If the snap ring groove is the stress riser that the shaft always snaps at, why not chuck it in a lathe, and turn a nice 1/8" radius on there, similar to the journals on a crankshaft. The extra free play shouldn't matter w/ the reluctor too much, and you could red loctite it on, if necessary. I haven't been inside my T56 in a year, so maybe this isn't possible. <shrug>

 

Reducing the stress riser from the ring groove could be of some benefit. That being said, the snap ring groove is into the splines only and does not go past the minor diameter of the spline into the shaft. It could still cause a bit of a stress concentration point or at least an interuption in the load flow through the part.

 

Just some added info that I found. 300M is a VAR (vacuum arc remelt). This steel is widely used in the aircraft landing gear systems and is certainly a fine choice for a T56 output shaft. It can be heat treated to a yield strength that is about 15% to 20% greater that 4340. It is supposed to retain its ductility and fatigue resistance.

I found that Mark Williams is making C5 half shafts out of this stuff.

I think the key is going to be getting the Q&T right! I would say that if this is done correctly there should be an improvement over the OEM shaft.

Any of you old Borg Warner engineers out there want to spill the beans on the OEM output shaft material spec?

Steve

 

Sean,

How about an update? Did you get your hands on that fancy shaft yet?

FWIW - I purchased a viper shaft, bushing, seal, and reluctor and I am about ready to pull my tranny. The viper shaft is about 1 3/8" longer than the F body shaft which should make the conversion interesting. All of the internal bearing surfaces and splines are properly located for the swap.

I'll keep an up date going on the process if anyone is interested.

Steve

 

Well I started another thread I guess I will put the update in here too.

The mainshafts are done. I believe there is one or two left to be claimed.

Contact Paul at Corvettes of Houston at 281-821-1222 for detailed information and price.

I will have mine on Tues or Wed of next week and will have it installed shortly and will post results ASAP!

I would like to hear about the viper conversion as well. I looked into that but it looked like a PITA. How much was that viper shaft?

Thanks,
Sean

 

Sean,

Somehow I missed your other thread.

So far in parts I've got

$150 for a used Viper shaft - Tremec absolutely will not sell these new! They're downright ignorant when you try to talk to them or try to get information about interchangeability.


About $50 in a reluctor, output bushing and seal.

This conversion is definately not a done deal yet. The extra length of the shaft really has me concerned. Yea, I could just whack off the extra and move on, but I'm trying to retain all of the spline engagement that I can. I've had problems twisting the ID splines on the 27 spline driveshaft yokes, so increasing the "bearing area" is an objective of this project as well as keeping the shaft in one piece.

Steve

 

I have had that problem (3 times) too the fix was a Strange billet slip yoke. Then the problem was twisting mainshafts!

If you could somehow come up with a longer slip yoke for your viper shaft that might work. Plus I believe D&D will sell you a new viper shaft.

How much do you think it will cost for you to bore/machine your tail housing? How much is a slip yoke for the viper tranny?

Sean

 

I tried the billet yoke too but had horrible vibration problems. Strange Engineering didn't control their spline size too well and the sloppy fit was really causing me problems.

I pulled the trany tonight and started investigating the machining. It's starting to look like all I'll have to do is bore the tail housing for the larger bushing and seal. This should be a piece of cake. Any machine shop should be able to do this for less than $100. I'm ordering the Viper yoke tomorrow and I'll finalize the machining and how much to whack off of the mainshaft.

The larger 30 spline shaft should also solve the problem with twisting yoke splines. We're transferring torque on a larger diameter which should reduce load on the splines. we're also picking up shear area on the splines going from 27 to 31.

So far this looks like a winner.

BTW D&D could not get Tremec to sell them a new Viper shaft. The owner of D&D was pissed, said he does over 2 million dollars of business with Tremec and still has trouble geting info and buying the parts that he wants.

More to come.

Steve

 

Have you tried Donato Engineering? John seems to be a stand up guy. I spoke with him this past Saturday about T-56 upgrades. He has a Viper output shaft conversion for the F-body T-56. He aslo has Viper upgrades. i.e. Carbon Kevlar friction lined synchro rings, Vespel fork pads, 3-4 steel shift fork. These are the same used in the Viper GTS-R race trannies. He seems very knowledgeable and can make recommendations for what you will be doing with the car. He is also working with several clutch manufacterers. You can reach him at 248-676-8554 or donatoeng@aol.com. Good luck.

