tifosiman

In my ongoing quest to create a 944 n/a trans that won't blow it's guts out every 18 months with heavy autocross usage, I have come acrossed something that I need to get opinions about.........

If I were to buy a new set of 944 R&P gears, and then had them cryo-treated, how much stronger would they be compared to stock? Has anyone had any first-hand experience with this? I have heard all about cryo'd brake rotors, but have never really been taken with that hype.

(of course this is assuming that I shim/pre-load/build the rest of the transmission perfectly)

TIA

Fishey

No Idea but it sounds good!

hacker-pschorr

I know a few people with Vintage Corvette's (stop laughing, when you have 600+hp and run sub 2:40's at Road America you can laugh). They are sold 100% on cryo brake rotors. Performance was not effected, the longevity of the rotor and pad were increased.

Another idea I've been playing with. I was doing some reading of the DEI team in NASCAR (ok, you can laugh this time) since they are very fast this year on the long oval's. I found out they are doing a few things other teams are not: Teflon coating their gear sets and bearings. They ran one car 600 miles (not on purpose) with no transmission fluid. It lasted the whole race - granted not much shifting on a 600 mile oval, but still a lot of stress on the trannie.

Hell, do both! Either way, please report your experience.

Geo

Tifo,

The SE-R guys have been doing this for a while with their gearboxes. The turbo guys with SE-Rs are putting down 951 numbers (well modded 951 numbers - from 200-600 bhp) and have a big problem making 3rd gear last. What they do is not only cryo, but also shotpeen. I don't know the numbers, but 30% pops off the top of my head.

If you like, I can put you in touch with a friend of mine who has great contacts for cryo and shot peen. He's an OEM engineer as well and probably can give you an idea just how much stronger they are. If you're intersted, e-mail me at <george@nissport.com>.

Geo

Oh, there are a couple of other techniques that may work, but I don't know anyone who has tried them.

One it Metalax. It's a vibration table that the parts are clamped to and shaken to some calculated frequency to relieve stress (magic fingers? ). It's supposed to work.

The other is microfine polishing. There are a few companies that do this and I'll have to dig through some old copies of Racecar Engineering to come up with them. That is also supposed to help stress relieve the material.

Zero10

The teflon coating sounds like a good idea in any transmission. I wonder why transmissions don't come teflon coated from the factory?
Since (I believe) the issue is the teeth stripping off due to stress, microfine polishing may not help the problem. It would only reduce friction, and help slow wear. Still a good idea though.

Predator

I've heard that frozed rotors last 2 to 3 times longer. No info on R&P. Have known some women you could use to freeze'm!

Ben Z.

Tifo-

Depending on the mode of failure and on how well the prior carburization and heat treatment had been done, cryo could be anywhere from not helpful at all to very helpful (providing the treatment was caried out correctly).

A quick search found one promissing reference:

Increased life of carburised race car gears by cryogenic treatment
Jordine, A.
Proc. IMMA Conf. 'The Heat is On!', Melbourne, Victoria, Australia, 24-25
May, 1995, pp. 107-111
Cryogenic treatment is commonly used after heat treatment as a panacea for
incomplete transformation of austenite, but there may be reason to consider
cryogenic treatment not as a fix for improperly processed parts but as a
standard step in the heat treatment process. Treatments on a wide variety of
parts (from drill bits to cylinder heads) have been proposed, claiming increased
wear resistance and longer service lives. The theory of cryogenic treatment is
briefly discussed to support the argument for using cryogenic treatment as part
of the heat treating cycle for special cases. Birrana Engineering were interested
in the possibilities of increasing wear resistance of gears manufactured for the
mining industry. An opportunity arose to rapidly investigate the effect of
cryogenic treatment on surface fatigue on carburized gears used in motor
racing. This case study discusses carburized En36A first/reverse gear shafts
for a Formula Brabham race car run by Birrana Racing. These gear shafts
were prone to pitting fatigue failures after a low number of cycles. The
addition of a cryogenic treatment to the heat treatment cycle has improved
the life of the gears by a considerable margin. The success of this trial has
led to cryogenic treatment being applied to gears manufactured for the mining
industry. Graphs, 5 ref.


-Since the best treatments seem to be where the entire process is designed to take into the effect of cryo, I'm not sure you could obtain optimal results by just cryo treating a set of gears that have already gone though a heat treatment, but this may be your only option. Further heating your R&P would probably mess up what the manufacturer had done, so the best advice may be to just take the as-received gears and go directly to the cryo. I'm not sure what the process is exactly, but if you could slowly imerse the gears in liquid N2 in a good cooler and wait a few days for it to evaporate, I don't see how you could hurt anything and it would only cost you a few bucks for the nitrogen. Let us know if you give this a shot!

oh, and btw, I won't be offended if you don't want to experiment because I realize that the gears are not cheap. Good luck!

