Pilot bearing was the weakest link! Need to find a new one but sealed high speed ball bearing this time.
Working on the GTs trans pics.
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Just wondering, did you indicate the bell housing in to make sure it is centered on the crank ? They make misalignment dowels to correct it if it is out. Just a thought.
Regards Brian
Regards Brian
Oh its centered. I've been driving it for years.
I Wonder... can you refit clutch, trans etc and if you can borrow a magnetic base dial gauge- place the magnet base on the sump/oil pan at rear of engine & place the probe on front lower face of bell housing, have someone push the clutch pedal while you read the dial gauge. If that action causes a reading on the dial gauge of say more than 0.005'' you have a flex issue between block/adapter & transaxle that might be causing a misalignment issue at the spigot bearing every time you use the clutch-change gear.
Bill Kearley
Supporter
Or, While things are apart. Mag base on flywheel and read the bore in the bellhousing on two planes. Check fit of trans brg retainer for fit in the bell. If all is good then go with an bronze oilite bushing.
Burnouts and donuts on 335s and a UN1 with a split shaft is my guess.
Thanks for the suggestion, I can definitely do that after I get a new bearing in place. I have plenty of magnetic base indicators. I have a few Haas CNC machines. Sometimes bearings go bad. I'm looking for a second UN1 so that I can build myself a solid shaft trans with a Q-LSD.
Will do! On the measuring on 2 planes. I do have some learning to do on why so many different preferences on the bearing type. A manufacture of heavy duty race transmissions said sealed high speed is the only thing they use and never Needle type bearings. Jac and others say bronze or roller are best. I'll have to read up on this choice of bearing topic and the advantages of each.
Hi Ken, all good suggestions for sure. You can't be too careful with tolerances when mating up non OEM parts like your Renault transaxle to a SB Ford V8. This is a well proven combination going back for decades. Jac Mac raises a good question, why did it fail? I expect checking the run out of the bell housing adaptor to the crank will be +/-.002 so you're OK there. Since the car ran for years there may be something else going on. I have concerns over the installed depth of the pilot bearing into the flywheel or crank bore. If its too shallow the bearing life will be reduced as the needles are not fully loaded. You will have to determine the distance of the transaxle mounting face to the bottom of the bore the pilot bearing sits in. Then determine the length of the face of the pilot bearing sitting on the input shaft to the transaxle mounting face. Subtract the bearing/input shaft length from the trans face/crank bore, if it's negative you've been pushing on the crankshaft (not good) and apparently gotten away with it so far. In this case the bearing might fail however both the input shaft of the transaxle and the crankshaft bearing are taking unintended loads. I know of a 347/G50 combination where the input shaft load on the crank shredded the main bearings in the engine, took about 320 miles to total the engine. More likely you'll find quite a large difference in the measurements, indicating the bearing was not fully engaged. The input shaft and crank end plays combined can't be more than .005 to .010 so .020 to .050 should work well. Which brings me to another point, if the bearing is carried on a sleeve adaptor make sure to count this part in your measurements. Also the condition of the sleeve, if it's been beaten up or worn down, that's a part you have to replace. The bearing sleeve was too long in the case I described above. Happy measuring my friend, Cheers
That is what I also saw Trevor. That is why I initially asked about indicating it in. I have seen similar results from misalignment of components.
Regards Brian
Regards Brian
ON-OFF throttle application under load will exacerbate the flex issue at bell housing/engine block interface that Ive mentioned, particularly in view of the manner in which your engine / transaxle is mounted front & rear. Under acceleration the engine lifts at front and drops under throttle closed. Since the instant center of those reactions is the output shafts of transaxle it tries the bend at that weak point between front/rear mounts.... hard to visualise, but I can assure you it does happen. A couple of 'tension' rods from front of block to bottom of bell housing helps for that.
I believe this is Faili's old car , any long term members remember if he had any problems?
Ian raised another point bout the spigot bearing adapter, if that extends too far rearward it can 'walk' out of the rear of the crankshaft over time, a better adapter can be made using 3 of the 6 flywheel bolts.
Was that a two piece or one piece input shaft Trevor? Point I was trying to make is how do you check the centerline of the transaxle input shaft in relation to the centerline of the crankshaft. Unlike a 'normal' trans like top loader etc which can be checked with a mag base dial gauge on the flywheel with probe of around the opening at bell housing/gearbox face, the UN1 bell housing is totally enclosed and only concentric area that might be able to be checked would be front seal opening on bell housing. In the case being presented on this forum there is an adaptor plate between engine & bell housing, but given Kens answers Im now starting to wonder if it was even checked by the previous owner at initial build, the problem has taken a while to show up after all.
Roller & ball bearing races do not tolerate mis-alignment for long.
Ball bearing races in the spigot of crankshafts- This area of the Ford crankshaft seems to have a variable tolerance range, often too tight and the bearing fails not long after if that is the case. ( Thats a fault/concern for Ford, but then they fit bronze or needle roller ( fitted into an alloy spigot adapter from factory, not Ball Race) both of which are soft by nature and tolerant of the dimension.
Yes its the original 2 piece. I take your point about the difficulty of trying to confirm concentric centrelines of the transaxle and crank. You're right its kind of an act of faith that misalignment is neglible. I decided to use a phosphor bronze spigot bearing originally and it's been trouble free for over 20 years now (touch wood)
I'll definitely make some brace rods. Yes this is Faili's old car. Most importantly still Aaron Johnson's engine, it's a Beast! The pilot bearing adapter did extend a bit, I did not check for squareness before using the puller to get it out. It seems that it's a two piece main shaft on the UN1 so I am looking for a second trans to build up. Thoughts?
