Driveline Slack? Center Diff?

[98 SNAKE EATER]

When driving my 91 LC, I feel a lot of slack in the drivetrain

Like if I'm cruising about 30mph and I let off the gas, then get back on it, the driveline makes a clunky sound and has a snappy engagement....

However, if I lock the center diff, it's smooth as silk

No slack at all....

Is this normal?

Also, would I hurt anything by leaving the center diff locked at all times?






Rick

Aztek T/A WS7 & 70 RAM AIR IV T/A
Moderator @ LS2, FAST LS1, FUELSLUT,
The F-Body Hideout, LS1Turd & ChopperForums

 

[WolfpackTLC]

(Pssst.... wrong forum...)

 

[98 SNAKE EATER]

Crap, I knew I did sumthin wrong

Can one of the mods please move this to the right forum?




Rick

 

[ShottsUZJ100]

Don't drive with the diff lock on, on pavement unless you want to destroy your truck.

 

[WolfpackTLC]

I've driven w/ my center diff lock on, on pavement, numerous times... how else do you drive your rig w/ a broken diff, or no front and/or rear driveshaft installed? Otherwise, you'd burn up your viscous diff (if you have on)

 

[ShottsUZJ100]

Snake Eater doesn't have broken parts or missing drive shafts. You take a properly working permanent 4WD vehicle, lock the center diff (turning it into part-time 4WD) and you can destroy your driveline and significantly wear you tires.

 

[98 SNAKE EATER]

Snake Eater doesn't have broken parts or missing drive shafts. You take a properly working permanent 4WD vehicle, lock the center diff (turning it into part-time 4WD) and you can destroy your driveline and significantly wear you tires.

Hmm, how is locking the center diff turning it into a "part time" 4WD?

Wouldn't it be full power to both the front and rear?

As for the tires, wouldn't the front or rear diffs have to be locked to cause more tire wear? (I don't think I have either)





Rick

 

[ShottsUZJ100]

Locking the center diff locks the front and rear axles together at the same RPM. When you turn, one cannot rotate at a different speed than the other like they need to. Tires will scuff, parts can snap, etc. Your manual explains this as well as many websites. It's not about "full power", it's about a unit (your center diff) allowing your F and R axles turn at different speeds when needed (like when you're turning)(just like our front and rear axles each having a diff so the wheels can turn at different speeds)
Then yes, lockers make things worse because when you need to turn not only do the front and rear axles need to turn at different speeds but your left and right wheels do too. Lockers don't allow that to happen and therefore there can be more failures.
Take a peek at your manual. You can also look here: http://trucks.about.com/cs/4wdtips/ht/4wd.htm Look at TIPS
Or here: http://yarchive.net/car/4wd_types.html

 

[WolfpackTLC]

You make a valid point, but I doubt you'd snap anything, unless you ALSO had your F/R diff's locked... maybe just some premature tire wear....

But who would want to drive around w/ the CDL locked all the time anyway?

(provided that the rig is 100% Functional)

 

[98 SNAKE EATER]

But who would want to drive around w/ the CDL locked all the time anyway?

Well, the reason I asked is because it drives so much smoother with the center locked


It's as if the center diff itself has excessive play, but when locked, has no play at all, so it just feels smoother


Well, at least in a straight line....

I only feel a slight wrap up when making very tight turns, but other than that, I don't really notice much stress on anything....


That being said, would it be ok to leave it on all the time except when turning full lock?





Rick

 

[WolfpackTLC]

You know what? I'm not sure... I usually only use my CDL when I'm crawling, or if I break a birf and/or d-shaft and need to limp back home...

Then there was the time I killed my rear d-shaft and drove w/ my CDL on for 3 months or so... go figure.

Each time, it hasn't adversely affected my rig, but you may have different results, seeing as how it appears that you already have an existing problem!

 

[mtycruiser]

When all the system is working properly CDL should not be permanently engaged in pavement, it will at the very least cause additional stress on the driveline when turning and additional tire wear.
If raining and/or snowing, pavement will have less traction and CDL engaged will give you both an advantage in traction and reduced or none additional driveline stress/tire wear.

 

[Jim_Chow]

Locking the center diff locks the front and rear axles together at the same RPM. When you turn, one cannot rotate at a different speed than the other like they need to. Tires will scuff, parts can snap, etc. Your manual explains this as well as many websites. It's not about "full power", it's about a unit (your center diff) allowing your F and R axles turn at different speeds when needed (like when you're turning)(just like our front and rear axles each having a diff so the wheels can turn at different speeds)
Then yes, lockers make things worse because when you need to turn not only do the front and rear axles need to turn at different speeds but your left and right wheels do too. Lockers don't allow that to happen and therefore there can be more failures.
Take a peek at your manual. You can also look here: http://trucks.about.com/cs/4wdtips/ht/4wd.htm Look at TIPS
Or here: http://yarchive.net/car/4wd_types.html

agreed. I've done this on my old 4runner before I knew it was a no-no. The sympton is that it'll be difficult to shift the t-case back into 2wd mode, causing one to back up/turn to unwind the drivetrain tension. It will load your drivetrain up unnecessarily, though, which isn't good. There's enough overbuild in the toyotas, at least, so stuff doesn't break.

 

[jeb]

To get back to the original question:

When I bought my '97 80 (in '98)- it had a little some driveline slop - but I drove some that really banged and clunked. I did some asking around at the time. The unanomous reply I got was "typical driveline slop - don't wory about it". The trucks I drove were only a year old to a couple of years old - so they did it from new.

Jeb
'03-100 (new)
'97-80 (on its way out)

 

[alia176]

Wolf,

Think of the CDL as the same thing as a locker. Would you drive around with your locker engaged on dry pavement? Same logic applies here. The center diff is an identical diff to the front and rear. There's a certain amount of slip between the front and rear that is allowed by the diff while turning. When you lock the center diff, essentially you have a locked diff and no give. Snap, crackle, pop!

Ali