Printable View
Hi Guys, just woundering if any one can check over my trans tune to see if i'm on the right track the vehicle is a stock ls1 a4, apart from the trans we just rebuilt with a wider band, transgo stage 1 kit , no stall, the shifts were a little soft for my liking with the stock tune so feel free to offer any advise etc to make it shift nice and firm so we don't wear out the box - thanks
Hello JCA,
Took a quick look at your tune. The Desire Shift Times are reasonable. The Base Pressures for upshifts could be increased somewhat - helps the clutches last longer. You’ve removed all of the torque reduction - which I don’t normally.
Your approach appears to be to remove torque reduction, but run slightly lower base pressures to arrive at a reasonable shift feel.
I prefer to increase the base pressures (to promote clutch longevity), and tailor the shift feel using torque reduction.
Both approaches may arrive at the same shift feel. Using more base pressure and some torque reduction may help the transmission last longer.
Regards,
Taz
Hi , thanks tas yep might bump up the pressures as a rule u don't increase past 640? I know down lower in the torque range its a fair bit lower, so maybe increase down lower in the range, with the torque limiting i dont understand increaseing pressure then pulling timing when the trans gears to soften the load- i m trying to get a firm instant gear change so the trans spends less time in beween gears, is it possable to have a look at one of ur tunes for a simiar type of set up, I what to get this right because we have just started building trans for these vehicles as it seems the locate buildiers can't build a desent trans and when they die they are blameing the tune which dosn't make sense because they always shift nice and hard when they leave i think it cos they also leave with a hell of a lot more power as well and we have pulled these trans apart that have been built by the so called experts and found pretty basic mistakes. thanks
Hello JCA,
Modifications to the valve body, as well as “hard parts” employed, can vary greatly transmission to transmission. I have learned for past experience that what works well in one transmission may not create the same shift feel in another.
I mainly use truck PCMs and harnesses, and run two shift programs – Normal and Performance (Tow / Haul). I set the “Normal” values to that which produce a quick, firm shift. I set the “Performance” values to produce quick, very firm shifts.
Appropriate shift “feel” varies person to person. I’m old school (or just old) and like a fairly firm shift. In my opinion “harsh” shifts (crash / bang style) do little to improve performance, but may accelerate wear on the transmission, universal joints, and rear differential.
Here is how I initially setup a 4L60E (A4) in a street driven vehicle - competition vehicles will be setup differently.
Desired Shift Times (D1108, D1109, D1110)
- set values to 0.2000 (up to 0.3000 is OK)
- Normal and Performance are set the same initially
Quick shifts help the clutches last longer, and decrease the amount of heat generated. I don’t set these values to less than 0.2000 (including D1110 - the 3>4 shift)
Trans Pressures (D0701, D0702, D0703)
- the maximum value is 96 PSI (660 kPa)
- this is where individual differences / preferences begin
- I look at the torque curve of the engine, and set maximum pressure to be reached at peak torque (and beyond)
- this may make shifts much too firm in some applications
- a graph of these values will generally look like a straight (or slightly curved) line from lower left to upper right
- a graph of the 1>2 shift pressures may end up having a “U” or “S” shape - to avoid harsh part throttle shifts
- I set the values of D1101, D1102, and D1103 (Low Pressure Adjust) to “zero” to prevent the PCM from decreasing shift pressures
Increased pressures at upshift help prevent the clutches from slipping for any longer (or not much longer) than the amount of time set out by the Desired Shift Times. This helps the clutches last longer, and decreases the amount of heat generated.
Torque Reduction (D0801, D0802, D0803)
- I always leave some torque reduction in the 1>2 and 2>3 upshifts
- 10% to 15% is generally sufficient (although more may be necessary) to decrease shift harshness, and promote component longevity
- torque reduction is generally not necessary for the 3>4 shift - as the vehicle is moving at a significant speed by this point - and shift “shock” is greatly reduced
In a street driven vehicle I would rather reduce engine power output for a split second (Torque Reduction), than have a clutch slip any longer than absolutely necessary.
My apologies for the lengthy response … hopefully it assists you in developing your own unique transmission tune.
Regards,
Taz
Hi Tas, thanks for ur help , I have got the trans shifting since and firm, pulled the shift times down to 2 upped the pressures a little, and gave it a little torque mangement in gears 1-3