The Stovebolt Site Forums The Parking Lot Big Bolts converting to two speed axle

how much work is involved with changing out a single speed axle to a two speed axle on a 65 c-60?

any thoughts are welcomed!

Its not as bad as you might think. Aside from the huge weights your dealing with. In other words you can crush yourself and chop off fingers if your not careful. You need to decide how your going to shift it. ( vaccum or lever shifting). Remember a two speed doesn't give you a higher end it gives you a lower one. Good Luck, Stay safe!

now that is something i didn't know. i just assumed a two speed axle would increase the to speed, but it does not seem to be the case.

what would be the best approach to increasing top end. i'm not looking for "warp speed" but a little more speed would be nice. i doubt i will ever have an exceptionally heavy load on the truck, so re-gearing the pumpkin might be enough.

the 2 speed was meant for heavier loads, not higher speeds - changing rear gears to lower numerical ratio or finding an overdrive is what you want

Bill

P.J. about the only way to increase your highway speed is to change your gear ratio. If you have a 4 spd you could change out to a 5 spd overdrive transmission. You could also change out your rear diff to a later model, maybe a Uhaul or something(might be cheaper) . The bolt pattern and width would be your biggest concern. I'm sure there are trucks out there with higher gears than your 65 has.

or put bigger wheels and tires on it

Look up ring & pinion service in the local yellow pages. They may have something you can swap into the rear end to rev you up a bit. A newer 5 speed may be the better ticket tho, it's all in the gear ratios.

Most of these old rears only have one ratio available for them. An NV4500 would be a good swap it's a 5 speed OD it would give you a 60 maybe 65 MPH top end and not mess with the low end pulling much first gear is not as low as your SM 420 4 speed that your truck came with but you said you doubt that you will ever pull much of a load anyway.

Seems to me the issue of whether a 2 speed will help your road speed would depend on what your current axle ratio is,and what the high side of the 2 speed is. That's what you need to look at first.
I've been thinking of checking out motorhomes for taller geared axles. The big problem here might be width,the motorhome axles are usually wider,as I recall.
Speed

I just swapped axles in a 61 f350. I was open to all possibilities to get faster gears. I looked for 1 ton pickup axles, motor home axles, older Rockwell 1750lb axles, and even the import cab over trucks.

I was switching from 4.56 to 3.54 or 3.73, depending on tire size and wheels.

I found that the new one ton pickup axles are often expensive, and the newer ones from a diesel will have faster gears like 3.54 or 3.73. The older ones from a gas engine are slower.
Motor home axles are usually a Dana 70HD, Dana 80, or a Rockwell. They are almost always 4.56.
The older Rockwell axles like form a Ford f700 are only available with slow gears, I looked at about a dozen and they were all slower than 4.56.
The little cab over trucks are only available with 5.xx and slower, although I forget if I found one with a high 4.xx, but still slower than 4.56. There are no gears available to go faster for those axles.

I ended up using a 2001 Rockwell Meritor 15,000lb axle from a freightliner. It has 3.73 gears. Two gear choices are available faster, but are about $2,000 and a few months lead time while they make them for you. The axle I found has 14" disk brakes and 19.5 or 22.5 wheels are available to fit.

Use this site to find the right combination of gears, OD, and tire size. You want your engine at it's peak torque rpm while cruising at your preferred speed in order for best fuel economy
http://www.drivetraindirect.com/t_gear_calculator.htm

If you do find a Dana motor home axle, which is probably the cheapest axle of your choices, you may need to change the gears and also the carrier, this will cost about $600 minimum in new parts.
I'll have pictures soon of the conversion I just did.


Grigg

HevyHauler, I was initially looking at the NV4500 pretty hard until I found this: Novak Jeep Conversions Knowledgebase: NV4500

Since then I've been looking at the AX15, although it is only listed as a medium duty transmission. My 1951 4400 1.5 ton won't be used for max effort hauling and the engine is probably going to be a 292, so the AX15 shouldn't be overpowered. The drawback is the cost of the adapter.

starkweatherr, Your 292 has the same bell housing bolt pattern as a Chevy V8 and has side motor mounts so if you find a truck with an NV4500 bell housing and transmission cross member you have got it maid. Just remove the cross member at your bell housing and use the new one at the transmission. The 4x4 NV4500 are getting hard to find but the two wheelers are everywhere.

wow! i am so out of my element here. not that i'm not willing to learn but i am for sure too new to the big bolt stuff to know what you guys are talking about.

not that you should stop the dialog regarding all the possibilities, but what i would really am looking for is a simple way to modify this 65 that has the stock 4 speed tranny and differential so i could get more speed out of it. and i'm not talking about 70 or 80 mph. my recollection of the top speed on this truck was around 50-55 mph.

bear with me guys. i want to learn but it may be a case of walking before i can run...

