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1970-1995 Range Rover Classic
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Discussion Starter #1
Greetings from the Black Hills. I've been trying to track down a vibration on my 93 LWB, and I'm running out of ideas. I'm hopeful that someone might have something I haven't thought of. Vehicle is in a stock drive train/suspension arrangement except for the addition of a new Medium ride/2" lift spring kit from roversnorth, and a new 2 piece front driveshaft intended for a Defender.

Symptoms are: Excessive loaded and unloaded vibration from 25-35mph, and again from 65-75mph with both drive shafts installed. Remove the front driveshaft, and the vibration is gone.

What I've done (in order): Balanced tires. Inspected tie rod/panhard bar ends. Inspected caster. Inspected indexing on OEM front driveshaft. Balanced OEM front driveshaft. Replaced OEM front driveshaft with aforementioned 2 piece driveshaft. Replaced front wheel bearings. Replaced swivel gears. Replaced rotors. Replaced both front axles. Replaced third member and gears.


My next step would be to replace the transfer case, which I really don't want to do. Not because of the cost or time, but because the vibration doesn't feel like it's coming from there. I've been a semi-pro racer for decades, on both high banked ovals and road courses, and I've learned to "trust my butt". My butt, (and hand on the Low/High lever), is telling me that it's not the transfer case. Also, there is no apparent "noise" coming from the transfer case. My thought was that if the front output bearing was causing this amount of vibration, I would definitely be able to hear it and feel it in the shift lever.

I've owned and wrenched on many LWBs since '98, and thought myself to be pretty knowledgeable, but I must say, this one really has me stumped!

Thanks in advance for any ideas or experiences that are shared.
 

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When you get to vibration speed
Have you put into neutral to see what happens
 

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Maybe it has to do with the VC
It is at the front of the transfer case
And connects to the front drive shaft
If it is locked up it will strip the splines off
The gear that goes through the VC
Just some imput
Mike
 

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Discussion Starter #4
I have. Vibration is still present. Loaded, unloaded, accelerated coasting, decelerated coasting, ect. A guy would think that would make it easier to troubleshoot!
 

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It does sound, such as Mikieman suggests, that the viscous coupling has locked.

Don't know if you're familiar with its operation, but if you lift just one front wheel just clear of ground you should be able to rotate it slowly. It'll take about thirty second or so to get a half revolution of the wheel. I do it by just grabbing the tire and turning it, think official method uses lever on wheel nut.

It should feel really stiff but fluid and yeald to torque if consistently applied.

It's the only real test you can do as if it's good it'll lock up and drive with prop removed, and if it's bad it'll already be locked and still drive anyway!

What it does is give you transmission conflict / windup which can't be dissipated through the centre differential operation so you feel any conflict as the tire tread mitigates the difference.
 

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Did you check if there is any play in the TC output shaft bearings (or diff for that matter)?

I had a series with vibration and turned out the TC outputshaft need to be reshimmed as the bearing had play. Was messing with the driveshafts till at some point I had an epiphany and just wiggled the whole shaft
 

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have you had your drive shafts balanced?, are they tight? any play on the Universal joints?. front shaft being two piece style, is is phased properly?, is the slip joint facing the transmission?
obviously if vibes go away with out front shaft you issue lies there, are you able to retrofit to old shaft? the bigger drive shaft is heavier, thus unsprung weight.
 

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Discussion Starter #8
Did you check if there is any play in the TC output shaft bearings (or diff for that matter)?

I had a series with vibration and turned out the TC outputshaft need to be reshimmed as the bearing had play. Was messing with the driveshafts till at some point I had an epiphany and just wiggled the whole shaft
The diff is fresh: new bearings/new gears. I did check the output shaft flange on the TC, and I couldn't feel any play.
 

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Discussion Starter #9
have you had your drive shafts balanced?, are they tight? any play on the Universal joints?. front shaft being two piece style, is is phased properly?, is the slip joint facing the transmission?
obviously if vibes go away with out front shaft you issue lies there, are you able to retrofit to old shaft? the bigger drive shaft is heavier, thus unsprung weight.
I thought so too. My sequence of trouble shooting focused on the drive shaft early and often. There was no change from rephased/rebalanced oem drive shaft to new drive shaft. The 2 piece drive shaft and u-joints are all new, built and tested by a specialty shop that I feel is competent. I spent two full seasons studying and testing drive line geometry and U-joints, and while I could be wrong, I don't think the drive shaft is the cause of this.
 

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Discussion Starter #10
It does sound, such as Mikieman suggests, that the viscous coupling has locked.

Don't know if you're familiar with its operation, but if you lift just one front wheel just clear of ground you should be able to rotate it slowly. It'll take about thirty second or so to get a half revolution of the wheel. I do it by just grabbing the tire and turning it, think official method uses lever on wheel nut.

It should feel really stiff but fluid and yeald to torque if consistently applied.

It's the only real test you can do as if it's good it'll lock up and drive with prop removed, and if it's bad it'll already be locked and still drive anyway!

