Gear Ratio Question - December JBL HEAT Status

[vector1]

Originally Posted by Machiavelli

victor1, you probably should google 'hub centric wheels' to learn a little more about the benefits.

well, i asked previously why and you stated cost and easy to handle, i told you my experience. if there was more benefit i must be missing something, maybe you can enlighten us.

[fordracing65]

get a six speed and go with 4:10 best decesion i ever made, dont fear the gear

[marcocsx3121]

In the long run, it won't matter, because if you really hit 160 mph every time you ride your bike, your gonna die fairly soon.

[fordracing65]

in 6th im at 1800rpm

[Machiavelli]

vector1,
"The other element that affects directly whether a wheel can be bolted onto a car is hubcentricity. Long ago, in the deep mists of time, wheels were located by the taper of the lug nuts or bolts. This could lead to all sorts of problems, but they can be summarized by saying centering was liable to be less than perfect, and the sheer stress on wheel bolts or studs could be enormous. I am not aware of any passenger car wheels now made that are not hubcentric. Hubcentric wheels have a hole at their center that fits closely over a round feature on the hub, serving to center the wheel on the axis of the spindle, as well as bear the vertical weight of the vehicle. The wheel bolts or studs then serve simply to hold the wheel onto the hub, and are loaded only in tension, where they are strong. If the studs were required to absorb vertical forces, they would be loaded in single shear, the weakest arrangement for any fastener. Factory wheels are all machined to fit their specific application exactly, and some of the better aftermarket wheels are, too. However, many aftermarket wheels rely on centering rings. This means that, instead of machining wheels specifically for each O.E. centering hole diameter, the wheel manufacturer machines all wheels to one size, and then uses inserts to give a centering surface of the diameter required for each application. This is obviously easier to do, and makes inventorying a complete wheel line much simpler and less costly. If you buy wheels that use centering rings, be sure the rings fit snugly in the wheels. If they are loose enough to fall out, how accurately can they be locating your wheel? Some tire shops automatically remove centering rings to balance a wheel, just to make sure there is no slop to make their balancing inaccurate."
http://www.modified.com/tech/0205scc...ide/index.html

marcocsx3121,
I'm into my 40th year on sportbikes, haven't dumped one yet. Obviously you have to know when it's safe to do a 160 mph blitz. (btw, 175 hp on a 520 lb bike gets you there in about 1/2 mile with a 80 mph rolling start).

[deckofficer]

As a new guy here, I've been busy reading and learning, great forum folks. This subject I feel able to contribute something back. I can not make any recomendations without first knowing how the engine was built as far as where your peak torque is. A general rule of thumb, don't cruise lower than 1/2 the rpms your peak torque happens at. Throw in another 100 rpms if using an aluminum flywheel. Most medium high performance crate engines will produce max hp at around 5600 and max torque around 4200 rpms. If using a steel flywheel then 70 mph highway cruise should be around 2100 rpms, 2200 for alumimun. I have had both a high hp, high rpm screamer 355 engine and at the opposite extreme a real grunt master 383. The grunt engine's hp is falling off at 4050 rpms, the torque is 516 lb/ft at just 2800 rpms. I don't expect anyone here has peak torque at just 2800. Because of that, I replaced the Muncie M21 with the TKO 600 0.64 OD 5 speed. My car weighs 400~600 lbs lighter than your Cobras and with 31" rear tires and a Jaq IRS 3.54 I cruise under 1700 rpms at a tick over 70 mph. The fuel mileage has improved from 12 mpg with the 355 to high 20's now. Last 1200 mile trip I saw 24.6, 30.2, 15.9 (got tired easy driving), and 28.4 mpg.