Geo

Actually, Teflon will just strip off. The micropolishing reduces stress.

Geo

The process takes something like 3 days to complete. The parts are brought down to temp, kept there, and then slowly brought up. IIRC there are several steps of raising the temp, holding it, reducing it, and bringing it back up. Again, this is all done over something like 3 days. I don't know the process in detail because I haven't needed to pay attention to it. My turbo G20 (same engine and gearbox as the SE-R) was a mild build so I didn't need it.

This is not a process you want to do at home. The shot peening the SE-R guys do is mil-spec as well.

tifosiman

Hey, all good info here. Thanks! The vendor I have been speaking with is PowerHaus II. They would be the ones doing the cryo treatment. I have to assume they know what they are talking about as they are the experts.

Couldn't sleep last nite, so I got up and did some reading/research in EWE and Peter Morgan's book. Both sources state that there were two different manual transmissions used in the 944 n/a cars from 1985.5 thru 1987. One for USA/Can/Japan spec, and one for ROW (euro) spec.They are as follows:

USA/Can/Japan Code: 016J Casing Stamp: QM (US/Can No LSD), QL (Japan No LSD), 8QW and 4M were LSD in those two versions.

ROW Code: 016K Casing Stamp: QK (non-LSD), 7Q (LSD)

Both books state that for 1988 and 1989 models, all cars received the ROW manual transmissions, there were no 016J transmissions supplied after 1987. The gearing was the same for ROW and US/Can/Japan transmissions. No mention is made pertaining to the actual difference between the two versions.

This leads me to another question: What is the difference? Are the ROW transmissions stronger due to the higher compression rating and higher HP/Torque ratings? If so, is it the R&P that was beefed up? I have noticed that the majority of the people on the BBS here that have had n/a R&P failures are driving pre-1988 cars.

97xray

Wow, interesting question... if there was a way (and I can't think of one) for me to reversibly open the box and check for strength, I would!
I've never had any bit of trouble from the gear box on my Euro - but that's about as useless as info gets since it's pure anecdote...

4re308

A friend of mine owns a shop just north of Atlanta that does cryogenic work on all kinds of parts, rotors, gears and other internal parts. My brother just dropped off his front rotors off his G60 Corrado. They also do a process called Cryo-REM, which is like super polishing and cryo. The place is called Professional Cryogenic Mettallurgy & Coatings 770 888 8818. They do awesome work, we use them often.

hoffman912

Jeremy,

i would think the cryo gears would be stronger.. i mean it does change the strength at the molecular level. but i dont know if a transmition is the right application or not.

just wondering, have you contacted carquip yet? http://www.carquip.com/

they are known for their performance gear boxes (ie race cars and street), and im sure they can give you suggestions or insight on the subject.

tifosiman

Actually, the guys at PowerHaus II did state that they would Cryo and Rem the gears, I just didn't know what "Rem" was. It sounds like the general concensus here is that if the price is reasonable for the Cryo and Rem (which it seems to be), it would be worthwhile to have it done while I have it all apart and purchasing a new R&P. I would like for PowerHaus to do the treatment there at their facility so that I have one source for the part and the treatment, and actually they are cheaper on the r&p gears than the two other places I contacted.

This whole tranmission issue has really put a crimp in my fun with the car. I love autocrossing it, but hate the thought of having to replace the trans every 18 months. I know, wha wah wah, you play you pay, all that. But still it is there in the back of my head now, and transmssions are pricey. I'm not doing the Corvette/Porsche shoot-out this weekend because I am paranoid at cutting the lifespan short on the trans that I have in it now. I really don't drive it harsh on the street, and am fairly smooth with the transmissions in autocrossing, but I really have come to the conclusion that the stock r&p is just not up to the task. This sucks, because I love everything else about the car, but this "achilles heel" is overhadowing everything else for me at the moment. I drove it to work today, and found myself listening to the trans the whole way to work wondering about the degree of mechanical noise verses whine. This one is actually the quietest of any transmission I have had, so maybe it is better. It is out of an 88 car, so that means it is the ROW trans that is "possibly somehow stronger", dunno, would love to hear some great firsthand knowledge on that from someone in the know.

Boy I seem to be rambling on, I apologize if anyone fell asleep during this post.