Oder the BEBs BEFORE surgery or AFTER it is started?

[83bj60]

Hey Folks,

The question I am struggling with at this point is the following: How crucial is it to install individual bearings based on the identifications on the connecting rods?

I would like to avoid having the pan off and waiting days (or weeks) before receiving the proper bearings for each connecting rod. I've talked to a few members and other people and have heard differing and contradictory opinions on the subject.

Toyota mechs insist each connecting rod should have its own specific bearing (I'm told there are 6 or 8 different possible size, not only undersize and oversize, but also different shell sizes as well).

I am asking this because I would prefer to install ACL bearings, and those don't come in the variety that the Toyota bearings come in, but I still want to do en excellent job that will insure years of reliable service.

What do you guys do out there:

1) Remove the pan then order the proper bearings from Toyota and finish the job when they arrive.
2) Order standard bearings from Toyota then do the job.
3) Order standard bearings from ACL then do the job.
4) I did it another way, see my post.

I obviously can't have the truck out of commission for more than a couple of days as it is my daily driver but I want to do a technically sound, reliable and durable job nevertheless.

Thanks for your input for your reasons, what bearings you installed and what method you used.

Thanks for putting in your poll on what you did.

Chris

 

[crushers]

buddy, of all the BEB we have had replaced we never had an issue with ordering them before yanking the pan. if the stock sizes don't fit you have more to worry about than the bearings...
$60 from Dan at 4wheelauto...

 

[83bj60]

buddy, of all the BEB we have had replaced we never had an issue with ordering them before yanking the pan. If the stock sizes don't fit you have more to worry about than the bearings...
$60 from Dan at 4wheelauto...

Great, truly appreciate your input, Wayne, just wanted to touch base with as many people in the know as I could. Was getting concerned after reading the manual and talking to Toyota techs in new England.

Chris

 

[Greg_B]

#3.

Ensure you plastigauge, however I've not heard of a set not being in spec yet.

gb

 

[kup99]

i didn't even plastigauge mine as every set i heard of was well in spec..ge them done...well worth it if not for piece of mind....i paid $100 for the beb at 4wheel auto.. highly recommended!!! all the best...

 

[dweisger]

I plasiguaged my BEB's....they were fine. But really guys what the hell can you do if they are out.......????

Where are you going to get non standard bearings in Canada? Can Dan at 4wheel even get them?

DW

 

[Adam B]

This is a question that will never be answered consistently...

I've spent a lot of time on supraforums.com because I rebuilt and swapped a 7M-GE from an '87 Supra into my '85 pickup to almost double the HP of my old 22R-E.

The 7M is a 3.0L inline 6 that is notorious for failed rod bearings (what you guys like to call "Big End Bearings") and the dreaded "rod knock", which most people attribute to poor oiling and low oil pressure due to internal engine clearances that are out of spec or riding the upper end of spec. Well, that and the head gasket failures Toyota engineered into a whole lot of their '80's engines...

The Supra guys all swear to their graves that you MUST use the properly-sized Toyota bearings of the correct number. IE, each crank journal is measured at the factory and the number is stamped on the crank. Same for each connecting rod. Those numbers are then compared in a chart which tells which bearing number to use. The same goes for main bearings. Bearing journals in the block are measured, numbered, and stamped as well as the crank journals. The same goes for pistons. Each cylinder bore is factory-measured, numbered, and stamped on the block on the oil pan mating surface. They use 3 different piston sizes in the same engine, although if you actually measure them I seem to recall that they are only about 1/2 to 1 thou increments (0.0005" - 0.001").

After being innundated with this for several months I decided that it was all foolishness and I went with a set of standard bearings, used them on all 6 rods, plastigauged them to check, and all were right in the middle of spec. Buttoned it up and called it a day. I had the unfortunate bad luck of killing a head gasket a couple of months later, which I caught really early. I was worried about water getting in my oil so I dropped the pan while I had the head off and I replaced all rod and main bearings with the crank still in (yes you can). The newish bearings had about 5000km on them and the wear pattern didn't suggest any sizing problems to me. They all looked similar so I went ahead and put in standard sized bearings again.

If anything, I think it's more important to make sure your oil pump is on the tight end of spec. I don't know about your engine but if the oil pump is in the pan like it was on the 7M then you may want to look at this while you have the oil pan off. If it's on the front of the engine then you can deal with it later. Oil pressure is good.

You may already know the rest but someone else might not......

