Compatible transmissions for the M35a3 with the cat 3116

[jrobinson5093]

6.71 are the stock ratios.

 

[Rambling Wreck]

6.71 are the stock ratios.

That should translate into a 37% increase in speed. So, 50mph x 1.37 = 68.5mph. Larger tires should then get me another 15%. 68.5mph x 1.15 = 78.8mph. This also means that I would be able to cruise around 65mph with the engine only hitting about 2,200 rpm.

I wonder how bad the acceleration would suffer though.

 

[clinto]

http://www.steelsoldiers.com/showthread.php?67616-ouverson-engineering-4-90-gear-set.html

 

[Rambling Wreck]

http://www.steelsoldiers.com/showthread.php?67616-ouverson-engineering-4-90-gear-set.html

Good thread. Seems like the opinion is that 4.90s would work in an A3 but that no one has tried it yet. Too bad as the acceleration on other driving characteristics are harder to quantify.

 

[jaymcb]

not to mention that it's $3600.00 plus labor - and that it probably won't get out of it's own way, especially if you've up-sized to 395's on your A3.

I like my A3, but again, increasing my cost basis on my deuce by over 4k is just

 

[Rambling Wreck]

not to mention that it's $3600.00 plus labor - and that it probably won't get out of it's own way, especially if you've up-sized to 395's on your A3.

I like my A3, but again, increasing my cost basis on my deuce by over 4k is just

I am going to wait until mine is bobbed before I perform upgrades for top speed improvement. Only having to do two axles means that I am only out $2,400. I will provide my own labor. Not sure about the "get out of it's own way" comment but if you mean that it will have poor acceleration, I have several thoughts on that. Bobbed my truck should weight about 3,000+ lbs less so there will be considerably less mass to accelerate. Additionally, the Cat 3116 is capable of generating much more horsepower than the 175 it runs in the A3's, so the engine could be turned up if acceleration suffered too much.

Thoughts?

 

[jaymcb]

turning up the fuel and reducing your curb weight by ~20% is going to help, as is losing the parasitic loss of turning the second rear axle. (That's simple physics)

I'd also look at manual locking hubs for the front.

 

[Rambling Wreck]

turning up the fuel and reducing your curb weight by ~20% is going to help, as is losing the parasitic loss of turning the second rear axle. (That's simple physics)

I'd also look at manual locking hubs for the front.

Good point about the loss associated with the second rear axle.

 

[Rambling Wreck]

Where would you put it?

They are the size of a transmission and are obsolete

I think you are mistaken. See the link below.

http://ep.yimg.com/ca/I/yhst-59523690850641_2214_25453689

 

[jaymcb]

That's Erik's from Erik's military surplus, and it is a Mitchell 3000a splitter. Good luck finding one.
It takes a TON of mods to fit, drive shafts, cross member, etc.

Also, that splitter makes the deuce pretty much a road-only truck because of the angle-limitations from the shorter fabricated drive shafts. Lastly, that splitter is rear wheels only.

**I am saying this having traded emails with Erik about those very pictures. Great guy, was responsive and helpful, on top of the parts I've bought.

 

[trukhead]

I had a total brain fart in thinking about how to make my A3 go faster and this is what I came up with.
I am going to acquire a nice M920 and to this said truck I am going to:

Replace front axle with super duty rebuilt front steer axle with huge brakes, (no gears type)
eliminate transfer case with a drive shaft
eliminate one drive axle gearset
install a 2.70 rear gear set
send 400 out to PA and have them bump it to 800 ponies
install frame that pivots on fifth wheel for A3 to ride on

on the A3 remove top, troop seats and fold down windshield and exhaust stack when A3 is on the 920.

I'm guessing I can get 110mph out of the A3 when installed on the modified M920

Why use a M920, it's got that kickbutt winch for tilting the bed to horizontal.

