Drive Shaft and transmission test

[Chuckles]

I am about to fit the GV overdrive, but I want to resolve a vibration problem first. From about 40mph to 55 mph a drumming/droning noise builds up. One time Mary (War Department!) felt the floor and declared some degree of vibration, so my thoughts have turned to prop shaft imbalance.

The P-30 manual refers to removing the drive shafts to enable checking the prop shaft at speed.

Here lies the question; Is this with rear wheels on or off. I see a flange with five nuts and the wheel fixing flange. I realise that oil from the rear axle lubricates the inner (and outer?) rear wheel bearing. So is it a) advisable to remove the five nuts and is there the drive shaft here? and b) advisable to test the prop shaft in this manner? c) is there an oil seal here to be replaced?
I want to resolve this vibration before starting the GV install, as I will then send all prop shafts away to be shortened, balanced and fit new UJ's etc. I need to know we are starting off with good shafts to start with.

[richinny]

the shop that will shorten the shaft should first be checking for balance and if it is true. i would just send it to them.

[Airslide]

I agreee with Rich,

Just have the guys at the balance shop do the cutting and rebalancing since that needs to be done anyways.. balance the rear section of driveshaft as well, check and replace all the u-joints, reinstall and test drive. If Karma is on your side you problem will be gone and you will be streamin with overdrive!

Vinnie

[GlenCoombe]

I'll third that vote.

Balance is done after cutting the front drive shaft. My delay was about a very bad vibration after the first shop messed up the shortening. We ended up at a machine shop that got the job done.

I had replaced the mid-carrier bearing a year or so ago so we didn't go there but if you've got the drive line apart why not if it looks like it's been there a while.

There is little to be gained in reinventing the wheel prior to shortening the drive shaft.

Install the GV and let the shop provide the balanced drive line from there. Wheel bearings won't give you enough vibration to be felt IMHO.

[Smartstream]

I also agree, have the shop straighten and balance both shafts when they shorten the front shaft. If you still have vibrations you need to check engine, drive shaft and pinion angles. I had to add wedges to the differential mounts to make all the u-joints happy.

As to testing, you just remove the 5 bolts on your rear axle hubs, pull the cover/flange and there is driver "lug" that connects the axle shaft to the hub. Remove the driver "lug" and replace the cover to hold the lub oil and you no longer have any connection between the engine, trans, driveline, differential and the drive wheels. Make sure you chock the wheels because your transmission park and driveline hand brake are no longer connected to the wheels either. There are some rear axles that the hub cover/flange and axle are one piece. You pull the flange/axle out 4" or 5" and you are disconnected from the differential gears. I have not seen this type of rear axle used on an AS but I haven't seen all the AS bulit. The one piece cover/axle is far more common on trucks than what was used on the AS that I have seen. I would do both sides just to be nice to the differential gears, picture the drive wheels on one side doing 60 mph while the wheels on the othe side are standing still.

[pwhittle]

I suspect it is a universal joint that needs replacing rather than a bad shaft. I had exacty the same symptoms.

Paul

[Chuckles]

Thank one and all for your very useful comments - once again the Forums comes out on top.

Unfortunately the project is on hold for a bit after being crushed between the AS 310 and our 'toad' a PT Cruiser...
On our last trip we were packing up ready for the return journey, and all that was needed was about 2 inches more for the PT to be coupled to the Blue Ox Aladdin towbar.... "her-indoors" (Mary - my wife - for a little longer!) thought different, and tried a lot more......
This is a lesson to us all, when the ground is wet, so too the car pedals become wet "I am sorry" she said" but my foot slipped off the brake pedal..." ........... I still believe that!

I am out of plaster now and hobbling around on crutches so it may be a few more weeks before I am allowed to carry on with the GV install. I will keep you all posted on the outcome - hopefully vibration free....

[HowieE]

One other area that can effect a drive train vibration that is all to often over looked is the brake drum. My son had several garages spend 4 months looking for his vibration when it ended up a warped drum do to over heating.

Everyone wanted to blame the tires.

In your case I would first inspect the shaft to see if it has thrown a balance weight, they are small square pieces that are spot welded on. If that checks out I would look at the the U joints first, the carrier bearing second,the drums third. Unless you hit the drive shaft or the problem has always been there I would not consider the shaft.

When I installed my Gear Vendors in my Suburban I replaced the 2 piece shaft with a single shaft. Don't think that will be the case on a motor home so I would consider replacing the carrier bearing completely if there are many miles on the rig.

