Transmission Problem ?

[rs73]

from Hyper rev the most popular Size in Japan for Staggered size is 245/35 19 and 275/35 19 which should disrupt the the VDC and closer to the speed read accuracy.

Yes those are the most popular size... I have that too

it's a very good proportional change where these sizes is 0.85% smaller in circumference (less than 1%) at the front

and 0.38% smaller in circumference at the rear. There is only 0.5% disproportional circumference front to rear which means

it is quite small that the VDC may not even detect the changes.

so whats the tolerance like? i mean in terms of % difference in diameter

would a 235/35 19 and 275/30 19 work???

If you haven't got to the bottom of it, this size you have is 1.9% reduction in circumference at the front and 4.4% reduction at the rear.

There is around 2.5% disproportional circumference front to rear which may be 'huge' enough to make the VDC computer thinks

either front or rear tyres are slipping all the time... it may upset the VDC. How big is that tolerance we do not know.

I think the tyre shop who gave you that combination must have assumed your coupe comes with non-staggered OEM tyre size front to rear.

Reason is because the front and rear circumference are just differ by 2mm. Where in fact they should have given you a bigger profile tyre

at the rear - you'll find 265/35 19 will work with your 235/35 19, alternatively use the sizes what pw350gt suggested above.

You can't use 275/35 19 at the back because that will be disproportionally too large compared to your front, so you must change the front

to 245/35 19 as well.

[whtbox]

from Hyper rev the most popular Size in Japan for Staggered size is 245/35 19 and 275/35 19 which should disrupt the the VDC and closer to the speed read accuracy.

sorry for the Typo if any one didn't get it.

What i meant is those size Should NOT disrupt the VDC..

[manda23]

VDC relies on the ABS sensors to tell the computer how fast each wheel is spinning. The other input into the VDC computer is a yaw sensor in the middle of the car. That detects accelerative forces on the car, so the computer can work out of the car's acceleration and turning rates line up with what the ABS sensors are telling the ECU as to how fast the wheels are spinning.

If that data does not correspond with "normal", it'll cut power to the engine by closing the throttle and it may grab the brakes as well.

You can unplug the VDC module. Your dash will light up like a Christmas tree and you'll lose the speedo/odo/ABS but the brakes will still work. If the car drives "normally" then you've found your culprit. Whether its the ABS or yaw sensor will require investigation.

Normally when the VDC detects a fault it'll just shut itself off as if you'd unplugged it as above. Its strange that the unit is just working overtime.

Josh at Pro Concept has a spare 6 speed manual gearbox. I'm not sure how negotiable on that price he is, but you can give him a call. Find out if its necessary though. If turning off VDC stops it then its not a transmission issue.

Tell him that you're after the spare 350Z gearbox that was in Alan's car for a while.

Excellent , thanks just what i needed to know. I did go for a shortr drive last night and i had the VDC switched off and didnt have a problem , but i didnt push too hard. Then when i stopped and then started the car again i drove off and the VDC OFF light wasn't lite on the dash so im ashumming it automatically turns back on when you re start the car. And the before 100m i had the same problem , slip light came on and the car wouldnt give power and bad noises from somewhere.

Why cant i just drive the car with the VDC OFF all the time. Is there any damage or could i do any more damage driving it?

The lube mobile guy didnt have a clue or where to plug in the computer for help !!

[rs73]

The OBD-II port should be somewhere under dash panel on driver's side under steering wheels - just like any nissan. Impul ECU is probably only a chip swap, so most obd reading might still work, give it a try...

If VDC relies on ABS sensor as said, might worth checking if the sensors are functioning ok. not damaged etc.

Why not try Nissan dealer that knows or done a 350Z? If the lube mobile guy dunno how to fix it?

[scathing]

Then when i stopped and then started the car again i drove off and the VDC OFF light wasn't lite on the dash so im ashumming it automatically turns back on when you re start the car.

It does. You can buy aftermarket modules to have it "remember" your last setting.

Why cant i just drive the car with the VDC OFF all the time. Is there any damage or could i do any more damage driving it?

You can. I do it all the time (well, TCS since I don't have VDC). The VDC is an electronic system that is meant to only work reactively. If you drive normally you should never make it work. It just means that you won't have the "safety net" of the stability control.

If the car's perfectly drivable without VDC then take it to a mechanic's. I don't know about Paden, but Pro Concept has a Nissan OBD scanner that works with our cars. As does CRD. Maybe drop them a PM, since they're on SAU?

Since the car's drivable with VDC off, you could test the ABS sensors by triggering it. Pump the tyres up to their maximum rated pressure, find somewhere open and deserted, drive it up to a reasonable speed, and jump on the brakes. If the ABS works then their sensors work. You're looking at either a yaw sensor issue, or electronics.

If the brakes lock up, then you can go to any mechanic and ask them to check your ABS sensors first. Its common technology that doesn't require V35 specific knowledge to troubleshoot.

