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Hi guys, this question has probably been discussed many times but I can't seem to find an answer. I recently bout a rear diff from 09-14 370 m/t and I'm trying to swap it with the diff I have on my 2012 g37 coupe a/t (basically changing gear ratios from 3.3 to 3.7). The problem that came up is that when I got the flange swapped, the input shaft from the 370 diff is much shorter than the input shaft on the G. The mechanic who was swapping the diffs for me told me these diffs are not interchangeable because of the different shaft size. Will the shaft make any difference? Please help.
If you a referring to the centering pin, I think most people say that on a mild NA car it doesn't matter but as you increase whp and wtq it can add vibration.
I think power-wise this is correct, you don't really need the centring pin on a NA car. but can you post pictures? it almost sounds like when you go to mate up your new parts the flange is too short to reach the driveshaft. (If this is the case you may have to use one of the other flanges or drive shafts or some combination of them)
I believe there are differences between the 7A/T and MT input shafts/carriers for the G37, as well as stub shaft differences between an open diff and VLSD from the factory. So you'd have to find the right combination of G37 MT parts and whichever diff you had in there previously, to make this line up.
Hey guys thanks for the replies. To make it clear this is what I'm talking about. My mechanic told me since the shaft is too small from the m/t diff, these diffs can't be swapped but I've tried looking at other forums where people did this mod and no one ever mentioned about this issue.
Hey guys thanks for the replies. To make it clear this is what I'm talking about. My mechanic told me since the shaft is too small from the m/t diff, these diffs can't be swapped but I've tried looking at other forums where people did this mod and no one ever mentioned about this issue.
I'm still not 100% clear on whether you've already swapped the flange and which one is the new one that Mechanic is saying wont work...it sounds like he hasn't done the actual flange swap otherwise he'd see how to make it work.
I can verify for a fact that if you take the 4 bolt flange (with the short pin) off and put the 3 bolt on the short pin it works. You should be able to bolt this upto a 3 bolt driveshaft without any modification.
I also can confirm that if you need to put that 4 bolt flange (previously on the short pin) on the long pin diff it works as well. In this second case you need to take an angle grinder and cut the pin down so that it is no longer than the flange to mate it up to the flat 4 bolt flange on the the drive shaft....this should only take a few minutes. Its also a good idea to drill a few mm's into the tip to create an indentation so you can use a puller on the flange at a later date.
Source of my information: I have three differentials sitting in my parents garage right now, one with a short pin mated to a 3 bolt flange, one an auto VLSD modified for the AWD platform with a cut long pin and one stock AWD 6 bolt diff and a 2011 6MT IPL coupe VLSD presently mounted on my AWD sedan all with 3.69 gears.
Last edited by Baadnewsburr; May 3, 2017 at 05:50 PM.
I'm still not 100% clear on whether you've already swapped the flange and which one is the new one that Mechanic is saying wont work...it sounds like he hasn't done the actual flange swap otherwise he'd see how to make it work.
I can verify for a fact that if you take the 4 bolt flange (with the short pin) off and put the 3 bolt on the short pin it works. You should be able to bolt this upto a 3 bolt driveshaft without any modification.
I also can confirm that if you need to put that 4 bolt flange (previously on the short pin) on the long pin diff it works as well. In this second case you need to take an angle grinder and cut the pin down so that it is no longer than the flange to mate it up to the flat 4 bolt flange on the the drive shaft....this should only take a few minutes. Its also a good idea to drill a few mm's into the tip to create an indentation so you can use a puller on the flange at a later date.
Source of my information: I have three differentials sitting in my parents garage right now, one with a short pin mated to a 3 bolt flange, one an auto VLSD modified for the AWD platform with a cut long pin and one stock AWD 6 bolt diff and a 2011 6MT IPL coupe VLSD presently mounted on my AWD sedan all with 3.69 gears.
He actually did swap the flange. But he said the pin is too shot and when he was Trying to twist the flange, it was not moving but when he swapped it back to the original diff he was able to twist it which I think made him determine that the diff with short pin won't work
He actually did swap the flange. But he said the pin is too shot and when he was Trying to twist the flange, it was not moving but when he swapped it back to the original diff he was able to twist it which I think made him determine that the diff with short pin won't work
I'm sorry man...wish I could help more...maybe its just late and I'm a little fried, but I'm not following (wouldn't be the first time )...the centering pin isn't bearing any load on that end its just for centering on that end...its the flange around it that is bolted to the driveshaft and bears the load...what your describing almost sounds like improper preload on the pinion or a smashed crush sleeve...the depth on the flanges may differ and if setting from the outside he should be setting the preload using an inch/lb torque wrench (i think its supposed to be between 21-29inch lbs) and not just be trying to count threads based on the old flange ...it also sounds a little like the difference in operation between an open diff and an lsd in general hopefully someone else on here can chime in, I'm curious to know what it could be at this point lol
)...the centering pin isn't bearing any load on that end its just for centering on that end...its the flange around it that is bolted to the driveshaft and bears the load...what your describing almost sounds like improper preload on the pinion or a smashed crush sleeve...the depth on the flanges may differ and if setting from the outside he should be setting the preload using an inch/lb torque wrench (i think its supposed to be between 21-29inch lbs) and not just be trying to count threads based on the old flange ...it also sounds a little like the difference in operation between an open diff and an lsd in general 
hopefully someone else on here can chime in, I'm curious to know what it could be at this point lol
