i noticed today their was different memcals for the same car with different axle ratios, since i have the memcal for the 2.77 axle, would i see any difference switching to the memcal for cars with the 3.27 axle? since ive swapped in a 3.42?

 

It can help, OTOH there may not be enough of a difference to notice. Typically the difference is in the shift light points (for stick trans) or the TCC lockup points (for auto trans).

RBob.

 

Sorry - guess I'd better post a separate thread on this question....

 

would the 3.27 memcal make my tcc lockup sooner? perhaps ill get better milage out of this? and once i get into tuning, can i fix this with burning a new chip to match my 3.42 gears?

 

This is hard to say without looking at the bins and comparing them. I do know that with tweaking the TCC tables a lot of driveability can be gained.

RBob.

 

Isint the vss calculated after the axel ratio in constant.
If you have a lower ratio the speedometer reads a lower mph
the car going faster at the same rpm (wrong value).
The tcc is working from the tps and mph values.
If the calculated valus in tcc is at 38 mph.
The speedo shows 38 mph but you are going say 47mph
The tcc tinks its 38 mph and looks(you are going 47 mph).

 

Yeah, if you change gears you will defintiely have to get one of the Dakota Digital VSS converter boxes to adjust the speedo back to the correct readings. In my case, that also messed up the shift light really strangely (it comes on telling me to shift when I'm in 5th gear now too) so it could also affect the TCC lockup since I've been told it is the same basic code in the memcal.

 

I have the drac on my car now you can calculate it an pin it for manny diffrent ratio and calculate the bins vss to get it right.
On my 7747 i hade before on the car there was no drac.
Hade a th350 an no vss on it.
But i hade kables from the vss to the ecm and values for the
vss in the bin isint the bin itself calculate after tiers/ratio to get
the values( some formula off a kind) cant you calculate after your
ratio and get a ny values to but in bin instead.

 

If the rear axle ratio has been changed, and the transmission VSS drive gears have not been changed to match, then yes, TCC and shift points will be all wrong.

However, changing the MEMCAL to one that matches the new rear axle ratio will not fix this error. Any time the rear axle ratio is changed the gears that drive the VSS are also required to be changed. These are located inside of the transmission.

Or, use a DRAC and fix the issue on the electrical side of the VSS (the Dakota box is a DRAC, GM also has a DRAC that can be found in vehicles). This will only work on non-cable driven speedometer setups, as found in the later f-body's. Otherwise the speedometer will still be incorrect.

This wasn't a part of TraviZ's question. He asked if after a gear ratio change would using a MEMCAL that matches the new gear ratio help with the TCC lockup and mileage.

RBob.

 

Sorry
I men that it locks on higher mph and the trans i sliping before it locks .