Scat Crank Repair

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rdakota340

rdakota340

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Has anyone ever had one welded up, Reason I ask my thrust bearing surface got ate up on the back side I found what was causing it this and it was a clearance issue in the transmission.
 
haven't done the repair, but curious what the clearance issue was in your trans.
 
It only has a 100 miles on it and this is the second time and second crank and this time is a FTI converter with anti ballooning plate on this one.
 
Forged crank, probably worth it; cast crank, probably getting close to even money repair vs replace. S/F.....Ken M
 
Its a very common repair a lot of stick cars take out the thrust surface from a lack of adjustment (no pedal free play)
 
A good crankshaft place can weld and repair the thrust for you. It will probably cost a few hundred so it's up to you if it's worth it. But it can be fixed.
 
I had a 340 forged, crank guy welded up a throw and said it was a great crank. said the cast chevy crank on the ground was unrepairable (in his shop at least) because it was iron.
Cast Eagle cranks are $250 all day. Forged changes everything.
 
Long story short put motor in car drove 300 miles and rear main started leaking pulled pan seen metal and found thrust bearing ate up, So I pulled motor rebuild again with new scat crank,while I was waiting on the motor I did some research on the cause and found cooler circuit restriction could be the cause. I found that the -6 to 1/8"NPT fitting I used in the trans had only a 3/16" opening so I was told that is most likely my issue. I tore the tranny down checked stator bushing made sure that it did not spin and cover cooler circuit hole in the pump and I drilled and tapped the cooler holes out to 1/4" NPT with -8 fittings and lines to cooler. OK got motor back and wondering about my Hughes off the shelf converter I ordered a FTI converter put everything back to gether drove it 100 miles and it's done it again......!

I just did some more measuring and found that the FTI converter pilot stout is .075" taller than a stock are my Hughes converter and I it looks like it bottomed out in the crank shaft so the cooler fitting might have fixed it but I created another problem with the FTI converter. I have measured the scat crank and compared it to a stock crank and they are the same so I'm at a loss right now.
 
:Di had the same prob and a welded crank from someone who knows what there doing will work fine, never had trouble with mine till I put a dynamic convertor in it, sent it back and checked it they said it was fine , go figure, guess what it eat another crank so goodbye convertor, I switched the convertor to a ptc and shortened the drive4shaft a little and no more probs, everything worked brfore the convertor, the driveshaft was a little long so I guess not enough clearance on that and the convertor combo was a killer hope this helps
 
I have 1 1/2 drive shaft slip with the car on the ground that was one of the first things I checked on the first crank but thanks for your input . That's whats driving me crazy is I have checked everything I can think of.
 
When you built the engine, did have your mains line honed? I messed up a crank on a 360 because the mains were out of tolerance. Not following the tranny being the problem. A torque convertor ballooning, I would think would be obvious when you removed it. I would think it is a problem in the mains.
 
The block was line hone both times and there was two different converters second one has a anti balloon plate.I have not put any power too it yet just some roll full throttle pass while driving around.
 
I found someone that can repair this Scat crank and treat it also at a fraction of a new crank. The place is called Mile High Crankshaft they can fix any crank they said.
 
We talked about this in one of your other threads and I was asking if the converter was anti ballooning. I guess it don't matter if the snout is too damn long. You must have had a pretty big gap from the Flex Plate to the converter bolting it up. More than a 1/4" gap that it is supposed to have. But again .075" is really not that much but just enough to take out your Thrust..... Dang
 
Mad Dart said:
We talked about this in one of your other threads and I was asking if the converter was anti ballooning. I guess it don't matter if the snout is too damn long. You must have had a pretty big gap from the Flex Plate to the converter bolting it up. More than a 1/4" gap that it is supposed to have. But again .075" is really not that much but just enough to take out your Thrust..... Dang
Click to expand...

I typed that clearance wrong it was .37'' taller than stock but anyway the snout is bottoming out inside the crank pilot hole. When I double checked my all my clearances the converter pads was .40'' away from the flex plate. I took the crank out of the motor and bolted the flex plate up turned the converter up and set the crank on the snout and leveled it. Even though I had plenty of clearance for the converter to slide backwards in to the transmission pump there was no flex forward because the converter was already pushing the crank forward does this make sense!
 
Well I got the motor back in and had the converter snout cut .100 and I have put 125 miles on the car rechecked end play and so far all is good. So the pilot snout on the converter being to long was the cause of the thrust bearing going. I just thought I would share my out come hope this helps someone else to check this before they install the converter. Check all clearances.........!
 
Tell me more about this stuff. I have two PTC converters. One has washers welded on the c0nverter lugs and it will go into the crank/flexplate and mate right up with no gap. The other converter has about a 0.070 gap between the vert and the flexplate, and it has no washers. That vert was used on an adapter to allow a A-fuel crank to be used with the flexplate in an automatic. It is now back back at PTC and I have not heard back from them. The issue is the ARP flexplate bolt heads contact the vert front side, not the snout bottoming out.

I cannot see pulling the vert/flexplate together that much and bending it. Is this gap you guys speak of what you see when the vert is all the way into the trans and the engine/flexplate is bolted up, with the 4 vert bolts yet to be put in? I am planning to mate my 540 and tranny together before I stuff it into the car, hopefully soon.
 
OK when you get the trans bolted up to the motor and before you bolt the converter up to the flex plate push the converter back as far as it will go there should be NO Less than .125- 1/8'' and no more .250-1/4 between flex plate and converter pads. The converter pilot snout should have a minimum .040 before it would bottoming out inside the register of the crank.

My problem was just that the converter snout bottoming out before the pads touched the flex plate. So yes this is the gap I'm talking about.
 
Kinda the same thing I had going on except my vert was bottoming out on the flexplate bolts for some reason. That vert has the snout ground down also and was attached to the A fuel crank with a kludge of an adapter that I will probably have to use again. It was not on the motor when I bought the car, it was a spare.
 
Just thinking if the converter is not bottomed out in the pump then when the snout bottoms in the crank all you are doing is bending the flex plate. Should not push the crank forward.
 
Tech857 said:
Just thinking if the converter is not bottomed out in the pump then when the snout bottoms in the crank all you are doing is bending the flex plate. Should not push the crank forward.
Click to expand...

Yes it will the flex plate will not be able to flex forward at all and it will keep constant pressure on the thrust bearing. I know I have bought two crank because of this and it the only thing that I have changed. I had the converter pilot snout cut down .100 to give the converter to be able to flex forward. the reason .100 is because it was liking .040 before the pads touch the flex plate and to give me .060 of flex forward if it needs to.
Hope this makes sense to you guys.
 
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