What is a high pinion diff?
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Postmaster
Joined: Oct 2006
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From: Davis & Newcastle, CA
What is a high pinion diff?
I'm looking at buying some new gears and a guy has brand new 4.10 ring and pinion for $95 shipped but he says they are NOT for high pinion front end. What does high pinion mean and do I have it? Also is $95 a good deal here?
On a related subject, how hard is it to change the ring and pinion myself? I've heard it is quite difficult. Worth my while if I have never been further than taking my diff cover off?
On a related subject, how hard is it to change the ring and pinion myself? I've heard it is quite difficult. Worth my while if I have never been further than taking my diff cover off?
Last edited by Skandocious; Jul 27, 2007 at 04:30 PM.
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Postmaster
Joined: Oct 2006
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From: Davis & Newcastle, CA
Okay so he replied back and said they they were GM or Dodge style gears, not reverse cut like Ford. Is this true? My ring and pinions are reverse cut? Only in the Ford rear or on both my differentials?
Senior User
Joined: Feb 2002
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From: riverton u.s
i think it was 77-79 when the started the high pin or "revese cut" you will have to have a R&P cut for that. I would assume you have a d44 up front 8.8 rear. if you stock truck is running 3:55's then you need more than just the R&P. You have to have all the guts and case as well plus master instal kit for both front and rear. you can buy the set up through randys ring and pinion. I tend to like to buy from a good store that can back up their products.
Post Fiend
Joined: Mar 2002
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From: Bonita Springs FL
Originally Posted by subford
You have a 4X4 right?
4.10:1 is LOW
2.75:1 is HIGH
You can not change the rear without changing the front.
In other words you can not have a 2.75:1 in the front and a 4.10:1 in the rear.
4.10:1 is LOW
2.75:1 is HIGH
You can not change the rear without changing the front.
In other words you can not have a 2.75:1 in the front and a 4.10:1 in the rear.
Chris, you have a high pinion reverse spiral Dana 44 in your truck. Since about 1977 or so, all Ford Dana 44 front axles have been high pinion reverse spiral.
Lots of people saw reverse rotation, reverse cut, etc. but the correct name is reverse spiral.
Here's a good website about it: http://77cj.littlekeylime.com/Dana44.htm
The dana 44 has a carrier break at 3.93. It's not a physical thing, it's an imaginary line that means you need a new carrier if you cross that line with your old and new gear ratio.
You have 3.55's now - so you could put as low as 3.93 gears in the front before you need a new carrier. If you go with 4.10's you will need a new carrier.
Last edited by andym; Jul 27, 2007 at 06:14 PM.
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From: riverton u.s
I dont want to doubt you, but I was allways under the impression that the break was 3:73's? Anywho I have been know'n to be wrong alot if you ask my wife.
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I checked, and the break is at 3.92, not 3.93. Lots of aftermarket companies make 3.93 gears for the 44.
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Postmaster
Joined: Oct 2006
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From: Davis & Newcastle, CA
Andy do you know how to swap the gears out if I change up to 4.10s?
And hey, I bought an electric fan, when it gets here we should do my truck and your Bronco at the same time
And hey, I bought an electric fan, when it gets here we should do my truck and your Bronco at the same time
Elder User
Joined: Oct 2006
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From: Redmond, WA
I replaced the 3.55 gears with 4.10's in the rear end myself. But I outsourced the front D44 to a ring and pinion shop. I needed the 4 wheel drive that weekend and was stretched for time to finish up the front end. The 8.8 was pretty painless. The crush sleeve on the pinion took some work...but the rest went by painlessly. I used a propane torch to heat the rear case to get the final shims in. Make sure you have your backlash set to spec!! Keep it between 0.008 to 0.012" and you'll be fine.
Spend some time painting the new gearset to get the proper pattern. You might have want to purchase an extra bearing there... I had to press and re-press the pinion bearing 3 times before the drive and coast patterns were set properly. I torched the cage removing the bearing the final time. That was the only hiccup for me. And this was my first rear end rebuild and gear swap. Once that pinion depth is set... the hard part is out of the way.
You will in fact need a new carrier for the front end. You can purchase a carrier with an LS for about $200. Carrier alone with an open diff...around $80.
Broncograveyard.com, ringpinion.biz all have good prices. Ringpinion.biz (JT's rearends) has excellent customer service as well.
Spend some time painting the new gearset to get the proper pattern. You might have want to purchase an extra bearing there... I had to press and re-press the pinion bearing 3 times before the drive and coast patterns were set properly. I torched the cage removing the bearing the final time. That was the only hiccup for me. And this was my first rear end rebuild and gear swap. Once that pinion depth is set... the hard part is out of the way.
You will in fact need a new carrier for the front end. You can purchase a carrier with an LS for about $200. Carrier alone with an open diff...around $80.
Broncograveyard.com, ringpinion.biz all have good prices. Ringpinion.biz (JT's rearends) has excellent customer service as well.
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Postmaster
Joined: Oct 2006
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From: Davis & Newcastle, CA
Once again, Mike, you have impressed me with your expertise and willingness to help. The problem is, I am not at all familiar with the insides of the differential or how anything works (or what its called for that matter). So most of what you just posted means next to nothing to me... I wish it made sense because I want to do this swap SO BAD!! Thats why I was asking Andy, hes the only guy local to me that has a good knowledge of these trucks.
Just out of curiosity, did you buy the gears for the front end and take them to the shop with your diff? Or did you buy the gears from the shop? Either way, how much did they charge you for that?
Just out of curiosity, did you buy the gears for the front end and take them to the shop with your diff? Or did you buy the gears from the shop? Either way, how much did they charge you for that?
Post Fiend
Joined: Mar 2002
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From: Bonita Springs FL
Originally Posted by Skandocious
Andy do you know how to swap the gears out if I change up to 4.10s?
And hey, I bought an electric fan, when it gets here we should do my truck and your Bronco at the same time
And hey, I bought an electric fan, when it gets here we should do my truck and your Bronco at the same time
There was a really good website that detailed exactly how to set up an axle. It was for a Chevy 8-bolt, but they're so similar to the 8.8" that it would be close enough.
Or.... there's a sponsor of the site, bad shoe productions, that sells a video on how to set up an 8.8". I think it's about $20.
If you want to try it, I'm game for it. At least then I know someone that has the tools for it.
The fan swap I've been putting off for a long time. I just have the fan, not the kit. The relays, etc. is something that I haven't researched a lot yet. Plus I've heard that a stock alternator on a 90 Bronco may have trouble keeping up with what an electric fan draws. I'm sure it would be kicking on a LOT here in the summer.