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gear ratio
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army_inc
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PostPosted: Fri Nov 30, 2012 10:35 pm    Post subject: gear ratio Reply with quote

Hey guys,
I was looking at my axles and the gear ratio's are 4.27. I was wondering if this would really affect my A1 after I had it restored. I know the original is 5.38 and my axles are not that. I'm rebuilding my axles now so since they were off I figured I would ask. I don't think this would be a problem, but I'm no expert. Thanks.
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wesk
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PostPosted: Sat Dec 01, 2012 2:04 am    Post subject: Reply with quote

It will force you to downshift on most all uphill grades and load the engine up. My guess is at some time your jeep had a Dauntless V6 in it or someone was hurting for axles and took what he could get cheap. I would look for the correct 5:38's.

Are the 4:27's posi?
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army_inc
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PostPosted: Sat Dec 01, 2012 7:49 am    Post subject: Reply with quote

Being in Virginia by Richmond, there aren't many big hills. Do you mean ALL uphill grades though? It was a USMC A1 so I'm not sure if it was the original axle with a diff upgrade or not. How can you tell if they are posi?
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wesk
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PostPosted: Sat Dec 01, 2012 10:05 am    Post subject: Reply with quote

Yes any long uphill grade greater than about 6%.

Put the transfer in neutral. Jack a rear tire off the ground and try to rotate it. If you meet a lot of resistance it will be a posi. Or jack both rear wheels off the ground and if when turning one the other turns the same way it's a posi. Posi's also have a metal tag on the pumpkin cover bolts that says "Use limited slip diff. lube only" or a metal tag with a "T".

USMC Contracts after about 1962 called for the Jeep Powr-Lok limited slip axles.
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Wes K
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army_inc
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PostPosted: Sat Dec 01, 2012 4:13 pm    Post subject: Reply with quote

well crap. I just don't have the $ right now to change the differentials... Well I guess my question now is would I be ok on the mostly flat Virginia roads? Would a bridge pose a problem?

THe A1 used to have a chevy small block v8 when I bought it so that could be why it has the 4.27's in it. How bad does "Loading" the engine affect/hurt the engine?

As for the posi. I haven't seen a tag saying "Use limited Slip Diff. Lube only" or a metal tag with a "T". Both axles are off of the frame so as for turning it... it's a little hard at the moment but I'll give it a shot later tonight.
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PostPosted: Sat Dec 01, 2012 8:06 pm    Post subject: Reply with quote

If you do what you are suppose to do when the engine engine starts to load up in high gear and downshift then there will not be any harm to the engine. The problem comes with operating in heavy fast moving traffic. IE if you start up a 2 mile long 6% uphill grade at say 50 MPH by the time you have gone a 1/2 mile you will have been forced to downshift to 2nd and the best you can do in 2nd is about 35 to 40 MPH. Now if that grade is on a heavily traveled 65 MPH highway you will be pissing a lot of folks off and at a severe risk of getting rear ended by someone banging out a text message. Wink

The small block Chevy was certainly a good reason for the prior owner to raise the gear ratio.

If stock is not your goal I would find a 90 Deg Chevy V6 and drop her in with all the adapters already installed for the small block V8 and enjoy some really pleasant cruises in a sharp OD Green M38A1!
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Wes K
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army_inc
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PostPosted: Sat Dec 01, 2012 9:00 pm    Post subject: Reply with quote

Stock is more my goal at this point in time. I'd like to take her to local car shows and such. Plus, I've got the manuals and everything for it so it's easier for me to work on as it's my first resto and really car work/maintenance. I don't plan on driving it past 55 MPH just because I didn't think it could really go faster than that without feeling uncomfortable. So basically what you are telling me Wes is that when I hit pretty much any kind of uphill grade to downshift and load the engine? I can do this until something else has to be replaced if that is what it takes. I'd like to take it back to the original 5.38 but my wife and $ are the contributing factors to keeping it at 4.27 for the moment.
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PostPosted: Sat Dec 01, 2012 9:20 pm    Post subject: Reply with quote

Quote:
So basically what you are telling me Wes is that when I hit pretty much any kind of uphill grade to downshift and load the engine?


Almost, but when you do downshift you are actually UNloading the engine. Which is a good thing. Loading the engine up means trying to make it work harder then it is capable of. If you left it in third the engine would let you know quickly that you have loaded it beyond it's capabilities when it starts loosing power and speed and suddenly you are chugging along at 25 or 30 MPH and black smoke is rolling out the tailpipe.

I drove my A1 to work every day in South Dakota at Rapid City on the Interstate at 55 to 60 MPH during the 1980's. It had stock 5:38 gears and 30" diameter Goodyear Wranglers and a bone stock F134 engine. It took a long 8% or steeper grade to start slowing me down any. Wink
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Wes K
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army_inc
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PostPosted: Sat Dec 01, 2012 9:51 pm    Post subject: Reply with quote

Ok. I think I'm getting this now. So I can keep the 4.27's in there and just unload the engine on long uphill grades? Whenever my Diff's decide to crap the bed, then just change them back to the 5.38's. From what it sounds like, I can also take the A1 up to 60 MPH and have no issues.

