Diff and gear question
03-02-2016, 04:48 PM
#1
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Diff and gear question
I've looked and researched but can't seem to find the answer. I have a 94 4x4 22re manual tranny with 4.10 gears. The code says I have 2 pinion open diff. Here are my questions;
1. I have 31" tires right now and I may go up to 32 or 33. I've located several threads that say 4.56 for 31 and 32 and anything more 4.88s. How high would my rpm be at 70 mph if I run 31 or 32s with 4.88?
2. I've found several used diffs. Most are off of v6 or automatic trucks. Some are 4 pinion. Will any diff swap into mine no matter auto or manual or v6 or i4 2 or 4 pinion?
3. Auto locking hub diff will not work on manual locking hubs correct?
Thanks
1. I have 31" tires right now and I may go up to 32 or 33. I've located several threads that say 4.56 for 31 and 32 and anything more 4.88s. How high would my rpm be at 70 mph if I run 31 or 32s with 4.88?
2. I've found several used diffs. Most are off of v6 or automatic trucks. Some are 4 pinion. Will any diff swap into mine no matter auto or manual or v6 or i4 2 or 4 pinion?
3. Auto locking hub diff will not work on manual locking hubs correct?
Thanks
03-02-2016, 05:32 PM
#2
1) here Check out your ratio and tire sizes with this nifty calculator:
rpm calculator
2) yes the third members are all interchangeable and the V6 thirds are the strongest.
3) the front thirds are interchangeable from auto hubs (add) or manual hubs (non-add) you just swap the axle tubes over and you are good to go, you actually get a better diff with the add (auto hub) because it has needle bearings where the axle shaft rides in the carrier.
If you are going from non add (manual hub) to add diff (auto hub) it can be done but I had to machine the carrier to fit the needle bearings but I'm a machinist and I have a mill in my garage so it was not a problem.
rpm calculator
2) yes the third members are all interchangeable and the V6 thirds are the strongest.
3) the front thirds are interchangeable from auto hubs (add) or manual hubs (non-add) you just swap the axle tubes over and you are good to go, you actually get a better diff with the add (auto hub) because it has needle bearings where the axle shaft rides in the carrier.
If you are going from non add (manual hub) to add diff (auto hub) it can be done but I had to machine the carrier to fit the needle bearings but I'm a machinist and I have a mill in my garage so it was not a problem.
03-02-2016, 05:50 PM
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Holy cow thank you!!! You answers my questions. But still a little confused about the add. I don't have add and want to keep it that way so do I need to get a none add 3rd? I understand it'll work but I have to modify it? For 31 or 32 as a daily driver would you go with 4.88 or 4.56? Thank again!!!
03-02-2016, 06:01 PM
#4
If you don't have add then you can run either front third member. The add diff is a little better because it has needle bearings in the carrier like this:
Last edited by Yotard; 03-02-2016 at 06:09 PM.
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03-02-2016, 06:25 PM
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I understand that. My truck falls on it face at higher rpms. If I go with 488 running 31 or 32 I'll be running 3500 rpm at 70. I wondering one what will that do to my mpg and two is gonna stop pulling at 3000 rpm and I'll be in the same boat I am now? Not being able to maintain highway speeds.
03-02-2016, 06:32 PM
#9
Well if you want to run 33s ever I would live with the higher rpm for a while rather than regear twice. Lower gearing gives you more torque so I would guess that it would give you better power through your power band but it's going to run the Revs up higher cruising on the highway unfortunately. If you run tires that put you back to stock gearing then expect around stock power again.
03-02-2016, 06:36 PM
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I figured and understand that. I'm just on the fence on 456 or 488. I think I going to go with 456 and 32" tires. Going to 456 with 32" tires I'm still a little higher in the rpm range then stock 225s and 410s I believe. Thanks again for all the advise.
03-02-2016, 06:41 PM
#12
I don't know what you want to spend but that picture I showed you is a 4.56 diff sitting in my garage. I also have the matching rear V6 diff 150,000 original miles. I upgraded to 4.88s in my auto trans truck 2 years ago and haven't put them on Craigslist yet. It's a 4 pinion open rear. Downside is that it would probably be 100 just in shipping
03-02-2016, 06:50 PM
#16
Pinion number doesn't matter. Just makes a difference in strength. I'm in California east Bay Area. I could probably sell these for 350 here on Craigslist so I would take 300 plus shipping so that would probably be around 400
03-02-2016, 06:53 PM
#18
Yeah it's an add front but I put a non add front into my add setup by machining it. Check out my build thread and you can see what I did. You don't need to machine anything by using an add diff in a non add. You just have to put in a $7 axle seal on the add side of the diff and reuse your axle tubes and axles.
In fact I didn't have to machine it, I chose to because it is an improvement to have those needle bearings.
In fact I didn't have to machine it, I chose to because it is an improvement to have those needle bearings.
Last edited by Yotard; 03-02-2016 at 06:55 PM.
03-03-2016, 05:57 AM
#19
It's more about the strength of the stub shafts, ADD vs. non-ADD. And the bigger carrier bearings in the front diff, V6 vs. 4cyl.. Than it is about needle bearings. The needle bearings are good for what they were used for. Such as in an ADD diff that spins constantly. You don't gain much buy using them in a non-ADD setup. And what you'd gain is definitely not worth the trade off of having weaker stub shafts.
http://home.4x4wire.com/erik/diffs/#IFS
'86-95 IFS trucks and 4Runners, and all '93-98 T100s use a 7.5" front diff that is offset to the passenger's side. Later models came with ADD (Automatic Differential Disconnect) which uses a vacuum actuated mechanism to disconnect the drivers side axle shaft from the differential. Carriers and gear sets are interchangeable between the two different versions (and also happen to be the same as used in the 2wd Toyota pickup 7.5" diffs). One difference between ADD and non-ADD diffs is that the carrier in an ADD differential has needle bearings supporting the axle shafts at the differential. The non-ADD diffs did not have this bearing and sometimes the passenger side axle flange wears the carrier and becomes loose or wobbly, eventually causing oil leaks, noise, and possible spider gear damage. ADD and non-ADD diffs are swappable as are most of their parts. This makes it possible to change your ADD diff to non-ADD by simply swapping parts as I've done in the picture to the right. This is desirable to some people since some of the ADD stubs are smaller diameter than the non-ADD stubs and are therefore slightly weaker.
03-03-2016, 02:20 PM
#20
It's more about the strength of the stub shafts, ADD vs. non-ADD. And the bigger carrier bearings in the front diff, V6 vs. 4cyl.. Than it is about needle bearings. The needle bearings are good for what they were used for. Such as in an ADD diff that spins constantly. You don't gain much buy using them in a non-ADD setup. And what you'd gain is definitely not worth the trade off of having weaker stub shafts.
http://home.4x4wire.com/erik/diffs/#IFS
http://home.4x4wire.com/erik/diffs/#IFS
Last edited by Yotard; 03-03-2016 at 02:23 PM.
