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Discussion Starter #1
I have a 35 spline Detroit for 4.56 and up and was attempting to install RC 5.13 thick gears. I ran into a problem of the ring gear hitting the pinion and not allowing the Detroit to position itself fully inside the diff. I called up Randy's R&P thinking there was a thin gear and explained the situation. They told me there were no thick and thin RC gears for a Dana 60, just the thick ones. They did say there was a different Detroit for RC 60's, but sounded unsure. Anyone have any insight to this?
 

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my spicers 5.38's are a thin gear, however many aftermarket rc 60 gearsets are a thick gear...sounds like what you have...
 

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That's odd.

I always thought that the purpose of a 'thick gear' was that if you had a 'low range' case -4.10 and wanted to put lower gears in it +4.56, you would get a thick gear so you wouldn't have to change out the carrier.

If you are using a thick gear on a 4.56 + case, you would have your problem.

I called Randy's about a month ago, and mentioned 'thin and thick' gears, and they asked 'which' I wanted? :confused:
 

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the thick gears won't work with the 4.56-numerically up case.
I had a long talk about this with a buy at Randys the other day.
you need thin gears or a 4.10-down case.
 

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Eric said:
IIRC, RC 60s use the 4.10 and down carrier for all gear ratios so this is why they make the gears thick.
nope, this is just what randy's wants people to believe...cause my front and rear axle both run 4.56 and deeper detroits and factory spicer 5.38 gears in the front, with richmonds in the back... When I mentioned to West Coast Differentials that randy's had told me that they told me that I wasn't the first person that randys had told that, and that he thought it was because randys was trying to make extra money off of selling new diffs to people who had already purchased the 4.56 and deeper diffs...
 

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I'm having the same problem in my research. What I've learned is that you need to buy your gears, then the carrier. I almost ordered the wrong ARB for my RC 5.13's. There are both thick and thin gears for RC60's, and not in every ratio. You just have to find out which ones you're going to buy, and then get the carrier that matches it. What a PITA!!
 

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Thanks for clearing that up. I thought I was screwed if I ever changed my rear 60 (5.13s w/ARB) out for a RC60. I would hate to buy another locker just because I wanted a RC housing. So if I can keep my 4.56 and up ARB carrier, I need to order thin 5.13s?
 

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Yeah, you may want to check on that. 5.13's are what I was looking for and I don't think anyone made them thin. Spicer definitely has 5.38's in a thin gear, but for some reason I was having troubles with the 5.13's.
 

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Randy's told me you had to have a thick gear bout 3 weeks ago
 

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Yes, all RC D60's use the same carrier.

Yes, it's the 4.10 and down carrier.

Yes, RC60 stock gearsets are "thick"

However, Detroit doesn't make an RC specific locker, just 2 pns for 4.10 down and 4.56 up. Which means if you had stock (thick) 4.56 gears for an RC60 and bought the 4.56 and up Detroit, you'd be SOL. Since you have the 4.10 and down, you're good to go.

Not all ratios from all manu's are available in thick and thin
 

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Discussion Starter #13
Well that cleared things up. Luckily Randy's sold me another Detroit (4.10 and down) and will take my Detroit in return and refund the money back...so I am told. I'll keep you posted on what I find.
 

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Is there a way to determine if you have a thick or thin gear?

I just bought a pair of RC 4.88's for my 60 and will be ordering a Detroit in the not to distant future. I want to make sure I order the correct one.
 

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Insayn said:
Well that cleared things up. Luckily Randy's sold me another Detroit (4.10 and down) and will take my Detroit in return and refund the money back...so I am told. I'll keep you posted on what I find.
Rob,

I tried to get you to use the other company! :flipoff2:

Chuck
 

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Did some research, and must correct an error in my above statement, and I'll update the article soon.

If you go to the linked BOM detailed table in my article, you will notice something.

The carrier is the same for all Ford RC 60's UP TO 98, and is the same as the GM/Dodge 4.10 carrier - namely part # 706040X.

BUT - you wil also note that the Ford RC60 was never offered stock with a ratio lower than 4.10 in those years. So I imagine all those stock Spicer gersets were not thick.

So, here's what I imagine happened - when afterarket vendors started making gears lower than 4.10 for RC 60s - they made the ring gear thick, so it could just go on the stock carrier. So if you bought aftermarket 5.38 gears for RC60 - they would likely be thick.

Now - if you buy an aftermarket carrier (i.e. locker) for your RC60 - I imagine, depending on where you buy it from, thay ask "year/make/model" and based on that would likely sell you the 4.10 down Detroit - that way - if you already had aftermarket lower gears, they would just go on the locker.

The problem you ight run into, is what happened to Insayn. You buy aftermrket gears first - lower than 4.10 and they're thick. Then you buy a locker by ration, not make and model, and naturally you'd think "I have 5.13 gears - I must need the 4.56 and up locker" but you get hooped because the gears are thick.

The 2000+ RC60- fords are offered with stock gears as low as 5.38 - but these are not thick and go on the same old 4.10 down carrier - they are thin and go on the same GM/Dodge 4.56 up carrier. The carrier break is 4.30 and down go on the 4.10 and down carrier.

I don't know if Spicer is the only manufacturer offering thin RC60 gears - I'll have to do some research.

Bottom line - you do have to match your carrier and gear set.
 

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Discussion Starter #18
Bella Vista hit it on the head. For a 4.56+ thick gearset you will need a 4.10- Carrier. Unless you find a thin gearset.
 

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Insayn said:
Bella Vista hit it on the head. For a 4.56+ thick gearset you will need a 4.10- Carrier. Unless you find a thin gearset.
OK, is this also the same scenario when buying a spool and gears for the rc60? Inquiring minds want to know.
 

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Discussion Starter #20
I would imagine that would depend on what type of gears you get. If you get a 4.56+ that is thick you will need a spool for 4.10-
Most RC gears are thick because the highest ratio available in a RC 60 was 4.10. So a majority of gearsets were made thick to fit onto the 4.10- carrier. Call the techs where you are purchasing your gears and ask them if it is thick or not. If it is then get a 4.10- spool.
 
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