Help.... Thrust bearing death.

We run a Wedge headed KB-5 block in a 3200 lb door car with a glide. We keep killing thrust bearings, only the rear surface, "crank wants to go forward". Last year this was an NA motor with only 1000 hp, we made 40 or so passes that year and when we looked in the motor we found a dead thrust bearing, VERY dead, we blamed it on the converter.

This year we are running 1500hp with a blower, made 5 passes this spring and again destroyed the rear thrust bearing surface, that time the crank wasnt to happy with it either.

Last weekend we ran it with a new Bradco converter and some new parts in the motor (crank and pistons), we made two 1/8 mile passes and its showing signs of thrust bearing in the filter. THIS @$#%*^%*@ THING IS GETTING UNDER MY SKIN.

On a better note I'm very happy with Bradco's converter, it did everything he said it would.

Brad told us its possible to build pressure in the converter from not enough return flow, that would turn it into a hydralic cylinder pushing on the crank, has anyone experienced this or heard of it?? I'm not the only high powered glide car out there I would think this would be a common problem.

We have a theary I wanted to run by you guys, Say I just launched this thing, now we have loaded all the driveline from the converter through the trans and driveshaft. Ok that puts all the splines in a state of bind ( converter to imput, imput to low gear drum, tailshaft to yoke. Now the rear suspension goes to work, after the first .5 sec or so the car starts to sqwat, with that the rear creeps forward a little, all that load goes right through the tranny and into the crank........ does this make sence??

I know Mike said to use a different bearing in the thrust and maybe I should, but with a dead bearing after two 5.40 seconds of WOT time I think I have other problems.

Im sorry for rambling on here but I have to solve this, we are an unsponsered nostalgia team, I cant keep tearing parts up like this.

 

I had a problem with this on my car, same deal 3100 lb door car. Lots of load on the crank, etc. Check the converter to make sure it has room to move back & forth inside the rear of the crank. If the flex plate tried to flex, but the converter is bound up on the back of the crank, it will kill the bearing. I switched over to a meziere 1 piece unit that has a centering hub built into it and haven't had any problems since then. Excess converter pressure can definitely cause this problem as it tries to push the converter away from the transmission.I do know that a lot of the big turbo motors go thru thrust bearings on a regular basis and have had to use a torrington type bearing in the front of the crank between the front throw and the front main.

 

Check the flow in the oil cooler and lines

 

I checked that when I put it together last time, it moved easily on the pilot by hand.

How much flow should I be looking for in the cooler lines, and how much pressure is suppose to be in the converter, I'm guessing the converter wants a little pressure in it to keep the fluid free of air and stop cavitation.

 

Most all stock powerglide pumps have a restriction in the pump stator support. You can buy all the trick high flow input shafts and never get any different flow until you remove the pump restiction. I think the restriction is about 1/8 inch hole. You can drill it out to 1/4 but need to remove the stator tube to get all metal out after, so then you need an after market stator tube to replace it.
We have always added extra oil to the thrust bearing. There are multiple ways to do it but the easiest way is to file the parting line of the thrust bearings from the oil channel back to allow a small amount to direct oil to the thrust. Never had a problem with thrust bearings.

 

Right now we dont run a cooler, never needed one. Instead we loop the lines with -6 hose, we just rigged up a pressure gauge in my loop and got 90 psi at idle in low gear and pegged my gauge at 160psi at 3000rpm in low gear.

Sounds like way to much converter pressure to me, I dont think my loop is the restriction or I wouldnt see that much pressure between my two identical fittings.

Where does the cooler circuit feed back to? Why is there a restriction?

Brad at Bradco told me to put a regular fuel system bypass set at 60 psi returning straight to the pan, sounds like a good idea to me.

What do you think?

About the extra oil to the thrust bearing, I think its a great idea and what could it hurt.

 

I just spoke to a racer yesterday about the same problem, he changed the convertor and had the same problem. he found out the new convertor was thicker by 1/8. by calling the manufacture of the convertor. not sure if this applies to ur case.

 

Cooler circuit feeds cooler oil to lube bushings and planetary gears. I wouldn't return the oil straight to the pan unless you want to have major problems from lack of lube. It can be done with some pump mods, like when running a ringless input shaft. If you plan putting a tee inline and returning the 60 psi to the pan so you still have lube then it will be ok. Normally during a run you will see system pressure on cooler. Most racing powerglides 180-250 psi depending on boost valve and regulator spring. Converter feed is off of line pressure and under load can create more hydraulic pressure. Converter stall is effected by charge pressure. Lower pressure = higher stall. Viscosity effects stall also so hot oil will raise your stall some.
I think the factory put the restriction in to keep the converter tight at high rpm, less loss when driving down the road = better mpg. Also would require less pump volume to be used. I would always run a cooler on a race transmission. I have seen internal converter parts blue from heat because the driver shut off the engine at finish line, then the oil left in the converter cooked everything. You need to let it idle for a bit to get the hot oil out of thel cooler, but if you have a converter that doesn't create heat then you don't need anything. Sorry so long.

 

Well if someone built a converter that didn't make heat they would be a millionare.

I always let the motor idle a while after a run, usually until im around the corner and stopped, I think it helps cool the valves down in the motor as well.

I took a temp reading on the trans after a pass and the pan was 120* and the converter was 200* I didnt think that was bad at all.

And yes i was talking about tee'ing the bypass to the pan.

 

Im telling ya man ya got too much motor for that car! Lets just swap motors and you wont have another problem ever again.

Youre being stubborn. Im beginning to think Ill never get that thing away from you.

 

With the problems I've been having I'm not quite sure why you want the damn thing anymore.

Never to much motor!!! Man is it a ride.

 

Ill be at the World Series this weekend. Im not racing but just camping out. Ill probably be way out by the return road. Red trailer with Farmboy Motorsports on the side in white. Lets talk a while and at least meet face to face. If you show up at the right time we'll have burgers or pancakes and sausage for breakfast if youre early enough.

 

Larry,

Do you see any evidence of the input yoke bottoming out on the output shaft of your tranny? How thick is your motor plate and do you have any engine limiters to keep the engine/trans from moving back on the launch? Could have the same effect as the rear end moving forward. Just something to check.

 

Ronny
We have 1/4 mid plate and front plates, we havent used any engine bracing but we are going to now. The yoke doesnt bottom out, but we are concerned with the splines getting bound under power, as far as I can tell the yoke moves .050 or .060 into the trans during a pass.


Flying Pig
I'm planning on being there for a while but im not racing either, and I will look for your trailer. It is nice to BS with other crazy Mopar people.

 

Ya know 23Ts got an idea there. Have you thought of putting the engine/trans in a different car? Something solid like a digger or altered with no suspension. Make a couple half passes and check the bearings again. Anybody close to you thats set up for Mopar?

 

Is that a hint that you want your car to be the host? I think it might fit.

 

I suppose it would fit but Im not certified. Still need helmet bars. We could try it if theyd let the car in for TT. I need a short trans too. Can you see why Im not racing right now???

 

Call me at the track.

319 981 7711

Ill answer if I can hear it ring.