Drive Shaft Vibration

[tommy33]

97 Disco I
120000 miles

Truck has run great since I replaced the fuel pump last year. Kind of expected something new to pop up and it now has.

Noticing vibration under load. Stops when I put it in nuetral while driving along.

U-joints and front axle look fine.

Flex joint on rear axle (the big rubber joint at the end of the rear axle) looks kind of frayed and like it is starting to tear.

Found the replacement part for about $100.

Questions: Do you think this is the problem?

How hard of a job is it to replace. It looks simple but once you get started I don't know what to expect.

Will the rubber joint fail totally while driving causing more problems. Meaning should I replace it asap or can I drive it locally while waiting for the part.

Thanks for your input/suggestions.

 

[joey]

I would say that it is the coupler/rubber donut that you speak of. Eventually it will fail, but remember it still has bolts going through it, so it will just make a lot of noise and vibration.

You can also upgrade it and remove the part and just make it a u-joint.


I would also call Nathan at Discount British Parts and see if he can get it for you cheaper.

 

[tommy33]

Hi Joey:

Thanks. I checked with Nathan and he DOES have it for about $16 less.

How would I upgrade to a U-joint?

Thanks for your help,

 

[joey]

There is a replacement part with U-Joint, cost a little more, but you will never change it again. It really depends on how long you plan to own it.

 

[tommy33]

I'm not getting rid of it so I will check on it.

Thanks,

 

[joey]

Now I have done some searching, and cant find the rotoflex (coupler) replacement other than a complete rear driveshaft... I thought I remember someone selling just an upgrade kit....

 

[tommy33]

Found it on Discoweb

After I lifted my 1996 Discovery about 2" with OME suspension, my rotoflex couplers started failing. I replaced the rotoflex driveshaft with a stock rear driveshaft and stock 4-bolt pinion flange from a 1998 Discovery.

To convert from rotoflex to u-joint, you not only need a u-jointed shaft, you also need the proper 4-bolt pinion flange (the rotoflex utilizes a 3-bolt pinion flange

 

[wolf]

If you want to go the whole route - here's what you are looking for (I picked this off the AB site):

Your Discovery has an angled drive shaft that uses a rubber flex coupling, wearing it down and causing annoying vibration in your drive train. When it comes time to fix it, replace it instead with our new and improved system. We've included a new drive shaft, flange, bolts, seal, spacer and dust shield that completely eliminates the rubber coupling and uses a standard U-joint.

Kit includes the following components:
# Product ID Description Qty. Required In Stock Cost
1 1389
SELF LOCKING NUT 8 Yes! $8.72
2 2910
BOLT - FRONT PROP SHAFT 4 Yes! $5.96
3 539745
DIFFERENTIAL SPACER 1 Yes! $11.95
4 FRC8387
DRIVESHAFT - REAR - SORT WHEELBASE 1 Yes! $299.95
5 INSTRUCTIONS INSTRUCTIONS 1 Yes! $0.00
6 STC3722
DIFFERENTIAL FLANGE KIT (4 BOLT) 1 Yes! $82.95
Total Value: $409.53
Your Cost: $399.95
You Save: $9.58

Seems pricey to me - but it could be worse if you went to the dealer!

 

[tommy33]

Driving with Rear Drive shaft Removed

If I remove the rear drive shaft to replace the flex coupling can the truck be driven with only the front drive shaft or will this destroy the drivetrain or something?

I'm thinking about this because if it were possible, would fuel economy improve dramatically since all the power will be going to only the front wheels?

Just an idea. I wouldn't try it unless Joey and the other gurus said it would cause no harm.

Thanks for your thoughts and comments.

 

[joey]

If you lock the diff lock, you can run without the rear drive shaft, but don't expect any fuel economy improvements.