Rear Differential 1978 Vette?
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Rear Differential 1978 Vette?
I'm rebuilding my rear differential and throwing in some new gears while I'm at. Hoping to go with 4.11's. I'm having some trouble tracking down exactly which rear diff is used.
I've found ring and pinion kits for the vette specifically, but they're considerably more expensive than non vette gears, so trying to track down the details so I can order a less expensive set.
I thought it was a 10 bolt Dana 44, but after doing some more research it looks like maybe that was only on 80's and newer?
I have a 1978, auto trans, 350 L48, (originally a California sold car). Any ideas on the exact specs or where I could find them? Thanks in advance for your help!
I've found ring and pinion kits for the vette specifically, but they're considerably more expensive than non vette gears, so trying to track down the details so I can order a less expensive set.
I thought it was a 10 bolt Dana 44, but after doing some more research it looks like maybe that was only on 80's and newer?
I have a 1978, auto trans, 350 L48, (originally a California sold car). Any ideas on the exact specs or where I could find them? Thanks in advance for your help!
Safety Car
Joined: Jan 2009
Posts: 3,736
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From: anchorage ak
I'm rebuilding my rear differential and throwing in some new gears while I'm at. Hoping to go with 4.11's. I'm having some trouble tracking down exactly which rear diff is used.
I've found ring and pinion kits for the vette specifically, but they're considerably more expensive than non vette gears, so trying to track down the details so I can order a less expensive set.
I thought it was a 10 bolt Dana 44, but after doing some more research it looks like maybe that was only on 80's and newer?
I have a 1978, auto trans, 350 L48, (originally a California sold car). Any ideas on the exact specs or where I could find them? Thanks in advance for your help!
I've found ring and pinion kits for the vette specifically, but they're considerably more expensive than non vette gears, so trying to track down the details so I can order a less expensive set.
I thought it was a 10 bolt Dana 44, but after doing some more research it looks like maybe that was only on 80's and newer?
I have a 1978, auto trans, 350 L48, (originally a California sold car). Any ideas on the exact specs or where I could find them? Thanks in advance for your help!
Burning Brakes
Joined: Apr 2013
Posts: 1,194
Likes: 109
From: Las Vegas NV
My understanding is that for a '78-'79 C3, 3.90 is the shortest gear that will fit in the stock housing. I'll be following this thread, if you come across anything interesting with alternative sources of gears/etc, I'd love to know about it. My local driveline shop wants close to $800 to regear my diff to 3.90, and that is if it is already removed from the car.
Last edited by AboveTheLogic; Jun 20, 2016 at 01:50 AM.
Instructor
Joined: Sep 2015
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From: Haverfordwest Pembrokeshire
The diff casing, the part that the ring gear bolts to, is different for the 4.11 and 4.55 ratios as the ring gear is a bigger diameter so depending on the ratio you have now you may need a new casing as well, I am going from a 4.55 to a 3.55 so went for an Auburn unit from JT transmissions and 3.55 crown wheel and pinion set, they also supplied a fitting kit with all the bearings seals etc
The 4.55 I have in mine at present will be available if you're interested but I'm not planning to change it out just yet as I'd rather spend time driving than under it!
Regards
Graham
The 4.55 I have in mine at present will be available if you're interested but I'm not planning to change it out just yet as I'd rather spend time driving than under it!
Regards
Graham
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Joined: Sep 2015
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From: Haverfordwest Pembrokeshire
Couldn't agree more which is why I'm changing my 4.55 out and going 3.55 and considering a 5 speed TKO 600 conversion if it's still too busy on the open road. It's like driving round in second gear at the moment!!
Graham
Graham
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Yes, I understand that. I have a 700R4 overdrive, sorry thought I mentioned that. I've run all the calcs and am comfortable with a 4.11 and where my RPM's would be. It's an around town street/weekend fun car that will also be used for 1/4 occasionally as well. I'm not concerned about mileage and would rather have the fun factor of a 4.11 if I can get away with it.
