Jump to content
SAU Community

Spraybar Mod For Gearbox And 3Rd Gear?

R32 TT
 Share

Recommended Posts

R32 TT Mentor

R32 TT

Posted
Posted

Hi guys,

Has anyone fitted an electric oil pump and cooler to their GTR gearbox? And/or have you done any mods to the return to direct oil directly at 3rd gear?

Everyone knows GTR boxes tend to break 3rd gear (most common). I happened to pull down my PPG box to fix a simple syncro issue on first gear and we noted wear on third gear.. no wear on other gears.

PPG have looked it and seem to think its lack of oiling.

I am running Motul 75W140 - so a good oil and yes it was 'full'.

It was suggested that with a hard launch, gear oil moves to the back of the gearbox, engulfing 1st and 2nd gear, but leaving 3rd with little on it.. by the time you do get into 3rd, there may not be sufficient oil to protect. And then of course you spend more time in 3rd than the previous two gears... hence wear on the teeth.

So perhaps - all these broken 3rd gears are partly because over time the gears get worn due to lack of lubrication.. then one day you give it some hard accel and bam 3rd gear breaks. Most people assume the gear was not strong enough - but perhaps it was prematurely weakened?

I note plenty of mods for thing like Porsche 915 boxes, rally cars etc that introduce spray bars to spray oil directly onto the gears for this very reason. And of course cooling the oil onto the gears doesn't hurt either.

I'm about to design something up to do this - but before I reinvent the wheel - has anyone done this kind of mod?

thoughts?

  • Like 1
jiffo Mentor

jiffo

Posted
Posted

I think your spray bar lube plan has merit for bearing lube and cooling if heat is removed via a suitable external cooler.

But having seen older style sugar mill gearing (transmitting over 1,000,000 ft lbs torque) tear teeth from pinions/bull gears, always fitted with lube spray bars, and to hear that lube crack out from the meshing gears with the noise of a 30/30………If it's not designed for the torque, lube can't stop the damage.

I may be wrong but typically in my 5 speed RWD cars, 1st and 2nd simply couldn't be loaded with the available hp due to wheel spin. Even 3rd would break away as the engine reached the peak power band.

Perhaps a GTR is simply reaching that traction grip point in 3rd and as such the box must then cope with the full power.

4th was direct and so the strongest gear in the box.

  • Like 1
MrStabby Grand Master

MrStabby

Posted
Posted

Hmm, from http://www.sau.com.au/forums/topic/414977-gearbox-oil-level-question/#entry6655671

"I'm getting it rebuilt at Award gearbox and diff, they will replace everything with new and do a internal mod to help with the oil feed to the front" - I wonder if that is related.

Would be nice to know which oils have a good boundary anti-wear additive pack (eg high levels of zinc and phosphorus) which is all 3rd gear would be left with if the oil has sloshed to the back. I couldnt find an oil analysis for Motul 75-140, but here's one for Redline MT-90 which has way higher zinc and phosphorus than the "universal averages", but i'd imagine there is a lot of cheap crap oil making up those averages. It would be interesting to see how the Motul compares as another high end oil.

TCI_31Jan.png

  • Like 1
R32 TT Mentor

R32 TT

Posted
  • Author
Posted

Thanks Jiffo - that does make sense.

now we've had a closer look at the gears some opinions are that the oil shear just couldn't cope. Perhaps this was because it was under-lubricated, or perhaps simply the oil could not take it.

I just realised that I did not note in my first post the box originally ran Castrol 75W90 Syntrax in it for the first 200kms of 'hard kms' or so - and only recently was running Motul 75W140. The question might be that perhaps the lighter oil couldn't withstand it, and perhaps the damage was done then..

Either way - its interesting its only on 3rd - and your explanation could be a valid one.

Cooling the oil onto third just might give the extra 10% it needs to avoid shear though... we won't know until we try I guess.

R32 TT Mentor

R32 TT

Posted
  • Author
Posted

Thanks Adam,

I might give Award a call and see what their thoughts are on it..

