chasman414

I think I may have a unique problem. I rebuilt my 461 last winter,( again). I race it all summer so I try to freshen it every 800 runs or every 2 years . I've had a transbrake on my TH400 for 3 years but I never really used it until this year. Last Sunday the car acted funny,(unusual times and noises), so I packed up and went home. I cut the filter when I got home and it was full of copper and iron dust.I pulled the engine and the thrust bearing was almost gone on the rear side.The crank side journal was eaten into so far that the crank will now move forward almost .075 in. I called my trans guy and he said it could be the torque converter pushing on the rear of the crank! I had used the transbrake for 98 races and I have the 2 step set @ 2400 rpm, nothing excessive. My torque converter is a cone 3800 which has been gone thru twice in the last 6 years by Ultimate and the trans was completely redone 2 years ago. I've used the transbrake occasionally before but none of my old bearings showed any sign of wear. Any guesses? Oh yes one month ago I had to change my flexplate because it started rubbing on the starter and the teeth got ate up. It never dawned on me then the crank had moved forward!

70W-32

If the converter has ballooned, it will push the crank forward, causing the damage you have found. Do you use Nitrous?

chasman414

No nitrous, and I have the 2step set @ 2400 so I'm not revving it very high. I can foot brake it to 2600.

cutlassefi

Your converter ballooned.

dragline

I took 455 Olds apart that looked exactly like yours. It had also been raced. I happen to ask a converter guy about the "BALLONING" theory. He said a converter would split or crack if it ballooned enough to push the crank forward. I'm not stating fact, just passing on what he said.

matt69olds

Look at the pilot of the converter, and the bore of the crank. See in there is any sign of metal to metal contact. The pilot shouldn’t bottom out on the crank. Call Coan, ask for what the height of the converter hub to converter pilot. Lay a straightedge across the hub, measure down to the surface the converter is sitting on.

Is the converter built for a transbrake? A transbrake compatible converter needs ballon plates.

oddball

My 403 block had something bad happen to it in its past. Don't know what, but the #3 cap doesn't fit worth ****. I have to very very carefully install, torque, check, knock it around, check some more, etc etc, to get it to sit square.
So make sure when installed that you have even clearance all around the thrust. A titled cap will cause hilarious problems.

chasman414

When I rebuild, (freshen), the engine I'm careful to set the thrust bearing and I always measure my clearances. I've had this engine for 15 years and rebuilt or freshened it 8 times because of the racing. I've never had this kind of damage before. I do appreciate the advice very much though. Charlie

chasman414

No this is not a balloon plate converter, that's why I've kept the 2step RPM low. The only measurements Coan could give me were GM specks so I will do that measuring today. What surprises me is that I race with a lot of guys who don't use balloon plate converters and rev higher at the line but have not had this problem. Of course I'm the only Olds equipped car there.
Thank you very much for your advice, It looks like ballooning will turn out to be the problem at this point!. Charlie

chasman414

I measured the converter today and it's right on the money as far as GM specks go. There are no marks on the pilot, so I have to assume the converter did not balloon! If the converter pushed the crank forward it was for another reason. does a trans pump make enough pressure to just push the converter out of the trans. thereby putting excessive pressure on the flexplate? I'm very perplexed by this.

