Axle problem

[futar]

I have a 91 winny 21 footer with 60,000 miles. I have been hearing what sounds like a tire flat spot between 30-40 mph. It stops when I let off the gas. I recently installed new tires and the noise is still there. My mechanic thinks it's a bad bearing in the rear axle. I thought that these full floating axles were bullet proof.

Anyone ever have a problem like this?

Thanks,

futar@charter.net

[nolan]

I have a 91 winny 21 footer with 60,000 miles. I have been hearing what sounds like a tire flat spot between 30-40 mph. It stops when I let off the gas. I recently installed new tires and the noise is still there. My mechanic thinks it's a bad bearing in the rear axle. I thought that these full floating axles were bullet proof.

They are a rugged little axle assembly, but you can break almost anything if you try hard enough Apparently you had the noise before the new tire install so rule out the tires, its possible wheel bearing problem, they are a neglected part of the axle and prone to debate from a few, they are grease packed the same as a front wheel bearing, not gear oil lubed like many think and fail to ever check. Other things that might be worth checking would be the carrier bearing on the center of the driveshaft, and the ujoints for loosness, another overlooked gremlin on toy houses is the driveline pinion angle, many are low slung and overloaded which can cause the rear axle to not sit in a normal unloaded position which can cause driveshaft vibrations. Another possibility could even be a warped or out of round wheel, but the tire shop should have caught that if they balanced the wheel tire combo. Good luck.

[futar]

Update on my rear axle. Number one is never tell anyone that you have a problem with your "rear end".

The best of the local mechanics thinks the problem is in the rear axle so he disasembled it. The ring gear appears to have a defect or damage to one section. I am amazed because my last Toy had twice the mileage and no problems. Also the ring gear is one beefy sucker. I never heard of one failing.

The rear box bumper on this toy has angle brackets attached indicating some sort of towing. I know that towing is not recommended. In addition, the original owner lived in the mountains. I will give an update when the repair is finished. That is I don't have a cardiac from the bill.

[Gulfstream Greg]

Your description sounds like a bad ring gear and not a bearing. A bad universal joint can have the same symptom but would be more noticeable at lower speeds. If you do happen to have to change out the rear gears (actually a very easy job on full floaters) think about going to a lower gear ratio. Here is a gear ratio calculator http://www.toyotamotorhomes.com/gear_ratios.htm and here is a source for gear sets http://www.marlincrawler.com/htm/diff/pickup_diff.htm.

Marlin crawler builds really strong gear sets that will not blow up. Anyhow a lower gear ratio can allow you to use overdrive, give you more power to climb hills and maybe improve your gas mileage because the engine does not lug as much.

[futar]

Update. The replacement of the ring gear and bearings have fixed the problem. I wish I had seen the comment on the different axle ratio before the work was done....sigh.

My latest fiasco is cooling for boon docking. Mainly it's for the semi arrid regions where I go prospecting. I have roof air but no generator. I used to have a roof mounted evaporative cooler but they have increased to ridiculous prices. There's nothing to them so they shouldn't cost more than compressor air conditioners. I guess Turbocool bought out Recair. I decided to make a misting system. I bought a 12 volt fan and will mount a misting nozzle on it hooked to the rv water system. Wally World has a great 10 inch box type 12 volt fan for $13. It is in housewares. I will update on the results.