I'd love to take my A1 to work and that is my goal eventually. It's about an hour drive on the interstate. Here in VA the speed limit is 70 MPH and the normal cruising speed is anywhere from 75-80 MPH. I probably won't take it on the interstate, but I'll take the scenic route and enjoy every minute of it. The only thing I can think of off the top of my head that I would need to downshift for is a bridge or something like that as I'll soon be working at Langley AF base (flat lands of Hampton and Newport News). Very Happy
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PostPosted: Sat Dec 01, 2012 10:39 pm    Post subject: Reply with quote

Always enjoyed that part of eastern VA. I am originally from NJ.

To be really comfortable and feel safe with the jeep in that kind of traffic will dictate several important considerations.

1-First and foremost she has to stop quickly and reliably every time! Hitting a mom and a 3 year old daughter as they step off the curb in Langley because you had to spend a few seconds pumping the pedal is really dumb. Fix em right the first time. Use the darn free book as well. I strongly recommend a dual reservoir master cylinder kit. The 9" brakes are very reliable when properly rebuilt and adjusted.

2-She has to go where you point her! Steering is no place to pinch dimes. Use the free book again and do it right the first time.

3-See and be seen! Lighting is very important. These jeeps were designed for use back when no one was talking or texting on their cell phones and when the streets were only half as crowded as they are now. Sort out your electrical right away and decide 12 or 24 volts. Then get started making all the lights work. Then find a friend with a stock lamped M38 or M38A1 and follow him around town for a half hour in traffic. Notice how hard it is to see his stock service drive lamps? Imagine that civilian who has no idea what those little pip squeak lamps are for or how they work rolling up on your butt at the corner where you are slowing to turn and wagging your arm as if to a friend on the corner. Whammo! The cure are full red circle lenses on both rear light assemblies. Also using a left light assembly on the right side so you have two red service brake lights in back instead of one. Now add turn signals. There are two 24 volt GI systems you can use and many civvy units that also are easily adapted. The front marker lamps can be upgraded with full circle amber lenses and dual filament lamps so they can be both parking lamps and turn signals.

4-Finally, get a horn they can hear before you hit them!

On another note check with your insurance company. Depending on what type plates you hang on your jeep they may not cover you doing daily driving with it.
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Wes K
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army_inc
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PostPosted: Sun Dec 02, 2012 8:46 am    Post subject: Reply with quote

I like this part of VA as well. I was born and raised here. I've been to Michigan, Chicago, New Mexico, Texas (deployment ruined that state for me though... North fort hood is no fun), and a few other states. I happen to like VA the best though, but the other states have their good qualities as well.

To answer your bullets:
1: I'm currently replacing EVERYTHING in the brakes. New lines, shoes, pads, cylinders... everything. It will all be brand new. I appreciate the heads up on the dual reservoir master cyclinder. Where can that be purchased? I'm also using the free book that was downloaded Smile I really don't want to hit MAJ Mom and Airmen Junior Sad

2: I plan on rebuilding the steering gear to make sure everything is as it should be. Using the Free book as well. I think as of right now, my steering gear is in pretty good shape as it steered ok until I pulled it off of the frame Laughing But with a rebuilt steering gear, as well as newly rebuilt tie rods and things, I think I will be ok.

3: See and be seen. I've thought about this. I wouldn't really drive it at night just because of the low lighting SOP for the A1. This would basically be driven during the summer months when it is light pretty much the entire time I'd be driving. I would like to have a 24V system with the original lights so I can still take it to car shows (More explination on this in the bullet 5). While driving though, I do plan on getting a colored blinking light (they sell them on base for runners and bikers) and I would attach it to the rear. With that, traffic behind me will be able to know I'm there wihtout having to squint their eyes to see my small lights. I know you can't fix stupid and I'm sure someone will still comment on it.

4: I do plan on getting this. It's never a bad idea to have a horn Wink

5: Insurance. The insurance company that I spoke with said I can put antique tags on it and only drive it for a few reasons. THese reasons are:
Vehicle maintenance drives
To and from car shows
pleasure drives (this is limited to weekends I believe)
To and from group events (MVPA or other Vehicles organization)

6: It wouldn't be a daily driver. I would just pull it out once in a while and take it to work to make sure everything is working just fine. If I didn't drive it to work, I would just drive it around my town. I won't drive to work in the beginning because I need to get used to the vehicle and make sure my mechanic skills did ok before the longer drives. I wouldn't want to drive it to work the first day only to realize I messed up on the *insert major problem here.*

I researched my scenic route and I'd basically be on a road that is 55 MPH or slower (once you hit Yorktown/Newport News area). THere is one bridge (York River Bridge) that I would have to downshift for so I don't load the engine and maybe a few small hills (maybe 3). Other than that, the road is pretty flat. So for small hills with a high grade, would I be ok in 3rd as long as they are small hills. Since I'm on the question, what is the definition of a small hill for this engine? What I consider a mountain in VA is considered a hill in Colorado Laughing
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PostPosted: Sun Dec 02, 2012 12:02 pm    Post subject: Reply with quote

