Gearbox reconditioning advice, bearing on my mind..

[Borgweiser]

I must start by saying I can't release details on the vehicle or the shop in question as I don't want to be involved in slanderous claims..

 

As most of you know, I do a semi roaring trade working on the weird and wonderful vehicles from all parts of Europe. Mostly old and obsolete and quite finniky to work with.

 

Customer has a lovely old real oddball thing that I'm currently stripping the spare motor down for rebuild, the equally low mileage gearbox was sent to a local manual gearbox specialist for a check over and rebuild. During the conversations after the stripdown, He kept annoying me saying it was in good condition for one of these gearboxes (there is no way he could have ever seen one before, I know this for fact) and I start to question him about the information he is using for the stripdown and assembly (ie torque settings, differential preload etc) and he reckons he's going to set it up just like every other gearbox, no worries...

 

Sorry this is so long winded, but I thought I'd give a back story, basically I went in today to check progress and they have fitted up the gearbox with NAC high load bearings over the original SKF bearings, which aren't expensive when brought in from my supplier in New York in a kit. I already have a load of stuff ready to be shipped so I wish they waited as instructed. Problem is the bearings are sealed, they reckon the gear oil gets past the seals and that's how they fit up all the gearboxes these days..

 

This is where I get annoyed, these are main shaft, layshaft and diff bearings, they should run in oil and not swim in their own junk..

 

Opinions please, I'd like some advice before I pull the plug on this and kick up a shit storm.

 

Also the original bearings were like new once cleaned, no lateral play, quiet and smooth.

[KKtrips]

I don't whether it is right or wrong to leave the seals on there, but you could just ask them to pull the seals off the bearings - they should come off easy enough.

 

 

 

[flyingbrick]

What he said.

I'm not a gearbox specialist but sounds very very odd to me. Those seals are pretty good be hard work for oil to get in and out.

That and the fact there's just no need to leave them in there when they flick out so easily!

Also, two random things to think about- does the oil flowing through the races provide a cooling effect on the bearings?

Is flow of oil to parts of the gearbox restricted by these seals?

With regards to the origional bearings being nice- without knowing how much care they took to remove them and how tight they were on their shafts/housings they could have been damaged.

Generally speaking bearings are cheaper than the labour to access them and the other associated extra costs with having them fail. I always consider assembling something with old bearings to be bad practice. (Rambling as usual soz)

[sentra]

read the bearing specification for double seal operation, the lifetime@operation speed seem plausable, jap stuff runs like that on mainshaft input side as an observation, taper rollers on the thrust side wont have seals and there the only ones that see any real heat, however im sure they would be fine if they did somehow

$0.01, no accuracy guarantees.

[SOHC]

I got told to leave the seals on by an old timer, he sed it doesn't relay matter, it will stop all the big chunks of shit getting in from other parts,

 

If they are not full contact seals so oil should still get in.

 

I do what Ktrips sed anyway  

[Borgweiser]

In the spirit of eric on the roof carlsson I'm gunna stick to my guns and demand oem SKF bearings coz they are the best.. also the gearbox was always a weak point on these cars and I do think oil supply was a factor as for the fact 4x the power flowing through as originally intended. Just heard from another forum that the gears need to be correctly shimmed and the diff pinion needs to be set up with the correct pre load only achievable with special tool blah blah etc. Going to make the tool and finish box off myself. When I do I'll do an update.

[CaMpylobacter]

+1 get SKF bearings if it was fitted with them from new. why try anything else? 

also, pretty odd that you'd replace oil splash fed bearings with sealed ones. seems silly.

[RUNAMUCK]

That grease, and those seals are intended for applications where the bearing doesn't see lube. I Always remove the seals when I do a gearbox. (sometimes the bearing supplier supplies a bearing which comes with the shields fitted)

 

Also, stay the fuck away from FAG bearings. My old man did a bearing preload course thru his old employer. Some Aussie from FAG was running it.

The old man took great delight in telling his that FAG stood for Fuck All Grease. Cos erry time you pull the sheilds out, the bearing has next to no grease in it.

[mattscort]

Nothing wrong with FAG bro use them all the time at work

[Borgweiser]

Hit and miss with some bearings, even from reputable manufacturers. I have huge respect for original pattern Timken bearings as I fit and fiddle them to heaps of old British stuff. Sometimes, I clean off solidified old much and dirt, blast shit through them, repack and good as new. I think it comes down to what the manufacturer specified in terms of size and load versus real world situations for reliability. I fit FAG front hubs to Volvos day in day out as it's the OEM manufacturer. 200k reliability and beautifully made, such German. In this case the bearings are totally undersize, so I want the best available for the application. It will be driven hard too.

NAC bearings might suit applications they were designed for, but by god are they cheap and rough when you handle them new.. Not a fan. Not a fan of being charged a fortune to have them installed in a unique gearbox. Not a fan of having myself look like a dick when freshly restored car gets trailered back to me when gearbox lets go over Christmas up Cape Reinga or similar. Basically not a fan of shit work and bullshit she'll be right kiwi attitude when it comes to budget shit parts.

Man, what a grumpy old fart oily gripper rant, I need to get out of this game. Might go in to real estate and sell all my old cars.

Thanks OS, this has been fun

/thread clocked

[sentra]

+1 get SKF bearings if it was fitted with them from new. why try anything else?

also, pretty odd that you'd replace oil splash fed bearings with sealed ones. seems silly.

(industrial gearboxes, only had a small dabble in automotive) if your operating inside reasonable spec for double sealed/greased for life, and your working on a splash oil gearbox that you have to disturb the gear mesh on allready workhardered teeth its a pretty normal um - arr what the worse of five evils is. will try remember some real examples tomorrow, workhardered bronze oil contam from remesh was a bad one in splash bath due to relying on magnet for filtration would stay in circulation, the stuff harmless to a gear, however would wipe out new bearings quickly.

0.005$ will go away now

just wanted to keep your minds open.

[UTERUS]

(industrial gearboxes, only had a small dabble in automotive) if your operating inside reasonable spec for double sealed/greased for life, and your working on a splash oil gearbox that you have to disturb the gear mesh on allready workhardered teeth its a pretty normal um - arr what the worse of five evils is. will try remember some real examples tomorrow, workhardered bronze oil contam from remesh was a bad one in splash bath due to relying on magnet for filtration would stay in circulation, the stuff harmless to a gear, however would wipe out new bearings quickly.

0.005$ will go away now

just wanted to keep your minds open.

 

+1 I have hazy memories of an old maaate fitter telling me tales of similar situation when gears need to re mesh in splash lube, but couldn't remember the whole story.