Make sure you check the inclination angle of the u joints on the new shorter shaft. The addition of the Gear Vendor will change this angle and if it falls below the allowable standards you will have U joint problems. U joints can not function with a minimum or zero inclination angle.

[GlenCoombe]

Ouch! Chuck, that had to hurt. Sorry to hear about your accident. I'm sure your wife is very sorry. Hope your life insurance is paid up.... you never know when she might try again.... to help you out.

Get well soon.

[Chuckles]

Thanks Glen,
You will see on the motor home mileage thread that I have started.

I have now let Mary drive the car all the time - its called practise!!!!

Mind you I keep clear when she manoeuvres in the drive way..... and as for going in and out of the garage..................................

[Chuckles]

Thanks Glen,
You will see on the motor home mileage thread that I have started the GV install.

I have now let Mary drive the car all the time - its called practise!!!!

Mind you I keep clear when she manoeuvres in the drive way..... and as for going in and out of the garage..................................

[slowmover]

My first thought was carrier bearing, too. Worth re-doing whole shaft (make as new) if any work contemplated. Like alignments, a shop with old guys is best (and do their own balancing).

[Aage]

Originally Posted by pwhittle

I suspect it is a universal joint that needs replacing rather than a bad shaft. I had exacty the same symptoms.

Paul

I agree, bad universal = vibration

Cheap to fix, too.

[Chuckles]

I think you're right. I have found a little play, say, "in-and-out" of the cup in the UJ. There is no lateral play.

I can understand with this amount of play, that the prop shaft will lose its centre initially when first started, which is the case. It "drones for the first 20 odd miles then improves.

I only hope that is the only snag although the first support bearing has some slack so that will go - are the support bearings standard or peculiar to P-30?

[HowieE]

Originally Posted by Chuckles

I think you're right. I have found a little play, say, "in-and-out" of the cup in the UJ. There is no lateral play.

The drive shaft is a Balanced system and any side to side movement in the cups will allow the shaft to be off balance.

As for slack in the carrier bearings that may effort the inclination angle of the U joint. U joints have to have a slight angle across the joint. That is what causes the needle bearings inside the joint to revolve. If this angle is too great or too small the needles will not revolve in the bearing and shorten the life of the joint.

[kmpro]

Chuckles center support bearings and carriers are available at most auto supplys here in the states even though they are found on P-30 many Chevy trucks use the same system. Pretty common part here. Since you are replacing the u-joints and rebalancing I would replace the center support bearings and carriers so all would be new just like OEM.

[Chuckles]

Well I hit snag One!

I went to a Chevy dealer in the North who normally is very good at sourcing chassis bits for me.
Either my micro is out but the measurements of the UJ was different to that in the books. I measured 1.185" x 4.185" for the front UJ and the book gave a considerably smaller version (cant remember the size now - it was late and about 530 miles away!). The nearest was 1.187" x 4.187" BUT that was for the axle end.
I bought two just in case and will give it a shot this week end and see how they fit. Hopefully they are all the same size so all I need is one more.

Snag 2 was that the support bearings and running spline are not available here - yet! will keep trying others.

[kmpro]

Bummer Chuckles. Given the work that u-joints do I would wait to put all the center supports and bearings at the same time as the u-joints. FYI u-joints change speeds 4 times per revolution, so even on a good day they take a real beating. Key is to get the right guy doing the installing so that there is no built in tension (tight place) in the joint. Good lube is also paramount.

[Chuckles]

It was my micro! the new UJ's fit.....

Thats one(or two) down another to follow. just waiting now for the prop to finished.

And yet another..... I have had this annoying chatter from the speedo dial, with the accompanying waver of the needle from start to about 45MPH, ever since I had the MH. I have replaced the lower cable and speed sender, and now with the GV (trans Brake) extension, I have another new lower cable and the additional speed sensor.

I removed the inner of the upper cable to the speedo itself cleaned and oiled it. No floors in it, but there was a very slight high spot somewhere. After the oiling, that seemed to go, but the clock needle still wavers, albeit a bit quieter!

Any Ideas chaps? I am thinking the waver or slack is in the head of the speedo, has anyone serviced these .... successfully?

[guy99]

Originally Posted by Chuckles

....

Any Ideas chaps? I am thinking the waver or slack is in the head of the speedo, has anyone serviced these .... successfully?

When I bought my MH, the speedo bounced erratically, then it stopped working.

I replaced it with a non-stock unit. Then I found a speedo repair shop and had the original repaired. When I asked them to add the mileage from the interim replacement to the reading of the original, they thought I was a bit odd. In any case I now have the original speedo, with the correct mileage.

If you can't find a local speedo shop, you could try http://www.speedometershop.com/