I am after the Naca ducts that fit in the undertray, I suspect I will need a couple to try to cool the gearbox, there appears to be the opinion that the gearboxes are failing due to overheating rather than over powered, so i want to add some cooling.
Anyone help?
Think you can get some generic ducts from Demon Tweaks, but don’t believe it will make any difference.
If it makes no difference then why did Lotus put some vents in, any cold airflow would surely be better than none?
What about a separate oil cooller for the gearbox?
Gav
Ok perhaps what I meant to say was negligible difference. I’m skeptical that the issue with the gearbox is due to heat rather than power and torque, although can see that the extra power and torque are going to generate more head in the box.
If you add a couple of extra NACA ducts then will get a little extra cool air onto the gearbox casing, but I doubt that would make a significant different to the temp of the internals. As Gav suggests I think you’d really need a gearbox oil cooler fed with cool air for it to work.
If you do still want to get more cool air just onto the casing then perhaps you could feed some ducting from the drivers side intake, or even the roof intake if you are using a charge cooler.
All just opinions.
some nice options there, I am going to look into an oil cooler but the box is not designed for it so it might be tough. I am not convinced either about heat being the killer but it can’t hurt to try to keep it intact till I can sort out a stronger gearset.
Just my opinion but I totally think it is heat that is killing the Toyota boxes. No one is really running ‘that’ much torque and the cars are relitivly light.
I don’t think anyone has any acurate data logging of gearbox temps and its something that should be done.
For instance PG1 gearboxes run very very hot, I have seen upwards of 150 degrees on track and my Quaife sequential was the same. I ran a mocal laminova type oil cooler on both of those and had no temp issues after that.
My VW box, doesn’t get hot at all, I only see about 85 degrees and this is having to put up with a lot more torque than the PG1. So i don’t bother with a cooler on that.
If the oil gets too hot it looses its ability to lubricate everything as it should and things start to wear and eventually it breaks. Helically cut gearboxes by design the gears are pushing away from each other, so introduce some bearing wear into that scenario and hey presto the gears are meshing on the tips and eventually something gives. Obviously the more torque you have the higher the wear rate etc.
Also the OE oil used in the Toyota gearboxes is known to be a bit shit. I have spoken to a few oil people who say that most OE gearbox “fit and forget” oil isn’t all its cracked up to be. Using a very specific, high quality synthetic oil is the way forward and this will increase the life of the box and improve the gear change.
Have a look on the redline oils site, they do loads of flavours all for very specific applications. For example they recomens a different oil for Honda boxes and toyota / VW boxes and at the end of the day they are all just helically cut synchro gearboxes of similiar design.
Just my 2p
Sean…
Ok Sean, really good information, now how the hell do I take the temp of the gearbox oil? would an external probe give a good idea?
My probably bad idea at present is to use the drain plug to send the oil to a cooler via an electric pump and the put the cold stuff back in the fill hole? Am I mad? I do have a spare gearbox to mock it up on but no idea yet what bits to buy to make it work…
Prior to getting that in I am going to try some plain old air cooling ready for Oulton Park
Which is the best Gearbox oil for the Toyota ? I am running 300Bhp and waiting for the box to go.
While a long term solution is found maybe a change to better oil could help ?
Thanks
Ex77
[quote=Exige77]Which is the best Gearbox oil for the Toyota ? I am running 300Bhp and waiting for the box to go.
While a long term solution is found maybe a change to better oil could help ?
Thanks
Ex77 [/quote]
Redline mt90 seems to be the one people go for, however my dealer just put an upgraded oil in mine that lotus sport are using. No idea what it is tho.
Yeah Ade, the way you suggest is OK, but not the best as the pipe runs wont be ideal. Your best bet is to have the gearbox casing drilled and tapped in the best places for fitment, but obviously this is a gearbox out job.
You need to measure the temp of the oil, not the casing really, I have found those external sensors to be a bit unreliable. Your best bet here (for time and ease of doing the job quickly) is to drill the drain plug and tap it for a sensor to be fitted into it. Ideally you would also drill and tap the casing for the temp sender.
The gearbox oil we recomend for the Toyota box is Redline MT-90. We keep it in stock and sell it at �13.05 per quart (0.946 litres) + vat & P&P
How many litres does the Toyota gearbox hold ?
Thanks
Ex77
2.3l
Thanks
Ex77
I’ve probably still got half a L in the garage from when I did mine if your on the same tday as me soon you can have it if you want?
There is a guide here as the manual is a bit naff (easier when you know what size bolt to look for):
Although I did the old hose pipe shoved in the infill bit instead. Use a 6 sided socket on the 24mm drain plug as it’s made of cheese. Took me a while to find till I noticed it was the one with a “read the manual before changing the gearbox oil” sticker on it 
Thanks Sean
I will look at options over the weekend when I can get the car on a ramp. Plus check out positions for the drill points in the castings, do you have any advice on a pump and cooler as my tame mechanic is normally an MOT and service type of guy (read: a bit old for this type of stuff) 
I’m pretty interested in the results from your work Ade. The thing that is putting me off from going charge cooler + smaller pulley on my Katana install is the recent findings of gearbox failure from Ronin & yourself. I don’t want to spend another �3.5k to get to 300bhp & 200lb/ft to then spend another �2 to 3k on a new gearbox or engine.
Good luck with your research and keep us updated 
Don’t forget Frank was running way more HP when his failed, and I had spent 1.5 hot days at Spa before mine failed. I don’t think you will have the issue if you use it on the street. I’m never sure I will or won’t know if I’ve cured it or not, but it can’t help to add this stuff if its cheap
NA ROCKS!
Right then the oiler cooler is my way forwards, I have been looking at electric oil pumps from Mocal but they do seem heavy and 10 litres a minute seem very high. I was looking at a small mocal cooler and some ducting from the side scoop. Any bright ideas I am at the limit of my knowledge here!