PCW 1500 with venture royale final drive vs stock final drive.

[steamer97]

I recently acquired a PCW 1500 and anticipate even more first gear skittish control under heavy acceleration. The longer ratio of the venture Royale final drive swap I'm considering will partially "tame' the first gear part and lower my top gear RPM's in fifth making for a quieter highway cruise. As attractive as these two results are to me I still wonder if quarter mile times will be slower with the final drive gear mod. Sean's writings describe a loss of ET and MPH on a STOCK gen 1. I am asking for actual experience or deduced opinion on quarter mile times with this mod. Will I be faster/quicker of slower in the quarter with this mod? Definitely easier takeoff in first gear I presume.

 

[DirtieGirtie]

A final drive will apply the same ratio change to all gears. In other words, if your RPMs are lower in 5'th gear at 75mph with the venture rear end then your RPMs will be lower in all gears. So yes, you would experience a little slower acceleration.

With chain or belt bikes you always had some people change the sprockets/pulleys in both directions... some want more low-end power, some want lower RPMs at cruising speeds. Unfortunately, you can't have both unless you spread out the internal gear ratios or add a 6'th gear.

 

[gentsvmax]

I recently acquired a PCW 1500 and anticipate even more first gear skittish control under heavy acceleration. The longer ratio of the venture Royale final drive swap I'm considering will partially "tame' the first gear part and lower my top gear RPM's in fifth making for a quieter highway cruise. As attractive as these two results are to me I still wonder if quarter mile times will be slower with the final drive gear mod. Sean's writings describe a loss of ET and MPH on a STOCK gen 1. I am asking for actual experience or deduced opinion on quarter mile times with this mod. Will I be faster/quicker of slower in the quarter with this mod? Definitely easier takeoff in first gear I presume.

My question with your Tourmaster would be, is the Venture box as strong as the Vmax unit?
As I think about it I'd bet the 1500 depending on how healthy would break some other piece of driveline before the final drive anyway.
Either way getting your answer should be fun.

 

[Fire-medic]

I've mentioned this before, my friend's shop has built a variety of Gen. 1 VMaxes: big-displacement, NOS, turbo, and supercharged, including combinations of the above.

A couple of the guys went with 17" rear wheels, and modified powerplants. They were very happy with the increase in acceleration, and credit went to Jon Cornell, because each of those two guys had bikes built at the shop that looked like catalog advertisements for UFO Products. Hot, hot, hot!

Their astonishment at being passed by a stock Vmax on top end, resulted in some phone calls to Ohio to speak with Jon Cornell, the guy at UFO. Jon took their comments, and then called the owner of the shop where Jon had sent the components for the bike builds. That would be my friend Steve.

Running a shorter height wheel/tire combo gives you more acceleration, but it affects your top end. Not in a good way, if more top end speed is your goal. Your gearing is 'shorter' with a smaller wheel/tire combo. More acceleration, but less top-end.

When Steve, the hot-rod bikes' builder, told Jon about the 17" wheels, he laughed and understood the 'problem.'

Be aware of the 'problem' of a numerically-lower final drive. Wind-drag and your bike's power output will conspire to lessen your top end. Then again, how many of us are looking to head to 149 mph?

A word to gentsvmax, the shop owner/VMax builder found that driveshafts were a common point of failure on the hairy builds. As Sean Morley has mentioned before, better to blow a driveshaft than ruin a pair of engine cases or a gearbox.

 

[steamer97]

I've mentioned this before, my friend's shop has built a variety of Gen. 1 VMaxes: big-displacement, NOS, turbo, and supercharged, including combinations of the above.

A couple of the guys went with 17" rear wheels, and modified powerplants. They were very happy with the increase in acceleration, and credit went to Jon Cornell, because each of those two guys had bikes built at the shop that looked like catalog advertisements for UFO Products. Hot, hot, hot!

Their astonishment at being passed by a stock Vmax on top end, resulted in some phone calls to Ohio to speak with Jon Cornell, the guy at UFO. Jon took their comments, and then called the owner of the shop where Jon had sent the components for the bike builds. That would be my friend Steve.

Running a shorter height wheel/tire combo gives you more acceleration, but it affects your top end. Not in a good way, if more top end speed is your goal. Your gearing is 'shorter' with a smaller wheel/tire combo. More acceleration, but less top-end.

When Steve, the hot-rod bikes' builder, told Jon about the 17" wheels, he laughed and understood the 'problem.'

Be aware of the 'problem' of a numerically-lower final drive. Wind-drag and your bike's power output will conspire to lessen your top end. Then again, how many of us are looking to head to 149 mph?

A word to gentsvmax, the shop owner/VMax builder found that driveshafts were a common point of failure on the hairy builds. As Sean Morley has mentioned before, better to blow a driveshaft than ruin a pair of engine cases or a gearbox.

 

[steamer97]

Thx all for the speedy reply's. Yes I fully understand what ratios do whether from gearing or tire circumference. when racing in the quarter mile I always over rev a little in 4th gear at the traps to avoid shifting into 5th and losing that small amount of time. The "brag" or rumor I have "heard" is that the 1500 will get off the line (generally) consistently quicker due to lessening torque with a 10 percent taller final drive thereby making the launch easier. After all we slip the clutch at the start anyway so with more torque at the crank but dampening it with a taller final drive sounds plausible as a quicker launch. What I am wondering is will that initial quickness plus not needing to shift to 5th gear at the traps (saving that small amount of time) be in total quicker or slower or the same in a 1/4 mile race? I'm just trying to get a solid Idea before spending money on a final drive and the work involved. I have a chance to buy a complete 1989 venture royale ($300) for a final drive salvage and I should have parts to sell to offset my expense that way. Again, thank you...

 

[Dansmaxresto]

If you’re running more horsepower and theoretically a higher trap speed, you may have to upshift to 5th anyway. You may be topped out in 4th.

 

[one2dmax]

With the big motor you will like the Venture conversion rear diff. It has the power and torque to push through the reduced gearing.

 

[steamer97]

If you’re running more horsepower and theoretically a higher trap speed, you may have to upshift to 5th anyway. You may be topped out in 4th.

I calculate 10% added to my speed in fourth (using the taller final) since I now do 118-119 mph works out to 131 mph without shifting into fifth. I highly doubt any faster speed unless I do power adders. Thanks for your input.

 

[steamer97]

My question with your Tourmaster would be, is the Venture box as strong as the Vmax unit?
As I think about it I'd bet the 1500 depending on how healthy would break some other piece of driveline before the final drive anyway.
Either way getting your answer should be fun.

The GAb goes that final drives haven't historically broken much with high HP. The driveshaft reputedly does first. This bike has HD shaft. According to those that have went further in the chain of weak links, the engine case at the gearbox is the failure after the driveshaft mod, not usually the final drive. This is why I like an older bike like v max. Many have modded in thirty years and everything that breaks is a matter of history/record.