I had a discussion with a friend regarding helical cut gears and straight cut gears. He thinks straight cut gears are stronger and i think helical cut gears are stronger. I have nothing to reinforce my point and neither does he. i kno about helical cut gears being quieter and costing more but does anyone kno or can guide me to somewhere that shows which style gear is Stronger. thanks


does this have to do with turbo/supercharge Maximas? I DUNNO!!!

 

having straight cut gears is going to make shifting very difficult. and the gears are weaker because there's less surface area for the teeth to contact creating more stress on smaller areas. helical is better =D.. i think only reverse gear is straight cut.. all forward gears are usually helical.

 

Helical. Tell him he's a tool.

 

Dunno, Why do all the racing sports cars run straight cut gears? Like the Rolex 24hr cars you can hear it as a whine noise. Arent the PAR gear sets straight cut?

 

For those who have been inside a 4g 5 speed, take a look at this web page. Dosent our transmission shafts look allot like the ones for the SR20 trans?

http://www.par-engineering.com/nissantirs.htm#nissansss

 

http://www.par-engineering.com/nissantirs.htm#nissansss

O.M.G

Mardi, you might really be on to something here. I know someone who has made a direct transplant from a GTi-R gearbox into a 1st/2nd gen (1993-2001) Altima gearbox.

And I have personally swapped some individual gears from a 2000 Altima into my 5-speed transmission.

So those beefy gears you linked us to, if they fit in a GTi-R gearbox, then they fit in an Altima gearbox, and if they fit into an Altima gearbox, that means they 100% fit in absolutely ALL 1985-2001 5-speed Maxima transmissions.

 

O.M.G

Well said! I just e-mailed them asking for dimensions etc so I can compare them. This would kick a s s !

 

Hopefully it's priced reasonably. But DAMN, I've been inside my trans 2 times and those gears are WAY beefier than the stock gearset. Way, way beefier.

Tell them you have a RS5F50A or RS5F50V (A=open differencial, V=VLSD) transmission.

 

$2500 to $3000 USD

 

Ouch! Too bad.

Maybe you can look on GTi-R forums for guys possibly selling used trans with these

 

Mardi, is that price for everything necessary to swap over to straight-cut? It's alot of money, but it would give some peace of mind about launching and shifting hard. The lsd would stay helical, along with its pinion on the main shaft, right? Straight-cut would relieve most all of the axial stress on the shafts, bearings, etc. in the tranny too.

 

From what I've read, straight cut is generally stronger simpy because they can be made bigger.

I've not really heard of any purpose built race cars using helical cut gears unless for some reason they're using a stock production transmission. Usually with straight cut gears you run a dog engagement syncry which means you have to shift pretty fast or they'll grind. The only reason they don't use straight cut gears on production cars is because they're loud. Basically imagine driving with the sound reverse makes all day and you'll get the idea more or less.

 

For that price I would much rather just buy 2004-2005 Maxima 6-speed trans and go through the nightmare of converting for less than a grand. Apparently the 6-speed is way beefier and some come stock with a HLSD. And he'd have a nice .63 cruising gear, and closer ratios.

 

I posted about PAR gearsets a couple months ago. PAR gearsets for SRs are running around $3500 with the conversion to USD for a PAR sychromesh set... Here's the thread I got the pricing from.

http://www.sr20forum.com/showthread.php?t=90403

Straight cut gears are stronger hands down. There is no comparison. Mostly because they are only made for racing applications because of the noise. If it's only used in racing applications, why would one make it weak. What I'm saying is that it's not an inherent property of the straight cut that they are stronger, but because they are only used in race cars, they always make them strong, whereas helical gears are used in street cars, and there's no need for street car gears to be that strong.

BTW torque is what you need to look at with regards to strength, it is what breaks gears.

 

Heres a little read on helical vs. straight cut gears. http://www.manchester-minis.cwc.net/...s_sc_gears.htm

 

mmmmm. Mind numbing noise from straight gears.

 

that guy doesn't seem to have a clue on what he's talking about.

 

I read until I saw the word cr4p - then I decided not to read anymore. If there weren't some advantage to straight cut gears, strength, cost, ease of manufacture, longevity, etc, every dog box and race transmission in the entire world wouldn't be using them.

 

After looking at PAR's website, I'm kind of confused. The GTi-R dog set says it will handle 650hp, and if the pictures are correct, they are helical gears. The SR20 dog set says it will handle 600hp, and they are straight cut. The gears that supposedly fit our transmissions are the SR20 ones, and we can't use the GTi-R ones, right? Or are they all interchangable? Is there any particular reason that the helicals are rated stronger, other than they might be made thicker?

 

I wouldn't put a whole lot of stock into the estimated hp ratings, given the fact that like i said, torque is what breaks things, not horsepower. As far as them looking the same yeah the sr20 set looks a bunch like ours, but all gearsets look a lot alike in my opinion. And man those pics are bad, lol trying to sell $3500 gearsets with cell phone pics on your company's website.

