Eagle

4.10s with 31" tires is perfect. 31" tires with 3.73 gears is exactly the same as 3.54 gears with stock tires, so 4.10s is only a small step more in gearing that stock when you run 31" tires. Check the ratio on that AMC 20. A lot of the 2.8L trucks and XJs had 3.73 gears.

Does your MJ have gauges, or idiot lights? If you have idiot lights, is the ALT light on when this GEN light is on? If you have gauges, what does the voltage meter show when running? I've never heard of a GEN light in an XJ or MJ, and I don't have a '91 vintage FSM to look at the layout of that auxiliary light panel. I'm half tempted to suggest removing the bulb from that space and forgetting about it.

What make and model vehicle are we talking about? "GEN" refers to generator, and the MJ doesn't have a generator. Where is this light?

Nope. The 2000 XJ uses coil-on-rail ignition. The '88 XJ head doesn't have the bosses to mount the coil rail to. And then, of course, there's the issue of ports not being the same size, shape, or height.

If the expected resistance is around 100 ohms, why are you using the 20,000 ohms range? Don't you have a 0-2,000 or 0-200 ohms range?

What's your stock tire size? And how fast will you be driving? Just go to the spreadsheet I provided a link to above. Let's assume your stock tire size is 215/75-15. Go up to the top of the sheet, to the section for 215/75-15 tires. Go all the way to the right, to the two columns under the 4.88 axle ratio. You don't have a 5-speed, so ignore the "O.D." column. Your 4th gear is a 1:1 ratio, so just read down that column to find the RPM for various road speeds. If you do that, you'll see that 60 MPH is about 3600 RPM. That's about the same RPM as 80+ MPH with your stock gears. It won't kill you engine, but I wouldn't drive very far or very often much faster than that. Here's my frame of reference. Both the 2.5L and 4.0L MJ engines are descendants of the 232 c.i.d. (3.8L) engine that AMC introduced in 1964. We've had several of them in my family, all mated to three-speed manual transmissions. The 3-speed also had a 1:1 top gear, so the setup is directly comparble to your MJ. They were all geared so that they ran 24 MPH per 1,000 RPM. That meant that 60 MPH was exactly 2,500 RPM, and 3,000 RPM gave us a 72 MPH cruise. 2,500 was sort of the sweet spot for getting the best fuel economy, but they weren't bad right up to 3,000 RPM. Above 3,000 RPM the fuel mileage fell off quickly. At a 3,000 RPM cruise, the engines lasted forever. My brother and his wife had a Gremlin that they drove more than 200,000 miles, then they sold it to an auto parts store where it was used as a delivery vehicle for another 120,000 before we lost track of it. The torque peak is closer to 3,000 RPM than it is even to 3,600, but you're probably okay up to around 60 MPH.

IMHO a 5th gear will be wasted. You'll only be able to use it at freeway speeds, downhill with a tailwind. 60 MPH in 5th will be less than 2200 RPM. The [fuel injected] 2.5L made 117 horsepower at 5,000 RPM and 135 foot-pounds of torque at 3,500 RPM when it was introduced in the 1986 model year. This was raised to 121 horsepower at 5,250 RPM and 141 foot-pounds of torque at 3,250 RPM for model years 1987 through 1990. With 35-inch tires, even with 4.88 gears you would be running FAR below the torque and horsepower peaks in 5th gear, and I don't think the 2.5L engine will enjoy that. The graph below is for the later MPFI version. The throttle body numbers are worse, but the overall shape of the curves is similar. I'm still looking for a graph of the earlier version.

Any monoleaf spring is non-progressive. Leaf spring packs can be made progressive by using slightly different arches for the leaves, such that initially only one leaf carries the load, then as load is added the deflection starts to pick up additional leaves. The extreme example is the overload leaf in an MJ pack.