66luvr

I believe it is a ballooned converter. I ruined 3 engines with one bad converter, ..
#1, The original engine in a 1993 Chevy 1/2 ton. 4X4, extended cab long bed. I used it to tow a lot, all over the country. One summer I was without a trailer and borrowed my buddies 28' enclosed, extra height and all the goodies, cabinets, winch, lights etc, ie heavy. Later that year, later that year, not towing just going to my house in town, I heard nor saw any warning signs, but started across an intersection in my small town and very near my house in a residential area, engine started making a heck of a racket, knocking horribly. I just coasted to a stop and called a friend mechanic/ machinist at the local machine shop. They build all kinds of engines, diesel, race, and whatever. He came listened said broken crank. So I told him to get a spare 350 I had at home with a blown head gasket, which I had switched out a few years back in a 1996 Chevy truck which I bought and then sold for fun and profit, and rebuild it real quick and swap them. He checked everything, including the converter while swapping them, deemed it all ok and just chalked it up to bad luck.
So now have engine #2 in truck, all is lovely until it started knocking and leaking oil in the front and rear seals.
Swapped it for an already built, new, 383 stroker short block with all new rotating assembly, and my stock heads.
Engine #3, the stroker engine with all new parts, crank, rods, pins, roller cam, built by another local racer/ engine builder for use in his truck but sold it to me instead. Ran good, not a powerhouse I thought I might have but nice. Same story, started making noise and leaking at the mains. Then I finally saw the writing on the wall, it had to be the converter.
I had engine #2 rebuilt again and pulled the 383. The same thing you are looking at in your engine was just how my 383 looked. Worn out rear thrust bearing and the thrust ring on the new crank badly worn. Nothing to do but put more money it and sell it, which I did eventually.
But I then put an expensive anti-ballooning converter and engine #2 which we fixed/rebuilt again back in the truck and drove it for a few more years and finally sold it. And bought a 2500, 2006 Chevy 4x4 extended cab truck and drove it for several years.
The #2 engine was great in the 1993 1/2 ton and no more problems after replacing the converter.
I really believe you have a bad converter based on my/ this particular series of unfortunate events.
Good luck,
Mike

chasman414

Thanks Mike, I have already talked to Coan and Ultimate about a non ballooning converter. $850 to 1600. Not cheap by any means.

matt69olds

There is a common modification that can be done to the pump to limit the pressure in the converter. Some people swear by it. I have done it a couple times. I understand the theory, it seems to me if it was really needed or a problem Hydromatic wouldn’t have made the hole so big to begin with.


Something push forward on the crank with enough force to wipe out the thrust bearing. Using a transbrake with a converter that’s not built for a brake is a definite possibility.

Coan, ATI, Precision, all make top quality stuff. Quality parts aren’t cheap.

oddball

A quality converter for a TH400 shouldn't be that much. Ultimate makes really good stuff (I run one of his in my TH350) but I have noticed he's pushing customers to buy the more expensive units now.
PATC also has pretty good stuff and really affordable. I think they're kind of between Hughes and the specialists, quality-wise.

chasman414

These are the type of things one usually learns the hard,(expensive), way. I wonder if my trans guy new this? I wonder if my trans guy at the time new this? He's gone now so it's water under the bridge. I very much appreciate the info even though it's too late for me! Yes a new TB converter $850/1600. or more. Charlie

matt69olds

It’s entirely too easy to make horsepower now. I build a lot of transmissions for turbo cars. I’m starting to add parts now that a few years ago would have been luxuries. The powdered iron forward clutch hub of a TH400 is pretty reliable until around 1000hp. I add a steel hub to just about everything now. I can’t tell you the number of times I have built a transmission thinking the customer is making 800-900hp, then some wastegate or turbo changes and now the engine is making 1200-1300 or more. I’m guessing converter builders are doing the same.

A reworked stock cast aluminum stator use to be standard In all but the really exotic converters 10 years ago. Now it’s common for junkyard LS engines with a eBay turbo to make enough power to shatter the cast stators. I’m guessing most converter builders are using custom made steel stators. It’s far cheaper to include the few extra hundred bucks for the upgraded parts, than to repair the damage when the cheaper stuff breaks.


When it comes to the drivetrain, it always seems like the budget ends at the flywheel.

chasman414

I'm not made of money either but I will spend money if I think it's worth while. I'm just wondering if I could do the pressure limit fix on my 400, and still run my coan. (non TB) and save the $$$ for the new TB converter. I'm making about 540HP. That's about all you dare ask out of a more or less stock Olds 455 block. What is done to a TB converter to keep it from pushing on the crank and causing the kind of damage I have??

matt69olds

This converter has balloon plates. See the solid plate welded to the neck, and covers the dip in the cover?

This converter has no ballon plates. Notice the dip under the hub.


The ballon plate basically prevents the converter from stretching and trying to force the engine and transmission apart. Some manufacturers build the rear covers from a chunk of steel, or on small diameter converter they will use fabricated mounts welded to the rear cover, anything to stiffen the body.


