R32 Gtr Long Term Love, Now Project

[r32-25t]

The sensor grounds all go back to the ecu and none of them are on the battery ground, Adam suggest putting the flex sensor straight to earth because of it being a frequency signal can play with the others 

it does it on the road now that I’ve driven it and paid attention, not sure if it’s rpm or load making it happen though 

[r32-25t]

One of the issues Adam mentioned was the tail shaft center bearing being flogged out, I took the shaft down to be rebuilt after a conversation with the owner of the shop it was decided a whole new shaft was the best way to go. 
 

so after taking measurements and waiting a week my new shaft was ready to pick up

 

new and old shafts next to each other, yes the new one piece shaft and was worried about vibration, after driving the car turns out that there is nothing to worry about 

[The Bogan]

1 hour ago, r32-25t said:

One of the issues Adam mentioned was the tail shaft center bearing being flogged out, I took the shaft down to be rebuilt after a conversation with the owner of the shop it was decided a whole new shaft was the best way to go. 
 

so after taking measurements and waiting a week my new shaft was ready to pick up

 

new and old shafts next to each other, yes the new one piece shaft and was worried about vibration, after driving the car turns out that there is nothing to worry about 

The only requirements/issue with one piece tail shafts is tail shaft RPM, the length of it, the diameter of it,  the pinion angle, and material used

Daily driving at 110 kph it top gear with a one piece will probably never see any harmonic issues at ???? tail shaft RPM, but, at 200kph you might see some harmonic issues if your tail shaft isn't spec'd right

I looked into this alot when I was looking at a new tail shaft for my VX SS after it constantly flogged out centre bearings and getting vibration over 160kph, in saying this my "pinion" angle from the gearbox to the centre bearing was the issue, slightly to much angle caused the centre bearing to flog out from harmonic vibration at high tail shaft RPM, but for me the issue was the 12mm lower engine mounts, after getting the angle of the dangle from the transmission to the centre bearing lined up correctly, and to within spec (OEM height poly mounts), the car is happy at 200 kph (125mph at the drags) now even with the OEM spec centre bearing and rebuilt OEM 2 piece tail shaft

What's your tail shaft specs?

[r32-25t]

Approx 1m long, chrome moly, hardy splicer unis. Didn’t measure the diameter. The shop that built it also builds the shafts for b2r, jem, maatouks, etc and built the shaft to the same specs as their cars that’s are running 7 and 8 second passes!! Which say to me that it can handle some big mph 

[Duncan]

I'd always suggest a tailshaft loop with a 1 piece tailshaft, just something simple from the original centre bearing mounts going underneath it

[GTSBoy]

1 hour ago, Duncan said:

going underneath it

And over it. Need to stop it coming through the floor.

[Dose Pipe Sutututu]

13 hours ago, r32-25t said:

can handle some big mph 

but for how long? would it handle a few laps around SMSP in anger? 

[Kinkstaah]

It also depends on gearbox ratio.

Those drag cars running 7s passes aren't doing it on an overdrive gear ratio (probably). 1:1 is "fine", the critical RPM for a 50' single driveshaft in chromemoly is 6900rpm....

....but when you shift into 5th and use 0:73 or 0:8 it all changes. Do you know their rear diff ratio? etc.

That's the stuff that matters with regards to it. Whether it actually matters given your use application is also relevent. You may never get into those scenarios, like most ruined GTR's from Western Sydney don't :p

[Dose Pipe Sutututu]

2 hours ago, Kinkstaah said:

You may never get into those scenarios, like most ruined GTR's from Western Sydney don't 😛

they might see those prop shaft speeds for 1 to 2 secs only 

[GTSBoy]

With same diff ratio, tyre diameter and road speed, the tailshaft rpm is the same regardless of the gearbag's ratio. Given that very quick drag cars are probably doing similar road speeds to the fastest circuit cars (circa 300 km/h), and there will be many of either category that can't go that fast and so you'd have inummerable matchups between drag and circuit car speeds at smaller numbers, and given that they are probably using rather similar tyre diameters and probably using similar diff ratios, and...where any of those numbers were different they could quite easily be in opposite directions thus cancelling out....

I think you'd find that there'd be more similarity than difference in tailshaft speed between these two use cases, no?

[Dose Pipe Sutututu]

16 minutes ago, GTSBoy said:

I think you'd find that there'd be more similarity than difference in tailshaft speed between these two use cases, no?

Shaft speed would be the same, however it's how long they hold it there for and repeated conditions.

FWIW half way down the main straight at SMSP I'm bouncing off 4th with a 8600RPM limiter. That shaft would be spinning at 8600RPM for a few seconds before I need to smash the brakes, by T2 it's getting close to that speed again. Now a drag car/roll race car would see that shaft speed for a 1 to 2 secs then they would coast, hit the brakes and that's it.

[GTSBoy]

Oh, yeah, no arguing that the duty cycle is different. And a circuit car will go to those speeds for more distance and longer times. But, I suspect that if a tailshaft has a harmonic problem, that it would cause damage and shit itself maybe even on the first pass. A second or two of running at the resonant/harmonic problem speed is already a couple hundred revolutions.