axle ratio?

[67_Gladiator]

It amazes me how many times these same questions are asked and how many times they get the same answers.


67, since you have been a member here(2 days) how many searches have you done? How many threads have you read?

Ive read as much as i can and searched, iv'e found a lot of info but some questions still weren't answered. And searching on a phone is a slow difficult process. sorry for my mistake

 

[doghead]

Using a phone to search a website to make a decision to buy a truck you are unfamiliar with, is a very bad idea.

There is more than 2 days worth of reading to do, in the modifing the deuce forum alone.

Is time of the essence? why not sit at a computer before spending $4000 and get all the facts.

 

[67_Gladiator]

I'm not rushing into it, just trying to get a game plan when the time comes. I have to finish the 67' mud truck before i can bring one of these deuce's home. I figure i have at least a years wait.

 

[Unforgiven]

Gladiator,

There's only so much you can do with the stock brakes. No matter what type of brakes, the most you can expect from them is full lockup, i.e. tires skidding.

Drum brakes will lock up just like disc brakes will. Therefore, there is no advantage to disc brakes over a well-maintained drum brake system. The only thing problematic with this is severe duty such as hauling logs out of mountain roads. In that case, the drum brakes can "fade" much quicker than disc brakes due to overheating.

The only way to stop the truck sooner is to add some form of auxilliary braking system. The extra energy has to be dissipated somewhere. This can take the form of an engine brake (that uses the work for piston compression to slow the vehicle), an exhaust brake (that compresses the exhaust gasses after exiting the discharged piston), or a transmission retarder (that uses a propeller immersed in the transmission hydraulic fluid to dissipate some of the energy). Some more fancy systems (not viable for mud or extreme off-road duty) have a driveline brake that makes electricity as you brake. It improves fuel efficiency & braking for public buses etc. But in a Deuce it would be very vulnerable to mud, sand & off road nastiness.

If an engine brake, exhaust brake, or transmission retarder (only available on automatic transmissions) does not appeal to you, then your only other option is to put larger brakes at the wheels. I'm sure this could be done but it would involve some very custom engineering. If you are not good with machining/designing large parts I would avoid this.

The pinion brake is only for parking purposes. It will not stop a truck in motion. It is not an emergency brake.

Keep it under 60 mph with a well-maintained stock drum brake system and you won't have any problems.

 

[m-35tom]

do the math, you cannot put 4.90 rears in a deuce. it will not have enough power to get out of 3rd gear. not to mention it would cost about $4500 plus lots of labor.

 

[wldrbob]

4.9 gears 55 mph 2150 rpm 42 in tire ..... 6.72 gears 55 mph 2400 rpm 52 in tire hp to get 14000 lbs to 50 mph in 1/4 mile 136hp theres the math if your original tires were 40 in and you switch to 52 in ..your ratio is now 5.17

 

[m-35tom]

with 4.90 axle ratio, 55 mph with 42" tires = 1681 rpm. with 52" it would be 1358 rpm at 55. too far below the power band to maintain speed even on level ground. i can't even imagine where you got the 5.17, since the overall ratio with 4.90 diff is 3.822.

tom

 

[wldrbob]

if you have a .7 overdrive in your deuce it efectively changes your 6.72 to a 4.7 so 4.9 and a 1 to 1 top gear will be fine .. just more money to change rear gears but you could also change axles to beef up your rearends . oh and im quoing your (m35 tom) old posts ya i do use search

 

[m-35tom]

but it's not a .7 od, it's a .78 od, so 5th gear, .78 od gives a final ratio of 5.24, not 4.7 . and that is a BIG difference. the change from 5.24 to 4.9 is much more than would be practical. you would loose much of the off road capability even in low range and never be able to use 5th.

tom

 

[jesusgatos]

4.90 isn't the only gear ratio available though.

 

[wldrbob]

oh your post says your od is .69 .. and the low range with 6.72 w.o.t. is 3 mph and with 4.9 its 5 mph (thats from the engenering site) not enough difference to bother . puting 52 in tires or bigger changes your final drive anyway thats where the 5.17 comes in .. talk to some 1/4 mile or stockcar guys they worry more about rearend ratios ,tire size and rpm than anybody ,used to fool with that stuff when i was younger.