trans gear ratio math, etc

[m-35tom]

ok, i think i did this right, but want confirmation...... ratios that are all reduction can just by multiplied to get the net result, like trans x transfer x rear = total ratio. in an overdrive trans there is typically a reduction then a increase in speed done through two gear sets. so........ input gear has 29 teeth, driven countershaft gear has 42 for a ratio of 1.4483 : 1 then the countershaft gear for 5th has 48 teeth and mainshaft 5th has 22 for a ratio of 1 : 2.182 so what is the overdrive ratio?? i get .664, yes? this gearset would give a stock m-35 a 60 mph rpm of about 2125 depending on exact tire size, sound good??

 

[jeli]

Something doesn't add up to me. I'm getting an overall speedup ratio of 1.505:1. 29/42 = 0.690 and 48/22 = 2.182, .690 x 2.182 = 1.505

 

[Westech]

ah no. stock m35 with 9:00 tires would be around 2900 at 60 mph even with 11:00 tires you would be in the 2600 rpm range. on the dash plate it states 56 mph at 2600 rpm.

 

[Stretch44875]

Did you swap out the stock gearset in the tranny? Would LOVE to see 60 MPH and 2100 rpm.

 

[m-35tom]

westech, you didn't read the question..........
jeli, if you divide 1 by your answer you get .664 as i did
strech, maybe soon, i am working on getting some gear sets

 

[jeli]

m-35tom, I hear ya but I'm not tracking. Assume 1000 rpm input speed. 29 tooth gear at 1000 rpm driving a 42 tooth = 690 rpm. The 42t gear is mated to the 48t gear which also must be turning at 690 rpm. If this is true then the 48t gear is speeding up the 22t gear. I'm still getting 1505 final rpm. What am I missing????

 

[m-35tom]

1000 rpm divided by the output 1505 rpm is the overall ratio, right?? is it?? look at it as the output turns 1 revolution, then the input would have only turned 2/3 or .66 revolution. this would be a overdrive of .66 instead of the standard m-35 od of .78 then 2100 rpm = about 60 mph which might be ok for level road............... and you can always go back to 4th for hills.
tom, redesigning the deuce

 

[ATC]

The first calculator on this site works great:

http://www.tyres1.com/tech_calcs.html


With a tire size of 46", tranny in 5th gear (.78 ratio?), T-case in Hi (1:1 also), 6.72 gears in the Rockwells....It comes out at 2297RPM at 60mph.

Not bad?

 

[gringeltaube]

........input gear has 29 teeth, driven countershaft gear has 42 for a ratio of 1.4483 : 1 then the countershaft gear for 5th has 48 teeth and mainshaft 5th has 22 for a ratio of 1 : 2.182 so what is the overdrive ratio?? i get .664, yes? ....

Yes, if you really have that 48/22 gear set for fifth (????). What is your trannys model#?
Although technically possible, 51% OD certainly is very strange! That gear combo is what comes std. in the 3052 as 1st counter shaft gear/input gear, respectively.
It would make a huge step from 4th direct to 5th OD and equipped with 11.00-20s a final speed over 70mph at 2600 rpm!
All the 3053s (version A ) I've seen had 29/42 and 46/25 which gives you that .79/1 overdrive ratio (or 27% OD) I wish somebody could tell us more about the 3053B gear ratios, their application and drawbacks...?

Gerhard

 

[jeli]

RE: Re: trans gear ratio math, etc

OK, I'm retarded. The whole purpose of your project is to make things spin faster than the engine!!!! It just took that long for it to sink in. I'm thinking more about tomorrow's trip to Canada fishing than gears.

 

[OPCOM]

RE: Re: trans gear ratio math, etc

Isn't the 3053A ratio in 5th 0.85 ?

Spicer 3053A
6
3.31
1.89
1
0.85

 

[m-35tom]

RE: Re: trans gear ratio math, etc

no, all 3053 and 3053A trans are .79 od. there are no others in mil use so what ever else you have heard or seen is wrong.

 

[m-35tom]

RE: Re: trans gear ratio math, etc

actually, the od is .7869, so you may see .78 or .79 but the -34 says .79

 

[gringeltaube]

Re: RE: Re: trans gear ratio math, etc

no, all 3053 and 3053A trans are .79 od. there are no others in mil use so what ever else you have heard or seen is wrong.

So what model/origin is your tranny to have that odd OD ratio?

 

[m-35tom]

RE: Re: RE: Re: trans gear ratio math, etc

gerhard, i will use a combo of mil and civvy trans gears to achieve a higher od. the possibilities include the stock od of .79 and also .71 and .66
there were 5 different od trans made for civ use with 3 different 5th sets and 3 different main drive sets

 

[gringeltaube]

Very interesting, Tom! Could you provide more info about these civilian Spicers, specially specs and application???

 

[m-35tom]

ok, next question...... with a .66 od and if you run 4th gear out to 2300 rpm and shift to 5th the rpm will fall to 1510. do you think there will be a power issue pulling from that rpm up to 2200 (if it will turn 2200) remember it will have much less torque applied to the driveshaft.

 

[gringeltaube]

That depends primarily on the torque curve of the engine you are planing to use.
I suppose it's not the MF? Even for the LDS 465-1A this would be a difficult task!
And than if you had a motor pulling strong enough at 1500rpm its torque at 2000rpm most probably exceeds the 400 ft-pound limit specified for the 3053.
I don't see a problem so much for the drive shafts as for your poor tranny with its little 22T fifth gear taking all the abuse and second gear spinning (free) at 792 on its main shaft journal doing 3314 at 2200 engine rpm (5th speed engaged). Delta is over 2500!! and you know they tend to seizing!

 

[m-35tom]

yes, well i intend to use a ldt turned up to 200 hp and will use 50 wt engine oil for trans to aid in lube. as to torque overload, they are all over the design spec of 300 when they went from gas to mf. even in the much newer cm6000 they only improved front mainshaft support with a tapered roller.

 

[houdel]

T-case in Hi (1:1 also)

To be technically correct (since you guys are slicing hairs out to 4 decimal places), the Rockwell T-136-27 transfer case ratio in Hi range is 1.010:1 .000 to the rear axle and 1.078:1.000 to the front axle (per TM 9-2320-361-20, pg 1-35)