If your engine makes 550 hp, and you set the transbrake and stand on the throttle, that 550 hp is still there. Instead of moving the car, the power is being converted into heat. When I worked at Coan 25 years ago, occasionally a transmission/converter would come in for repair that got hot enough to actually melt the aluminum stator. The stink would linger in the building for hours!!


There are no “new” converters being made. All the aftermarket converters start life usually as fwd 4 cylinder converters. The 245mm (usually referred to as 10 inch) are commonly built from 4T60 like what is found in Buick park avenues, Chevy Malibu, etc. The converters are cut part on special lathes, the individual parts are modified, sprags and stators are adapted from other bigger converters, the turbines/pumps/stators are modified or replaced with other parts that have the fins at different angles, all to give the desired stall speed. It takes a lot of modifications to make a converter designed to go behind a 200hp engine, and have it live reliably with 5 times the power. It’s amazing if you think about it. Those modifications and machine work takes lots of time, and time is money.

Battenrunner

Sorry to hear about your misfortune Chasman414.

Please keep us informed of what you find. Are you sending the converter to Coan (or elsewhere )to have it cut open and examined?

If the converter isn't ballooned.... I am spitballing here and assume you already have done the following:

Did you pull the pump out of the Th400 to inspect the drive lugs on the gears and everything in it for the Pressure regulator to make sure it isn't stuck? Did you closely inspect the pump drive notches on the converter nose?

Also, did you look closely at the bellhousing of the trans to make sure it doesn't have a crack that might have allowed flex during a high pressure event like releasing the brake where the converter could pop out and stand on the pump drive lugs?

Matt69OLDS is an awesome resource of knowledge here, and we are lucky to have him on our forum.

chasman414

This is all extremely good information and I am learning a great deal here, but I'm confused about something. I called Coan and they gave me the GM specs for my converter and told me how to measure it to see if it had ballooned. I did that and the converter measured right where it should, so should I assume the converter did not balloon but something else happened. Is it possible the converter was just pushed out of the trans?

BillK

I just looked at the picture of your bearings. If both of those bearings are from your engine it looks like only the upper bearing is worn on the thrust ? That tells me the cap was not aligned properly when the engine was assembled. You have to get the cap set so that the crank is hitting both upper and lower thrust bearings on the back side of the bearing. Otherwise you only have half of the available thrust bearing working ?

The only time I have had a badly worn thrust it was on a small block Chevy engine that had been align honed and the cap had been cut on an angle.

Excessive line pressure will definitely cause it so the modification looks plausible.

chasman414

I am very fortunate for all of you so far because I no longer feel completely lost.
I did pull the converter but that's as far as I've gone so far.You guys have lead me with this as far as the trans and converter go. I know little or less about transmissions so I'm may not be sure what you are talking about. Some things I just don't know or haven't learned yet. I will look at the bell housing next. Here are some pictures of my converter. I assume these are the pump drive notches you refer to! Once again I want to thank you all for your valuable time!

chasman414

The bearings are both from my engine but the good one is from 2019 when I tore down for the last refresh. Both halves of the thrust bearing look identical, I only used one to show the difference, but I do appreciate you looking and replying!

matt69olds

To the best of my knowledge, once a converter balloons, it stays that way. So if it measures correctly, then I would have to agree that the converter didn’t ballon.

So, the mystery deepens! It takes lot of force to tear up a thrust bearing. The question: where did the force come from? (Insert Star Wars reference!) Will the converter slip into the back of the crank smoothly? No binding or hanging up on a burr? What do the pump gears look like? Any rough edges that the converter hub can hang up on?

Once the engine is back together, and the transmission gets a clean bill of health, put a line pressure gauge on the transmission. With the vacuum modulator unhooked (which simulates WOT) you might see 250-275ish in reverse, and hopefully around 180-220 in the forward gears.

The guys at Coan have forgotten more about converter design and theory than I’ll ever know. If the converter does turn out to be ok, I hate to say it, your stuck in the middle. Engine builders always blame thrust bearing wear on the transmission, the transmission people blame the engine.

