Red Lion

iTrader: (13)

In a month I'll (hopefully) be installing the 6th gear that SR20DEN installed, maybe a different 2nd gear that came with the set too. Since the transmission will be open I thought I might as well either cryo or shot-peen some of the internals, or both.


Should I do one or the other? I'm not too familiar on shot-peening and I've heard good and bad about cryo; I've heard some people say it makes parts brittle, and others say it had no real noticeable effect; others had nothing but great things to say about it.


Should I do one first then the other or does it not matter the order?


And of course, which parts should I get done? I figure the gears of course, how about the bearings? Shift forks? Differential? the entire casing? input shaft?


Thanks!

d00df00d

iTrader: (4)

I don't know much about cryo treating but AFAIK it can make parts brittle at the limit of their strength. It does raise that limit, though. In other words, it makes parts take more force to break but shatter when they do.

Shot-peening has slightly different effects at the molecular level but I know even less about it than I know about cryo treating.

Red Lion

iTrader: (13)

Thanks! anyone else have some input?

DAVE Sz

iTrader: (2)

yeah, you cry then shot peen. Cryo makes it brittle and the shot peening makes it quite stronger...

Red Lion

iTrader: (13)

hmmm, so you would recommend just shot-peening, or would the combo of the two make it even stronger than shot-peening alone?

eng92

iTrader: (3)

Shot peening is used to improve the fatigue resistance of a part. Hammering the surface with high speed "shot" creates tiny dimples. The end result is a very thin layer of surface material that is in compression.

The compressive residual stresses serve to reduce the overall stress state at the surface. This can really extend the life of parts subjected to cyclic loading by lowering the magnitude of the mean stress level.

The decision to go with shotpeening, or any other material treatments, should be made based upon the type of failures that are being experienced.

If you have the expertise, you can examine the fracture faces of parts that have failed to determine the failure mode. Otherwise, you can research what the high power transmission builders are doing to keep their stuff together.

DasYears

do we know of anybody on here who has blown a 6-spd which could be looked at for cause of failure?

Torgus

iTrader: (10)

with all the money you would spend on cyro you could better spend it on making your car go faster imo.

THT

iTrader: (8)

1. Cryo-treating isn't that expensive.
2. What's the point in going faster if your drivetrain can't handle it?

Torgus

iTrader: (10)

I know plenty of fast maximas that don't need to do any of that.
Whats you def of inexpensive?
Last time i looked into it isn't wasn't very inexpensive. but things could have changed.

Unless your putting down in excess of 300+whp i would think it would be useless considering bang for ya buck...

Nealoc187

iTrader: (23)

I wouldn't bother doing anything to a 6 speed unless you're going to be putting down in excess of 350-400ft-lbs. Are you?

There's no way to know whether or not cryo treating will be beneficial enough to justify without knowing the specific alloys and treating processes used to manufacture the gear. Shot peening is almost always beneficial even though gears are shot peened from the factory. Shot peening is usually charged by setup time - it doesn't much matter usually if you are getting 4 pieces shot peened or 8. So you might as well shot peen all the gears and the input shaft imho, unless the shop you go with charges by the piece. I wouldn't bother with the main shaft or ring gear or anything else.

Cryo treating is usually done by weight, so the more parts you have cryo'd the more it's going to cost you.

Of course as I said before, if you're not going to be putting down a significant amount of power, I wouldn't bother doing any of this. It's pointless for an NA car with the 6spd imho.

Red Lion

iTrader: (13)

I'm eventually going to spray, at least a 100 shot, so I would imagine I'd be very close to 400lb/ft when all is said and done.

In addition, I do a lot of auto-x/road racing, and while I try to be gentle I would still like to do whatever I can to prolong the life of the gear box as those particular motorsports can be tiresome on a drivetrain.

Money's not a big deal to me and the gear box will be opened anyway while I install the taller 6th gear. I'm going this far with the engine and transmission swap so why not spend a little more for safety's sake? And for the record, the highest I've been quoted for an entire transmission for cryo-treatment is about $350, and if it really does help like it's supposed to I would call that a good investment.

nismology

iTrader: (8)

The 6-speed will laugh at a 100 shot. Srsly. The 6-speed is good for 400+ lb-ft TO THE WHEELS. If you're going to have the tranny open anyway I guess it would make sense to do it. :shrug:

Nealoc187

iTrader: (23)

well if you can tear the transmission down and reassemble it yourself then it's not a big deal. sounds like you were going to install the 6th gear yourself anyways so I'm assuming you have access to the necessary tools, a press, gear pullers, etc. I'd get the shot peening done at least, cryo if you feel it's worth it. it probably won't hurt, how much it will help though is unknown without an analysis of the alloys.

Red Lion

iTrader: (13)

hate to bump a thread and ask this question, but I'd rather not make a new thread.

There are two securing rings that clip around the shift levers, one at the top and one at the bottom. I can't get these off, I'm using a pair of snap ring seperators, cheap ones and it isn't working. The FSM doesn't tell you how to take these off, all it says is "remove the two securing rings". What did you guys do to get these off?

Nealoc187

iTrader: (23)

i just take my snap ring pliers and put them on the tips of the C-clips and then bang the handle of the pliers with a hammer, they will go flying off so you ought to have a rag behind them to keep from losing them unless you have replacements.

Matt93SE

iTrader: (44)

small needlenose pliers here. I cover the handle with a rag and give it a good hit with my palm.
either that or I'll use a large flathead and thump on it until I get one side coming off, then I'll stick a small screwdriver in the back and pry it out.

Nissan (Kent Moore Tools) also sells a special tool for these clips. it's not a lot of money..

Red Lion

iTrader: (13)

Well, since I've been working and haven't had time to take apart the gears to get them cryo'd or shot-peened, I'm just going to install them in the Maxima bellhousing. Got another question lol:


My 3rd-4th Coupling Sleeve is moving. In fact, it can move right off my input shaft. I didn't mess with anything after I removed the gears so i'm not sure why it can come off. In fact the other coupling sleeves all move, this one just isn't blocked by the gears. Is that normal or did I accidently loosen something after I removed them? How do I get it to stay put?

Nealoc187

iTrader: (23)

you are missing the little spring shift keys it looks and sounds like. coupling sleeves often can be moved completely off of the hub because of how 3rd and 4th gears are usually designed, but in the case of that particular trans, if you do that, you're going to lose the shift keys. better start looking around on your bench or the floor, or just order some new ones, they should only be a couple dollars.

ScottS

iTrader: (2)

I am cryoing my complete tranny and case for my 88 Daytona. The complete top end is already cryoed. Including all the bolts, cam, lifters, valves, intake, exhaust mani, turbo etc... So far I noticed spark plugs last longer.

No plans to do it to the Maxima though...

Red Lion

iTrader: (13)

forgot to tell you thanks, i found them, all three of the little shift keys/teeth. lol they were down between the cracks of the box I had my shafts in.