TheHeadFL

So I'm finally working on my car again after having it basically be a once-a-month Saturday driver garage queen since 2006...

Way back when (2004) I did my cam, I noticed when removing the crank hub that my crank had excessive (visible to the naked eye) endplay. I assume that this means my thrust bearing is toast... (It is an M6 car BTW)

Some history on my motor: It is not the factory motor, it was a warranty replacement (crate LT1, 4-bolt longblock) manufactured in 2001. It has probably 50K on the motor. Cam went in at 30K.

Now, since it was my daily driver back then, I just ignored it and hoped for the best. I didn't have the money to go tearing into it and it wasn't a problem, knock on wood. It still isn't... Oil pressure is great, car runs and sounds great, no noticeable metal on the oil drain plug, etc.

Now I have a bit more disposable income and a nice daily driver, so I'm in a bit different mode as far as working on the T/A. I'm starting to think about performance mods again, like ported heads and a more aggressive cam. Eventually a 383.

If I did a 383 at some point, I'd want to 'do it right', meaning get quality parts, etc. I don't currently want to spend that kind of budget, but maybe in a year or two.

Keeping in mind my requirements (weekend driver), I see my options as this:

1) Ignore it. Wait until it blows up. Do whatever mods I was going to do and when it goes, it goes. In the mean time, start acquiring parts for a nice 383 bottom end.

Pros: Costs nothing. Has run OK like this for probably more than 20K miles.

Cons: Will certainly destroy the crank in the long run, and letting it take out the rest of the motor will (maybe) damage the block. Might blow up sooner than anticipated.

Other factors: Stock crank is worthless to me for a 383 project. Can't use a factory 4-bolt block for 4-bolt splayed mains anyway, AFAIK.

2) Take the shortblock out and inspect the main bearings and (probably) try to replace them.

Pros: Minimal cost. May be able to fix the problem and save the stock bottom.

Cons: May get the shortblock apart only to find that the crank is too damaged to reassemble, or needs a lot of machining. Don't want to waste money on a stock rebuild, don't have the money for a 383 (yet).

Other factors: Car sitting undrivable until I can do a 383 (a year?) means a pretty good chance of this becoming an eternally unfinished project.

3) Try to do some kind of 'budget' 383 sooner rather than later, skip some of the forged stuff.

Pros: Costly, but affordable. Probably will make better power. Likely to outlast my current bottom end.

Cons: Not 'doing it right'. Will not be as strong as it might otherwise be.

Opinions?

gatorhead

iTrader: (4)

Damn that is a loaded question lol

If there have been no problems then leave it alone. You know the saying if it aint broke don't fix it.......

There is supposed to be a little end play, unless you can measure it to be sure it is out of spec you are just assuming, again refer to the if it aint broke......

Unless you plan on making HUGE by HUGE numbers the factory four bolt will work just fine for your future build.

Take the money you were gonna play around with for this one and start stashing it away for your future parts. If you have a hard time saving buy a part at a time. It is more expensive that way but it is effective.

One more cliche' for you.......you get what you pay for~ Don't skimp on parts get decent stuff.

TheHeadFL

Yeah, it is definitely a loaded question... that is why I am putting it to the experts on here I honestly could go any way with this one.

Anyway, I am not looking for huge numbers in the future, but I'd like very good durability when I do a 383. Keeping the OEM 4-bolt block is a definite possibility since I know all the history of it. (It was installed when I owned it)

FWIW, I haven't measured the endplay, but I know the spec is measured in thousandths, and it was very obvious visually. Easily hundredths or maybe a tenth.

TheHeadFL

Also, I am fairly mechanically inclined (have done LT1/LS1 H/C installs, replace clutch/trans, all suspension stuff, etc), but I have never worked on a bottom end. This is just a fun project for me and I'd like the experience of understanding what is going on with that... what do you all think is the feasibility of assembling the bottom end myself in the future? (Obviously not including all the machine work to the block, etc)

Big Al

iTrader: (1)

Did you try it with a new rear main bearing? They make rear mains with an undersized thrust area. I'm out of time but look around in this catalog:

http://www.mahleclevite.com/

Al 95 Z28 with steam pipe problems

TheHeadFL

I've never changed any of the bearings. This bottom end has never been apart. Actually, I did a cam only, so the heads have never been off either.

gatorhead

iTrader: (4)

You could do it by yourself, but unless you have all the special tools, mag based mics etc. I would just let the machine shop do it. Otherwise you will have to shell out several hundred dollars in tools.

duh

iTrader: (16)

Doing a bottom end is not as hard as everyone seems to think. The last one I did was a ring and bearing job. I used a set of sockets, feeler gauge, ring compressor and a Tq. wrench. The biggest thing is talking with the machine shop and making sure things are done properly. A nice Mic set is good to have but not necessary. I would recommend getting the rotating assembly and the block done at the same place at the same time though. That way they can balance it and have physical measurements to go from. But if you have the piston manufacturer and pt. number they can get the numbers they need. It will take some time and diligence, but it can be assembled in your garage relatively easily. It's all about having numbers and even part numbers for the machine shop to go off of. Since you're not going for an insane HP build, I would say save some money and do it yourself. There are plenty of books available to give you great pointers. Just my opinion and I'm sure half of the world will disagree with me, but I say do it yourself. Hell if you're close to Chicago I've got another 2 bolt block I'd let go so you can build one and have the other still in the car, that's the best of both worlds. G/L with it and keep us updated!