Getting the pan off can be really difficult if its been well-sealed in the past. I use a flat gasket scraper (like a putty knife but as thin as you can get) and tap it with a hammer. I work my way around the pan in several passes, which can take up to an hour in total. Don't try to pry too much and don't use a screwdriver or anything thick because you will create a gap that's going to leak in the future. Take your time, this will determine how well you can seal it later on.

When the pan is off to do the job, use a small wire wheel on a Dremel to clean off all the old gasket material, make sure the pan surface is burr-free and FLAT (there's a great trick for fixing it), clean up all your nuts 'n' bolts in a bucket of solvent with a wire brush (and gloves and a mask, of course), use brake cleaner to prep both mating surfaces, do not EVER use the cork gasket some kits provide, apply a bead of _____ as per the FSM diagram (some will say only use Toyota brand FIPG but I think they're crazy....I always use Copper RTV for oil pans and it never leaks), line 'er up, start with the nuts on the studs, get all bolts started, and do the whole thing in several passes - I like to radiate out from the center just like bolting on heads and manifolds, make sure you do not over-torque these since that's actually the cause of most oil pan leaks.

 

[mac]

Great info and good reminders Adam!

 

[83bj60]

A theory explaining the reason for different bearing shells.

I would like to thank all those who have partcipated so far and those who have made the effort of writing me about this issue so far. Your advice is very valuable!

I would also like to tell you what I have come to unsderstand about this issue and the theory behind the 'unique bearing' that Toyota proffesses. Surely, ths unique bearing method must exist for a good reason. So let me tell you what my theory is and why Toyota is probably right in the long run about this way of doing things, and why this may possibly not apply to ACL bearings:

We all think that once a design is implemented and parts are machined,they are all of the same exact size and composition. However, reality teaches us that this is not truly the case when parts are examined at the microscopic level.

Therefore, it would be reasonable to assume that an engine crankshaft and other parts will have minute variations between one an another. Now we know that bearing clearances are significant in dimension: this is to allow the presence of a layer of lubricant between the parts. We also now that as these parts wear out, clearances increase and can eventually lead to loss of oil pressure and eventual failure due to metal to metal contact from insufficient lubrication.

Now why would a manufacturer such as Toyota insist on such a perfect fit between a connecting rod and its bearing? My theory is that although oil clearance can and will most of the time be adequate when such standard bearings are installed, what about the clearance between then bearing shell and the connecting rod? It should be exactly 0, or possibly slightly negative in order for the bearing shell to fit very tightly to the connecting rod so as to avoid possible failure from shock between it and the connecting rod (from the forces borne of differential accelerations between bearing and connecting rod due to space bewtween those part).

Now I would suppose the reason ACL bearings are not supplied in non standard external sizes is that their shells are all a little bit oversize and probably made of a different, more malleable metal that that from Toyota's OEM bearings, making it possible for a standard bearing shells to easily conform to the connecting rod's minute variations.

What do you think of this theory? I'd love to hear your opinions on this!

Chris

 

[lshobie]

An old timer down the road from me told me a story about an old car he worked on back in the 40's. It came into the shop that he worked at and it needed a connecting rod bearing - a bearing - because they didnt have alot of money to change all of them (I forget what kind of car). Anyway, they couldnt get one for it so he used a strip of leather cut from the sole of an old shoe he had. He cut it to size, thinned it and set the "bearing" in place. Started it up and off it went.

Many years later (1970's) the same guy bought a car just like the one he worked on in the past. He decided to restore it - took the engine apart - and what did he find? The leather bearing - engine still ran. True story.

As for your theory, no idea, but I know they work - so that's good enough for me.

Regards,

 

[83bj60]

An old timer down the road from me told me a story about an old car he worked on back in the 40's. It came into the shop that he worked at and it needed a connecting rod bearing - a bearing - because they didnt have alot of money to change all of them (I forget what kind of car). Anyway, they couldnt get one for it so he used a strip of leather cut from the sole of an old shoe he had. He cut it to size, thinned it and set the "bearing" in place. Started it up and off it went.

Many years later (1970's) the same guy bought a car just like the one he worked on in the past. He decided to restore it - took the engine apart - and what did he find? The leather bearing - engine still ran. True story.

As for your theory, no idea, but I know they work - so that's good enough for me.

Regards,

Sounds like the story my father told me... He had bought a second hand Buick in the late 50s. In those days, in France, there were very few American cars around. Anyway, he thought the engine wasn't running smoothly as it should so he had it checked... Guess what, one of the pistons had been removed and replaced with a block of WOOD