Gearbox oil cooling

[mighty kitten]

I've had several different failures over the years with the saab gearbox , blowing diffs and stripping gears but the last three have been synchro failure on 2nd gear

It's gone to a specialist this time as the man I use locally doesn't do this sort of work .
The specialist is talking about adding a pump and cooler as he thinks it's a temp issue with the oil not being able to lubricate the synchro properly , .
The last three failures have been the same and always on trackdays .
I've been reading what I can find on the net which isn't much regarding temperature and I have been using a Morris's lodexol mtf for the last few years .
does anyone know how hot the oil can get in a manual box and what does it do to the oil that stops the synchros from being able to grip the cone on the gear . Tia

[mighty kitten]

Thanks for the replies , it is in part down to my shift technique .never gave the oil temp a thought but as said with only 2 litres and no cooling it probably does get pretty hot with 450 hp and similar torque .

[mighty kitten]

I've gathered some bits together to turn it on and off based on temp and switch a small 8" fan ducted onto the cooler with the outlet under the car facing backwards . Discussing it with other Saab guys running similar power I do tend to run longer sessions on track and have had more failures than a mate with an identical motor and box set up .

I don't know wether having to cool and lubricate the final drive makes it harder work for a fwd box but the box builder has done cooler systems for transverse noble v6

[mighty kitten]

30min duty cycle whivh should be ok for track sessions and these have been used for gear oil without falling to bits as long as the oil is 60c plus .
Around £65

[mighty kitten]

ive blown diffs before fitting the Atb and since then it's been the same failure each time . The rest of the box looks good as far as gear wear etc . We all run the same clutch set up for 450+ and we put an adjustable push rod in the master to stop any drag at high rpm . Flywheels are lightened but not super light . Had a look at some Gopro stuff from cadwell last November and I was out for nearly 40mins in the afternoon when the synchro went

[mighty kitten]

Conventional 10" sprung plate with a Sachs race engineering cover which will hold 450lb ft reliably . I can data log quite a bit of stuff from the Saab trionic Ecu but I doubt there is anything I can do to cut ign

[mighty kitten]

It's partly me and going over to a ball bearing turbo has put the box under more load lower down the rpm range .
I normally don't need to go past 6500 on track with the garret .
There is a circlip mod on 3rd gear that needs to be done as it was a factory mod on very late saab 9000 boxes and std on all the later 9-3 9-5 . The earlier boxes can have some movement under high load which is another factor with mine .

[mighty kitten]

This is a steep learning curve as I've concentrated on getting the motor to be reliable at fairly high output for a 4 Cyl .
Fortunately my current car in build has a Toyota r154 box so I won't have to worry about breaking it .

[mighty kitten]

I don't like hassling specialists especially busy ones but finally had an update before the rebuild starts . He puts the failure down to losing preload on the shaft when the box gets a good cooking on track and the taper bearing cage had split on the pinion end of the shaft . The preload issue has let the synchro part come out of its slot in rhe gear despite the crush sleeve being the later updated part from a 9-5 . New sleeve will be a solid part machined to suit and cooler ports added to suit . First outing is at blyton next month so got a couple of weeks t build the cooler system .
My mate was seeing 100+ case temps on his turboed civic at Anglesey but the honda doesn't have a bolt on end case so might be better at holding the shafts than mine with 5th in the end of the box .