 

here's what some straight cut gears sound like
http://www.supercarchallenge.nl/video/assen-bmwSTW.wmv

also, here's something i noticed one site said about helical vs. straight cut:

Q. Aren’t helical gears stronger than straight cut gears?
A. Yes and no. Manufacturing parts or making parts that will work together is all about compromises. Although it is true that helical gears contact 1 1/2 teeth making them stronger for the selected pitch, it puts thrust loads on the case (left to right) which is not what the factory case was designed for. It is much stronger in a radially (up down). Straight cut is the way you want to go to take the left/right loads off of the box.
Instead of using helical, and because we are using a better material to begin with, you can now get a beefier, stronger pitch in a straight cut gear within the same transmission case dimensions. This will take far more load than a smaller pitch helical gear, which is limited to having rather small teeth in comparison in order to be effective. Basically starting from a clean sheet of paper with a whole new concept we were able to achieve what we were looking for.

Helical gears are used for quietness, just like synchromesh transmissions. I, as many of you also probably did as well; used to sidestep the clutch back in the day. Bad idea. Not so bad when the car was stock, but very bad after we started making a bit of power. You should never sidestep, or drop the clutch if you appreciate your wallet. Now that am wiser, I know this. We would actually send shafts through the transmission casings, and if we didn’t we would totally demolish the bearings. Three transmissions in one weekend and I soon changed my driving style. They used to say I could break transmissions by looking at them. Not the best moniker to have.

The straight cut gears, on the other hand, are far better at withstanding this kind of abuse. Had we had this transmission then, I could have saved a lot of money.

 

NOW YOU KNOW !!!!! [/ end bill nye the science guy "now you know" voice]

I feel so enlightend

 

I wonder if maybe strengthening the case where the higher "thrust" loads would be would make the trannies last a bit longer...

 

maybe, i know that a really common problem with T5's once you push the limit "roughly 500whp" the case flexes to much and causes the shafts to seperate enouph to where the gears teeth loose full contact and they just strip tipically this happens in 3rd because its in the middle of the shaft and it loads the engine real good

 

There's been a couple of good threads lately about tranny's. So, with many of us looking for something we can depend upon....what is the final word? I undestood the final word to be $3500 and straight cut is stronger.

Other than rebuild and cryo treatment, what are options? Is the Ve tranny with LSD not stronger than the VG? I'm still unclear as to whether these two manual trannys are even interchangeable? Are they? If so, I'll swap mine from my VE into my VG turbo project car!

If "how the gears are built" is the main theme here, then is there not a company that build better/stronger helicle gears for our tranny's? Is this the solution?

 

Apparently GTI-R and 240/silvia (SR20) tranny is interchangable and also stright cut to a point in factory trim. They also happen to swap right into the max's R5 something something tranny. Given the right combination from the three or just throwing in GTi-R internals will cost you around 3500. The cheaper alternative would be cryo but it's not clear on the results beign the same.

 

are GTiR salvage units not available to experiment with?
sorry, not familiar with what the GTir is

 

It's a JDM only nissan car so the shipping and availibility is what kills you.

 

thanks from the resident

 

Anytime.....

 

The VE tranny will swap right onto the VG. They're supposed to be slightly stronger (they at the very least have stronger axles) but they aren't without their problems. I helped a guy change out his VE tranny that had the same input shaft bearing problem that the VG trannies have.


VQ guys... do your input shafts utilize the pilot bushing/bearing? (i.e. does the shaft actually go into the bushing/bearing or does it stop short?)

 

Well, if everything was made equal (material, cryo-processing blah blah), helical gears are stronger in general since they have more surface area in contact at any one point in time when they mesh. For racing applications, people make straightcut (or spur gears) because they sap less power. There is no lateral loading as with helical gears. Typically, when manufacturing these you will want to make them out of a material stronger than stock hence the misconception that spur gears are stronger.

Now in the overall system of a transmission, the lateral loads induced by high torque/HP will put more stress on other components in a helical gear configuration. This may cause other components to fail before the gears themselves. This in turn will cause the gears to mesh incorrectly and finally the gears themselves will fail. In short, if you are talking about the gears themselves, helical is stronger. If you are talking about the transmission system and aftermarket components available, spur gears are better. Make sense?

 

LOADS !!!!

 

This would be nice to add to some sort of tranny sticky. Any confirmation on gear options available?

I plan to pick up another tranny, and I am curious to what all options I have and still keep it a good price vs value ratio :>

 

Did you find out about the dimensions?

 

They asked me to send them pictures of our shafts. I havent gotten around to it.

 

Helical gears do not have the entire tooth face in contact with the other tooth face at the same time however. Helical gears "roll" across the face of the other gear tooth, whereas straight cut gears have the entire face in contact because of how they are designed. Helical gears have more face area, but the entire width of the face isn't in contact at any given time.

The other consideration with helical gears is that they create axial loads on the shafts, whereas straight cut gears do not.

 

Either way it all boils down to preference,this thread could go on forever

 

Yeah, there are so many variables that it's virtually impossible to calculate which is "better". Better is purely situational in my mind. And to conclusivly answer the question for "your" application I think you'd need to field test each style a number of times, and do failure analysis on them, record the data, make sure that any anomalous failures are weeded out, and the list goes on.

 

but to be fair u should also mention the reduction of noise with helical gears as well as the fact that helicals also have multiple teeth engaged at any given time.