Gearbox blueprinting...

[cstegall]

I am taking my 2001 GTS into my local Viper tuner next week to install a "brake cooling" system that forces the air from the front dam around the brakes...the system looks good and should work well. Here's my question...said tuner wants to "blueprint" my gearbox and it does sound interesting. However, I don't have the foggiest idea what this will do for me or the car. The tech at this facility speaks very highly of it and I would like some of your input on the idea.
Thanks for your efforts,

Clark Stegall

 

[Tom and Vipers]

I have rebuilt and modified many muscle car 4 spds ranging from the T-10, Muncie, and the Ford toploader. I have seen the inside of the T-56 and while it appears to have heavy, robust gears, it does employ an extremely high helical angle.

This is the exact opposite of the "Rock Crusher" Muncie which had a low helical angle. (A zero helical angle results in a spur gear which has the maximum torque capacity, however, it howls like reverse in older transmissions.) Helical angle increases thrust loads.

With the higher helical angle, much more thrust is generated - much more than muscle car 4-spds. In the older transmission, thrust washers were used, in the T-56, tapered roller bearings are used. Further, needle bearings are used throughout.

Clearly, there may be shimming issues in this transmission or whatever is used to establish tapered roller bearing clearance. Note that that clearance affects the center to center spacing of the gears.

I would question just exactly what would be done during "blueprinting."

The first area of modification are synchronizers, however, this is usually associated with drag racing power shifting. Of course w/o slicks, powershifting is a moot point. There may be synchronizer substitutes that may affect shifting. If they exist, I would require full disclosure of these parts and what they are supposed to do.

The GM T-56 can benefit from the stronger shifter arms that are already used in the Viper T-56.

I guess, aside from shimming (I am assuming that this is part of setting up a T-56) and some kind of trick synchronizer mod, all that remains is simply rebuilding the transmission.

Oh, there may be something done to the shifter action...

Again, get the details, complete with the numbers. Then judge for yourself if it seems worth it.

 

[TOOOFST]

CLARK,You didn't here correctly,he said,"I need you to pay for my september vacation."If YOU don't understand exactly what tuner wants to do YOU ask him first.If you need some honest info/direction,call John @ parts rack.That's why You bought this car,race car with a warrenty,right! Have fun and bust a couple parts,enjoy!

 

[luc]

"Blueprinting" is a term used to describe the machining of mechanical parts to better tolerance and come from the fact that ALL parts are designed from a "blueprint" or drawing.

As an example, let's say that the OD (outside diameter) of a piston is supposed to be 4 inches with tolerances of + or - .002 (2 thoushands of a inch).
That's mean that the diameter can be anywhere between 3.998" to 4.002".
If you have 10 pistons as in the Viper,they can all have slighty different OD and still being in the specifications.
Bluprinting in this case, mean that all the pistons will have lesser tolerance,may be 4" + or - .001 and consequently will have size ranging from 3.999 to 4.001.

Another example will be with weight.
The same pistons could be specified at 125 grammes + or - 5 .
Blueprinting will reduce the difference in weight between each pistons.

The advantages of blueprinting is a longer,smoother runing part.

But like everything else in life, you have to balance the benefit against the cost.
In the case of your tranny, I will said forget about it, it would not be worth the $.

Luc.

 

[Tom and Vipers]

Luc,

I agree with your comment it may not be worth the money.

Your description of blueprinting is precise, pistons (and bearings) need to be fitted. I am not aware of anything that needs to be fitted in a transmission - except the shimming of endplays.

Further, there are so many theories regarding piston clearance, cylinderwall finish, and rod big end treatment. If done to the competitive state-of-the-art, this information is closely guarded and not disclosed. Here you have to trust the shop. In some cases, builders will not give you the The Edge because they are providing this to make their top customers win races. Their top cusomers usually have non-disclosure agreements in which, for example, their heads may not be sold or given away since secrets may be lost.

The gears, bearings, and shafts are precision machined and used as such - they cannot be "fitted." Gear pitch diameters and bores do not come in different sizes as pistons and bearings do, nor do shafts and bearings. Specialized, precision machinery would be required to change dimensions. I sincerely doubt if people are changing gear/shaft clearances.

Substitutes for these parts can be made but still, there is no fitting that I am aware of, except perhaps (I'm speculating), the shifter mechanism hence the term Modified rather than Blueprinted applies.

I have heard of T56 blueprinting charges of $600-$700 and frankly, if I signed up for one, I'd want the shop to "Show me the Beer,... er, Beef."

My concern is that a shop may simply call a quality Rebuild, Blueprinted.

People usualy pay more for Blueprinting......