741 upgrade question

[JimShine]

I am trying to figure this all out. If I want to upgrade my 741 to a 742, what parts from the center section do I need to do the conversion? Does it have to be components from a B body rear, or does any body style work? Thanks!

[Nacho-RT74]

I don't think is that easy, since I think housing and carrier are not interchangeable, so the same to internal parts.

Not sure about that.

I think will be better try to find a complete 742

[JimShine]

Gotcha. So if I want to upgrade my gears, I need to find another 741 with better gears to steal for the swap?

[doctorpimp]

Any center carrier will fit into any housing.  You can find a 742 or 489 and drop it in!
If you are considering rebuilding your 741, then you have to get 741 gears etc to replace the ones IN that 741 center.

[mikepmcs]

 
There it is JIM, we're on a roll now.

[JimShine]

Thanks Doc! Thats what I needed to know. I will go get a 742 or 489 center.

So this brings up another question. Is there any way to identify gear ratio on the rear end itself? Finding the rear ends around here is easy, but many have been removed from vehicles.

[doctorpimp]

MOST 8.75 rear gears have the ratio stamped on the outer edge of the pinion:
3.55:1

[firefighter3931]

Why replace the whole centersection ? Just get a set of gears for the 741 case. 

Most folks mistakenly believe the smaller pinion on the 741 case will snap. Here's a little tidbit of info worth considering : the 741 pinion is the same diameter as the mighty dana 60 pinion 

The weak link is not the pinion....it's the caps ; those are what break first fallowed by snapped axles. I have yet to see a broken 741 pinion and lots of those cars were abused hard, 4 speeds/strong 440's etc... Unless you're planning on running slicks, you'll never break it. I wouldn't think twice about running a 741 with a 500hp motor as long as street tires were going to be used. Back in the day, max-wedge cars all had 741 cases and survived quite well. 

Some companies now carry gers for the 741 case ......they're available new. The 741 will also have the rebuildable clutch style suregrip if it was originally a suregrip style rear end.


Ron

[RD]

Why replace the whole centersection ? Just get a set of gears for the 741 case. 

Most folks mistakenly believe the smaller pinion on the 741 case will snap. Here's a little tidbit of info worth considering : the 741 pinion is the same diameter as the mighty dana 60 pinion 

The weak link is not the pinion....it's the caps ; those are what break first fallowed by snapped axles. I have yet to see a broken 741 pinion and lots of those cars were abused hard, 4 speeds/strong 440's etc... Unless you're planning on running slicks, you'll never break it. I wouldn't think twice about running a 741 with a 500hp motor as long as street tires were going to be used. Back in the day, max-wedge cars all had 741 cases and survived quite well. 

Some companies now carry gers for the 741 case ......they're available new. The 741 will also have the rebuildable clutch style suregrip if it was originally a suregrip style rear end.


Ron

Totally... My 71 Charger had a 741 suregrip and I ran slicks on that puppy for 3 years without any problems.  Recommend it? no, but the car was a frankenstein at the time and I wanted to race damnt!

oh and doc, that is the ring gear, not the pinion.  The pinion is the peice that turns the ring gear and is connected to the driveshaft via the yoke.

[doctorpimp]

oh and doc, that is the ring gear, not the pinion.  The pinion is the peice that turns the ring gear and is connected to the driveshaft via the yoke.

OOOPS - I do know that I was thinking ring but wrote pinion 
It's been a long day...
Hence the name RING and pinion

[JimShine]

I did not realize there was new gears available for the 741. I had been led to believe finding any new parts for them was difficult and expensive compared to the 742. My thinking was if I could get a 742 or 489 center for $50-75, it would make life a whole lot easier getting parts for my rear and if I could improve my gears at the same time, then that would be cool too.

My car has 2.76:1 gear ratio. That is the main thing I want to upgrade.

[firefighter3931]

I did not realize there was new gears available for the 741. I had been led to believe finding any new parts for them was difficult and expensive compared to the 742. My thinking was if I could get a 742 or 489 center for $50-75, it would make life a whole lot easier getting parts for my rear and if I could improve my gears at the same time, then that would be cool too.

My car has 2.76:1 gear ratio. That is the main thing I want to upgrade.

Jim, check the link below. Randy's carries 3.55 and 3.73 gears for the 741 case. Other companies may carry them as well....