Just remember to dump the air pressure afterwards, to get a bit more grip back.

FYI the VDC module/ABS pump is bullshit expensive new, but I have seen quite a few on eBay USA for not a great deal of cash. You're luckier than me - my car has TCS only and my pumps are impossible to find. eBay / Yahoo! Auctions Japan only have non-TCS units for base model cars, or VDC units for top-spec ones.

The lube mobile guy didnt have a clue or where to plug in the computer for help !!

The port is above the right-side knee on the driver's side. The Lube Mobile guys can be idiots sometimes - a mate of mine had a MR2 and the Lube Mobile guy went to the front of the car to check the engine.

[rs73]

LOL - the concept of rear mounted engines probably unfamiliar to them... how many Porsche owners will ring Lube Mobile to fix their cars....

Well, scathing, is yours 350z?

[scathing]

Yeah I have a 350Z.

[Stephen Thorpe]

some good stuff there guys, great advice...

[manda23]

Yeah I have a 350Z.

Well i have been driving around town just keeping it short sorta hoping for it to do it again and it did. I had the VDC switched OFF and i have discovered whilst the car in not level the slip light comes on and a definate grinding sound from the front of the car.

I think my only option is to take it to nissan , unless you guys can tell me a cheaper option ?

[fcruz3r]

maths looks complicated. But I plugged the tyre measurements in 1010tires.com for comparison and this is what it came up with

Tire 1 - 235/35R19 >Search Tires Tire 2 - 275/30R19 >Search Tires

Section Width: - -

Section Width: 9.25 in 235 mm

Section Width: 10.82 in 275 mm

Rim Diameter: - -

Rim Diameter: 19 in 482.6 mm

Rim Diameter: 19 in 482.6 mm

Rim Width Range:

Rim Width Range: 8 - 9.5 in

Rim Width Range: 9.5 - 11 in

Overall Diameter: - -

Overall Diameter: 25.47 in 646.93 mm

Overall Diameter: 25.49 in 647.44 mm

Sidewall Height: - -

Sidewall Height: 3.23 in 82.042 mm

Sidewall Height: 3.24 in 82.296 mm

Radius: - -

Radius: 12.73 in 323.34 mm

Radius: 12.74 in 323.59 mm

Circumference: - -

Circumference: 80.01 in 2032.2 mm

Circumference: 80.07 in 2033.7 mm

Revs per Mile: -

Revs per Mile: 816.6

Revs per Mile: 816.0

So to me that looks close enough on the difference on circumference, unless I'm totally missing the point again?

[scathing]

I think my only option is to take it to nissan , unless you guys can tell me a cheaper option ?

Being an import, Nissan Aus may not touch it. It has plenty in common with the Z33, but you know what stealerships are like with greys.....

Try Pro Concept otherwise. Josh has a Consult computer that can be plugged in to the OBDII port. If the dash lights up that badly, it'll probably be returning error codes. He's also quite familiar with the platform, and aware that it has electronics issues.

He's not cheap, but you get what you pay for.

I've never been to Paden so I don't know what gear he has at his disposal, but I know Josh has the equipment and experience to be a good "first bet" for troubleshooting the fault. If Paden can read ECU trouble codes, and you've got previous experience with him, then I'd suggest contacting him first.

[rs73]

So to me that looks close enough on the difference on circumference, unless I'm totally missing the point again?

yes you did it again.... :-)

put tyre 1 as 225/45/18 (your front OEM) and tyre 2 your desired aftermarket (235/35/19)

compare the 2, and note the % of decrease or increase in circumference between the two. call this 'a'

this is probably not on tire1010.com but it's easy:

(oem circumference - new circumference) divided by oem circumference times 100% = the % you're after

then re do the calc above and this time put tyre 1 as 245/45/18 (your rear OEM) and tyre 2 your desired new rear tyre (275/30/19)

compare the 2, and not the % of decrease or increase that happens. call this 'b'

to prevent VDC playing up or getting confused, you need to make sure 'a' & 'b' are as close as possible.

the reason why you can't compare your 235/35/19 to 275/30/19 is because your OEM tyre on V35 is staggered.

V35 tyres are intentionally bigger at the rear. your method above will only apply if your OEM tyre size on the V35 is not staggered

(e.g. V35 sedan or AWD GTR).

So you must always compare OEM front vs new front and OEM rear vs new rear, and make sure the % differences

on each axle is the same... e.g. if the new front is 1% smaller than OEM front, the new rear must be 1% smaller than OEM rear.

[fcruz3r]

ah ok....that totally makes sense now. I didn't realise that the coupe's came with staggered sizes from the factory. I was comparing this with my beemer where I had the same problem but managed to run staggered because the overall diameter were almost equal (factory tyres were same profile front and rear).

Edited September 1, 2009 by fcruz3r