Refer to my spreadsheet -- it goes up to 35-inch tires. For an AX-4, just ignore the OD column (that's fifth gear for the 5-speeds) and use the "1:1" column (that's 4th gear for the AX-4). https://docs.google.com/spreadsheets/d/1pHFuhGgj6dQDfzyfFJH5z7NCDLW2KX3ABQgAJr3lBvM/pub?hl=en&hl=en&output=html With 35s and 4.88 gears, 60 MPH is 2923 RPM. 70 MPH is 3410 RPM. Scroll up to one of the stock tire sizes (215/75-15) with 3.55 gears (which was the stock ratio behind the AX-4)and you get 2669 RPM at 60 MPH and 3114 RPM at 70 MPH. So with the 4.88s and 35" tires your RPMs will actually be slightly less than the stock setup -- which means the engine will work a little harder, but you don't have to worry about over-revving it.

That makes sense.

Fibreglass -- I don't trust it. I've owned two fiberglass sailboats and a fiberglass canoe. I have the surviving half of a fiberglass extension ladder, and the top rung has partially pulled out and isn't safe to support any weight. There's no way I'd put fiberglass in place of steel springs.

So what's going to control the relay? Wouldn't it be easier to accomplish the same thing just by running a larger wire to the input side of the switch?

How will adding a relay ahead of the switch reduce the current flowing through the switch?

What did you put in? All the front shocks I can remember installing came with new hardware. When I have reused older shocks on "lower grade" XJs or MJs I generally replace the bolts with new anyway, as a preventive measure, and I use abundant amounts of anti-sieze on the threads.

What year MJ are we discussing? The wiring diagrams above are for the 1997-2001 XJ. The older XJs and MJs didn't put the resistor pack in the ground leg, downstream of the blower motor. It was upstream, on the supply side, and the blower motor connected directly to ground. I suppose you could put a single relay between the resistor pack and the blower motor input, but then the heater switch would still be carrying the load of the resistor pack. Putting multiple relays upstream of the resistor pack takes all significant load off the blower switch -- all it would be carrying is the load of a single relay control side.

If you want to use relays, you will need four relays. In essence, there are four circuits feeding the blower motor. They go through a multi-position switch, but each position represents a separate circuit. Three of the four go through resistors, the high-speed position skips the resistors and delivers the full system voltage to the blower motor. To wire it with relays, you will need four relays, each with a fused lead to a 12-volt power source that's fed through the ignition switch. The output from each relay will then go to one of the four circuits feeding the blower motor -- three to the resistor inputs, and one directly to the blower motor. The outputs from the four positions on the dash switch will be wired to the control side of each relay.

But this thread is about the NVG3550, which is a 5-speed. And which has less overdrive than the BA 10/5 or the AX-15.

So?

If you have a 1988 Comanche, you do not have an AX-15 (unless it was swapped in by someone). The '88s used the Peugeot BA 10/5 transmission (with the 4.0L) or the AX-5 (with the 2.5L).

Not to belabor the obvious (although that IS my function in life) ... if you knew you were looking for an instrument voltage regulator, why did you post a question about a relay? We're mostly pretty friendly and helpful folks around this forum, but most of us aren't mind readers. I once tried to be one, but I sure didn't pick up "voltage regulator" when I read "relay."

Meanwhile: https://docs.google.com/spreadsheets/d/1pHFuhGgj6dQDfzyfFJH5z7NCDLW2KX3ABQgAJr3lBvM/pub?hl=en&hl=en&output=html With 4.10s and 33s, at 60 MPH the engine is only spinning at 1965 RPM. That's not anything to be concerned about.

I've never heard of an instrument cluster relay. What's the source for your information? I believe there is a fuse for the gauges -- have you checked the fuse panel?

Unless I'm missing something, it would seem that the ECU can be eliminated or indicted by simply unplugging the connector from the ECU under the dash, then check the draw again. If there's no draw, the drain must be either in the ECU, or downstream from it. If the draw is still there, there's either a cross connection upstream of the ECU, or the problem is in some circuit that has nothing to do with the ECU.

More than likely you'll have to destroy the bushing and take it out in pieces, then clean up the spring eye and press in a new bushing. You might get lucky and be able to drill out the bolt.

Dynatrac http://www.dynatrac.com/