So Here Is What I would Like To Know

[ruger92]

I bought this jeep a few years back in the fall of the year, brought it home and put it for the winter because it only had a bikini top on it. Well summer finally come and I got it out drove it a few times and the motor locked up. So back the shed it went until I had the funds to fix it and here is what was done to it.

The jeep has a AMC 304 motor that is newly rebuilt has around 500 miles on the new motor, it was bored out at 30 over, small cam, new 2bbl carb, headers, exhust pipes coming out the side new starter, plugs, plug wires and so on.

It has a 3 speed manual tranmission (here is the problem) this thing runs so tight in 3rd gear that I'm afaird I'm going to blow a freeze plug out of it. The fastest I have ever had it was about 60 mph and she she was running tight. It sounds like I need another gear to shift into, but I don't have one.

Would it help to replace the 3 speed Transmission with a 4 speed Transmission and if I do that will that help it from winding so tight going down the road.

Any and all replies are welcome and let me thank you all in advance for helping me out.

Thanks
Ruger

 

[TroyaCantrell]

Hey Ruger92,

Couple that would help get better advice is more info on what you are running.

What size tires?
What gear ratio are you running?
What Transmission ?
What T-case?
Any other Mods?

All these things can impact the Transmission of RPMs of the engine to the speed you are traveling and the RPMs of the tires at those speeds. They also impact power applied (torque) as well. While a new Transmission mission might be in order it might be as simple as changing the gearing in the diff. There is a big difference if you are running 4.11 with 44" tires or a 3.73 with 28" tires.

This little tool can help too. http://www.ramblerman.com/blazer/gearcalc.htm

 

[ruger92]

Hey Ruger92,

Couple that would help get better advice is more info on what you are running.

What size tires?
What gear ratio are you running?
What Transmission ?
What T-case?
Any other Mods?

All these things can impact the Transmission of RPMs of the engine to the speed you are traveling and the RPMs of the tires at those speeds. They also impact power applied (torque) as well. While a new Transmission mission might be in order it might be as simple as changing the gearing in the diff. There is a big difference if you are running 4.11 with 44" tires or a 3.73 with 28" tires.

This little tool can help too. Tire/Gear Calculator

I know where I can find the trie size, how do I go about finding out about the rest, I think when I had the Transmission rebuilt the guy said it was a T-90 does that sound right

 

[mylittlecj5]

It doesn't matter if you replace the 3 speed with a 4 speed, it won't change the top gear ratio of 1:1. You would have to replace the 3 speed with a 5 speed, or install an Overdrive to change your top gear ratios.
Larger tires would help (not very much unless you go with very large tires), but depending on what gears you have now, repacing your differerential gears is your best bet. But (and there is always a but) there are trade-offs here a well.
The cost involved, future plans for larger tires, budget, other "I might a well's", ect. all need to be considered when doing a gear change.
And the biggest thing to consider is that it is a JEEP, not a sports car. For many reasons, 60 MPH is a really good speed for a Short Wheelbase Jeep. They are NOT meant to be a hiway machine, but a back country explorer. If your front end and steering is not absolutely perfect, you may find the Jeep to be a real handful even at 60. 70 may be downright scarey! lol Not to say it can't be done, My personal CJ5 has hit 80+ (verified by GPS since the speedo doesn't work) and was stable enough to go hands-free just for a second. I have driven others that I wouldn't keep 40MPH in...

 

[mylittlecj5]

I know where I can find the trie size, how do I go about finding out about the rest, I think when I had the Transmission rebuilt the guy said it was a T-90 does that sound right

If your Transmission guy says it has a T-90 in it, I'd run away from him as fast as possible. Those haven't been used in a JEEP since around the early '70s. maybe sooner.

Look here for info on identifying your drivetrain, as well as good advise on what you do have.
NOVAK Knowledge base gateway

do your research, then let us know what you have, so we can continue to help you build your JEEP the way you want it.

 

[ruger92]

If your Transmission guy says it has a T-90 in it, I'd run away from him as fast as possible. Those haven't been used in a JEEP since around the early '70s. maybe sooner.

Look here for info on identifying your drivetrain, as well as good advise on what you do have.
NOVAK Knowledge base gateway

do your research, then let us know what you have, so we can continue to help you build your JEEP the way you want it.

