Overdrive on turbo apex

[T-rav 27]

Hey guys I just have a few questions on my 290 Mcx apex I recently purchased a primary with overdrive cut into it just wondering off this will have any affect on gearing or clutching and also belt life I am running radar runs 1320ft I run 25/38 gearing I ran 128.2 I 1320 with my stock clutches with stm weights at 79.3 grams and straight 47 helix but lost 5 mph with overdrive primary any ideas and suggestions greatly appreciated

 

[Woody255]

T-rav, I had a very similar issue. In my opinion, the OD primary was shifting out to quickly, and the secondary could not compensate for it. Essentially it was like shifting a manual transmission from 3rd to 5th, causing the engine to lug down. I replaced the primary with a stock OEM clutch and the problem was solved. My application is for snow drags so the OD May be more beneficial for you on speed runs.

 

[Macheater]

Is that a Yamaha helix you are running in the secondary! If I remember correctly, stock helix's do not allow the secondary to shift out into overdrive. I recently had an exchange with G-force about their primary clutch sheave and they told me their "kit" came with an additional component that when installed, allowed the secondary to reach full shift (overdrive) position.
If your primary is trying to reach overdrive and the secondary is not allowing that to happen, that might explain the 5 mph loss.
25/38 gearing with an overdrive setup sounds a little to tall also. Maybe going back to stock 24/38 with the overdrive might be a better starting point.

 

[Woody255]

In my setups I used Yamaha/Bender/Dalton helixes, and also went to a Team Tied secondary, with no real changes. This is what prompted me to swap out the OD primary. Depending on which drivers TRav is using, I’d think he’s in the right ballpark on gearing. For 1320’, I would be looking at 25/38 for mine.