For describing road conditions that effect performance I have used the grade system above. 6% would have an increase of height equal to 6% over any distance. Or as a ratio about one foot rise for every 16 feet traveled. I don't try to describe slope grades by the terms "small hill" vs "big hill". There are no real values expressed by these terms. A small hill could be a short distance but sharp upward climb or a long distance and slight uphill climb. Use the chart below to learn what grades are and how to determine what slope or grade you are facing.
http://www.1728.org/gradient.htm



Get used to the sound of your jeeps engine rolling on flat terrain at 50 MPH then go find a hill and listen to the sudden change in engine noise. Compare the rate of that noise change to the loss of speed rate you see on the speedometer. This will teach you when it is time to downshift. Or ride with someone who has already learned this a few times. I have listened to folks unfamiliar with standard transmissions start rolling up a hill and loosing power with the speed dropping and the engine starting to ping and they simply sit there and do nothing accept push harder on the gas pedal which does nothing but increase the pinging or detonation inside the cylinders until eventually they burn holes in the top of their pistons and destroy their clutches. Learn the right way. Also the state highway departs usually post slopes/grades warning signs with the percentage right on them for truckers. Generally 6 to 8 % are the limit for the stock jeep with 5:38 gears to continue uphil in third gear. Your higher gears will lower that figure slightly.

It was your statement above that prompted my cautions:
Quote:
I'd love to take my A1 to work and that is my goal eventually. It's about an hour drive on the interstate. Here in VA the speed limit is 70 MPH and the normal cruising speed is anywhere from 75-80 MPH. I probably won't take it on the interstate, but I'll take the scenic route and enjoy every minute of it.


That small 1" high by 2.5" wide red lens on the left rear lamp is more useless in the daylight then it is at night. It is even harder for the untrained eye behind you to see it in bright daylight. You can make the simple lens change and increase your visibilty to the rear in daylight when stopping 400%. It a simple screw on screw off proposition and you can carry the original lens for the shows in your glove box.


With the stock rear lamps and your light switch in the service drive position where it should be when driving on public roads the red lamp displayed to the rear is the left small oval unit which is in the top left of this photo. By installing a second left unit on the right side you double your red light visible to the rear.


By installing these Gama Goat lens you increase your visibility to the rear day or night by over 400%.

The key here is to base your decisions on road safety not only based on your driving skills level but the perceived driving skills level of those folks you share the road with. When modern cars hit the brakes in front of you, you are seeing about 2 square feet of red lighted lens that is lit up by 5 bulbs. The people behind you are maybe going to see all 2 square inches of your red lens lit up by a single bulb! Wink

Dual master cylinders were installed by jeep on the 68 to 71 CJ5's under the floor in the same spot as your single master cylinder. So you can buy this cylinder and adapt it to your frame mount or you can buy a kit from Herb the Overdrive Guy. http://hermtheoverdriveguy.com/
http://hermtheoverdriveguy.com/?page_id=826



Keep in mind if you are not using new brake drums then you must compensate for the bigger inside diameter of the used or turned drums by shimming the brake shoe linings or using oversized shoes. If you don't you will loose up to 1/3 of your braking ability due to incomplete drum contact of the shoes.
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Wes K
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PostPosted: Sun Dec 02, 2012 3:31 pm    Post subject: Reply with quote

Back to gear ratios here's a handy web site for computing road speeds based on gearing.

http://www.public.asu.edu/~grover/willys/speed.html[/quote]
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Wes K
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army_inc
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PostPosted: Sun Dec 02, 2012 6:21 pm    Post subject: Reply with quote

THat's a lot of good information Wes. I didn't know I could just change the door but it makes sense now that I think about it. I will definately just use two left hand rear lights and change the doors when I go to a Show or what not.h Could I also do the same thing with the front black out lights? I have the turn signal doors, but not the B/O doors. I found out that the turn signal doors come right off while I was taking apart the A1. Wasn't sure, but am only assuming that the front bo lights will do the same thing.

Also, just by chance to not have to start a new thread, you don't happen to know what size the front spindle nut is would you? I've tried a 2 5/8 and a 2 3/5 (not much difference in size I know, but that is all that was available) and can't seem to find one that'll work for me. Do I have to special order a spindle nut remover?
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PostPosted: Sun Dec 02, 2012 7:02 pm    Post subject: Reply with quote

The decision to start a new thread is up to you. A minor straying from the original topic for a couple of posts is not a big deal.

The front spindle (or hub) nuts generally use the special socket that is deep enough and thin enough. You can usually find the correct one at your local auto parts store.

You really shouuld peruse my photo album. There are hundreds of photos there that answer 80% of the new guy questions that normally come up.

http://www.willysmjeeps.com/v2/modules.php?set_albumName=Wes-Knettle&op=modload&name=gallery&file=index&include=view_album.php&page=1

That's the actual measured distance from flat to opposite flat.
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Wes K
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