Cracked the steering Gearbox!

[CCousins]

So, slightly annoying to say the least.

the bus has covered 80k miles and on the weekend, went to move it in the yard. Very slow full lock right, i could hear the power steering make a slight 'whine sound' of what i thought was normal for a hydraulic system? Of which it then made a relief sound.
Sure enough once parked, it was pouring out hydraulic fluid from the crack shown!



Emailed a few gearbox steering engineering places in the UK.

Some of the suggestions were welding the disk? whilst attached (But limited welding experience myself and its cast, which needs pre heating/ cooling?)

Other suggestion was Liquid E metal repair (but that is a bit of a bodge in my opinion, we need it reliable)

One company said they can remake a disk from the old one, to which i can myself as i have access to a engineering workshop with skilled machinists.
I think this may be a good idea to try?



I have found this from a seller in the States, but requires us to send our one and i image (not broken)

So with shipping included etc, that will be near $1000 knowing they wont want our cracked unit.



Does anyone know of replacements that would fit?

Lastly is this common, how would it even happen, one place suggested a loose ball bearing loaded between it and the end cap and cracked it on full lock, one place suggested cold weather? but it was about +5 degrees C not -20!

[Robin97396]

Personally I'd go to a junkyard to look for a replacement, but pay attention to the mileage on the donor vehicle. Also, I think that's what people are talking about when they say don't turn the steering wheel so far that it makes that whining noise.

Your bus education begins.

[CCousins]

Originally Posted by Robin97396

Personally I'd go to a junkyard to look for a replacement, but pay attention to the mileage on the donor vehicle. Also, I think that's what people are talking about when they say don't turn the steering wheel so far that it makes that whining noise.

Your bus education begins.

I think so too! I didn't know turning the wheel so far could damage it! once fixed i will be seeing if theres a way i can weld a deadstop to the underside carriage to stop it happening again.

Sourcing a new one of these will be fun, more so that im a million miles away from the states!

All the best

[Iceni John]

Originally Posted by Robin97396

Personally I'd go to a junkyard to look for a replacement, but pay attention to the mileage on the donor vehicle. Also, I think that's what people are talking about when they say don't turn the steering wheel so far that it makes that whining noise.

Your bus education begins.

Not too many American school buses in England! That would be like trying to find parts for a Bristol RE or Mercedes O-603 in this country.

Isn't there a poppet valve (or several) to relieve over-pressure? Has it stuck? I would replace all of them if you repair the cover. Or find out what the maximum working pressure is for that box, and then use an external pressure relief valve to prevent over-pressure from even reaching the box at all. I did that for my hydraulic fan motor after a brand-new replacement motor burst after just 6 miles - the brand-newer motor now has a Prince RD-1875H relief valve to ensure no more problems.

Happy whatever from the colonies (I'm from Norfolk),
John

[CCousins]

Thanks John, I know! The struggle is real! i would of assumed it had pressure relief valves, as those mechanical pumps being extremely high pressure.
Im half tempted to see if there is a more modern design i could make work and retro fit to some sort of plate maybe?
But that may require changing the pump etc and would actually not be worth it.

It looks like i can buy an overhauled one from the states for nearly $1000 delivered which is mad!
However im waiting for some more companies to get back to me also.

[cadillackid]

doesnt help a lot now.. but NEVER hold the steering wheel at the full lock position.. that whine you hear is the pressure going sky high as it tries to turn against the lock.. when you hit the end, back the wheel off by just an inch or so.. it will not affect your turning radius and your power steering system will be much happier..

I posted in your other thread... didnt realize you are in the UK.. these devices are often wanted back because peiple re-manufacture and re-sell them.. so they need the "core" its hard to find brand new older parts that wont cost twice or more as much as the new box and shipping your old one back.
-Christopher

[Tango]

A core typically only needs to be "rebuildable". And yours certainly is.


And the hold short stops are a good idea. My little 4BT runs something like 1500 pounds of pressure as normal.

[ol trunt]

Pry out the snap ring and look at the inside of the cracked cover. Check it carefully for signs of the shaft it covers having pressed or rubbed against it. If you find such damage it indicates that the bearings and or bushings in the gear are worn and the gear will need to be replaced. Also, while the cover is off, have someone turn the steering wheel back and forth (engine off) and watch for vertical movement in the shaft. That movement shouldn't exceed a couple of thousandth of an inch. Jack

[CCousins]

Thanks a lot for the replies guys. I’m already learning a lot haha!

I will see if I can get an end cap machined out of billet at work, then rebuild it (I build things like this as my day job so shouldn’t be too much sweat)

Has anyone got a good supplier I could use for a rebuild kit?

I have had a quick look myself, with not a great deal of luck for that box. Most of them were for Chevys and more car related.

[CCousins]

Thanks for this, this also sounds like a good idea, I’ll do this, I’m tempted to take the box off anyway and rebuild it with new bearings and seals. Can’t imagine the wear is too excessive as it’s a 80k mile bus not say 300k

But I may be completely wrong!

Again thanks for some good advice all the best

[Tango]

Like a lot of components, the steering box can be worn down prematurely if not not treated and maintained properly. I've seen Ross units still tight and drip free after a half million miles. Other that were ready for the scrap heap in barely 30K.

