05 differential, how bad are they?
Thread Starter
Instructor
Joined: Aug 2003
Posts: 139
Likes: 0
From: Liberty Mo
05 differential, how bad are they?
Just purchased an MN6 05 and had planned on supercharging it. Was not to happy to find out after purchasing that the 05 has a weak differential. Now not only am I thinking it would be a bad move to add a supercharger I am thinking it might be best to sell and get a 06-07.
So is the weak differential overblown? Car will be street driven only no sticky drag tires.
So is the weak differential overblown? Car will be street driven only no sticky drag tires.
Advanced
Joined: Jun 2010
Posts: 53
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I just had this issue about a week ago believe it or not. I fully built my motor and no more than two days later bam, cracked my rear diff housing... I got the tip to call RPM Transmissions 765-378-0625 and they hooked me up fat. They have some special on us 05 guys. He said they felt bad for us and gave me a bad *** discount.. give them a call and let them know what you have and I gurantee they will be more than happy to help. Great guys
Safety Car
Joined: Jul 2009
Posts: 3,755
Likes: 190
From: Baton Rouge LA
St. Jude Donor '14, '16
Just purchased an MN6 05 and had planned on supercharging it. Was not to happy to find out after purchasing that the 05 has a weak differential. Now not only am I thinking it would be a bad move to add a supercharger I am thinking it might be best to sell and get a 06-07.
So is the weak differential overblown? Car will be street driven only no sticky drag tires.
So is the weak differential overblown? Car will be street driven only no sticky drag tires.
The 05 MN6 car has the weakest diff of them all from what I read. It is cheaper to upgrade than replace since you currently have a useable core, and simply upgrading the diff will certainly be less hassle than replacing the entire car IMHO.
Pro
Joined: Apr 2009
Posts: 581
Likes: 10
From: NJ
plenty of guys running blowers on their 05s without issues. I think as long as you don't drag it, you'll be alright with highway pulls. From what I have read, wheel hop is the main culprit. But, I like you have an 05 and I'll do a preventative upgrade down the road after I get the blower on.
Instructor
Joined: Oct 2008
Posts: 196
Likes: 0
From: South St Paul Minnesota
I have an 05 and do not plan on doing anything major to the motor and am going to put a brase on the diff. I hope that will be enough. I don't track or race my car so I should be fine. If it does break ill deal with it.
Racer
Joined: Oct 2010
Posts: 357
Likes: 14
From: Friendswood TX
i have a 05 and mine is still together. I have made a lot of passes on nitrous and nothing has happened. I just launch at idle and don't really get on it till 2nd gear. my times are only 12.0's but I'm still trapping 125 plus. (stock tires)
if you feel wheel hop let off and you will be fine till you upgrade.
if you feel wheel hop let off and you will be fine till you upgrade.
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Le Mans Master
Joined: Aug 2002
Posts: 8,472
Likes: 38
From: Houston TX
St. Jude Donor '11
I have the DTE brace. I don't expect it to make it bullet-proof but it has held up so far. Yes, the smart money says replace it with an '06+ diff, which also involves changing the tailhousing of the tranny as well. But I just can't bring myself to do it. If it does grenade my plan is to fab up an adapter to house a built C5 diff ala Sparo2. They are much cheaper.
PS: Wheel hop is a son'beach. I lost a short side output shaft to it when I had NAWS on my C5.
PS: Wheel hop is a son'beach. I lost a short side output shaft to it when I had NAWS on my C5.
Last edited by 5 Liter Eater; Mar 2, 2011 at 03:34 PM.
Melting Slicks
Joined: Jan 2005
Posts: 2,326
Likes: 5
From: louisville "derby city" kentucky
the bad part is............when your diff goes, so does the transmission main shaft usually. then you get to not only replace/upgrade the diff, you also get to repair the trans. BIG bucks. just got done upgrading the case and gear ration in my 05. guys at RPM TRANSMISSIONS are top notch. now i can make all the hp i want and go to the track with confidence 
of course, some people have to learn the hard way, don't be one of them...............
of course, some people have to learn the hard way, don't be one of them...............
Racer
Joined: Jun 2009
Posts: 374
Likes: 0
From: Houston Texas
the bad part is............when your diff goes, so does the transmission main shaft usually. then you get to not only replace/upgrade the diff, you also get to repair the trans. BIG bucks. just got done upgrading the case and gear ration in my 05. guys at RPM TRANSMISSIONS are top notch. now i can make all the hp i want and go to the track with confidence of course, some people have to learn the hard way, don't be one of them...............
of course, some people have to learn the hard way, don't be one of them...............Yup I bent my main shaft when my diff exploded and fell off. I wish I could go back in time...... If I had it to do over I would have sold the 05 diff and replaced it to save the tranny.
Tech Contributor
Joined: Jul 2002
Posts: 14,950
Likes: 265
From: St. Louis, MO
St. Jude Donor '08
the bad part is............when your diff goes, so does the transmission main shaft usually. then you get to not only replace/upgrade the diff, you also get to repair the trans. BIG bucks. just got done upgrading the case and gear ration in my 05. guys at RPM TRANSMISSIONS are top notch. now i can make all the hp i want and go to the track with confidence of course, some people have to learn the hard way, don't be one of them...............
of course, some people have to learn the hard way, don't be one of them...............Took out my tranny mainshaft too. I had a brace. When the diffs break they usually take out the trans.
You can swap to a c5 diff and sell your 3:42 diff to an automatic guy and not be much money out of pocket, and it's not a hard swap (contact Sparo2 or check his how-to). That's what I did and it's a great mod so far (131 passes so far, 1.49 to 1.5x's regularly).
If you don't go from a dead stop, my guess is you'll be fine. Seems that most guys who break them on the street do it wheel hopping so let out if you get any. I never get it even on the street but I don't race on the street either. Problem is, if it goes, it'll most likely take out the trans, and plan on about a $5k bill when that happens because you won't have a core.
Summary - depends on how you are going to drive. A few spirited runs now and then, it'll probably live a long time. If you race often, switch now and save a lot of money.
Race Director
Joined: Oct 2005
Posts: 14,555
Likes: 1,255
From: Saint Albans, WV
plenty of guys running blowers on their 05s without issues. I think as long as you don't drag it, you'll be alright with highway pulls. From what I have read, wheel hop is the main culprit. But, I like you have an 05 and I'll do a preventative upgrade down the road after I get the blower on.
Last edited by saplumr; Mar 2, 2011 at 07:03 PM.
Thread Starter
Instructor
Joined: Aug 2003
Posts: 139
Likes: 0
From: Liberty Mo
After thinking it over I think my best bet is to skip the supercharger, leave the car stock and save for a Z06, that's what I was wanting to begin with. I figured by the time I spend $7,000 on a supercharger, $2,000+ on a new diff. and while it is apart a better clutch $1,000 then add in what I have in the car I would be withen $5,000 of a 2006/2007 Z06. Hopefully the diff. will last 1-2 years and if not I guess I made a bad choice.