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Q45 VLSD tearing up cages


CrayZ

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Here are a few things I see and I hate that I can't compare to my car right now:

 

Strut tubes do not look like they were welded straight "plum"

The stock uprights look bent towards the rear of the car

The "homemade" cage looks like it mounts the nose of the diff downward - I def can't see over the top of my diff.

 

 

Take measurements of the rocker to the ground, diff mount bolt that is in the ttt MS bar to ground.

 

I took a look at rags car today which has the 280zxt axle setup and with the car on the ground the rear control arm is almost parallel to the ground and the angle of the axle from cv adapter to diff is small. Your angle of the axle looks like my car at full droop.

 

EvilZ%20%2815%29-X2.jpg

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The diff should be positioned slightly back from the wheel hub. This was moved slightly back by Datsun in 72.   I just some measurements on my car. My ride height at the back of the rocker in front of the rear wheels is 7 inches from the bottom of the pinch weld to the ground. I run 18"350Z wheels which also plays a part in where the hub sits in realtion to the ground. I also took a measurement from the ground to the diff mounting bolts. There I have 12 5/8" between the ground and the bottom of the bolt that comes through the mustache bar.   I'd take measurements on your car and compare them to mine. I'm sure you are going to find that your diff is much closer to the ground than mine.   Joe
I measured the car height (lowest part of the rocker panel) I'm assuming is the pinch weld. My car measures 6" clearance. From the bottom of the bolt in the mustache bar to the ground measures 11 3/4"  I talked with techno tunning and they said they make two mustache bars. One that requires the frame to be notched and one that does not. Edited by CrayZ
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Here are a few things I see and I hate that I can't compare to my car right now:

 

Strut tubes do not look like they were welded straight "plum"

The stock uprights look bent towards the rear of the car

The "homemade" cage looks like it mounts the nose of the diff downward - I def can't see over the top of my diff.

 

 

Take measurements of the rocker to the ground, diff mount bolt that is in the ttt MS bar to ground.

 

I took a look at rags car today which has the 280zxt axle setup and with the car on the ground the rear control arm is almost parallel to the ground and the angle of the axle from cv adapter to diff is small. Your angle of the axle looks like my car at full droop.

 

[img=http://evilz.smugmug.com/Cars/Clive-Bogle/i-jrjqcWR/0/X2/EvilZ%20(15)-X2.jpg]

 

 

You are correct the dif is slightly pointing downward. I was actually told that this was a good thing.. Supposedly drag car do this in order to compensate the dif being torqued upwards on hard launches. I have no idea if that is legit or not..

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Your new snap ring groove is how the factory ZXT axles are done. it's a double-thick groove to hold a double-thick circlip in place, the clip has a square cross-section. the outer clip is a regular snap ring on the outer CV and a round-wire push-in clip on the inner, but you *really* have to push hard to get it to compress into place.

 

I think your inner bearing races are pushing up on the shafts and shortening your axles up.

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Your new snap ring groove is how the factory ZXT axles are done. it's a double-thick groove to hold a double-thick circlip in place, the clip has a square cross-section. the outer clip is a regular snap ring on the outer CV and a round-wire push-in clip on the inner, but you *really* have to push hard to get it to compress into place.

 

I think your inner bearing races are pushing up on the shafts and shortening your axles up.

 

I hope so too, well see in a couple hours

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Page 10 here looks interesting, although the whole catalog is worth browsing - http://www.ntn.ca/Catalogues/NTN/CVJ-ForIndusrial_en.pdf

 

Here's one of the Pathfinder axle threads, only because it was mentioned, sounds like you're going a different way - http://forums.hybridz.org/topic/72805-using-pathfinder-and-zxt-axles-to-install-30-spline-nismo-lsd-kit-56k/page-3?do=findComment&comment=942447

 

I think I might try this route ! Anyone have any info ?

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  • 2 weeks later...

Installing a "drag" angle for the differential is unnecessary because the diff is mounted SOLID at the rear. I don't know what your front diff mount looks like but I doubt it will twist or dip like an OEM rubber bushed differential in a car with lots of extra HP. I would look at the moustache bar and front mount with some careful measurements. I have a MM setup for the Q45 VLSD with AZcar rear bar and TTT front mount, IIRC. It is all on the shelf if you want measurements to compare the moustache bars.

I think double floating is not too bad if you don't have extreme angles while actually driving, which can be improved by ensuring the axles are level at rest. Some travel for suspension extension and some travel for suspension compression. Your diff is using too little for extension and too much for compression. That is probably what caused the failure that everyone seems on board with.

It sounds to me like you may have built a way to safeguard from immediate failure but I would consider relocating the diff up as far to level as you can get.

LUK

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  • 3 weeks later...

Installing a "drag" angle for the differential is unnecessary because the diff is mounted SOLID at the rear. I don't know what your front diff mount looks like but I doubt it will twist or dip like an OEM rubber bushed differential in a car with lots of extra HP. I would look at the moustache bar and front mount with some careful measurements. I have a MM setup for the Q45 VLSD with AZcar rear bar and TTT front mount, IIRC. It is all on the shelf if you want measurements to compare the moustache bars.

I think double floating is not too bad if you don't have extreme angles while actually driving, which can be improved by ensuring the axles are level at rest. Some travel for suspension extension and some travel for suspension compression. Your diff is using too little for extension and too much for compression. That is probably what caused the failure that everyone seems on board with.

It sounds to me like you may have built a way to safeguard from immediate failure but I would consider relocating the diff up as far to level as you can get.

LUK

 

 

Mounting the Differential more level is probably a good idea but in no way directly related to the issue is was having. IMO the car sits far lower than MM ever considered for their axles.. In turn they are to short for my particular application. I can safely say that my spacers have corrected the problem and i have put several thousand HARD miles on this rear end and it is working perfectly.

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