R33 GTR vibrations issue over 160km/h

[Tomak]

Hello,

I have an issue  with my car R33 GTR after swapping Rb26dett (which i killed) to Rb25det neo. Some vibrations has occured. 

This swap took about 12 months so i did not run my car for 12 months and i have no idea what issue can be.

i have light flywheel dedicated to rb26dett with the clutch NIsmo Super Coppermix Twin Plate that i am using now with rb25det neo

I am strugling with big vibrations that starts over 160km/h and  go away when car accelerate faster, I can feel smaller vibrations also from 120km/h. From the range 0 -120km/h fell no vibrations almosts at all. At 250km/h can hear weird howling metal noise and i am affraid to accelerate faster. 

When i stop my car on traffic lights and i start drivin again i can hear one metal knock sometimes and weird rubber grinding noise.

Any ideas what it can be? I am strugling with this issue for some time now, changed some parts in my drivetrain already and put a new set of tires but nothing helped.

So far i checked all things related to the wheels, gearbox and engine pillows and driveshafts but all changes i have done did not helped so far.

Can be this related to light flywheel not being balanced properly with rb25det neo?

 

 

 

 

[Duncan]

If the vibration is related to road speed, not revs, it is not engine, flywheel or clutch; it must be in or after gearbox.

Howling noise occurring over 250km/h is most likely a cop siren and is indeed a sign you should slow down

[Tomak]

 

57 minutes ago, Duncan said:

If the vibration is related to road speed, not revs, it is not engine, flywheel or clutch; it must be in or after gearbox.

So you are saying i may need to buy next gearbox? Thats what i was wondering and left this for last part to change eventually, .... 

Quote

Howling noise occurring over 250km/h is most likely a cop siren and is indeed a sign you should slow down

LOL, they dont use sirens in my country anymore, they try to race undercover with BMW's so i need to be cereful when i see any BMW on my tail now....;/

Edited June 18, 2020 by Tomak

[BK]

7 hours ago, Tomak said:

my car R33 GTR after swapping Rb26dett (which i killed) to Rb25det neo.

I'm confused by this. You have an R33 GTR and you're saying you pulled the 26 out and replaced it with a neo 25 ? Why on earth would you do that ?

[KiwiRS4T]

I guess you have removed all the front drive components. I would have a good look at the parts you put in to replace them. You don't want a wheel falling off at 250km/hr ...especially on a public road.

[Tomak]

12 minutes ago, BK said:

I'm confused by this. You have an R33 GTR and you're saying you pulled the 26 out and replaced it with a neo 25 ? Why on earth would you do that ?

Because Rb25 is 10 times cheaper in my country than RB26 and more accessible and i like to kill the engines, so that was the decision. Rb25 is not bad at all i dont see any differences except lower revs limit 7500.

[Tomak]

24 minutes ago, KiwiRS4T said:

I guess you have removed all the front drive components. I would have a good look at the parts you put in to replace them. You don't want a wheel falling off at 250km/hr ...especially on a public road.

Yeah  i was thinking about this for some time now. I think this is the only way to take apart everything and check every part and joint. I am pretty sure its coming from the front, cus i can hear this rubber noise when i brake and accelerate. I hope i will find something finally. 

[BK]

34 minutes ago, Tomak said:

Because Rb25 is 10 times cheaper in my country than RB26 and more accessible and i like to kill the engines, so that was the decision. Rb25 is not bad at all i dont see any differences except lower revs limit 7500.

[dyl33]

50 minutes ago, BK said:

Isn't the rb25 neo better then the rb26?

 

 

[BK]

12 minutes ago, dyl33 said:

Isn't the rb25 neo better then the rb26?

 

 

No.

[Duncan]

Anyway....if converted to 2wd some how the issue is likely the bearings in the front hubs are not retained properly without a driveshaft and driveshaft nut, the 2wd front uprights are different.

[dyl33]

58 minutes ago, BK said:

No.