I've always run Redline Shockproof in my stock box.. PPG recommend the Motul 75W140 though - but as above - can't now be 100% certain that was the oil in it when the damage was done.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
Go to topic listing


  • Similar Content

  • Latest Posts

    • MBS206
      R34 Skyline climate control unit transistor

      By MBS206 · Posted

      I came here to note that is a zener diode too base on the info there. Based on that, I'd also be suspicious that replacing it, and it's likely to do the same. A lot of use cases will see it used as either voltage protection, or to create a cheap but relatively stable fixed voltage supply. That would mean it has seen more voltage than it should, and has gone into voltage melt down. If there is something else in the circuit dumping out higher than it should voltages, that needs to be found too. It's quite likely they're trying to use the Zener to limit the voltage that is hitting through to the transistor beside it, so what ever goes to the zener is likely a signal, and they're using the transistor in that circuit to amplify it. Especially as it seems they've also got a capacitor across the zener. Looks like there is meant to be something "noisy" to that zener, and what ever it was, had a melt down. Looking at that picture, it also looks like there's some solder joints that really need redoing, and it might be worth having the whole board properly inspected.  Unfortunately, without being able to stick a multimeter on it, and start tracing it all out, I'm pretty much at a loss now to help. I don't even believe I have a climate control board from an R33 around here to pull apart and see if any of the circuit appears similar to give some ideas.
    • GTSBoy
      R34 GTR Seats / No longer reclining

      By GTSBoy · Posted

      Nah - but you won't find anything on dismantling the seats in any such thing anyway.
    • GTSBoy
      Questions on potential new purchase

      By GTSBoy · Posted

      Could be. Could also be that they sit around broken more. To be fair, you almost never see one driving around. I see more R chassis GTRs than the Renault ones.
    • GTSBoy
      Ethanol Content Sensor - Always at 11%?

      By GTSBoy · Posted

      Yeah. Nah. This is why I said My bold for my double emphasis. We're not talking about cars tuned to the edge of det here. We're talking about normal cars. Flame propagation speed and the amount of energy required to ignite the fuel are not significant factors when running at 1500-4000 rpm, and medium to light loads, like nearly every car on the road (except twin cab utes which are driven at 6k and 100% load all the time). There is no shortage of ignition energy available in any petrol engine. If there was, we'd all be in deep shit. The calorific value, on a volume basis, is significantly different, between 98 and 91, and that turns up immediately in consumption numbers. You can see the signal easily if you control for the other variables well enough, and/or collect enough stats. As to not seeing any benefit - we had a couple of EF and EL Falcons in the company fleet back in the late 90s and early 2000s. The EEC IV ECU in those things was particularly good at adding in timing as soon as knock headroom improved, which typically came from putting in some 95 or 98. The responsiveness and power improved noticeably, and the fuel consumption dropped considerably, just from going to 95. Less delta from there to 98 - almost not noticeable, compared to the big differences seen between 91 and 95. Way back in the day, when supermarkets first started selling fuel from their own stations, I did thousands of km in FNQ in a small Toyota. I can't remember if it was a Starlet or an early Yaris. Anyway - the supermarket servos were bringing in cheap fuel from Indonesia, and the other servos were still using locally refined gear. The fuel consumption was typically at least 5%, often as much as 8% worse on the Indo shit, presumably because they had a lot more oxygenated component in the brew, and were probably barely meeting the octane spec. Around the same time or maybe a bit later (like 25 years ago), I could tell the difference between Shell 98 and BP 98, and typically preferred to only use Shell then because the Skyline ran so much better on it. Years later I found the realtionship between them had swapped, as a consequence of yet more refinery closures. So I've only used BP 98 since. Although, I must say that I could not fault the odd tank of United 98 that I've run. It's probably the same stuff. It is also very important to remember that these findings are often dependent on region. With most of the refineries in Oz now dead, there's less variability in local stuff, and he majority of our fuels are not even refined here any more anyway. It probably depends more on which SE Asian refinery is currently cheapest to operate.
    • bilbo117
      R34 GTR Seats / No longer reclining

      By bilbo117 · Posted

      You don't have an R34 service manual for the body do you? Have found plenty for the engine and drivetrain but nothing else
×
×
  • Create New...