513 Rear End Gears for stock housing
Thread Starter
Gen 2 Raced Hard NA 13B
Joined: Apr 2006
Posts: 272
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From: Canada
513 Rear End Gears for stock housing
Hi All,
I have a plan to change from the stock LSD 4.11 rear end gears to 5.13 for my race track application. Can any one post the procedure and specifications of changing over the (Gen1) 513 pinion gear on to the 4.11 pinion shaft (Gen2)? I have a complete shop to do the necessary work. I am looking for some help full information to stay away from the old trail and error area.
Thanks
I have a plan to change from the stock LSD 4.11 rear end gears to 5.13 for my race track application. Can any one post the procedure and specifications of changing over the (Gen1) 513 pinion gear on to the 4.11 pinion shaft (Gen2)? I have a complete shop to do the necessary work. I am looking for some help full information to stay away from the old trail and error area.
Thanks
Lives on the Forum
Joined: Sep 2003
Posts: 5,707
Likes: 6
From: BC, Canada
ISC Racing does just that, if you call them they might be willing to talk about it.
http://www.iscracing.net/
http://www.iscracing.net/
Thread Starter
Gen 2 Raced Hard NA 13B
Joined: Apr 2006
Posts: 272
Likes: 0
From: Canada
Thanks I e-mailed them and waiting for a reply. But mainly not looking to buy the set up. Only looking for the info on the machining of the spines to the shaft and gear to make the change. Any answers out there.
Thanks
Thanks
I love it when people that don't know what they're talking about post...
To put together a 5.12 for a 2nd gen you need to start with a 1st gen gear set. For the peanut gallery the 1st gen uses the same 7" ring gear as the NA 2nd gen. The tricky part is that the 1st gen uses the short pinion gear and the 2nd gen uses the long pinion gear. So the 1st gen pinion gear needs to be cut and have a section welded in to make it the proper length. As you can guess this is not a process someone does in their garage. ISC and Speedsource off the gear. I imagine they both have the same shop doing the work for them in Florida. My advice is to buy the gear set from one of them.
Now all of that assumes you are talking about an NA diff. If you have the 8" turbo diff you're out of luck. Places like Haussman can custom make a gear set for you in any ratio you desire. The price is quite shocking though.
As far as installation it's pretty straight forward. The process and specs are outlined in the FSM.
The gear set from Mazdaspeed is $608. The machine work is around $500.
The performance gains going from the 4.10 to the 5.12 are very noticeable. The nicest part of the swap is that you go from using 2-3-4 on most tracks to using 3-4-5. The gear spacing between the upper gears is tighter which allows you to avoid the big RPM drop when shifting from 2nd to 3rd. It's pretty much required to convert the trans to the .756 GTUs OD gear if you haven't done so already. With that combo and a 225/45-15 tire you'll be gear limited to around 140mph (8000rpm) which is plenty on all but the fastest tracks. If your rules allow look into finding the OD gear out of one of the 1st gens. I forget which year I found but there is one that works out to an .814 when teamed with the 2nd gen tranny. The tricky part in spotting the gear is that the input ratios of the trannys has varied over the years. The actual OD ratio of that first gen gear in it's native trans was something like .71, or something like that. However the 2nd gen tranny has a shorter input ratio which turns the same gear into a .814 when swapped. With that gear you'd be gear limited to around 130 which would be perfect for all the tracks that we race on in this area.
To put together a 5.12 for a 2nd gen you need to start with a 1st gen gear set. For the peanut gallery the 1st gen uses the same 7" ring gear as the NA 2nd gen. The tricky part is that the 1st gen uses the short pinion gear and the 2nd gen uses the long pinion gear. So the 1st gen pinion gear needs to be cut and have a section welded in to make it the proper length. As you can guess this is not a process someone does in their garage. ISC and Speedsource off the gear. I imagine they both have the same shop doing the work for them in Florida. My advice is to buy the gear set from one of them.
Now all of that assumes you are talking about an NA diff. If you have the 8" turbo diff you're out of luck. Places like Haussman can custom make a gear set for you in any ratio you desire. The price is quite shocking though.
As far as installation it's pretty straight forward. The process and specs are outlined in the FSM.
The gear set from Mazdaspeed is $608. The machine work is around $500.
The performance gains going from the 4.10 to the 5.12 are very noticeable. The nicest part of the swap is that you go from using 2-3-4 on most tracks to using 3-4-5. The gear spacing between the upper gears is tighter which allows you to avoid the big RPM drop when shifting from 2nd to 3rd. It's pretty much required to convert the trans to the .756 GTUs OD gear if you haven't done so already. With that combo and a 225/45-15 tire you'll be gear limited to around 140mph (8000rpm) which is plenty on all but the fastest tracks. If your rules allow look into finding the OD gear out of one of the 1st gens. I forget which year I found but there is one that works out to an .814 when teamed with the 2nd gen tranny. The tricky part in spotting the gear is that the input ratios of the trannys has varied over the years. The actual OD ratio of that first gen gear in it's native trans was something like .71, or something like that. However the 2nd gen tranny has a shorter input ratio which turns the same gear into a .814 when swapped. With that gear you'd be gear limited to around 130 which would be perfect for all the tracks that we race on in this area.
Thread Starter
Gen 2 Raced Hard NA 13B
Joined: Apr 2006
Posts: 272
Likes: 0
From: Canada
Found my own answer.
Hi All,
I did my home work and found out what has to be done. 4 deg. taper from largest diameter of the pinion shaft to the end of pinion gear on the 4:11. But to machine you must grind the case hardened gear away. On the end of the 5:13 pinion you must grind the face of the pinion end to get through the case Harding. Then machine a taper in side the pinion gear to match the 4:11 shaft. Make them size on size. At this point preheat the pinion gear to 350 Deg. And freeze the tapered 4:11 pinion shaft to below 32 Deg. Press fit with 1000lbs of force and hold till room temperature. After which you weld the end of the shaft will a 1/8th 7018 welding rod let cool and machine end smooth so you do not leave any stress marks for cracks to form. I have done it and no problem. Time from start to finish 4.25 hours.
I did my home work and found out what has to be done. 4 deg. taper from largest diameter of the pinion shaft to the end of pinion gear on the 4:11. But to machine you must grind the case hardened gear away. On the end of the 5:13 pinion you must grind the face of the pinion end to get through the case Harding. Then machine a taper in side the pinion gear to match the 4:11 shaft. Make them size on size. At this point preheat the pinion gear to 350 Deg. And freeze the tapered 4:11 pinion shaft to below 32 Deg. Press fit with 1000lbs of force and hold till room temperature. After which you weld the end of the shaft will a 1/8th 7018 welding rod let cool and machine end smooth so you do not leave any stress marks for cracks to form. I have done it and no problem. Time from start to finish 4.25 hours.
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