switching out the rear end to a higher ratio

parkerm

Guys,

I know there was a discussion a while back about replacing the Hudson rear end with a Ford Explorer rear end because they were the same size (width I believe) I searched for the discussion but I could not find it.

Can some one direct me on how to search for that discussion or explain to me how to determine if the rear end from another vehicle will fit my 1940?

Thanks,

Marvin

[Deleted User]

I put a rear end out of a 99 cherokee in my 47 hudson p/up.Not only was it the right width ,but the driveshaft length was good and ujoint was the same...easy swap.

Jon B

If you wait long enough I think some others will jump in with additional ideas.  The favored swap in the past, was for mid-60's Mopar, and Ford Mustang, rearends.  The problem is that, now, cars of that era are very collectible and thus their parts are no longer inexpensive.  That, and the fact that you no longer find cars of that vintage in many junkyards!

12BoltTom

It was our 41 Big boy. We used a (free) 93 explorer 8.8.1/2 inch narrower. Bought some cheap 2" wide purches on eBay . ground them to fit tubes and lined up rear in the truck with springs. Took a few measurements and welded them on to the tubes. Had to cut some offending hardware off first. 93-95 drum brakes newer are disc.

Browniepetersen

My 1936 English built Hudson has a later model Lincoln in her. She should go eighty (but will never happen while I am driving?) My Essex Roadster Pick up has a 1981 Bobcat rear end in her. I have had the roadster pick up at the 90mph mark. Stupid to have that small, light car at that speed!!!!

53jetman

Brownie:  The best suggestion here is the Jeep Cherokee substitution.  It is essentially the same source as Hudson used, and can be found with a 3.78 to 1 ratio if you look hard enough.

Jerry

parkerm

53jetman,

What year Jeep Cherokee are speaking of? Blacksheep said he used a 99 Cherokee in his 47 is that the same year you are speaking of.

By-the-way, thanks to all of you that commented I  appreciate it.

Marvin

junkcarfann

I put a Ford Explorer rear end unit in a 1936 Terraplane, and it was 1/2 inch narrower, (only 1/4 inch on each side, which can be remedied if you want to with a spacer available at hot-rod shops that fits between the wheel and the axle flange). 

The Hudson U-joint fit with a change of the pinion flange were the U-joint attaches. I got that at the local rear-axle repair garage, which most larger cities have, as that is a specialized area of repair and is used by all the new car dealerships.

The driveshaft length was the same, even the hole at the top of the axle housing where the hydraulic brake fitting screws in was almost in the same place, with the same threads!

Those Explorer units are known as "Ford 8.8", are very common, and have many different axle ratios available. 

If you cannot find one with the ratio you want, a shop that specializes in axles can change it, as the 8.8 does not have a "pumpkin" than changes out as a unit, so a specialized shop needs to do the gear setup.

The only big problem was the spring pads, which I had a welding shop do. Be careful of keeping the proper tilt to the axle...the pinion needs to tilt downward a few degrees. If it is lined up straight to the transmission, vibrations will occur. 

I made a fixture while the Hudson axle was still in the car which measured the tilt using a protractor or something (been a few years) and had the welder make sure that measurement was followed. The welder I used was a shop that built hot-rod Jeeps and such, and knew exactly what that was all about.

Also, if I remember correctly, the Hudson spring pads were angled inward a bit.

53jetman

Any of the small Cherokees from 2006 on back to about 1980 or so.

Jon B

Marvin,your rear end conversion sounds like the makings of a wonderful technical article for the WTN.  Maybe you could jot down your experiences (when it's all over), the exact specs of the things you had to buy, and you could take some photos during each step of the process.  Then you could either write it up, or find someone to do so (once they're given the raw material) and it would make a very good article in the newsletter.  There are many others, no doubt, who are contemplating such a changeover, in order to drive their cars at highway speeds.

Bob Elton wrote such an article for the WTN back in the 1990's, as I recall -- "Making the Terraplane a Highway Cruiser".  But it needs to be updated in light of the fact that the transplanted parts he suggested have themselves become antique, scarcer and in higher demand than they were 20 years ago.  The Cherokee and Explorer rearends would now be more plentiful, not to mention the fact that parts for them would be readily available.

parkerm

Jon,

I may not start this project until summer is over and I won't be driving the car. Thanks for the suggestion I will keep this in mind when I begin.