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My understanding is that for a '78-'79 C3, 3.90 is the shortest gear that will fit in the stock housing. I'll be following this thread, if you come across anything interesting with alternative sources of gears/etc, I'd love to know about it. My local driveline shop wants close to $800 to regear my diff to 3.90, and that is if it is already removed from the car.
I found a 4.11 that supposedly can fit in a 3 series carrier (which I believe is what the stock diff has) from Duntov Motors, but I'm not positive if it will fit. I'm gonna call Duntov and see what they have to say and we're pulling apart the diff to see if we can get any usable numbers or info from the carrier that tells us exactly what we're working with.
Does anyone know if a 78 has a Dana 44? I know it's a 10 bolt and I thought it was a Dana 44, but not positive.
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Not sure I'm going to be able to hook up very well, but want to stick with street tires as I'm not ready to throw a 12 bolt in just yet and from everything I've seen that'll be the only thing holding the rear together haha. We are rebuilding the diff, got new hardened end caps to replace the ****** ubolt straps, and might do a few other things to keep the rear a little sturdier (maybe weld up a truss?). Just got done rebuilding the suspension with a VBP street and slalom kit and all poly bushings as well. Between all that, the upgraded/rebuilt brakes, the new Borgeson unit, the fitech fuel injection, the already installed but fresh motor/700R4 trans, and soon to be new interior, it's basically gonna be a whole new car lol.
Burning Brakes
Joined: Apr 2013
Posts: 1,194
Likes: 109
From: Las Vegas NV
Check this out:
https://www.yukongear.com/diffdetail...ron%2bCorvette
This is some interesting wording:
Zip corvette lists the need for a 3-series carrier (whatever that means) for its 4.11 gear set, but does not list a 3.90 gear set.
http://www.zip-corvette.com/68-82-c3...ons-gears.html
Duntov sells the complete unit for $1499 and lists 4.11, 4.33, and 4.56 options:
http://www.duntovmotors.com/differentials-63-79.php
I'm kicking myself a bit because last year I had my rear end rebuilt by a local driveline shop for about $1300 including a replacement carrier because mine was cracked. At the time I didn't foresee a T56 swap in my future. Now they want almost $800 to re-gear it. I almost want to just save my pennies and pick up a $1499 unit, then I guess maybe sell my rebuilt unit with its 3.36 gears? Not sure which way I'll come ahead. I wish I had a friend who knew how to set gears properly, the gear sets are under $400.
Edit: Here is the catalog from Richmond Gear ring and pinion sets for '96-'79 Corvettes:
http://www.richmondgear.com/pdf/Rich...n1.pdf#page=11
Note the asterisk by the 4.11 set that doesn't exist with the 3.90 set.
https://www.yukongear.com/diffdetail...ron%2bCorvette
This is some interesting wording:
Carrier Breaks: 2.76 / 3.07 - 3.90 / 4.10
http://www.zip-corvette.com/68-82-c3...ons-gears.html
Duntov sells the complete unit for $1499 and lists 4.11, 4.33, and 4.56 options:
http://www.duntovmotors.com/differentials-63-79.php
I'm kicking myself a bit because last year I had my rear end rebuilt by a local driveline shop for about $1300 including a replacement carrier because mine was cracked. At the time I didn't foresee a T56 swap in my future. Now they want almost $800 to re-gear it. I almost want to just save my pennies and pick up a $1499 unit, then I guess maybe sell my rebuilt unit with its 3.36 gears? Not sure which way I'll come ahead. I wish I had a friend who knew how to set gears properly, the gear sets are under $400.
Edit: Here is the catalog from Richmond Gear ring and pinion sets for '96-'79 Corvettes:
http://www.richmondgear.com/pdf/Rich...n1.pdf#page=11
Note the asterisk by the 4.11 set that doesn't exist with the 3.90 set.
Last edited by AboveTheLogic; Jun 20, 2016 at 05:11 PM.
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Joined: Feb 2016
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Check this out:
https://www.yukongear.com/diffdetail...ron%2bCorvette
This is some interesting wording:
I'm trying to find the online catalog where I saw gear sets available and for the sets that were numerically higher than 3.90 there was a caveat, still looking.