What it does is give you transmission conflict / windup which can't be dissipated through the centre differential operation so you feel any conflict as the tire tread mitigates the difference.
Thank you both. I will say, I don't know much beyond the basics when it comes to the AT and the TC on these rigs. Mainly because I've never had any issues with them on any of my rovers.

Have either of you ever had to replace a VC? Is it serviceable without TC removal, or is it a non-serviceable piece that is internal?
 

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The VC can be replaced
It is easily removed from transfer case
It is in the part connected to the front drive shaft
You can source one from a p38 up to a 2002
If that is the problem
At least you have a direction to investigate
Good luck
You have the skills
 

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Normal mode of use to keep it mobile in event of VC failure is to do as you've already tried, remove front prop shaft which will just give you rear wheel drive. Take it easy as all torque is now on rear axle. If you don't do this, it'll run as if the centre diff is locked all the time and will eventually snap something from transmission wind up.

To avoid chasing other causes, you really need to establish if it's failed first else you'll just chase your tail through other stuff. It's really quick to check as method above, or same jacking one wheel then put a lever through UJ on front prop were it comes out of transmission, you'll be able to turn it fairly easily if ok, it just has a sticky fluid feel to it a bit like walking through a swimming pool. But it should rotate fully as much as you want when turning slowly, you are in effect spinning the centre diff planet gears by overcoming the viscous resistance.

VC unit is not serviceable if siezed, it can be removed with transmission in place and swapped out for good unit to repair.
 

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this is an old repost but it will give you some insight into changing the VC. worst part of the project is spending $ for the VC! not saying the VC is you're problem.



Your VC problems posted by geneo on03/12/2003 11:16:45:
>The coupling is nottoo hard to change. You remove the front driveshaft housing, remove thecoupler, and assemble. The transfer case mount has to be removed so you need asupport. No special tools needed, 1/2 day job.
· robison service
 

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Discussion Starter #14
Thank you all. I will run the test on it this evening, but I'm thinking you steered me in the right direction. I seem to recall not being able to turn a raised front wheel. To try and help the next guy with a similar problem, I will continue the thread until this issue is fixed. Thanks again.
 

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Discussion Starter #15
VC test via LF off the ground failed with certain results tonight. The RF would have counter spun with broken u-joints before that VC would have even thought about rotating. I pulled another VC off a low-milage parts vehicle and bench tested it according to the RRC workshop manual, and it passed. I hope to install and test it tomorrow night.

vc1.jpg
vc2.jpg
 

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It’s always good to have parts
Makes repairs quicker
Mike
 

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Another thing you may as well check
When you remove the b
VC hoisting
Is the splined gear behind it
If your VC was locked it can damage it and strip it out in the middle
It can cause you it just stop moving
And apear the transmission has gone out
This happened to me and have read it had happened to others
I have a picture some where on here
I’ll look later and post it
Good luck
 

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Discussion Starter #20
Eureka!!! Thank you Mikieman for the beta, and RRLondon for the second. It was totally the VC. While I think (from driving with a bad VC) I may have damaged one of the new u-joints, 100% of the vibration is gone at 35mph, and 95.2% of the vibration is gone at 80mph. Turns, coasts, and accelerates better, and surprisingly, it freed up the handle. I live in a snowy climate, and this vehicle had always had A LOT more understeer than my other RRCs did. That condition is also now fixed. It's very neutral/loose now, just like it should be!

In case someone else has these symptoms and stumbles upon this thread:

Tools needed-13mm socket and wrench, 14mm wrench x2, 17mm socket and extension, 19mm socket and extension, 27mm socket and extension, a smaller pry bar, and a drain pan. You may also need a wheel puller if your yoke is stuck. You will also need some ATF, and some RTV black silicone.

1- Remove front drive shaft by removing the rear flange of front drive shaft first with the 14mm wrench. (you only need to wrench the nut, as the bolt head locks against the shaft.) Then remove the front flange with the two 14mm wrenches.

2- Remove yoke from front of TC with the 27mm socket. If it doesn't slide of with a little force, you may need to use a wheel puller.

3- Remove bottom nut of mounting rubber with the 17mm wrench.

4- Remove the three 13mm bracket nuts/bolt that pass through the frame. Slide bracket down and out.

5- Remove the two 19mm mounting rubber bracket bolts that are now exposed, and remove bracket.

6- Remove the two 13mm brace bolts from the side of the TC. (these bolt the support rod that runs forward from the TC to the bell housing)

7- Drain TC. (keep your pan close. The VC housing is going to have some fluid still)

8- Remove the eight 13mm bolts from the front of the TC that hold the VC housing in place. GENTLY remove VC housing by spinning and prying. There is a 1/4" sleeve that mates the housing to the TC, so you will need to apply pressure straight forward until you've cleared that sleeve. It takes a little creativity, but you can work the VC and housing out from the vehicle without removing the exhaust or the cross member.

If you are replacing the VC only, and not the housing, you will need to get further instruction. It looks fairly straight forward to remove the VC from the housing, but I didn't need to do it, as I replace both from a donor vehicle.

Took me about 90 minutes to remove and replace at a decent pace.
 
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