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      07-31-2019, 08:01 PM   #147
First Lieutenant

Drives: 2007 Z4 M Coupe
Join Date: Oct 2012
Location: Woodstock, GA

iTrader: (0)


So the astute listener may have noticed a gear whine in the above video. After a bit of research and deliberation, I decided to give it a go with an H pattern straight cut dogbox transmission. This particular box uses the ZF 320 case so it's a simple plug and play if you're already set up for the ZF 5 speed. Cost is about 1/3 of a Drenth sequential. Upshifts are clutchless, but downshifts still require clutch and rev match. The gearing is track specific so you essentially have 4 gears on track where with standard street gearing you really only have 3 (on tracks I run). Gear range is about the same, so tighter ratios means the motor stays in the power zone longer. First and reverse are locked out. Gears 2 - 5 are in an H pattern with 2nd up and to the left. Very cool!

So, I was just getting the hang of using this box, and digging the shifting, when the damn thing went BOOM! Very scary to watch. I was very lucky the gear oil did not ignite on the exhaust. You may notice my water temps are high. Forgot to bleed the radiator and was thinking I better pit in when, well, I got a ride back to the paddock...

The case split open like a melon. Initial suspicion is that it somehow engaged 1st and 3rd simultaneously.

As I am in discussion with the manufacturer, I will not disclose who they are.

For now, back to a standard ZF 5 speed...