Ok guy's thanks for the help, this website is GREAT here is what I have found out so far by reading and looking at the pictures

Transmission T-150
Transfer Case Dana Spicer Model 20
Gear Ratios
1st Gear 2.99
2nd Gear 1.75
3rd Gear 1.0
Reverse 3.17
Transfer Case Ratio
High Range 1:1
Low Range 2.0
Rear End Gear 3.54

And you are right jeeps are not a sports car, my main concern was putting that much stress on the motor going down the road, the places that my wife and I like to ride to are 25 to 30 miles from where we live they are mainly 2 lane roads until we get to the mountains or state campgrounds. I just want someones input on the way the jeeps run's. It run's like a top and surely has the power. My wife has cancer and our weekly jeep rides kinda takes the stress away that we both feel. You guy's have been a hugh help, but I think I will stay with the 3 speed and drive a little slower..lol.....:us::us:

 

[mylittlecj5]

this will sound stupid, but I'm gunna ask anyways...If the engine is wound up so tight at 60 mph with 3:54 gears, are you sure that the Transfer Case is in high range?

 

[Old Dog]

How did you determan that you had 3:54 gears?
If thats what you have the engine should NOT be wound tight at 60.
Do you have a tack to see what rpm's you are really doing.

 

[Incommando]

Stock ratio may have been 3.54 but that was 35 years ago. Unless someone has swapped 12" tires on it the engine should not be "tight" at that speed. As "tight" is a very subjective term with no real table for comparison do you have any idea of the actual RPM at 60 mph? Tire size? Actual gear ratio? Or maybe your Transmission guy who doesn't know what Transmission he rebuilt screwed it up.

 

[GatorBate]

At 65 mph my AMC 304 is running about 2300 RPMs. I have 3.31 gears. With your 3.54 you should be about 2500 RPMs at 65. Just to my two cents worth.

 

[ruger92]

yep.....i will write all these questions down and this weekend I will take it for a spin and get back with you guy's

 

[jswatson0917]

At 65 mph my AMC 304 is running about 2300 RPMs. I have 3.31 gears. With your 3.54 you should be about 2500 RPMs at 65. Just to my two cents worth.

If I run 65 with my AMC 304 I will overheat. I have to maintain 60 just to keep the motor cool. I don't have a tach so I cant say what my RPMs are.

 

[Petescj]

What temp thermostat? Do you have a fan shroud? My CJ5 would run all day at 65 -70 with 4.10s and a 360 no overheating.

If I run 65 with my AMC 304 I will overheat. I have to maintain 60 just to keep the motor cool. I don't have a tach so I cant say what my RPMs are.

 

[jswatson0917]

What temp thermostat? Do you have a fan shroud? My CJ5 would run all day at 65 -70 with 4.10s and a 360 no overheating.

i think it is a 195 thermostat. and I don't have a shroud

 

[mtnwhlr]

A shroud makes a big differnce.

 

[ruger92]

Hey guy's sorry I haven't been here in a few days but been busy with Honey Do List, But today I did the beast out and just my luck got caught in a very nasty thunder storm and heavy rain, and yep not top sure got my butt wet and btw the I did notice that I was turning 3000 rpms at 55mph couldn't get much faster the wind was blowing pretty hard and I didn't want to lose control and crash.

 

[Old Dog]

Sounds like you need to pull the diff. cover and see what gears someone put in there.

 

[Kilo19]

what about adding a fan shroud first and see if that helps.

 

[Petescj]

i think it is a 195 thermostat. and I don't have a shroud

Get a shroud. Your engine will appreciate it.

Hey guy's sorry I haven't been here in a few days but been busy with Honey Do List, But today I did the beast out and just my luck got caught in a very nasty thunder storm and heavy rain, and yep not top sure got my butt wet and btw the I did notice that I was turning 3000 rpms at 55mph couldn't get much faster the wind was blowing pretty hard and I didn't want to lose control and crash.

At first I thought You had it in low range like mentioned before but its time to pull the diff cover and start counting teeth. Who knows when the last time your fluid was replaced anyway.

 

[72rtchallenger]

get a shroud for sure and if its a clutch fan check that too,,and it does sound like your gears are not stock , count the teeth and some may even have the ratio stamped on the side of the ring gear