Regards,

Marvin

jjbubaboy

Hey,

I discovered, after all the work to pull a Explorer rear end, that the axle tubes where a bigger diameter than the ones on my 36 T. Ended up getting an 89 Mustang rear and using the gears (3.55) from the Explorer in that one. Put the Mustang gears in the Explorer one and sold it.

Jeff

[Deleted User]

I also have a 40 travler that I put an AMC 20 hiney in. It was outa an AMC Spirit AMX 1982. Also an easy swap. It has a 2.86 gear that worked really well with a SBC with a T350 trans.

46HudsonPU

Hey,

I discovered, after all the work to pull a Explorer rear end, that the axle tubes where a bigger diameter than the ones on my 36 T. Ended up getting an 89 Mustang rear and using the gears (3.55) from the Explorer in that one. Put the Mustang gears in the Explorer one and sold it.

Jeff

Yup - the Explorer tubes are 3.25 inches, the rear being more heavy-duty than the jeep, etc..  The 'swap' to Explorer rear is somewhat popular with the Jeep crowd, as Explorer rear is more heavy-duty, and almost a 'plug-n-play' swap with the Jeep.

If you go back far enough, Mustangs in the 60's to early 70's had the 9" Ford rear end.  However, they are no longer easy to come-by, and if found are very expensive.  In general, Mustang rears are not the same width as the Explorer, and that width will vary by years (and version of 'stang).  Careful, as it may also may be a 7.5 or  8.8 rear, depending on what it is supporting (a 'six' banger, an '8'; automatic trans or a manual 5-6 speed trans, etc..), as well as most 8.8 rears having disc brakes (meaning a conversion of the rear end's brakes to drums or converting the front brakes to disc will probably also be necessary). Depending on the version of 'stang', they also have different types of suspension (older units are leaf spring, newer tend to have coil spring w/4-link (a variation of the triangulated four-link), and the latest have fully independent rear suspension - which has also been used in at least a couple 'rods' I've seen ('PowerBlock TV did one a few months ago).

A lot of info here -
 http://www.therangerstation.com/tech_library/Explorer8_8.shtml

Park_W

jjbubaboy, how do you like the 3,55s in your '36?

Ducor Kid

I am using a ranger rear axle in my Pacemaker. The earlier Rangers were 56 1/2 wide and later are 58 1/2 wide. The tubes are 2.80 dia. I used a 1990. I took my Hudson rear end to local fabricator along with Ranger rear end and he fabbed mounts to match. It went in like it always had been there. Therangerstation.com has lots of info on the 8.8.
Larry

jjbubaboy

Hey Park,

I like it. Its a good compromise without having an overdrive. Havent had any lugging problems and seems to be fine to do hills without downshifting. Seems like 55 on the freeway is her 'sweet spot' where she likes to run. 

Jeff

Kdancy

Larry, you didn't have any issues with the offset pumpkin?

Jon B

Marvin, have you thought of transplanting an overdrive into your car?  I believe the 1941 through 1952 Hudson-built ones would fit, physically, into your car.  And of course they have the Hudson style linkage (one lever "cable" style) just as yours does, so the linkage problem is taken care of.   (I think Hudson put the 4:55 rear into all overdrive-equipped cars, "back in the day" but you can probably find a 4.11 if you don't already have one, and that should work quite well with an eight or 3x5 six.) 

With the overdrive you will have more flexibility than if you simply changed rearends.

Ducor Kid

Larry, you didn't have any issues with the offset pumpkin?

Which offset? Both axles have an offset of 2 in. to the right of center.
Larry

parkerm

Jon,

I had not thought of installing an overdrive on my car. I will look into this and see if I can find one available. When you say I will have more flexibility with an overdrive  than I would if I just changed the rear-end. Can you explain that; what do you mean exactly?

Thanks to all of you that contributed to this discussion I really appreciate it.

Marvin

Jay_G

I put a 46 overdrive in my 46 truck and upgraded to 16 inch rims.  Best thing I have done in a long time.  It hits 60 to 65 on a good day and likes 55 most of the time.  Also great for around town driving.  Easy install, drop the old trans, bolt in the overdrive and shorten the drive shaft.  Nothing else to change.  Although there were a few wires and a relay but no big deal.