TheHeadFL

I am in Florida, but thanks for the offer!

I really want to learn about the 'magical' and 'mysterious' bottom end stuff so I'm really kind of wanting to assemble it myself. I probably wouldn't do it on a $4000 stroker motor, but I may give a whirl at doing a bearing job on my stock bottom. If it blows up, well, whatever... Granted, this isn't something I'm doing tomorrow or next week or next month.

What all is involved in something like swapping the bearings?

I've heard of people 'refreshing' a bottom end this way. Can you just retorque the main caps and away you go? Do you need to replace all the fasteners? Do you need to refigure your bearing clearances (plastigage, etc.)?

I am kind of leaning towards a 4th option. I may look to get a set of heads and a more aggressive cam (more than my CC503), and rather than doing the swap in the car, I'll pull the motor and do it on an engine stand. That may be a wash time-wise anyway since doing that stuff in the car requires a bunch more frustration, and dropping a T56 and yanking a motor isn't something I find all that difficult. So once I yank it out, I'll pull the pan and make a determination then. May just replace the bearings to be safe, but I'd want to do it myself if possible...

Decisions, decisions...

duh

iTrader: (16)

Doing bearings and rings is not hard. I would recommend a hone job, just to give the rings a fresh place to start. But aside from that all that is required is making sure the ring end gaps are within spec. As for the mains and rods, Use plastigage when reassembling it just to verify that the bearing clearances are within spec as well. The main bolts are reuseable, providing they are not tq. to yield. Now that being said, I have yet to see TTY bolts on a gen I or II SBC. Most guys will tell you to get new ones to be safe, but assuming there is no damage to the bolts, you will be fine (especially on a bearing and ring job). As long as you pay attention to what your doing it will go back together very easily. If you're going through the trouble of doing main and rod bearings, I'd definitely have the cam bearings done as well, its just cheap insurance.

TheHeadFL

Is doing rings mandatory even with such low mileage on the engine? (<50K)

gatorhead

iTrader: (4)

I also fall into the DIY category. The thing that seperates me from the rest is my tools. I have inside Mic's, outside mics, telescoping mics, mag based you name it and pretty much I have it lol.

Measurements are CRITICAL. I know millions have used plastigauge but it is hardly accurate. I posted a few things about it on here not long ago. I use plastigauge to sorat double check myself.

You cant measure crank endplay or cam thrust with plastigauge. Nor can it measure cam or crank run out, cylinder roundness etc.

Typically on a standard rebuild rings and bearings should still bode well at 50k dependant upon how well it was taken care of and how much abuse it saw.

TheHeadFL

I am not opposed to investing in some quality tools... I love DIY because I feel like I don't truly understand something until I've done it myself. I hate parts of my car that I feel are mysterious to me, because it leads me to worry about things unnecessarily. I want to see how it goes together.

I do everything on my car. I mean *everything*, with maybe the exception of alignment or mounting tires or something. I've spent a bunch in A/C tools, brake line tools, etc. May as well invest in some nice measuring tools.

gatorhead

iTrader: (4)

Forgive me if I already asked before, but where in Fl?

moehorsepower

iTrader: (3)

I would leave it alone and just go, Once you start tearing into it even just for inspection you WILL be replacing a lot of parts and if you are not ready now, either your car will sit until you have the cash, or you will have to fix whats absolutely necessary and their goes your cash for your future project. If you are planning on a stroker you cannot use the stock crank anyway, and when you purchase a kit, it will come with crank, rods, ect.

TheHeadFL

Orlando

TheHeadFL

I guess my question is mainly... when you start getting crank endplay like that, what has physically occurred to allow that? I understand that the thrust bearing is 'gone', but what does that mean? The bearing has worn down? Broken off? Crushed?

From looking at pictures of that area, it seems like it would have to have worn off completely... but there are oiling holes there, so then I shouldn't have oil pressure... and my oil pressure is fine?

I lost my last motor to main bearing failure and so this particular problem sounds 'scary' in that sense. But I guess I just wonder how long this could conceivably run like this...?

95sscamaro

iTrader: (6)

Hey man I was talking to you @ the meet last sat. Does that motor still have a warranty?

moehorsepower

iTrader: (3)

Yes as you know the thrust bearing evidently has side wear thus causing the end play, what caused this? maybe when the motor was built the bearing was not seated properly. usually it is more predominant in automatic cars due to converters ballooning putting excess load on the thrust bearing. You could try and drop the pan and just pull off the main cap and look how much wear there actually is and go from there.You could just replace the thrust and the other mains if you want a little piece of mind but that means pulling the motor because I don't believe its possible to do that with the motor in the car, but it sounds like you enjoy doing stuff like this so grab a few friends, and do it in a weekend. I did a small block in my truck with a friend in one day, we pulled the motor and I installed a new crank, granted it was a heck of a lot easier than our cars but you can do it in a weekend...

TheHeadFL

It would be time expired by now (motor went in 2002) or voided by installing my cam. But it did have a 50,000 mile warranty.