'98 TJ Questions

[blake23]

Hey! I've recently picked up a '98 TJ. I'm probably going to have a bunch of questions so thought id just stick them all in one place rather than starting a bunch of new threads.....

Mods already done to the TJ are:
- Rancho 2.5" lift kit including trans spacers (Which I've measured closer to 3" but maybe my measurements were wrong)
- 33" tyres
- Front and rear steel bumpers
- Winch
- Steering dampener

I've noticed 1 thing that doesn't seem right to me but maybe its the nature of a lifted jeep
- Shudder when taking off in 1st and up to 6-10mph. I've read a heap on this and my conclusion is that I may need a new flywheel.... But I'm also not sure if it could be pinion angle or control arm bushings due to the lift.. There are no other vibrations in any other at all. Doesn't shudder take off in low range either...

How do I go about making sure the 4wd system is working properly? Is there anything I should do or check to make sure its working right?

Thanks!
Blake

 

[Steel City 06]

What RPM do you hold when using the clutch when starting? With my 2006 if I let it drop below around 1200 it doesn't sound as happy.

Also, 4cyl or 6cyl?

As for the 4wd, find a local gravel lot and simply shift through all 4 settings. 4hi/2hi can be shifted while moving in a straight line. I like to hold in the clutch while shifting between 2hi/4hi just to keep pressure off the transfer case. It's not necessary, though.

Shifting into 4low should be done at a very slow speed in neutral or with the clutch in. You usually can shift into 4low while stopped, but not always

 

[blake23]

6 cylinder..

If my RPM is below 1000 and i take off 'normally' it shudders pretty bad, if i take off at 1500rpm and ride the clutch it doesn't do it anywhere near as bad.

I will give it a go in a gravel carpark.. is there anything in particular i should look out for? Noises, shudders, anything like that?

 

[Steel City 06]

Don't be too worried about the clutch. The clutches on these are pretty stout. I always keep my RPM over 1000, usually over 1,200. sometimes over 1500 when starting. If I really want to launch I'll keep it around 2000 in 2nd gear.

One of my lazy ways to start is to rev the engine to about 15-1600 and then use the clutch with increasing pressure to drop the RPMs to like 1200, while at the same time increasing throttle.

I usually start from 2nd gear, but depending upon your gear ratio, transmission ratio, and tire size, it may not be the best option for all jeeps.

The shift from 2hi to 4hi and back should be pretty smooth. A clunk or two when shifting is normal. You'll feel the drivetrain bind and skip a bit when turning. This is normal for any 4WD vehicle. (AWD does not do that.)

Shifting into neutral shouldn't be too difficult, and may have a clunk or two. Shifting into 4low can be a bit tricky if you're not moving. If that happens, move forward or backwards just slightly to get the gears to mesh. The transfer case is like an unsynchronized transmission. The gears have to line up or they won't mesh. Attempting to shift at any significant speed will cause grinding.

If you have any of the following modifications, test them out too:
1. 2Low range kit - unlikely but possible. Gives you 2WD low range between neutral and 4low.
2. Front/rear lockers - engage and try to make a tight turn on gravel. You'll feel the tires skip and hop, and you'll have to power through the turn.

 

[89grand]

It may very well be your driveshaft angle is too steep. You didn't say whether it had a t-case drop, or a SYE.

Does it get worse the faster you take off from a stop?

 

[blake23]

Thanks Steel City... I shall see how i go with the 4wd system stuff!

I do have spacers between the skid plate and the body (This is the TC drop isn't it?) and no SYE... I though it could be the driveshaft angle as It looks not right but I've been known to be wrong about these things.. Does the pinion angle vibrate and shudder on acceleration from a complete stop only or would it have vibrations no matter what speed or gear I'm in? I've checked my control arm bushings and they look to have been replaced recently. Looking at this photo it doesn't look quite right..

 

[89grand]

I need a SYE, and even though I have a t-case drop, and it sounds like you do too, I still get vibes pretty good if I accelerate too hard from a stop. I don't have serious vibes otherwise, but I still do even at speed at times.

I'm lifted a little higher than you, so mine may be worse than yours.

 

[blake23]

Yeh right... So a SYE would probably be an upgrade worth looking at or is there other things I can adjust to get it right?

Is it going to do any damage driving it without a SYE? I don't have the funds to be buying a SYE just yet and I need to use the jeep everyday...

 

[89grand]

Yeh right... So a SYE would probably be an upgrade worth looking at or is there other things I can adjust to get it right?

Is it going to do any damage driving it without a SYE? I don't have the funds to be buying a SYE just yet and I need to use the jeep everyday...

I've owned mine for almost 11 years without a SYE and the same lift. Just take off a little easier from a stop.

Some other things can reduce the vibes, like a motor mount lift, but the SYE is the real fix.

 

[astjp2]

Thanks Steel City... I shall see how i go with the 4wd system stuff!

I do have spacers between the skid plate and the body (This is the TC drop isn't it?) and no SYE... I though it could be the driveshaft angle as It looks not right but I've been known to be wrong about these things.. Does the pinion angle vibrate and shudder on acceleration from a complete stop only or would it have vibrations no matter what speed or gear I'm in? I've checked my control arm bushings and they look to have been replaced recently. Looking at this photo it doesn't look quite right..

View attachment 86213

yours needs to look like this, your pinion looks high

 

[blake23]

Ok sounds good. I will be gentle with the poor little thing ha

And here is a photo of my new play toy... And my friends ex Australian military land rover.