 

[Rambling Wreck]

I never claimed that it would be easy. Not sure about the angle limitations. I know what you mean just not sure how much it would limit the off road abilities.

 

[jaymcb]

putting that Mitchell in is going to limit the amount of articulation of the rear suspension due to driveshaft angle limitations.

 

[Rambling Wreck]

putting that Mitchell in is going to limit the amount of articulation of the rear suspension due to driveshaft angle limitations.

Yeah, I understand that. To what degree the articulation would be limited is the question.

 

[Rambling Wreck]

Today I spoke with a guy at Southern Gear (Southern Gear Co. - The Standard Transmission Professionals) and after I explained my situation his suggestion was to change the differential gearing. I still plan on giving myself more time to research transmission options but I think I am leaning toward the Overson axle gears as the most viable option.

 

[m-35tom]

not sure what tire size you are really going to use so i did the math with radius being 21", trans with lockup converter, 4.90 diffs. 2200 rpm would be 56.1 mph, 2500 rpm would be 63.7 mph. still think it would be worth it? i think only if you really want to keep the auto.
with 4.90 rears and 1:1 trans, your final ratio is 4.90, with 3053 and gear set final ratio is 4.64. any way you go tire radius means a lot.

tom

 

[Rambling Wreck]

That should translate into a 37% increase in speed. So, 50mph x 1.37 = 68.5mph. Larger tires should then get me another 15%. 68.5mph x 1.15 = 78.8mph. This also means that I would be able to cruise around 65mph with the engine only hitting about 2,200 rpm.

I wonder how bad the acceleration would suffer though.

m-35tom,

Is my math wrong?

6.71 / 4.9 = 1.37

Basically a 37% increase in final drive speed from the Ouverson gear set.

On my M35A3 I can run 50mph at 2,700 rpm with the 3116 Cat.

So 50mph x 1.37 = 68.5mph

Tires are about 42" diameter so going from that to a 46" or 49" diameter tire would roughly translate into an additional 15% increase.

So 68.5mph x 1.15 = 78.8mph

 

[trukhead]

Circumference = Diameter x PIE (YUM) PIE is actually a funny looking character but I like PIE! Yes I do!!!!!

14.5 x 20 Michelin is 42ish inches in diameter ( I didn't measure one )

PIE = 3.14...... (3.14 for this discussion)

So:

Michelin tire goes 11 feet/rev

11ft x 2200rev x 60minute x 1(gear ratio) x 1 mile
rev.....minute..... 1 hour........4.90............. 5280 ft


a stock 14.5 x20 michelin with a 4.90 gearset at 2200 engine rpms is going about 56 mph

 

[Rambling Wreck]

Circumference = Diameter x PIE (YUM) PIE is actually a funny looking character but I like PIE! Yes I do!!!!!

14.5 x 20 Michelin is 42ish inches in diameter ( I didn't measure one )

PIE = 3.14...... (3.14 for this discussion)

So:

Michelin tire goes 11 feet/rev

11ft x 2200rev x 60minute x 1(gear ratio) x 1 mile
rev.....minute..... 1 hour........4.90............. 5280 ft


a stock 14.5 x20 michelin with a 4.90 gearset at 2200 engine rpms is going about 56 mph

Yeah, BUT, I am not turning 2,200 rpm. The cat will do 2,700 all day every day.

So... according to your math, if you apply the right rpm:

(56 / 2200) x 2700 = 68.73 mph which is basically the 68.5 that I have shown above.

You really need not even apply pi to figure this out. Given that I know what speed I can travel at what rpm (50 mph @ 2,700 ish), I only need to know the different gear ratios and tire sizes to determine the speed. The pi's and everything else cancel out of the equations.

 

[m-35tom]

sometimes other methods work, sometimes they give false info. the simple math formula for this is :
mph = ( rpm * radius) / ( 168 * ratio)
using loaded radius is more accurate, ratio is final drive ratio including trans, rears, etc.

tom