Q40 rear diff swap?
#1
Q40 rear diff swap?
So I'm looking into swapping the differential out on my 15 Q40 to a VLSD with 3.69 gears. I found a decent deal online and the seller says it has 3.69 gears. Is there anyway to know for sure if it has 3.69 gears and will it fit my Q40?
#2
Premier Member
iTrader: (2)
The door plate on the car it comes from should have an axle code that reads RC36. You can also physically turn the input and for every full 360 degree turn of input you should get 3.69 turns out of the outputs.
As for it fitting a 2015 Q40, all data online says it will. From what I can find only the newer cars with the 3.0t had the new rear sub-frames. However that could be incorrect.
As for it fitting a 2015 Q40, all data online says it will. From what I can find only the newer cars with the 3.0t had the new rear sub-frames. However that could be incorrect.
#3
Registered Member
#6
They assured me it was definitely a 3.69 ratio have me a free return guarantee. So for $185 shipped with 60k seems like a good buy to me. If I diy it myself what if any parts will I need for the complete install?
#7
Super Moderator
iTrader: (3)
The "KG" stamp denotes a vlsd...AFAIK they only came in 3.69 and up (except on the G35 coupe and 350z)
if its from an 07 or 08 sedan they were all 3.69
it will fit but it MAY require you to swap and cut the pinion flange and get one or both stub axles or different axle bolts
theres lots of threads on this as many many people have done it heres a few:
https://www.myg37.com/forums/engine-...-on-awd-g.html
https://www.myg37.com/forums/
https://www.myg37.com/forums/engine-...hes-oh-my.html
the missing information is what you're starting wiht ? AWD or RWD if RWD Manual or auto? that might help narrow it down for some of the options you need but you will have to look at your diff to see what kind of pinion flange you have and which way the stub axles bolt up (some are threaded on the axles and some on the stubs)
also keep in mind that at 60K the VLSD should be just about completely worn out will start functioning as an open diff soon if it hasn't already
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Atl3128 (04-28-2019)
#9
Premier Member
iTrader: (2)
Yep, no i got that switched around. 3.69 turns on the input should be 1 turn on the output to the wheels. If it was a normal driven car it's doubtful the VLSD is worn out. If the car was tracked, auto-crossed, or the like then maybe; but if it was just a grocery-getter/daily-commuter it's most likely fine. Of course, you have zero way of knowing that until you get it in your hands. All that aside the information you are looking for is scattered across these forums, but without more info on your car we can't answer more directly with accuracy.
#10
So the more I think about it I'm leaning towards 3.90 gears over 3.69. is there a certain year G that came with 3.90 and LSD that would be a fairly easy swap? I'm looking for pretty much a plug and play set up if possible bif not then I'll do the 3.69 gears
Last edited by Atl3128; 05-07-2019 at 10:17 AM.
#12
I haven't had much luck finding one from a convertible G and not real big on 3.90 gears and no vlsd.. I may end up just going with 3.69's for ease of install.
#14
Super Moderator
iTrader: (3)
the issues with it begin "plug and play" don't relate to the gearing but the pinion flange and stub axles on your car now and whether they match the doner pumpkin you still have to look at those variables to determine whats what...the easiest thing to do is just look under your car so you know what your working with