 

Yes I have Emailed John Donato numerous times and he offers ythe Viper shaft conversion. I couldn't find a real business or web site so I was uneasy about going through him. Don't get me wrong, I've never heard good or bad things about Donato Engineering. It just seemed too small for me to risk a couple hundred bucks.

Update: I've received my Chrysler 30 spline trans yoke from Denny's and have done a bunch of measuring on the OEM design and a CAD layout on a Viper retrofit design. It looks like if I whack 3/4" off the viper shaft, Bore the housing for the Viper bushing, and bore the housing for the Viper seal this system should work fine. I'll still have as much or more spline engagement than the OEM design, I'll have more bearing overlap in the housing bearing. Overlap is a good thing. I now believe that my conststant battle with vibeshaft was caused by an egg shaped very low overlap OEM bushing. This allowed far too much yoke wobble and If you breathed on anything it would set up a harmonic even with Denny's super balanced Nitrous ready shaft.

Project will be slowed slightly. I found some crunchies on the magnets. Looks like pieces of those little syncro tabs. So I'll have to inspect carefully and order some more parts.

Steve

 

Well my new 300M (looking awesome!) shaft is here and getting installed tomorrow, have the t56 apart right now. All I have to do is take the old mainshaft and the 300M to a tranny shop for some press time to swap gears over. I sould have it together tomorrow night. I will take pictures.

Sean

 

Viper Shaft Upgrade Update:

Bored out tail housing for a 003" to .004" press fit on viper bushing.

Bored housing for .005" press on viper rear seal

Whacked 3/4" off mainshaft (need to use abrasive cust off saw) those shafts are hard as a MF. Definately not ductile iron!

Reassembled the trany and every thing looks hunky dory. The trans yoke is definately more stable with the longer overlap on the 2" long viper bushing. All I need to do now is respline my GM reluctor to 30 spline Chrysler. It will probably not be easy to find someone local with a broach. If all else fails, I'll bore the reluctor for a tight fit on to the 30 spline shaft and run some pointy set screws in radially into the spline groove to keep the reluctor from rotating. I don't think it will take much, there's really not any torque load.

This upgrade so far looks like a winner. I won't get to really try it out for a while, I'm pulling the motor for a budget bottom end refresh befor the season starts.


I'll keep posting as things move along.

Steve

 

Steve,
Thanks for the update. It might be hard to find someone with that exact broach. An alternative would be to have it wire EDM'd. You should be able to find someone local for that, or even mail it off. We've got one here, but it's pretty much booked solid. Let me know if you can't find someone to do it. What were the necessary machining dimensions for the bushings? This is something I'll probably do if I snap the output shaft. Another alternative would be to find some high temp epoxy, machine the reluctor for a ligh press fit, and epoxy it on. There aren't any forces, so it just has to not slide. I wouldn't want steel setscrews to scratch the shaft and create a miniscule chance for a stress riser. They do have nylon-tipped setscrews that might work, or possibly find some aluminum ones. I don't know if machining a hole for a setscrew would play havoc w/ the magnetic field.

 

I don't recall the exact bore size I used. I just mic'd the OD of the bushing and gave it about a .003" press fit. You'll need to mic the bushing OD in a couple of spots and average the numbers. The bushings are very thin wall and a slight bit out of round as received.

Had'nt though about wire EDM. You think you could hold a couple thousandths tolerance with wire? I'll check into that. I also have a contact that knows the folks a Winters Transmission and they migh have a Chrysler broach.

The other possibility is to just use the Viper reluctor. It has far fewer pickup notches. I'm not sure how far LT1 Edit will allow a deviation in Gear/ Tire size. Im not sure I can fudge far enough to make things work.

Steve

 

We can hold to plus/minus 2 tenths (.0002) with our wire EDM, if you take the time for a perfect setup. It's very easy to hold a tolerance of a few thousandths if that's all you want to do.

I think the easiest solution would be the viper reluctor, with the Dakota Digital (.com) speedo conversion box. That's what we recommend to most first and third genners doing the T56 swap, and need a different pulse count for the speedo/ECM. It's about $75, and just splices inline from the VSS signal.