Ron



http://www.ring-pinion.com/content/products/default.asp?vid=0&pid=4

[JimShine]

Thanks Ron! I will go check it out now!

[Nacho-RT74]

sorry, I have allways being confused about all the axles stuff... and looks I still do LOL. I had an excelet website info about that and I was to check and post on my first post, but is not available anymore

http://www.moserengineering.com/moser_interior/axletech.htm

[doctorpimp]

Here's the new address Nacho:
http://www.moserengineering.com/Pages/axletech.html

[mikepmcs]

OK so here's my deal.  Jim and I are in the same boat.  We both have 2.76:1's. I have a 489 case though.  I want to put 3.55 SG in my 383 as I do not have a SG.  So i'm thinking after talking to jim and reading this that my best bet is to find a center already loaded from a yard or from someone on this site.  The only problem with replacing R& P's is setup, am I correct on that.  If you are not a rear end dude then you could really screw this up with tolerances and stuff.  I have always been scared away from this cause that's all i've ever heard. But firefighter makes it sound like you can just bolt em right in, is that true.
Anyways I don't have a SG unit and that's what I want so unless someone makes the SG center with that gear ratio 3.55 that I can slap in new, i'm thinking the best bet is still a yard or here.
Am I way off on this
v/r
Mike

[Nacho-RT74]

Ok think maybe that's not the right website I wanted to post, but whatever. I can't find it.

If that was the info website I had, then is not the same info that it had

[firefighter3931]

OK so here's my deal.  Jim and I are in the same boat.  We both have 2.76:1's. I have a 489 case though.  I want to put 3.55 SG in my 383 as I do not have a SG.  So i'm thinking after talking to jim and reading this that my best bet is to find a center already loaded from a yard or from someone on this site.  The only problem with replacing R& P's is setup, am I correct on that.  If you are not a rear end dude then you could really screw this up with tolerances and stuff.  I have always been scared away from this cause that's all i've ever heard. But firefighter makes it sound like you can just bolt em right in, is that true.
Anyways I don't have a SG unit and that's what I want so unless someone makes the SG center with that gear ratio 3.55 that I can slap in new, i'm thinking the best bet is still a yard or here.
Am I way off on this
v/r
Mike

Mike, you are correct ; the new gears will need to be set up properly for backlash and on the 489 center there is a crush sleeve that needs to be torqued to spec to achieve the proper preload. There are a few companies that make solid spacers to replace the collapsable crush sleeve. The solid sleeve is recommended because the collapsable crush sleeve often causes a ring/pinion failure and this is the weakpoint of the 489 centersection. Ratech and Richmond both carry the sleeve replacement kit for around $30.00 and it is money well spent.

Auburn and other companies carry suregrip units for the 83/4 center. The same SG unit will fit in any of them with the proper caps & bearings. It might be easier or cheaper to find one allready set up....then it's a simple swap and go. But they're not cheap, unfortunately....anything 83/4 is expensive...even used. 


Ron

[doctorpimp]

Auburn and other companies carry suregrip units for the 83/4 center. The same SG unit will fit in any of them with the proper caps & bearings. It might be easier or cheaper to find one allready set up....then it's a simple swap and go. But they're not cheap, unfortunately....anything 83/4 is expensive...even used. 

I can attest to this...

Used 489's with SG and performance gears are going for anywhere from $400 - 650 used, in good condition !!!
I got a quote from Cass at DrDiff for a rebuilt clutch SG, 4.10 gears (new) 489 housing for $850

[JimShine]

Mike lives near me, and up the road from where I live a very short distance is an old junkyard with dozens of already removed old Mopar rear ends and numerous rears still in cars. If You approach the guy looking for a sure grip (and he knows what you picked out is a sure grip) he will nail ya. But I do believe one can be had cheap just by going in with a casting number knowing what to look for.

[mikepmcs]

Jim
I've been thinking about this nonstop and i'll want to do this shortly after the show.  If you are willing to help me out in finding the right replacement I would be in debt to you.
We can change the rear with you and Matt here or down your way, that way we all know how to do it and yours will be a snap when it comes time.  Whatta you think?

http://vids.myspace.com/index.cfm?fuseaction=vids.individual&n=2&videoid=711473209&Mytoken=91932A9C-14F1-A7A7-0E09A066F590E67B4428283


ok i won't be doing that much of this cause tire cost too much money but you get the idea

v/r
Mike