Well p.j., starting with the rear axle in you truck. First a two speed axle has a low ratio of 8.72 to 1 and a high of 6.4 to 1 the high ratio being the same or near the same as you stock rear doesn’t get you anywhere. Gear sets for the old axles come in come in one ratio the one you have so that is out.
So this brings down to 4 options when looking for more road speed.
1 change the rear axle for a later model rear with a taller gear set or with optional gear ratios
2 swap your transmission for one with an over drive.
3 install an aftermarket overdrive unit (i.e. Gearvender) behind you existing transmission.
4 use taller tires.
Now for the pros and cons
Changing the rear axle pros
1 may be the easiest if you can find a suitable axle.
Things that make a suitable axle 1 track width. 2 spring perch spacing. 3 perch width or the width of the springs that it was mounted to. 4 Dose it use the same wheels? If not you may want to change both axles. And 5 don't forget dose it have the gears you want.
2 you may kill multiple birds with one stone like improved late modal brakes. Parts that are more available should you break your new rear. Of course this all depends on your choice of a replacement axle.
Cons would be finding a suitable axle.

2 swap you transmission for one with an overdrive.
Pros will not hurt your low end pulling power.
It can be easy to do.

Sorry my short attention span is getting to me I'll have Finnish this later.

p.j.,

When I got my '57 Fire Truck it had a 7.17:1 single speed rear and had a top speed of about 53 mph. It has an 18,000 pound Eaton rear, so I found a 2-speed pumpkin (that fit my housing) that had a higher high ratio and a lower low 6.14/8.36:1. I added 10 mph on the top side and have a deeper low for pulling (Granny and 'Low Rear' will pull a house down). I drive it like a 6-speed, set the rear to 'low rear' and work up to 5th low then shift the rear to 'high'...I'm very happy with the results.

I was able to swap the pumpkins out without jacking the truck up or removing the wheels. I just slid the axles out, removed the drive shaft, removed the rear cover which drained the oil, removed the the pumpkin. To help align the new pumpkin I installed 2 long studs about 12" long into the bolt locations and slid the pumpkin in...found out the new ring gear was larger diameter then the old and I needed to cut a slot in the housing (about 1" wide by 1/2" deep). Once I got that done I installed the pumpkin, had a new drive shaft made to have it match the new U-joint size on the new rear and ran the electric lines to the gear shifter.

The 2-speed pumpkin and electric switch cost about $250. The drive shaft work was about $80. I didn't have to touch any of my brake stuff which was great!

Mike B

bingo! that's what i was looking for! will want to pick your brain more about your conversion, but this is along the lines of what i had in mind.

i drove a company truck with a 2-speed and that's how i went through the shift pattern. low/2 up to low/4, then high/4.

again, i'm not looking at trying to achieve warp speed here, just something a little above the stock top end.

will be back in nebraska in july and will do some more investigation of the current set-up and will go from there.

thanks!

o.k. not sure why that posted twice, and i don't know how to delete one of them...so there you have it.

pj - to delete a post, click the [img]http://www.stovebolt.com/bboard/ubb//edit_ubb6.gif[/img] icon above it to 'edit post', then check the 'delete post' box toward the top left there and click the 'edit post button at bottom .... bingo it's gone

Bill

thanks red.

pj,
I don't know your truck but the absolute quickest, cheapest and easiest way to elevate gear ratio a wee bit is to increase the diameter of the rear wheels. For example, if you are running 19.5 inch wheels and your overall tire height is lets say 33 inches, replacing with 22.5 inch wheels might increase your overall tire height by one or two inches, thus lowering engine R's accordingly. You can go to an rpm calculator to estimate benefit. Only downside is that it makes your speedo slightly inaccurate and you end up with different size wheels front/rear.

Mike,

That's pretty interesting. On the way out to Winchester I was wondering what you did to that thing to make 65 MPH.

John