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4.0 gear drive

88 Honcho

NAXJA Forum User
Location
howell NJ
Does anybody know about a gear drive for the 4.0. I was reading the jeep engines book vol 2 and the listed a part number for the gear drive. However i havent been able to get anymore info on it.
 
I think clifford made that.
I just went to the website I have bookmarked and it doesn't appear to exit anymore. Does anyone know what happened to clifford performance's website?
 
Nobody makes one anymore, probably because demand was too low to make it worthwhile. Mopar Performance used to make one and might still do it under special order.
 
Dr. Dyno said:
Nobody makes one anymore, probably because demand was too low to make it worthwhile. Mopar Performance used to make one and might still do it under special order.

Yeah - and I'm thinking it was something like $600...

I'd like to see one come back - I think it would be compatible with AMC I6 and the 2.46L I4, but I'd have to check to be sure. That's a "blue-sky" goal of mine - improving the AMC I4 & I6 aftermarket options...

5-90
 
The stock timing set is good for up to 6000rpm according to the Jeep Engines book though Hesco claim the chain will snap because of harmonics from the cam (it only has four bearings) if you rev the engine above 5600rpm. Hesco also say that the only cure is to fit a gear drive if you want to rev the engine safely above 5600rpm (the Cloyes dual roller set doesn't help).
Be aware that the gear drive does make a whining noise whereas the timing chain is silent.
 
Dr. Dyno said:
The stock timing set is good for up to 6000rpm according to the Jeep Engines book though Hesco claim the chain will snap because of harmonics from the cam (it only has four bearings) if you rev the engine above 5600rpm. Hesco also say that the only cure is to fit a gear drive if you want to rev the engine safely above 5600rpm (the Cloyes dual roller set doesn't help).
Be aware that the gear drive does make a whining noise whereas the timing chain is silent.

i think the whining noise is kinda cool. when i had my chevy we put a set of those in.....most guys here call them "screamer gears".
 
i had read somewhere that the MP piece was not for street driving as it didn't have the longevity build into it. That seems kinda dumb considering it cost over $600.

Dingo
 
scorpio_vette said:
i think the whining noise is kinda cool. when i had my chevy we put a set of those in.....most guys here call them "screamer gears".

Spur gears whine - due to the "intermittent" engagment of the gearset. "Silent" gear drives have helical teeth.

Most forward gears in transmissions are cut helically - not only does this make them quieter, it increases gear longevity by allowing the gears to remain constantly "meshed," thereby reducing 'instant' stress on the gear teeth. Reverse gears are usually still spur cut, since you don't usually spend a lot of time in reverse.

5-90
 
5-90 said:
Spur gears whine - due to the "intermittent" engagment of the gearset. "Silent" gear drives have helical teeth.

Most forward gears in transmissions are cut helically - not only does this make them quieter, it increases gear longevity by allowing the gears to remain constantly "meshed," thereby reducing 'instant' stress on the gear teeth. Reverse gears are usually still spur cut, since you don't usually spend a lot of time in reverse.

5-90

that explains soo much. i'd always wondered why manual cars whine while in reverse. thanks
 
I believe the chevy m22 was an all straight cut gear trans.
anyone know why less pitch on the gear teeth increaces power handling?
 
By "less pitch," do you mean "less space between tooth centrelines" or "less teeth per unit length?" The two are opposites.

If you mean fewer teeth per unit length (teeth per inch, for instance,) then it increases power handling due to the greater material in each tooth and the greater cross-section of each tooth, which makes the teeth stronger. Granted, there are more variables involved than that (a gear that is thicker will have more lateral distance than a thinner one, and will also therefore handle more torque without shearing off teeth...) but that's the gist of it.

If you're talking the other way - less space between centrelines - then you'll end up with a gear that actually handles LESS power, assuming the same material used as the other "two" (the normal one, and the one with fewer teeth per inch.) Reducing the distance between centrelines actually will increase the number of teeth per unit length, and reduce the material in each tooth.

5-90
 
streetpirate said:
Sorry, i used the wrong term, i meant the angle of the helix the gears are cut at.
http://www.5speeds.com/muncie3.htm


BY including a helix cut on the gear set, you are tranferring rotational torque into thrust torque. In essence, as you apply power, the gears want to spread apart due to the "ramping" effect of the helical gears. It can be mitigated somewhat by using larger thrust bearings.

On the harmonics issue, there is a narrow band on all inline 6 engines where harmonics are an issue, usually right around 6k. It's not a problem if you rev through the harmonic and then shift. It's only a problem if you are consistantly running at the harmonic. Not many of us run at the harmonic for long periods.

On a side note, I use a dual roller setup with adjustable timing of Australian manufacture, and I've been very happy with it. Quiet, and it smooths the idle a bit due to the nice, tight chain.
 
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