Rollerizing vs plain thrust washers...

[theo]

Now I'm getting into my 200-4r rebuild the questions are coming thick and fast

For some background, I bought a very rough looking core unit after a long search, to put in my 1980 vette. See the thread linked here:

http://www.turbobuick.com/forums/transmission-talk/310891-cu-code-200-4r.html

I want to build it for reasonable power, although my vette is probably under 300 hp/tq, I want it durable, and capable of coping with any further engine upgrades I might carry out.

So I'm building a shopping list of jobs and parts for this unit. One thing I've noticed is that many folk seem to advocate rollerising in some of the thrust surfaces where plain thrust washers are normally used. I'm debating whether I will do this or not. If I do, I can machine the bearing pockets myself, but I'm wondering whether this is really necessary for a non-competition transmission.

I happen to know a bit about bearings and lubrication so I hope I'm making educated assumptions here, but am I right in thinking your prime goal in replacing plain thrust washers with roller thrust units is the reduction in losses?

In theory (a dangerous way to start a sentence I know!) the load support of a properly lubed plain bearing should be a lot greater than that of a similarly sized roller unit. But in terms of drag losses the roller unit is much lower. That to me says that for durability one would stay with plain, but for all out racing where every little fraction of HP is crucial, you can justify going to rollers.

I'm not trolling for an argument because "I think I know the answer" here; as I said I know what the theory says but the practice can always be much different. Just interested to hear what the experienced builders have to say.

Cheers
Theo

 

[bison]

Rollerizing is done for longeivity of thrust bearing more so than reduction of loses. The roller bearings will take extreme pressures and not fail. Imo there are 3 area that really need the attention. They are the front of the center support, the front of the low reverse center support, and the rear internal gear. All used tabbed babbit thrust washers stock and they are often heavily worn. Other locations dont really benefit because the thrust is in the opposite direction under load. It may seem that the tabbed washer with an oil film would be a better than a roller bearing but its not so.

 

[Alky V6]

Good question. I would suggest that you very carefully study the direction of thrust loading of the components. If you do it properly, you will come to find out that the needle bearing thrust washers that are already in the unit from the factory are the only washers that are taking on serious thrust loading.
The low/rev clutch housing to sun gear shell thrust washer will sometimes show excessive wear due to other wear points that setup an excessive amount of thrust on that washer. Correct those wear points and the normal flat washer will do just fine.

 

[theo]

Interesting points, thanks guys. I must confess I've yet to sit down with all the gear parts cleaned up and just study them for where all the forces react, but I do intend to. It seems logical that the factory Torringtons would only be used where the thrust loads are high.

In the other auto transmissions I've had apart the thrust washers always show some wear, and this one's no exception. So I guess they're not always running with a fully developed oil film, meaning you can't assume that they'll have better load carrying ability than a roller unit.

Don, without the benefit of having it all in front of me, can you explain which other washers wear in order to set up excessive thrust on the sun gear shell/low suport washer?

cheers

 

[Alky V6]

Interesting points, thanks guys. I must confess I've yet to sit down with all the gear parts cleaned up and just study them for where all the forces react, but I do intend to. It seems logical that the factory Torringtons would only be used where the thrust loads are high.

In the other auto transmissions I've had apart the thrust washers always show some wear, and this one's no exception. So I guess they're not always running with a fully developed oil film, meaning you can't assume that they'll have better load carrying ability than a roller unit.

Don, without the benefit of having it all in front of me, can you explain which other washers wear in order to set up excessive thrust on the sun gear shell/low suport washer?

cheers

It's not that other washers are wearing, setting up the excessive thrust on the sun gear shell T/W. It's actually a couple of the main components that are responsible.

Look closely at the load contact points where the sun gear shell lugs into the high/rev clutch housing. If it is an early non-hardened sun gear shell, you may see wear on those contact points. If it is a hardened shell, and that's what you should use to prevent premature sun gear shell spline wear, then you don't need to pay attention to those load points on the sun gear shell. The hardened shells don't wear out.
The high/rev clutch housing, on the other hand, does wear a lot at the load points where torque is transferred to the shell. Those points, as they wear, will commonly develop a ramp effect that ends up wanting to push the sun gear shell and the high/rev clutch housing apart. The ramp is very subtle. It's these ramped wear points that cause the sun gear shell T/W to take on excessive thrust load and, on occasion, prematurely wear out. We correct that wear by welding up those points and refinishing them.

