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I can't drive 55

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Mark W. View Drop Down
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    Posted: 26 Jan. 2019 at 6:05am
In another thread someone showed they are going to put their 2A tub on a Suzuki Samurai chassis. In that thread it was mentioned how neat it will be to have a Flat fender be able to to 75 down the hwy.

I got to wondering what is it about this Samurai that allows it to go 75 mph so I got to looking at some spec.


Engine  displacement   Zuk 1.3L 80cu in              Willys 2.2L 134 cu in
Compression ratio             8.9-1                                 6.48-1
HORSE POWER           60 hp @ 6500 rpm            60@4000 rpm
Torque                          76 ft lbs                             105 ft lbs

OK its clearly not the engine that is the difference as the Willys engine produces the same HP and 25% more torque.

Lets move on to the drive train

The Zuk has a 5 spd gear box with a 20% OD in 5th
The Willys can run a 25 or 30% OD

OK so turning the drive shaft isn't the reason.

Lets look at the rear end ratio

NOW heres a big difference

Zuk       stock 3.73 optional 4.56 and 5.38

Willys  stock 5.38


OH but wait we have to look at the tire size cause that can make a big difference

STOCK TIRES ON A ZUK are P205/70-15" which run about 25-25.5" tall

Stock on a Willys are 700-16 which are 30.5" tall

So by the time we add this all up

Zuk 60 HP 20% OD 3.73 gears 25.5" tires = 2950 rpm at 75mph

Willys 60HP 25% OD 5.38 gears 30.5" tires = 3350rpm

The Willys has to turn 400 rpm faster to go 75 mph. 650 rpm where the rated HP is.

Now for fun lets look at my combo

Willys 60+ HP 30% OD 5.38 gears 29" tall tires. = 3275rpm

The Zuk has way less HP at speed then the Willys since its running at less the half the rpm its HP  is rated at and The Willys is actually pretty close to its rated HP rpm  So lets say it has 2/3's its rated HP at half the rpm its rated at So with 40HP the Zuk can push its brick at 75mph. 

Oh but this all assumes a Willys 134L in good condition will blow itself to pieces if run at these kinds of RPM's Except when you take into consideration the Factory tests that ran an engine off the line at 4000rpm for 100 hours with no problems or appreciable wear.

My point I see no reason a Willys CJ-2A with a sound engine and drive train should not be able to operate at 55-60mph. Yet people constantly tell me 45mph is its limit.

I Know I know Marks at it again.


Edited by Mark W. - 26 Jan. 2019 at 6:08am
Chug A Lug
1948 2A Body Customized
1949 3A W/S
1957 CJ5 Frame Modified
Late 50's 134L 9.25"clutch T90A D18 (1.25") D44/30 flanged E-Locker D25 5.38 Since 1962
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JeepN95YJ View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote JeepN95YJ Quote  Post ReplyReply Direct Link To This Post Posted: 26 Jan. 2019 at 1:39pm
Interesting

I bought my samurai new. 75 is about the max limit stock. I immediately replaced my tires with 30s and still ran 70. It isn't all roses, however.  If I had a headwind my speed was limited to however strong the wind was.  Just like an airplane, lol. 20 mph headwind almost equaled 50mph top speed. 

Speed is also highly dependent on grade.  Hills were always actively managed. Speed up on the way down, wind it out and downshift on the way up. My favorite speed control measure was drafting tractor trailers.  Get up in the pocket and comfortably cruise for miles. Get greedy, however, and think you could pass? Try it! As soon as you whip out into the air stream it was like opening a parachute. 

Driving a samurai is an active experience!

Good times!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote JeepN95YJ Quote  Post ReplyReply Direct Link To This Post Posted: 26 Jan. 2019 at 1:47pm
My samurai also had a stock, computer-controlled carburetor. I believe it had a defect from early on in ownership. The reason I believe this is because sometimes I could drive it without any of the above hi jinks. It would run so well it felt like the secondary's on a four barrel carb were opening.

The stock carb did actually have a small 2-barrel primary and secondary but mine didn't work more often than not.  The fuel economy and side-hill-ability were excellent, though.

I will run either a CV Harley Carb or the 3k Toyota carb on this one to eliminate the computer control all together.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 3-48s Quote  Post ReplyReply Direct Link To This Post Posted: 26 Jan. 2019 at 2:21pm
I have owned both and 75 in my 1988 Zuk was a bit scary to say the least.
I think 45-55 in either is all anyone should expect or do as one small oops and you are a bug on the bumper of the big rigs out there. IMHO slow and steady is a better & safer way to operate the stock versions of these little guys!
If you want to go fast get a Corvette or something more highway appropriate.
I'm just saying.

P.S. Or you can modify your WILLYS like Jpet did to Bam Bam and go anywhere, fast or slow!

Edited by 3-48s - 26 Jan. 2019 at 2:25pm
1945 CJ2A #10536
1948 CJ2A #176528 "Elmer"
1948 CJ2A #155970 "Gray Mule"
1948 CJ2A #155365 "Old Yeller" (GONE)
BANTAM T3C # 6147 (GONE)
BANTAM T3C # 30856
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Post Options Post Options   Thanks (0) Thanks(0)   Quote athawk11 Quote  Post ReplyReply Direct Link To This Post Posted: 26 Jan. 2019 at 2:40pm
Another factor to consider is the weight difference between the two vehicles.

