"You do not need the spacers. We've installed many of these type differentials without using spacers, with great success. Ring gears are secured by the the torque of the bolts. When properly toqued, the ring gear will not move." I followed their advise! Think about it, if you make spacers and they are a shade too long, they will prevent proper torque on the ring gear....hmmmmm! If you make spacers that are of the proper length, then they will just float in place....doing nothing! Again, I followed the tried and true advise of certified proffesionals.....you make the call!!!

 

Tom

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Think about it, if you make spacers and they are a shade too long, they will prevent proper torque on the ring gear....hmmmmm! If you make spacers that are of the proper length, then they will just float in place....doing nothing!

Tom and I have been back and forth on this one what, maybe 10 times now? :wink:

 

One difference between an R200 and pretty much any other diff you'll open up is that most ring gears are a PRESS FIT on the carrier. You literally have to beat them onto the carrier with a dead blow hammer.

 

On my R200 the ring gear literally fell off of the carrier once the bolts were loose. In addition to clamping the ring gear to the carrier, if the ring gear should slip on the carrier (which again I think is much more likely on our diffs because of the loose fit) then the bolts would take the shear loading between the gear and the carrier. If they are loose then I think a tighter fit between the bolt and the carrier would mean that the bolt would be less likely to shear. If the ring gear spacers were $200 I'd say forget it, but they're not. You can make them cheaply and I still feel it's worth doing.

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The only metal 12 mm OD - 10 mm ID tubing McMaster Carr carries is made out of copper. After looking high and low for 1/2 inch SS tubing to make a fuel pick up tube I can catagorically say if MMC doesn't have it good luck.

 

They have 12 mm OD and 9 mm ID that could be reamed out to work I guess.

 

I like the no spacer route.

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The only metal 12 mm OD - 10 mm ID tubing McMaster Carr carries is made out of copper. After looking high and low for 1/2 inch SS tubing to make a fuel pick up tube I can catagorically say if MMC doesn't have it good luck.

 

They have 12 mm OD and 9 mm ID that could be reamed out to work I guess.

 

I like the no spacer route.

McMaster Carr is not the only game in town. Mat found it online. Some leads (I don't think it would take more than 5 minutes to track it down).

 

http://www.google.com/search?sourceid=navclient-ff&ie=UTF-8&rlz=1B2GGGL_enUS176&q=metric+tube+stainless

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I found a place called Metric Metal (www.metricmetal.com) that lists 12mm OD x 10mm ID steel tubing. I sent an email asking for a quote but never heard back, maybe they only deal with large quantity orders.

 

Anyway I finally decided to see if I could make some for myself. I had some sheet metal laying around the garage that it turns out was 1mm thick. So I cut a strip long enough to make 10 30mm long strips. I made sure the strip was narrower than the depth of the holes in the diff. I cut it into 10 30mm long strips and wrapped them around one of the 10mm bolts from the diff. There is a 3mm - 4mm gap between the ends of the strip once you wrap it around the bolt, I oriented the gap to face the outer edge of the diff when I placed them in the holes. The gap can be widened to provide an interference fit that locks the spacer in place, this means they won't just float.

 

So what do you guys think of this idea?

I can take some pictures if you want so you can see what I did and let me know if the idea is totally wacked.

 

I also ordered a dial indicator to do the install myself, it should arrive on Thursday.

 

Wheelman

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The wrapped shim will work fine as long as it is not a soft material that can squish. The tighter the gap the better. The whole idea is not allowing the ring gear to rotate upon the face of the diff. Without the bushings you are hoping that only clamping forces prevent this movement. If it does move then it is possibly/probably just a matter of time before the bolts shear because clamping forces would not have been adequate. I personally prefer to err to the side of caution because problems here would cost a lot to repair. Any machine shop could pump these bushings out with ease.

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The material is some alloy of carbon steel, not sure what alloy exactly but I'm pretty sure it isn't stainless.

 

I'll update this thread once I bolt the ring gear on, it may turn out that the shims get much tighter as the bolts are threaded into the ring gear and any alignment issues with them come into play.

 

Wheelman

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The material is some alloy of carbon steel, not sure what alloy exactly but I'm pretty sure it isn't stainless.

 

I'll update this thread once I bolt the ring gear on, it may turn out that the shims get much tighter as the bolts are threaded into the ring gear and any alignment issues with them come into play.

This whole wrapping the bolt with a piece of metal thing sounds like a huge PITA to me. Mat was able to find the metal. He had to buy a stick that was 6 or 8 feet long, but he made a hundred spacers and sold them to guys like me. I'd find them or leave them out, but trying to make them just seems like a huge hassle.

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Guys..........If an R200 w/lsd can servive the rigors of the Baja 1000 without these spacers, it will surely survive in your street car....I think Precision Gear knows what they are talking about when they say the spacers are not necessary!!!!! Jon, this is not directed at you by the way!

 

Tom

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I have no clue as to what is better spacer or no but I can comment on drilling and tapping the ring gear.

 

Simply put, I wouldn't do it. That ring is hardenend steel that was most likely cut first then heat treated later making it exreamly tough. Carbide tools would do the trick but unless you have very good SOLID mounting hardware for your drill press, getting done will be difficult.

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Guys..........If an R200 w/lsd can servive the rigors of the Baja 1000 without these spacers...

The person who did that is really stupid. Why you wouldn't spend $50 and have some shouldered ring gear bolts made, or better yet, get the right carrier in the first place is beyond me. I wouldn't base any decision I made on some random moron's good fortune. Not trying to get bitchy about it, but that's a pretty damn stupid thing to do.

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McMaster Carr is not the only game in town. Mat found it online. Some leads (I don't think it would take more than 5 minutes to track it down).

 

http://www.google.com/search?sourceid=navclient-ff&ie=UTF-8&rlz=1B2GGGL_enUS176&q=metric+tube+stainless

 

Has anyone found a source of tubing yet?

 

Guess we need a source that will return emails and is not in England. Then they need to be willing to sell something smaller than a ton at a time.

 

Did find some 12 mm OD - 9 mm ID. Guess that could be reamed out.

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