Thread: 6 speed shaft, close to chassis?

Hi all,

I've got a 6 speed in my RHD B14 (AUDM N15). My left hand side inner joint boot runs very close to the chassis rail and has of late begun to rub on the rail when under acceleration.

Does anyone else with a B14 and a 6 speed have this problem ? I am using P12 inner joints with custom mid shafts and B13 ABS outer joints. I don't know if its just my combination of parts (specifically the inner joint type) that is causing the clearance issue (as we don't have B15's here to steal shafts from) or if there's really anything i can do about it.

I have a solid rear prothane, solid right hand side prothane, OEM Maxima rubber gearbox mount (which if made solid would probalby fix this issue) and i don't currently have a front strap at all.

Cheers for any info.

By left do you mean our passanger (your driver) side? If so, I had that issue as well. I first I thought it was due to the axle carrier bracket I got (was useing a stacked p12 bracket but a friend got me the mazworx' one) but they said it sat correctly. I just ground down the chassis rail a good deal at the area where it was slightly touching and called it a day. Now if your talking about our driver's side (your passange side) then I have no clue what's up 'cause it clears fine on my setup.

For the record I have a '98 B14 with the B15 CV axels, solid rear & passanger (your driver) poly mount and a full metal front dogbone; the driver's side mount (your passanger) is stock. From what I understand the B15 axels are a little wider/bigger then the P12's, but I could be wrong.

Thanks for the reply.

I had trouble with my driver (your passenger) side shaft very lightly rubbing and only on heavy acceleration, but putting a solid mount in fixed that. I wanted to avoid solids because the car is my daily, but seems that's just not possible. The P12 shaft that attaches to the carrier bracket is a few inches shorter than the B15 shaft before the first boot which sorts out that major clearance problem on that side of the car. I have a mazworx bracket and when comparing it to the stock P12 bracket i could imagine that clearance would have been pretty bad with the B15 ones.

I'll get some pictures up shortly to demonstrate the issue i'm having (much easier that way huh!)

Here's a couple of pics.

My driver side / your passenger side. One of the 'ribs' on the boot was rubbing on the rail. That was fixed by using a solid mount.



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My passenger side / your driver side where the major problem is. in this picture the shaft is sitting real close to the rail, usually i can fit my index finger up there but i have the crossmember out of the car right now so the engine is supported with a jack.



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hmmm, thats interesting, i test fit my 04 6 speed box w/ motor into my b13 and looked it all over and doesnt look like i would have any axle clearance problems. Im using the Mazworx mount kit as well too. Interesting. Ill post up pictures as soon as i get my flywheel back from Competition Clutch and get the motor, trans, and axles in as well. Ill have pics in my build thread of it.

Oh and btw, how do you like the 6 speed trans. Im assuming your using the 4.1 final drive, same one in the 04+ boxes spec V boxes.

My box is 100% P12 original with the 4.75 final drive. Its great driving everyday, 6th gear ends up being very close to the stock N15 5th gear (B14 SER basically) which is a little annoying, i would have liked to have a lower RPM in 6th at highway speed of 110km/h (68mph). (Sub 3K would have been awesome, but meh! i still get great mileage)

Please let me know how you go with fitment and if you can take a picture of the inner joint of the shaft you're using and take a measurement of the diameter of the fattest part of the boot that would be great.

There is basically no-one else in Australia that i'm aware of that has done this conversion, only one guy in NZ did one to an NX but he sold the car and doesn't recall some of the finer details of his conversion other than he cut the cups off the inner joint and welded on stock 32 series cups.

Its possible that my chassis to gearbox mount is in the wrong location because i'm not using a mount kit (mazworks kit wasn't availible when did mine) so its really hard to get any information locally to compare. I guess my other issue is that i have no front strap mount to stop the motor from torquing back towards the firewall under throttle, i'm hopefully going to sort that out in this coming week.

ah, yeah the 4.1 FD from the 04 spec V box mixed with the longer 4-6th gear is gonna be killer on the highway. Basicly 1-5 are almost identical to a P11 gearstack. I was running the 99 p11 gearstack which has a slightly longer 3-5th but uses the same 4.1 final drive as in the b13/b14 trans so this trans 1-5 come out to almost identical speeds at same rpm as my old box but then add a 6th gear. I think ill be around 26-2700 rpms around 75-80mph on the highway fairly easy.

Yeah im thinking its your custom rear mount thats making the clearance issues. Mine appears that its gonna clear no problem. I didnt even have to take much off the left-side, my driver side subframe for the differential housing to clear but i ended up taking more off than needed, lol.

But yeah ill take some pictures of mine as clearance should be fairly similar in the b13 and b14.

Ill be using the complete spec V axles and changing hubs w/ new bearings. I want to keep the larger axles complete so they will hold up to some serious launches.

Yea, that's sort of the same rubbing I had on my passenger (your driver’s) side. Like I said, I just ground that down some and it was fine. Here is what it looked like on mine before the grinding of the frame:


(One of the pics I sent to Mazworx)


However, on your passenger side (our driver’s side) where your bigger issue I can't really give much input. I'm using the stock B14 rear mount for the tranny/motor not the mazworx mount and i can still get a finger easily between the frame and the boot. I will get some pics in the morning for you and some measurements if that might help.

ashtonsser: I got a '04 tranny with a 3.8 final in it and i see 80mph at about 2900rpms in 6th. It is very sweet for my driving style and highway use. The rest of the box is almost identical in the layout to my previous '98 B14 non-LSD tranny.

Now that i think about it my passengers side one was a little close, but never a problem.

Thanks for the pic. When i compared the Mazworx axle bracket to the P12 OEM bracket, it was immediately clear that the shaft, as you pictured, would be very close to that side. I bought the mazworx bracket as they said it would work for the P12 shaft, but it doesn't because the P12 shaft is an inch and a bit shorter than the B15 at that point. Thankfully the small amount of rubbing on that side was solved with a solid mount to keep the motor stable.

How many holes does your B14 mount line up with on the tranny? 2 holes? one up top and one down low? I modified my mount to use the 2 holes down low and the one up top, but it was hard knowing if the angle was right or not.

If you have time i'd really appreciate a pic or two of your driver side shaft clearance. Thanks.



Thanks mate, i was hoping to hear from you, but i know it was a long time ago that you had the car. I think what it comes down to is that not having a front mount is letting the engine move too far, and with an OEM rubber type mount on the gearbox, it just has too much movement/give in it, which until now (about 22,000km since i put it all in) its just softened up and is allowing more movement.

I was trying to fit up a P11 crossmember to the car, although it bolts in (length is identical) the alignment and offset of the mounts isn't right and will require some fiddling to get it to work, i just don't have the tools to do the mods to fit it (no welder etc).