[bluebird90]

Unless you know the steering box was rebuilt in the recent past, Do not repair it. You don't know what else is wrong . Get a rebuilt. Contact the closest truck parts store in the U S and order one in. It would not surprise me if a truck parts store where you are at could order it in.

[CCousins]

Iiiiiiiiii

[Mountain Gnome]

What he said:

Originally Posted by ol trunt

Pry out the snap ring and look at the inside of the cracked cover. Check it carefully for signs of the shaft it covers having pressed or rubbed against it. If you find such damage it indicates that the bearings and or bushings in the gear are worn and the gear will need to be replaced. Also, while the cover is off, have someone turn the steering wheel back and forth (engine off) and watch for vertical movement in the shaft. That movement shouldn't exceed a couple of thousandth of an inch. Jack

The whining noise when turning the wheel "all the way" is from the pump being strained (usually, unless something else is wrong). If you add a bump-stop to keep the wheels from turning so far, the pump will still whine when it hits the stop and you try to go farther. You just won't have the same turning radius. The real limiting factor is the stability of the suspension system as the wheel turns farther, not so much the gearbox; but it also will reach maximum throw, based on the geometry of the swing of the arm.

[CCousins]

Originally Posted by Mountain Gnome

What he said:


The whining noise when turning the wheel "all the way" is from the pump being strained (usually, unless something else is wrong). If you add a bump-stop to keep the wheels from turning so far, the pump will still whine when it hits the stop and you try to go farther. You just won't have the same turning radius. The real limiting factor is the stability of the suspension system as the wheel turns farther, not so much the gearbox; but it also will reach maximum throw, based on the geometry of the swing of the arm.

Very interesting. I’m amazed it’s left the factory with such a floored design then. Would they solely rely on the bus drivers being told to not go full lock to save the part from damage?

I’ve started stripping down the gearbox last night and will follow up with some photos when I’m home from Work

Currently getting a new end cap machined up at work today, but I’m sceptical of using it because I think the end caps are designed to burst, where this part being machined is billet stainless steel.

Can not see any other valid reason for why they would use a cast ally end caps and the rest of the body of the unit being a much stronger cast steel/iron.
It must be to save the whole unit from cracking and not the easy to replace end caps.

Can anyone recommend a website I could use to get OEM spare end caps for that Saginaw steering gearbox. They have series numbers on the outside and inside, but not had any luck!
I’m willing to pay postage to get it here to the uk.
However really struggling to find anything on google the past few evenings, not even sure if they still exist either!


Thanks chaps for your help so far! Very much appreciated!

[Twigg]

Originally Posted by CCousins

Very interesting. I’m amazed it’s left the factory with such a floored design then. Would they solely rely on the bus drivers being told to not go full lock to save the part from damage?

Not really. It's a function of power-steering systems. They all do this, even in your car.

You never hold power steering on full-lock, in any vehicle.

[CCousins]

Originally Posted by Twigg

Not really. It's a function of power-steering systems. They all do this, even in your car.

You never hold power steering on full-lock, in any vehicle.

Yeah it was only momentarily on full lock for a couple of seconds.
I was always under the impression that any fluid systems should have relief valves in or near the pump. I know that’s the case for any hydraulic equipment I’ve ever worked on.
Cars not being an exception I would imagine, otherwise there would be a lot of broken down cars sat in car parking lots! Not to mention the dangers of high pressure systems.

I think I need to address the pump strip down too, I have a feeling there’s an issue with a valve inside it, if it has one, amazed if not! Haha

I’ll upload my findings in a second of what I have found inside the gearbox

Cheers

[CCousins]

So of course, some nice rain and complete darkness didn't help, but welcome to England i suppose

Got it off, taken it home



Stripped the main parts out of the broken Cylinder, quite happy with the guts of it, doesn't look like its had a bad life. Happy with the fluid colour too.



Wasn't impressed with this bodge i found however!
Appears they have made up a crude alloy spacer and packed sealant behind it, before reconnecting the output shaft.
Most likely to stop a leak as a 'quick fix' as over here its a straight FAIL for the M.O.T testing and leaks on the drive units etc.



However, its pushed sealant into the roller bearing as shown!
Again not too worried as its a slow moving component and doesn't see a lot of action. Will be measuring up a proper seal and dust seal for its rebuild though. After removing as much of it as i can.



Appears that the alloy spacer used has started to attack the shaft it was on, but looks like it will be in front of the seal, so not too concerned.



Teeth all look good etc.



Finally the end cap that i need to find!

The O-ring is good to use again also, checked at work with 'flow-serve' technical department, but that was the least of my worries!

The suggestions from someone at my work are the end caps have been engineered to burst if the relief valves fails to operate. Which has happened. Hence saving the assembly and only destroying the cap.

Now need to strip apart the pump, and find an end cap!

ill keep you posted.

for your input/help

Shaun

[jazty]

Could be that your power steering unit was not adjusted properly in the first place. That coupled with pushing too hard could have done you in. Once you get the unit repaired or replaced, make sure you follow the relief adjustment procedure.

Here's a video of how to do it with Sheppard systems. Looks to be the same for the one in my International, as well.

https://www.youtube.com/watch?v=6-zAfAqpyoU

[ol trunt]

That shaft is trash. It will continue to spit bits and pieces and eventually fail at which point you won't be able to steer--not worth the risk! Jack