Hewland Gears - choosing ratios for gear strength

[dereklola]

My engine (Buick V6) is somewhat over the torque range for my gears (FT200).

Which is the better choice of ratio for gear strength - more teeth? - or fewer (and therefore bigger) teeth? And why?

For instance is a 19:24 better than a 26:33 or vice versa - both are same ratio (almost).

[AU N EGL]

what is your RPM range for your tq and hp?

[dereklola]

Indy Lights engine - nominal 425 bhp at 7000, torque about 310 at maybe 4000. How does this affect relative gear strength?

[jedrinck]

Don't ask. Around which latitude will you be running your car and
what color is it?

[AU N EGL]

Originally Posted by dereklola

Indy Lights engine - nominal 425 bhp at 7000, torque about 310 at maybe 4000. How does this affect relative gear strength?

Hewland, X-trac, Emco, Rockland Standard all have gear sets for above 500 lbft of tq

Have you looked on the Hewland web site for an apporate ratio?

http://www.hewland.com/svga/ratio_list.htm

[chevy34]

We had a similar issue with our Trans-am car with the STA Hewland this box is only rated at 450 To 500 lbs-ft torque and we are running around 590 lbs-ft. We kept destroying 2nd gear and found that on some ratios Hewland had changed the tooth count to the lower count aperently because they had issues with certain tooth counts failing.

Didn't Help us much thought ended up having to fork out for a new MVE-STA wide tooth to fix the issue! (got sick of doing Gearboxs in 20 min in between races)

[Tony C]

Originally Posted by dereklola

My engine (Buick V6) is somewhat over the torque range for my gears (FT200).

Which is the better choice of ratio for gear strength - more teeth? - or fewer (and therefore bigger) teeth? And why?

For instance is a 19:24 better than a 26:33 or vice versa - both are same ratio (almost).

I havent tried on a practical level to see which is stronger or why but what you are talking about was a problem in Australia for early Formula Holdens that ran the FT200 (Ralts). We experienced gear problems, 2nd normally, and pinion issues (would last only 1 race meeting). I overcome these problems by using a Carroll Smith solution. Use a die grinder to linish the base (root) of the teeth and remove the machined undercut (and sharp points) then get the gears shot peened by a renowned shop. Everyone will tell you that it wont improve the stress because the gears are hardened, but trust me Carroll Smith knew what he was talking about.

[dereklola]

Thx Tony - sounds good advice - I've decided to make sure I have the latest manufactured 'M' gears and to have them super-finished (REM process) - we'll see! Derek

[mracing]

Hi did this work out for you Derk I'd like my gears to last a bit longer