Really? I was under the impression the neo was better. Can you explain why it isn't? 

[BK]

Look, I don't want this thread to be hijacked with neo vs 26 details, that's for another discussion, but for a start I'd take a 26 head over a neo any day. Look up the differences like neo head shim over bucket vs 26 shim under bucket, 26 unmodified heads flowing far more air than other RBs etc. Someone else can elaborate more on other differences if they want, but the point earlier was referring mainly to replacing the 26 in a GTR with a 25 being a bit silly. Hardly a GTR anymore is it ?

[GTSBoy]

But to continue the hijack.....the Neo has VCT, which any RB26 owner should feel bad about not having. In every other way the 26 head is at least as good as or better than the Neo.

[Kinkstaah]

I had my neo head hiflowed back in the day by a reputable person, and from that point on my neo beat the shit out of any 26/28 for power and response vs PSI going into it. I guess you'd cost up the head work ($1300-1400ish) to adding VCT to a 26/28 to really compare.

I mean 11psi (10.9) to make 330kw on a 3076 size turbo. That's a lot of flow.

If you're going to go single turbo anyway...  yeah this isn't as dumb a swap as you may think. I'd gladly drop a NEO/Stagea Drivetrain into a GTR/GTS4 shell and sleep happy about it.

As for the original issue - I don't know/I didn't have it with my neo, though I had a clutch/flywheel from a R33 GTST Gearbox. Someone here would probably know how close a 33 GTR/33GTST gearbox/flywheel etc relate to one another.

But if the issue doesn't follow RPM, it's unlikely to be that set of spinny bits.

[Ben C34]

put a GTT bonnet and front on it also!

[Tomak]

10 hours ago, Ben C34 said:

put a GTT bonnet and front on it also!

Thanks for great ideas. I have cut my rear spoiler already because i found it is to heavy and too big and also cut front lower spoiler lip. It looks like shit now but at last i can go to the supermarket to pick up some patatos. I plan no further modifications between GTR - GTS so far. The front from GTR r34 would be nice by the way, maybe i think about this conversion one day. It will be GTR/GTS NEO/R34/ converted also forget to add its already left hand drive converted for EU roads with cockpit from Maxima 1995. LOL

 

13 hours ago, dyl33 said:

Isn't the rb25 neo better then the rb26?

 

 

My mechanic was a pro drifter swaping rb25 to S14 and he said there are some advantages over rb26 but i dont remember now what he was talkign about LOL. He is deep inside these engines and run the store with parts to Rb's

I also rebuilded my Rb26 once with forged pistons and rods.  after spun bearing. It cost me around 8k USD and then i spun the bearing again after 3 years of driving. THis engines has problems with oiling and high revs. So in this case i changed setup to RB25. I spun bearing again in Rb25 after 1 month and got another Rb25 at 2k with labor. Driving like gold now for one year on stock internals. I dont mind spunning bearing again pretty soon LOL

 

[Tomak]

Guys i remember now that the only part i have changed in my car before swapping to Rb25 motor was the rear differential. Before killing my RB26DET my rear diff also died and i have replaced it with different one. I am not sure about the source where i bought this rear diff, i got it from some local garage shop that does not have good feedback on forums. It was very cheap too, around 200 USD, this is why i took a risk and bought it. So my car suffers vibration right after the rb25 swap and this rear differential. 

Can such a vibrations be from this rear differential? When my old differential died i could hear loud howling sound like siren this is why i changed it. But i dont remember such a harsh vibrations, it was 2 years ago. Actually i have my old differential in my house so i can put it back to check if also vibrates. Maybe this way i can at last check the rear differential. The prices of rear diff on ebay are killing me, 1500 pound from UK ;/ 

If this is the issue what do you suggest? Get the third one used OEM or maybe change the diff internals for new one some brand like Quaife? https://shop.quaife.co.uk/nissan-skyline-gtr-r32-r33-r34-rear-quaife-atb-helical-lsd-differential

 

Edited June 19, 2020 by Tomak