4+3 Callaway Question

[87Z52]

I have heard over the years that the 4+3 transmission was essentially being pushed to its max torque rating in the standard L98 cars of '87 and '88.

What did Callaway do, if anything, to these units to get them to survive the seriously amplified torque of the TT cars? And do they survive?

Just curious!

 

[*89x2*]

Turbo Joe (aka Magic Dragon) knows a bit about the 4+3's - Hopefully he will chime in here as we were just talking about this last week

 

[mangusta1969]

4+3 Survivability in a TT

According to several knowledgeable guys that I have talked to over the last 3 months, at least in the later versions of 4+3 twinturbo cars, Callaway disabled the automatic downshift from overdrive mode to regular mode when under boost conditions. I think this was to help survivability of the Doug Nash overdrive unit. The PROM change simply eliminated the auto downshift mode. You still had manual control of the overdrive unit (engaged or not) via the regular top of shifter button.

I had an 86 4+3 transmission and wish that I had only manual control on that car. My standard 86 car seemed overly eager to downshift from overdrive mode when accelerating fairly mildly. This behavior eventually (about 80K miles) hurt the overdrive unit.

The 88 Callaway car that I was considering a short while back had already eaten its original 4+3 transmission within the first 32K miles. I am not sure if it had the PROM modification to prevent downshifts under acceleration. I do know that its replacement transmission (from another car) did not have the modification, so I was planning to have that modification made, but the car was traded away before I could purchase it. The replacement trans had about 10-11K of safe miles on it at the time that the car became unavailable to me.

Steve

 

[SurfnSun]

Yeah, the OD in my car bought the farm about 30 miles from home after I picked it up in NY. It spun out on an auto downshift, so I can tell you that it hasn't been disabled on my car.

My car had 33k miles at the time of death.

 

[TAC]

Mine's going strong at 39k miles. It does not downshift.

 

[*89x2*]

Surf, I wonder why your car would auto downshift when TAC's and another 4+3 I am aware of do not:confused It was my understanding that the "downshift" was a weak link and Callaway "took care of it" by eliminating that feature, found on standard Vettes...

Do you think the 4+3 unit had been replaced before at some point??

 

[maxrevs85]

you can adjust the sensitivity of down shift with the detent cable where the throttle cable hooks up.

 

[Stan A]

4 + 3 Questions

Hi to Everyone........

Callaway TT's even in stock form were too much this for system to handle. Actually GM specs listed 400ft-lbs torque as the upper limit to what this tranny could handle.

To best of knowledge, Callaway never made the prom change to eliminate the automatic "up/down" shift. However, I did hear of individuals doing this after the 1990 model was released.

As everyone knows that David and I did this mod and it helped with the Callaway Show car. But it did fail too as 800ft-lbs of torque will eventually made this setup fail even without shifting in or out of overdrive.

On the stock Callaway car this mod will hold up much better but not forever.

In fact, a number of ZF units began to fail in the early 90's when people would "power shift" or "speed shift" their cars. The torque limit figure that I heard on the ZF was between 400-430ft-lbs.

You can party much count on a repair on your tranny no matter which setup you have going.

Take care all,
Stan

 

[MagicDragon]

Reeves told me that it wasn't a good idea to activate the OD while under WOT. I'm not sure if it was Reeves or one of the good Ole B2K boy's at the shop that told me the PROM was changed to deactivate the auto downshifting of the OD unit on the B2K cars. On my first TT (nonB2K) the change to the PROM was not performed. My current B2K TT does not automatically downshift. Callaway Cars should be able to answer the question though. My current TT has 52K miles and I have not had any troubles with the OD unit other than the OD switch in the shifter (3.22 at radio shack) and leak at the fitting for the cooler line. I don't do any side stepping of the clutch but I do drive it like it was meant to be driven-hard. My non B2K TT had 31K miles when I sold it and I never did anything to the trans\OD. I hope everyone is having fun with their rides!

 

[*89x2*]

Found this Transmission service - Claims to have experience with keeping the 4+3 alive behind the B2K http://www.gearzone.net/dne.htm
Hope this helps - Plz let us know if the service is a good option

 

[MagicDragon]

That's great info! I will file it, I love this fourm.

 

[*89x2*]

Here is a TTT for Tony C. Our newest B2K Owner

This thread has some info about the 4+3 we were talking about the other day