 

[blake23]

astjp2 - yeh that image is what made me think it wasn't right

I might save up and get myself a SYE and some adjustable arms to get it all set up correctly

 

[89grand]

That image posted is what it "should" look like, but unfortunately it can't be done as it sits now. The drive shaft is too short, which is why you need a SYE, CV driveshaft (don't forget that), and the adjustable control arms.

 

[blake23]

Hey
Transfer case and front diff etc. all seem to working well!

So I have 3 things that I've been wondering...
- If I only have a slight vibration in first gear from a dead stop can i keep driving it safely? I cant really afford the SYE at the moment but I'm keen to get out and do some 4wd and just don't want to get stranded.. doesn't vibrate at all in 1-2 4LO
- When I parked I noticed a puddle of water under my gearbox area.. It was just water nothing else. So im assuming probably some sort of water draining out of some part of the jeep....
- Before I go out onto the trails what maintenance/vehicle check things should I be doing to make sure everything is working etc.

Sorry for the random questions just been thinking of a few things over the few days

Blake

 

[astjp2]

Hey
Transfer case and front diff etc. all seem to working well!

So I have 3 things that I've been wondering...
- If I only have a slight vibration in first gear from a dead stop can i keep driving it safely? I cant really afford the SYE at the moment but I'm keen to get out and do some 4wd and just don't want to get stranded.. doesn't vibrate at all in 1-2 4LO
- When I parked I noticed a puddle of water under my gearbox area.. It was just water nothing else. So im assuming probably some sort of water draining out of some part of the jeep....
- Before I go out onto the trails what maintenance/vehicle check things should I be doing to make sure everything is working etc.

Sorry for the random questions just been thinking of a few things over the few days

Blake

Good belt and hoses, idler pulleys are in good shape or carry a spare.

 

[blake23]

sounds good! I'll grab some spares just in case...

 

[ac_]

I don't believe that image is correct for a TJ. I think that image so for a leaf sprung Jeep. I am pretty sure you want your rear end pointing to your transfer case. I think the angle issue you have is too steep. I think an SYE will fix your issue. I have a 4 inch lift, and not transfer case drop and a SYE and no vibrations.

Unfortunately a warped flywheel and too steep of a driveline angle will give you the same symptom. It is possible to distinguish between the two, but I couldn't tell you how.

Here is a picture of mine with the SYE: (BTW mine is a 98 also)

 

[Steel City 06]

I don't believe that image is correct for a TJ. I think that image so for a leaf sprung Jeep. I am pretty sure you want your rear end pointing to your transfer case. I think the angle issue you have is too steep. I think an SYE will fix your issue. I have a 4 inch lift, and not transfer case drop and a SYE and no vibrations.

Unfortunately a warped flywheel and too steep of a driveline angle will give you the same symptom. It is possible to distinguish between the two, but I couldn't tell you how.

Here is a picture of mine with the SYE: (BTW mine is a 98 also)
View attachment 87362

No, the image posted above is in fact correct for a conventional driveshaft. The pinion should only point at the transfer case when a single double cardan shaft is used. The reason the above image is correct is because the u-joints do not have a 1:1 turn ratio throughout a complete rotation. Setting them up at opposing angles cancels out the difference in rotation.

For a DC shaft, the DC joint itself is designed to cancel itself out, so the pinion u-joint should have minimal angle, aka the pinion should point at the transfer case.

Both of the below images are correct and applicable to a TJ:

 

[JEEPCJTJ]

No, the image posted above is in fact correct for a conventional driveshaft. The pinion should only point at the transfer case when a single double cardan shaft is used. The reason the above image is correct is because the u-joints do not have a 1:1 turn ratio throughout a complete rotation. Setting them up at opposing angles cancels out the difference in rotation.

You have this right.

I usually start from 2nd gear, but depending upon your gear ratio, transmission ratio, and tire size, it may not be the best option for all jeeps.

This may not be wrong but back when almost half the vehicles on the road were stick shift there were only two kinds of vehicles where this happened and they came with two different results.

1) Any trucks with the granny gear. As long as it wasn't loaded, first gear wasn't needed. This resulted in less shifting and no problems.

2) Any vehicle without the granny gear, unless starting out while headed down a decent hill. This resulted in a shorted life of the clutch. Different vehicle weight, horsepower, and tire size can make this less, or more of a problem.


As for Blake23's "Shudder when taking off " Is this happening while your foot is still on the clutch pedal or after you take it off?

Foot is still on the clutch pedal? Probably flywheel.

Foot off the clutch pedal? Probably too low rpm.

 

[Steel City 06]

There are a couple reasons I usually start from 2nd.

The biggest one is that I believe the 2nd gear synchro is worn out or busted. Shifting from 1st to 2nd in motion requires a long pause to prevent grinding gears. A clutch is far easier and cheaper to replace than worn gears or synchros. 2nd to 3rd also has some issues, but it seems to be mitigated by shifting at 3000 rpm.

The 2nd biggest one is that 1st gear, with the 4.46 ratio and 4.10 axle ratio on 31s is effectively quite low. I can start off far more quickly in 2nd than in 1st, except on moderate to steep inclines. 1st gear in a NV3550 and 3.07 axles is much closer to 2nd gear in a NSG370 and 4.10 gears than it is to 1st.

Starting down hills, I’ll even just roll and engage 3rd at around 10 mph.