 

[theo]

I'd be very surprised if this unit has a hardened sun shell, but also very pleased! I think it's of 1981 vintage. Are the hardened ones only heat treated at the splines, or is the whole unit a tougher material? Thinking or running a needle file over the metal to see if it's hard or not... I was going to buy one anyway for the rebuild.

Thanks for the pointers about the high/rev drum wear - I'll have a good look over that.

 

[Alky V6]

I'd be very surprised if this unit has a hardened sun shell, but also very pleased! I think it's of 1981 vintage. Are the hardened ones only heat treated at the splines, or is the whole unit a tougher material? Thinking or running a needle file over the metal to see if it's hard or not... I was going to buy one anyway for the rebuild.

Thanks for the pointers about the high/rev drum wear - I'll have a good look over that.

Unless the shell was replaced with a hardened unit during a past rebuild, the sun gear shell should be the early non-hardened unit.
The whole shell is hardened, not just the splines.

 

[theo]

OK, cheers mate.

I'll look it over when I get a minute. The dirty work's pretty much done now - all stripped down and cleaned. I just need to inspect and start writing the shopping list!

Not rushing on this though, it's clear the project won't be finished in time to use it this summer so I can afford to wait until next, and take my time and do it right.

 

[chris718]

I agree Brian.

 

[WE4]

I agree as well

I believe that the most critical one to replace , even in a stock rebuild, is the l/r clutch housing. That is the most thrust and even GM wishes they would have done that from the factory. The rest are for durability under load conditions. But like the gentlemen above said, the main ones are front of L/R housing and front of OD housing. I like to bearing the forward drum as well, but that is me.

Bruce

 

[bison]

Rollerizing is done for longeivity of thrust bearing more so than reduction of loses. The roller bearings will take extreme pressures and not fail. Imo there are 3 area that really need the attention. They are the front of the center support, the front of the low reverse center support, and the rear internal gear. All used tabbed babbit thrust washers stock and they are often heavily worn. Other locations dont really benefit because the thrust is in the opposite direction under load. It may seem that the tabbed washer with an oil film would be a better than a roller bearing but its not so.

I should add that not all 200- 4R have a babbit washer on the low reverse center support but it should be rollerized in that location regardless
.

 

[theo]

I certainly need to put something new in the thrust location behind the rear sprag - the plastic thrust washer there has snapped in two, which is common according to what I've learnt so far.

So it looks like time to get some of these parts chucked up in the lathe! This all leads to the obvious question - I'll be getting a kit of stock Torrington bearings obviously, but what are the part numbers of the bearings that are used in the various non-stock locations?

 

[bison]

I certainly need to put something new in the thrust location behind the rear sprag - the plastic thrust washer there has snapped in two, which is common according to what I've learnt so far.

So it looks like time to get some of these parts chucked up in the lathe! This all leads to the obvious question - I'll be getting a kit of stock Torrington bearings obviously, but what are the part numbers of the bearings that are used in the various non-stock locations?

That is common. The high performance 200 4R's have a flat roller bearing in that location from the factory.

 

[theo]

Does that mean that a good rebuild kit or thrust bearing kit will come with the roller bearing for that location? Can anybody tell me the part#s of the roller bearings for the remaining non-stock locations we've dicussed above?

Cheers!

Theo

 

[jakeshoe]

Does that mean that a good rebuild kit or thrust bearing kit will come with the roller bearing for that location? Can anybody tell me the part#s of the roller bearings for the remaining non-stock locations we've dicussed above?

Cheers!

Theo

You need the torrington for the rear planetary, it came in the later model units, it's still available from GM/AC Delco. I use it in all my builds and it's included with my rebuild kits.

However you aren't going to have much luck getting builders to just tell you the source of the other non-stock bearing locations. It takes a considerable amount of time to find a bearing that will work well at each location and once you do, it allows you to be a step ahead of the average builder. Not something most vendors are going to just give away for free.

I would suggest either buying the parts already rollerized from one of the vendors here or be prepared to spend some time figuring it out.

 

[theo]

Ok, thanks for the info - I'll have a look at the Delco website.

Fair point regarding the non-stock locations. I would probably feel the same way if I was doing these mods for my job!

One thing I do have plenty of in this build is time, so I'm quite happy to have a look at working out suitable replacements myself. Proper engineering!

Cheers
Theo