Mon5ter

Anyone out there have any idea what the torque capacity is for the 5 speed gear box. Does the later model 6 speed offer much more?

farrell

Hi
A little clarification needed here.

In 1997 I instrumented the supercharged I6 3.2 as fitted to the DB7.
I also took bulk oil temps from the Getrag 280 fitted to this vehicle.
We ran this car @ Millbrook bowl sampling oil at 30 sec intervals.
It exceeded the design limits at speed beyond 140 mph.
This was also a function of the installation & compromised location within the transmission tunnel as measured heat rejection figures revealed.

It could not handle the torque of the Jim Clarke inspired duratec 6.0 litre V12
@ 400 lbs ft.
Infact the torque of the I6 supercharged engine @ 335 lbs ft wreaked havoc with the transmission beyond 50,000 miles partly due to overheating & 1800 kgs weight of vehicle.

We looked to Getrag to try & get in on the transmission being developed in conjunction with BMW for the M5 E39. Copyright & licence cost made piece part a non starter....so.

The DB7 Vantage has a BWT Tremec T56 Transmission.
This unit although less refined, appeared in the Viper & Camaro.
It took some real hard work to get some feel & shifter precision into that unit.
I later developed an auxilliary pumped cooler circuit for this transmission when bulk oil temps taken at Arizona proving ground showed that at speeds above 130 mph @ 40 degrees Celcius the bulk oil temp exceeded the temp limits for the oil seals & gear sets.

So then, the Getrag 280/290 series of transmissions without a pumped cooler circuit is not durable for engines producing more then 350 lbs torque MAXIMUM.
By durable, I mean a vehicle capable of meeting all emission 95th percentile customer usage and last 100,000 miles min.

If it were capable of being used in an engine developing 400 lbs ft, then it would have been fitted to the E39 M5.

Regards
Farrell

Sorry Ivan.
This was an SOB job for me then.
Just wanted to add some clarity.

Mon5ter

Thanks for the in depth explanation. Youre experience with this area (and i'm sure many others) is quite impressive. Do you recommend any upgrades to the current unit or is there an aftermarket replacement that perhaps can handle 400+ lbs ft?

farrell

Hello
I would first get a TRUE understanding of the torque & power curve.
I hate rolling roads but in this instance, if power & torque are as high as claimed, then prove it to yourself.

What really kills these transmissions mechanically is 1st & 2nd gear hard usage from cold.
It should be remembered that even with a 30 degrees C ambient, the oil in the transmission will be the last lubricant / coolant on the car to reach working temperature.
At the opposite end of the scale, high speed driving for extended periods overheats the oil & breaks it down.
When this happens, any metal debris in the transmission becomes a cutting compund with the oil & starts to work on the surface hardened & heat treated faces of the gear sets.

Does the car come with proven history of regular transmission oil changes ?
Is your Getrag whining in any or all of the gears on drive or coast ?
Is their any perceived backlash when you drive in fourth (1:1) at 30-40 mph
Open & close the throttle in rapid succession to excite the transmission.
No big clonks or slop on pick up ?

Assume the transmission is good then.
If you drive lots of extended high speed or track days days, I would do the following :-
If power proves to be as you have been told, I would take the course of running an auxilliary trans cooler. Apump, a modine & Earls autoflex with associated connectors, an inline wax stat designed to open the circuit above 100 degrees C
This will improve cooling & extend life of the oil & preven it becoming a cutting compund.

With reference to the clutch.
Address the oil leak.
Are you doing a lot of hard launches for dragging or 1/4 mile runs..?
Is your present cover std or increased stiffness / greater clampload.

Personally, I would use a std friction disc with a stiffer clamp load cover OR an uprated friction disc with A std cover.
You have to change a lot of clutches to reach the cost of one transmission & saving it would be my priority.

Heres the rub.
I would bet one of my gonads that your engine is not producing 380 bhp @ the flywheel including parasitic lossses.
It certainly wont make as much torque as the Supercharged DB7 so I dont recommend an alternative transmission & bespoke bell hsg etc.
If it does, I will go under my car & work out the cooler installation for you & what parts you will require to make the system up.

Hows that for a deal !

Seriously, Im happy to help anyway I can & if as I suspect, that your engine is performing @ around good 3.8 level of performance, go get std o/e parts.
They will be fine.


Farrell

Mon5ter

Goodness, I guess what needs to be done is get dyno numbers first then see from there. The oil cooler sounds like a great idea. Your knowledge is greatly appreciated.