Last thought, once it’s all back together, before you start the engine, verify the clearance between the converter mounting pads, and the flex plate. The ideal measurement is 3/16 to maybe a 1/4 inch. Good luck!

chasman414

Thank you for all your help matt69olds. My plan now is to have the trans gone through and get the engine back together then go on from there. I found this video yesterday and thought it would be a good idea to go through the trans because I drive it on the road alot.

matt69olds

I also remember seeing a video about how to modify a transmission with fixed line pressure (one without a vacuum modulator) to something that only runs max line pressure at raised engine speeds. If I remember right, you drill a hole from the forward clutch feed into the reverse boost feed at the pump. I remember thinking it was a clever idea, now I’m going to have to try and find it.

Battenrunner

not a video, but a good read about TH400 pump :

http://www.ckperformance.com/images/...ut/OILPUMP.pdf

matt69olds

Found the video.

matt69olds

Well crap. I just watched that video again, its a manual/auto shift style valve body. Not going to work with your setup

chasman414

Thank you for that info, I don't know if I'm going to try to do this myself or not. I've never touched a transmission. I guess your never too old to learn though! The trans was completely redone when the transbrake went in, 2017. I just dropped the pan and there is essentially no debris in the pan or the screen so I'm thinking things should be OK.

chasman414

I had watched the same video earlier along with about 5 other long videos. I think I might educate myself on the trans and try to at least look at the pump myself. The thing is I had driven this motor for 2 years worth of road and racing with no damage to the thrust bearing on my last tare down in the fall of 2019. I'm convinced this is all because I started using the transbrake this year from day 1 on a fresh rebuild. I started seeing bearing debris in the 1st and 2nd filter. I made the wrong assumption that it was brake in debris. The Olds has always had bearing debris in the filters to some extent. This just turned out to be the thrust bearing and crank.I wish I knew more or understood more about the TH400. I guess it's time to go to school!
I'm thinking maybe of going back to foot braking. I would hate to do that because I'm just getting used to the TB, it makes for a more accurate reaction time. As always: thank you, Charlie
PS if you find any useful info please send it to me!

matt69olds

Since you have a transbrake, you can remove the pump, forward clutch, and direct drum without valve body removal, just by supporting the trans in a bellhousing up orientation. Remove the extension housing, get a 5gallon bucket and a sturdy piece of plywood, drill a hole big enough to fit the output shaft through, homemade holding fixture!!! Drill a few extra holes in your plywood so oil can drip into the bucket.


Remove the pump bolts, there are either 6 or 8. There are 2 threaded holes in the pump for a slide hammer. They are 3/8x16 thread. One hole is around the 10 o’clock Position, the other is at the 5. If you don’t have a slide hammer, you can use a 2-3 ft section of chain. Put the some 3/8 bolts thru the chain into the threaded hole of the pump, Put a long pry bar or piece of pipe thru the chain, set it on the bellhousing, and pry it with a quick jerk. The pump will pop out easily.

chasman414

I'm going to assume your name is Matt. I haven't decided yet if I'm going to attempt this myself or not. I have a lot of things going on right now so I don't want to rush into anything. I'm certain that my racing season is over for this year anyway,(it typically ends at the end of Nov. here in Michigan).
I think our discussion has led me to a probable cause. I'm almost certain the converter did not balloon but something is causing the pump to put excess PSI on the converter when the T brake is used. If I knew what I were looking for I might attempt it but I don't think I'm ready yet! When I decide what I'm going to do I will let you know. I'm sure that if I decide to tackle this myself I will need plenty of help.

BillK

Chas,
Although I am normally the type that wants to do almost everything myself if it came to an automatic transmission in a race application like yours I would almost certainly get it to someone who knows what they are doing and have them take care of it. If doing it yourself would only cause a problem with the trans then I would say go for it but as you can see the damage goes further and I know you don't want to have to buy another crankshaft

If it was mine I would have ATI do it but they are close to me. I am sure if you ask around there should be someone in your area. Go over to the "class racer" forum and ask there. Those guys are brutal on parts
http://classracer.com/classforum/index.php

chasman414

BILL, Thanks for the advice. I just talked to Charlie@ Hipster,He gave me what I think will turn out to be sound advice. He told me to call COAN and have them look at my old converter first. I just got off the phone with COAN and I'm sending the old converter in to them today!