Pinion angle on short nose R200 carrier

Im basically starting this as a guide for what to do and what to avoid doing in my application.

My application being a quick road going car with ease of use, large range of aftermarket support, and choice of gearing.

The only constant will be the short nose S15/R33 carrier with 2 larger bushes up forward and 2 bolts aft.

My intention is to build my own short nose R200 diff cradle to locate it in the 260z chassis for various reasons

1: Avoid high freight costs from the states for existing stock.

2: Different design, as the existing kits have no aesthetic value IMO.

3: Produce my own first and foremost (am a qualified boilermaker) and if others are interested to build some for them too.

What NOT to do:

Existing solid front diff mounts as they are designed for the v8 crowd ( am planning 4 cyl turbo) and will disintergrate bushed rear mounts (chassis) as the pinion angle is set for the amount of preload expected from "that" much torque.

This preload in the V8 appliation will run true to 0 DEG under acceleration, but i believe this is not the case with lower torque application as the pinion wont have enough torque applied to get into alignment and so constantly run "whatever" NEG DEG. Im using whatever as i dont have a value on hand.

http://forums.hybridz.org/topic/112539-r200-front-mount-shimsheight/?hl=%2Bpinion+%2Bangle&do=findComment&comment=1053526

Align drive shaft straight and true, this will cause its own issues. This was pulled from author "BIG-Foot" #17  link below:

http://www.ffcars.com/forums/17-factory-five-roadsters/169229-does-pinion-angle-matter-irs.html

Having zero degrees difference between the transmission and the pinion is a good thing

BUT

while you do want the centerlines to be perfectly parallel (when possible) you also want the centerlines to be offset slightly.

If the centerlines of the transmission and differential pinion are perfectly aligned, the loading of the needle (roller) bearings in the Universal Joints will not be distributed but will be continually on one or two bearing rollers on each of the trunions. If the bearings are not allowed to rotate, they will not be lubricated and with all that load on just a couple of bearings, they will begin to fail quickly.

This is one of the reasons that many solid axle cars have the pinion offset to one side slightly.

So - it's not an easy answer.

Yes a perfectly aligned pinion and transmission centerline will yield the least amount of power loss.

However, the cost of recovering an insignificant amount of power is a small price to pay for a happy and long lived driveline.

So this seems to be food for thought.

What TO DO:

IRS equipped cars have to have the correct static pinion angle / preload to avoid vibration under load, and also a small amount of parallel offset to allow for drive shaft uni lubrication.

How much angle is a question im hunting for.

Noticing the alignment under the z with the longnose r200, it seems nissan knew this as the mounting points for the nose of the diff is set more to starboard than central.

Another great read is #24 author Tim whittaker on said link or permalink:

http://www.ffcars.com/forums/17-factory-five-roadsters/169229-does-pinion-angle-matter-irs.html#post1480413

This has some follow on consequences:

1: Allows for lubrication mentioned above.

2: Brings the axles on either side in closer dimension (length) to one another which as we know at full droop and full swat the operating angles are different due to different lengths,  as the pinion gear is offset in the housing relative to the stub axles /output shafts.

I.E. a longer axle will have less of an included angle as compared to a shorter axle for the same amount of wheel travel up and down.

Note:This post is far from finished and will continue to be revised to get the full scope of what im doing in one place for ease of access.

Feel free to add your experiences about this.

If there are any users who have done the conversion, i would like to hear you input.

Between 4 to 6 degrees down.

If you run <4 degrees (compound angle) you can use rubber couplings (Jurid, etc). That's what I've done.

I've raised this several times before but I don't know why more Holden diffs are not installed? There is a huge range of ratios and they run 930 Porsche CVs of which there are cheap clones as they are the choice of off-roaders. The diffs are cheap and axles are available from off-road sources.

Between 4 to 6 degrees down.

Hey thanks for the reply.

Is this based on a similar application or something like a v8?

Obviously the engine will be on the same parallel plane under acceleration, but the 4 - 6 DEG would be from parallel?

Does a short nose really move that much? 4-6 degs is 15-22mm from parallel that the nose goes up under full acceleration

Just thinking out loud, but i was speculating that movement would be restricted to max 2-3 degrees since the diff is captive. Is this right to think so?

If you run <4 degrees (compound angle) you can use rubber couplings (Jurid, etc). That's what I've done.

 

I've raised this several times before but I don't know why more Holden diffs are not installed? There is a huge range of ratios and they run 930 Porsche CVs of which there are cheap clones as they are the choice of off-roaders. The diffs are cheap and axles are available from off-road sources.

Thats a good point about cheap cvs and range of gears, and will do some research in to it.

Did you get yours engineered?

How its the tailshaft for vibration?

Its funny as actually saw this set up for the first time under a soarer and asked myself what the hell was that there haha!

Cheers

Darius