Zip corvette lists the need for a 3-series carrier (whatever that means) for its 4.11 gear set, but does not list a 3.90 gear set.
http://www.zip-corvette.com/68-82-c3...ons-gears.html
Duntov sells the complete unit for $1499 and lists 4.11, 4.33, and 4.56 options:
http://www.duntovmotors.com/differentials-63-79.php
I'm kicking myself a bit because last year I had my rear end rebuilt by a local driveline shop for about $1300 including a replacement carrier because mine was cracked. At the time I didn't foresee a T56 swap in my future. Now they want almost $800 to re-gear it. I almost want to just save my pennies and pick up a $1499 unit, then I guess maybe sell my rebuilt unit with its 3.36 gears? Not sure which way I'll come ahead. I wish I had a friend who knew how to set gears properly, the gear sets are under $400.
https://www.yukongear.com/diffdetail...ron%2bCorvette
This is some interesting wording:
I'm trying to find the online catalog where I saw gear sets available and for the sets that were numerically higher than 3.90 there was a caveat, still looking.
Zip corvette lists the need for a 3-series carrier (whatever that means) for its 4.11 gear set, but does not list a 3.90 gear set.
http://www.zip-corvette.com/68-82-c3...ons-gears.html
Duntov sells the complete unit for $1499 and lists 4.11, 4.33, and 4.56 options:
http://www.duntovmotors.com/differentials-63-79.php
I'm kicking myself a bit because last year I had my rear end rebuilt by a local driveline shop for about $1300 including a replacement carrier because mine was cracked. At the time I didn't foresee a T56 swap in my future. Now they want almost $800 to re-gear it. I almost want to just save my pennies and pick up a $1499 unit, then I guess maybe sell my rebuilt unit with its 3.36 gears? Not sure which way I'll come ahead. I wish I had a friend who knew how to set gears properly, the gear sets are under $400.
Luckily my brother is a mechanic and has worked with differentials/gearing so he's helping me do it. I'm sure I'd pay an arm and a leg to a shop. I have also considered just upgrading the whole differential, but I don't really want to shell out the money for a 12 bolt conversion right now and I am likely only going to have around 500 horsepower, so I think a rebuilt stock one should be alright. I'm upgrading to new 3 inch halfshafts and doing some other stuff to strengthen back there, but I'm hoping I can get by with the rebuilt 10 bolt for a while.
Burning Brakes
Joined: Apr 2013
Posts: 1,194
Likes: 109
From: Las Vegas NV
Yeah...
I'm hoping that I like the T56 with the 3.36 gears enough to not really want to regear right away and keep it as an option later when I want some quicker acceleration.
I'm hoping that I like the T56 with the 3.36 gears enough to not really want to regear right away and keep it as an option later when I want some quicker acceleration.
Last edited by AboveTheLogic; Jun 20, 2016 at 05:34 PM.
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Not sure if anybody's had experience with SVL drivetrain parts, but I'm not really into paying more just because a part is marketed for a corvette. SVL has a 50,000 mile/6 mo warranty on their parts and I can't find any bad reviews on them, though there's no positive reviews on Summit for them either. Any opinions on if it's necessary to spend more on a ring and pinion set?
The only crappy thing is I figured out my vette apparently has 3.55 gears in it now so it won't be as big of a jump as I thought it would be to 4.11's!!! I guess it was ordered special with 3.55's as I haven't seen any info on 78 Auto's typically having 3.55's.
Burning Brakes
Joined: Apr 2013
Posts: 1,194
Likes: 109
From: Las Vegas NV
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Speaking of that, anybody got 4.56 gears in a street car lol?!?!?! I'm tempted.... but I'm thinking a 4.11 mated with the new blower should be enough to keep a smile on my face and not too crazy for the street. I mean I do have a .7 overdrive ratio so I guess I COULD run more, but probably not the best for a street car right? Talk me out of it...