Sounds a lot simpler than a rear end swap.  I am not sure you can bolt in a 46-47 overdrive as I know 40 overdrives are very rare and difficult to find.  So if anyone has one, I would like to buy it to put in my 37.

Jay

Jon B

By "flexibility" with an overdrive, I mean this:  with merely three speeds and a higher speed rearend (like 3-5/8) you have essentially one "cruising" gear and it must serve you both on hills and on the Interstate.  With an overdrive, you have the same third gear ratio, but you've gained a better cruising ratio (fourth gear), for even higher speeds.  Yet by tromping the accelerator you can shift back to your regular third gear, to get up steep hills or pass someone.  Like an automatic transmission. 

You don't have that flexibility with a three speed.  If you put in a really "tall" set of rearend gears (like 3-5/8) so you can travel fast down the Interstate, and you come to a steep hill, your only recourse is to drop down to second gear.  And THAT will have your engine really screaming.  If you compromise and put in a 4-1/9 gear you will have a good all-around third gear, but you may not be able to cruise at more than 50-55.

The overdrive gives you the option of that lower gear ratio or your regular 3rd speed ratio, and it provides the changeover instantly, without even moving the gear lever (like if you need extra power to pass someone).  When in overdrive, your engine is doing only about 70% of the RPM's it was doing in conventional third.

Actually, your option extends to "second-overdrive" as well, so with OD you effective have a 5-speed....though few people use second-overdrive.

parkerm

Jon,

Thanks for the explanation you have made it very clear and I understand what you mean. I do not understand what you mean by second overdrive. Do you mean one can go into OD when using second gear?

Jay,
Please don't hijack my discussion by offering to buy an overdrive if anyone has one when I may need to buy it. It seems to mean that fair is fair; I started the discussion and I don't appreciate you offering to buy an OD out from under me. Overdrive sounds like a better option now that Jon has explained it so clearly to me.

Marvin

Jon B

Marvin: Yes, if you can get to 30-35 MPH in second, you can lift your foot and overdrive will kick in (just as it will in third).  Which will give you a new and unusual gear ratio good for...practically nothing!  (Actually, it might be good for driving around town without having to shift...)

The 1940 OD is a one-year-old and appeals to the earlier Hudson owners because it can be converted for floor shift.  However, you have a column shift and unless you are a super originalist, you would be well advised to look for the newer overdrives (1941 right up to 1952) because they would adapt well to a column shift car.  Plus, those transmissions are syncro and generally a better trans than the 1940 anyway.  And certainly more available!

Lee ODell

All through High School I drove a bored and stroked six cylinder 40 Ply 2dr sedan with overdrive. I sometimes showed off to friends that I had a 6 speed trans.
1 - First gear
2 - First gear O/D
3 - Second gear
4 - Second gear O/D
5 - Third gear
6 - Third gear O/D
I wouldn't recommend doing this a lot. After replacing the trans twice I chose not to try for a third. Perhaps regular drag racing and speed shifts had something to do with trans demise.
Lee O'Dell

parkerm

Guys,

This has been a great discussion and has helped me clarify what to do with the rear end of my car. Thanks to those that spoke about the different swaps of rear ends your information was very helpful. Thanks to Jon for the really clear explanation of the operations of an Overdrive. Jay I wasn't being trying to be an ;dlfkhole when I chided you about offering to buy the OD. I appreciate your comments too. Your information helped me understand the value of switching to an overdrive.

Thanks to all,

Marvin

46HudsonPU

Marvin,

There is a lot to take into consideration.  Between the mods needed to fit the OD trans in (Electrical, driveshaft, possible cutting/mod of the frame), it ends up being about equal-to or a bit more difficult to do the OD as opposed to exchanging out the rear.

The OD effectively doubles your choices as far as gearing (minus reverse, as the OD must be locked-out(?)), while also expanding the gear range - lessening the RPM to achieve greater speed, much more than the exchanging the rear.

Exchanging the rear end is a much more simplistic approach - No change in shifting patterns, no electrical modifications, etc..  The three-speed trans is still there, although (depending on gearing), you probably won't be pulling-up any more stumps with 1st gear.  Do the math (trans, rear, tires) to figure out the RPM needed for the MPH you want to achieve on the road...