I'm with 3-48s.  Regardless of how fast I can push my Willys Jeeps, the suspension and steering design limits my comfort when at higher speeds.  Maybe I'm just getting old...and don't feel bulletproof anymore.
1- 1946 CJ2A   
2- 1949 CJ3A
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Unkamonkey Quote  Post ReplyReply Direct Link To This Post Posted: 26 Jan. 2019 at 2:49pm
Not sure if I should add this but a Buick V6 is a lot easier to do and all the parts are less expensive. Both of my Jeeps run a 225 and will do over 80 MPH. I don't know what my MB with a 198 V6 would do as it just ran out of speedo and I never got clocked.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Craig M Quote  Post ReplyReply Direct Link To This Post Posted: 26 Jan. 2019 at 5:28pm
Along with your thoughts here is another idea take a stock L134 get the HP up to 70 with minor mods.
install 4.27 axle ratios to eliminate a little driveline drag from the OD add lockouts to the front to eliminate even more driveline drag. Speed with 29.5" tires at 2700 RPM would be 55, and I think the engine will pull the load just fine and if you want to go 60 your RPM would be 2925 then the argument is the LO side gears at 2700 RPM your speed would be 8 MPH instead of 6 MPH with no OD and 5.38 ratio at the same RPM and LO range HI gear would be 23 MPH verse 18 so if you want a better on road vehicle with good of road ability this would be my solution. Experience has taught me it is easer to speed up to the end than to go over and come back down to get the same result. 
Snojet slice & dice on the ice
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Mark W. Quote  Post ReplyReply Direct Link To This Post Posted: 26 Jan. 2019 at 5:46pm
Well the combo I am going to be running.

rear end 5.38
OD 30%
Tires 29"

55mph = 2400 rpm

60mph = 2620 rpm

As my engine is computer spin balanced from Crank Pulley to Pressure plate I should be running just fine at that rpm all day long.

As to will I have enough power to pull some hill at speed, Don't know I am working diligently at increasing my available power.
Chug A Lug
1948 2A Body Customized
1949 3A W/S
1957 CJ5 Frame Modified
Late 50's 134L 9.25"clutch T90A D18 (1.25") D44/30 flanged E-Locker D25 5.38 Since 1962
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Craig M Quote  Post ReplyReply Direct Link To This Post Posted: 26 Jan. 2019 at 7:58pm
posted to the wrong discussion should pull good
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Post Options Post Options   Thanks (1) Thanks(1)   Quote Nothing Special Quote  Post ReplyReply Direct Link To This Post Posted: 26 Jan. 2019 at 8:58pm
I'm just a wannabe, I haven't driven an old Willys.  But I think a lot of the time the limiting factor for speed has nothing to with anything you've mentioned.  And sometimes they aren't really the limiting factor people think they are.

Back when I had my CJ5 (258, close ratio T-18 4 speed, 4.27 gears, 29" tires, soft top) I felt like 50 mph (2475 rpm) was a reasonable limit and 60 mph (2970) was the max.  But one time I was following someone and I had no idea where we were going, so I needed to keep up and he was going 80 (3960 rpm for me).  I kept up with him for close to 1/2 hour like that, but my ears were ringing from the noise and my neck and shoulders were knotted up from trying to keep it in my lane.

So could it go 80?  Sure.  Should it?  As it was at that point at least, I don't think so.  Maybe some maintenance would've made it track better, and a hard top wouldn't have been as loud (actually it was quieter with the top down on the freeway).  Your plans with Chug should address a lot of that too.
Bob

Flatfender wannabe
'71 Ford Bronco
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Mark W. View Drop Down
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Post Options Post Options   Thanks (1) Thanks(1)   Quote Mark W. Quote  Post ReplyReply Direct Link To This Post Posted: 26 Jan. 2019 at 10:00pm
All I want to do is cruise non Freeway roads at a normal traffic speed. Around here that 55-60 granted some of the trips I have planned it would be hard to avoid a bunch of freeway driving. But then here in Oregon Truck speed is 60 auto is 65. SO the right lane I should be just fine at 55-60. I ready know how fast it will go (I assure you in High school and the summer right afterI found every limit CHUG had. From How fast to how far you can lean it over on its side before the guy sitting in the pass seat will fall on you when he undoes his seatbelt. To how steep it can go up a hill before the front tires start lifting and you have to put the clutch in to keep from going over backwards. heck I even know you can jam 4 guys and 2 girls into one with the top on without two much cussing about he's touching me.




Edited by Mark W. - 27 Jan. 2019 at 12:36am
Chug A Lug
1948 2A Body Customized
1949 3A W/S
1957 CJ5 Frame Modified
Late 50's 134L 9.25"clutch T90A D18 (1.25") D44/30 flanged E-Locker D25 5.38 Since 1962
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