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Jamo's RB25DET ''250Z''


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Hi mate, nice build. Ive also done the RB swap and have a slight vibration too when under light load. very mild but when feathering throttle in 4th or 5 th you can here the vibration a little more....is that similar to your issue? R200 also?

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Keen to hear how this pans out, I have a rb26 in mine and when on the dyno the guys says there is a vibration at higher rpms, need to bring it back to investigate. Might look on hybridz to see if any other guys with rb conversions had similar?

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Hey chaps..yes, I am running the R200 diff.

 

I will let you know what I find....I am comfortable there is an answer....uni joint driveshafts aren't rocket science. I am pretty sure it is just a front/rear joint angular conflict. The angle checks with the special tool will tell the story. I don't think it is related to load (ie diff angle changing due to torque reaction), as I can get the vibration even at light load/high vehicle speed, whereas full load at lower speeds creates no vibration.

 

Dat240Z: Yes, that description of the vibration is similar in my car....you can get it under both load and trailing throttle, but the characteristic/sound/feel changes slightly....it is related to speed...for example I can go to say 120km/h down a hill and get completely out of the throttle and the vibration is still there...it is a function of the driveshaft speed, not the load.

 

Cheer, Jamo

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Hey chaps..yes, I am running the R200 diff.

 

I will let you know what I find....I am comfortable there is an answer....uni joint driveshafts aren't rocket science. I am pretty sure it is just a front/rear joint angular conflict. The angle checks with the special tool will tell the story. I don't think it is related to load (ie diff angle changing due to torque reaction), as I can get the vibration even at light load/high vehicle speed, whereas full load at lower speeds creates no vibration.

 

Dat240Z: Yes, that description of the vibration is similar in my car....you can get it under both load and trailing throttle, but the characteristic/sound/feel changes slightly....it is related to speed...for example I can go to say 120km/h down a hill and get completely out of the throttle and the vibration is still there...it is a function of the driveshaft speed, not the load.

 

Cheer, Jamo

 

Yeah it sounds like we are all in a similar boat. My vibe is almost undetectalbe 1st/2nd/3rd. 4th/5th on light load seem to be most noiticeable.... Easy fix im sure... relatively...

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Hi TBOWGN

 

I run 17x8's on mine. 235/40R17 tyres. Suspension is King springs on shortened legs with Koni special D shocks. Adjustable spring perches which once set I have never adjusted again!

 

I am happy with those tyres, although 225 would be ok too. I had to roll the guards to get them to fit too.

 

I run Dunlop Direzza Z1's and they hook the RB up very well. I have about 450 BHP (not sure what that is in rear wheel kilopascals I am afraid).

 

Cheers, Jamo

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  • 8 months later...

OK chaps....after some time off the car, I finally got a hold of an angle cube to figure out my driveline vibration. I checked the Universal joint angles, and as I suspected, the diff pinion angle was sloping up toward the front, making the pinion and trans output shaft 2.5 degrees out of parallel. Maximum permissible angle for joint misalignment is 0.5 degrees (note this is NOT the angle the joints can run at, but the DIFFERENCE in angles they are running at as a pair). So, I dropped the gearbox crossmember 5mm, and the differential front cross member (the one that holds the front mount) 15mm. That got the parallelism to 0.25 degrees. I didn't worry about alignment in the lateral plane at this stage, only the vertical plane.

 

Took it for a road test and all sorted...whereas the vibration reliably turned up at 100km/h and up before, this time I went to 160km/h and no sign of any vibration at all. So...I will call it sorted. It's a bit of mucking around to refashion the diff crossmember to drop the mount that far, and it also means the torque reaction strap mount has to be re-made to ensure it is applying a restraining force to the diff housing against torque reaction in the lowered location.

 

Anyway....while it was never a problem when the L series was in the car, there certainly was misalignment present, that once corrected, eliminated the vibration....something to think about if you are having problems with your RB installation.

 

In other breaking news, I found that the front bushes on my rear lower control arms were shagged (they are urethane that I washed in thinners, and that seems to have attacked and degraded the material). Soooo.....does anyone have a set of lower control arm front bushes, or a complete set of original rubber or urethane?

 

Cheers boys n girls

 

 

Jamo

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  • 10 years later...

10 years! Time flys...

Jamo drops into my shop with his Z a few months ago.
Unfortunately he'd clipped a wombat with it which had shattered the spoiler and damaged the RH front guard, and he wanted to know if we could fix the guard and paint it.
Not a problem.

In July he dropped it off.
Jamo had fixed the fibreglass spoiler himself, but the guard had a crease in it, so we tapped the crease out and then prepped it for paint.

AP1GczP-C33_sWsLajml5Qxxgs7k1DzvAfIvmaOb

AP1GczOK_am1JkIbN1uYnxk4wQcwyFCqJ-3Aqjab

Straightening the guard:

AP1GczOa25cwvjdGZtXfUO7q4rx6rvUDryp4ezyR

Feathering the paint back:

AP1GczOZY2BpBr3DFIPd4J-h11jSYSGNBuoxresk

AP1GczMy7E59mEyHVMK4mBRLdOkMSHvK5dcFEPxn

AP1GczNEQON4ESJuqeHfsFf-He-gz9oeljubzhQz

Base coat:

AP1GczMFhgcEHsZ1A87hwyW24ERSG4kmGt_KN9ko

Clear:

AP1GczP7mU_husMm9WyXRcRtee93ZsP-hsn9l66b

The Z got a cut and polish, then we reassembled it:

AP1GczOF34xvIpf0Vm_JvFnmtoxPNKwFT49WjgbX

:)

Edited by C.A.R.
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