Helical cut gears

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Are they worth the money or should i just replace it with the straight cut deals the straights are 30 and the helical cut are 70

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Blown

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[Natedog]

Did you read the stickies and shim the diffs as directed? I've read that the helicals (properly shimmed of course) are more durable than the straight cut standard gears. I'd give the helical gearset a try.

[Jtlittle]

Most people think that straight cut (actually called spur) gears are stronger than helical gears and that’s why their used. While generally race transmissions with straight gears are very strong, its not because of the straight teeth on the gears. What may shock you is that straight cut gears are actually weaker than a same sized helical gear. The reason for this is quite simple: helical gears have more teeth meshing and thus have a greater load bearing surface area. Another myth is that straight cut gears are more efficient than a helical gears; but the difference in efficiency is negligible with both spur and helical gears having about 98-99% efficiency.

So why are straight cut gears used in race transmissions? Well, there is only one real reason, and that is because straight gears don’t produce any axial loads (thrust loads). Its very easy to build strong gears that are either straight cut or helical, so that’s not the problem. The problem is when you start putting a lot of torque through helical gears, the axial loads become so high that you need a very strong transmission case and shafts (axles) to contain the loads; this can add significant weight to the transmission. Straight cut gears simplifies the transmission case design and also the types of bearings used. This allows for a very light weight transmission to be designed – and we know that weight is everything in a race car. The one negative of straight cut gears, and its a big one, is that they produce a lot of noise.

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Originally Posted by Jtlittle

Most people think that straight cut (actually called spur) gears are stronger than helical gears and that’s why their used. While generally race transmissions with straight gears are very strong, its not because of the straight teeth on the gears. What may shock you is that straight cut gears are actually weaker than a same sized helical gear. The reason for this is quite simple: helical gears have more teeth meshing and thus have a greater load bearing surface area. Another myth is that straight cut gears are more efficient than a helical gears; but the difference in efficiency is negligible with both spur and helical gears having about 98-99% efficiency.

So why are straight cut gears used in race transmissions? Well, there is only one real reason, and that is because straight gears don’t produce any axial loads (thrust loads). Its very easy to build strong gears that are either straight cut or helical, so that’s not the problem. The problem is when you start putting a lot of torque through helical gears, the axial loads become so high that you need a very strong transmission case and shafts (axles) to contain the loads; this can add significant weight to the transmission. Straight cut gears simplifies the transmission case design and also the types of bearings used. This allows for a very light weight transmission to be designed – and we know that weight is everything in a race car. The one negative of straight cut gears, and its a big one, is that they produce a lot of noise.

I agree with this 100% ..... How ever are the upgrade helical cut gears more durable in this application. I did read the sticvkys and moved the shims. My 3rd member bolts had backed out a touch. So the damage is done and its a matter of time till the spool fails.

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[BIGW0RM]

Did you get the fancy gears?


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Originally Posted by BIGW0RM

Did you get the fancy gears?


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I did not. Wanted to know opinions before i bought them

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[TheManOfMiracles]

My diffs in my tf2 lwb r shot..I shimmed them and they work just find..luckily i have a set as spare.

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Originally Posted by TheManOfMiracles

My diffs in my tf2 lwb r shot..I shimmed them and they work just find..luckily i have a set as spare.

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Did the same. Just pondering options. Really wanna go 1 ton or 2 1/2 ton axle too bad the blackwell x1s are 250$ and only 1.5 mm wider

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[Ditchrat]

Originally Posted by Natedog

Did you read the stickies and shim the diffs as directed? I've read that the helicals (properly shimmed of course) are more durable than the straight cut standard gears. I'd give the helical gearset a try.

That is the nature of helical cut gears. The have more contact area at any given moment, with more individual gears involve, and thus prove more strength.