another tremec/gearbox/clutch problem

[Disturbed1]

well mystery solved

the hub on the disc closest to the gearbox were bottoming out on the input shaft splines

1.5mm made all the difference


cheers for the suggestions guys.

chuck: have been informed that a 17/32 sealed bearing, which besides being very hard to get a hold, dont have big enough balls. was usign a custom made needle roller bearing but they to are also not recomended by tremec or mal wood

[DX20VT]

while the gearbox was being rebuilt, i also had the clutch looked at and was shown signs of wear... the clutch is a osgiken twin plate)
we had to machine 1.5mm off the flywheel cage to preload the pressure plate properly so the fingers went flat when bolted up.

That sounds a bit weird to me, the clutch was working before and you've machined 1.5 mm of the what does basically the same as the flywheel step?

[petergoudie]

In addition to the roller bearing problem, I don't think you should use plain brass as the bearing. Flywheel bearings are normally the sintered type that have very small pores throughout the bearing. They are impregnated with oil and it is normal to soak them in oil overnight before fitting.

They are made from brass powder and pressed into shape under high pressure. The bore is toleranced to allow for the press fit so that when fitted, it is the right size plus clearance for the oil film.

Do a Google on sintered bronze bearings. There is one company at Summer Hill (Sydney) and another in Melbourne. If one doesn't have the size you want try the other. They are only a few dollars in fact the train fare to get there costs more.

I think the Sydney company is called Sintered Bearings.

Some sizes are available in steel also.

(P.S Most of the oil pump gears use sintered powder as do other gears including power tools)

[Disturbed1]

sorry i used a sintered bronze material with the pores etc

didnt soak it in oil over night though - is that necc?

[petergoudie]

The soaking is what is recommended by the manufacturers however they are normally pre-soaked by the manufacturer anyway. I guess if you put a drop or two of oil onto the bearing before the shaft goes in it would soak into the bearing as well.

You mentioned in the earlier text that you turned up the bearing. If you used one of those brass rods with a hole up the centre often seen on the sales counter at bearing suppliers it is not sintered but extruded. Those rods are spewed out of an enormous press just like a piece of tooth paste from a tooth paste tube.

[Disturbed1]

come in a solid bar - about 40mm diameter.

asked for sintered bronze so can only assume thats what they supplied me with

[petergoudie]

I hope you're right. My experience with many people behind the counter is that they lack knowledge about virtually anything they sell. The company never trains them; they are expected to learn on the job (at your expense). If it was a 300 mm long bar I doubt it was sintered because I think it would be too hard to fully pack and compress in a die at that depth. It's possible the person behind the counter does not know the difference between sintered and extruded.

[Disturbed1]

will go take a pic of the stock material - was only about 100mm long

[petergoudie]

If it's extruded it often has a few lines along its length as the dies wear and leave marks. The bar will be a dull colour and often there are grey coloured patchs all over the bar. These could be burning of lubricant used in the extrusion process.

Sintered is normally quite clean and has a dull shine. It should feel greasy as well if there is any oil in it. If it was only 100mm long it could be sintered because at 40mm diameter the powder should be able to be compressed at that depth. If you look closely with a magnifying glass you might see the pores..

[Disturbed1]

[petergoudie]

The first photo shows what looks like some grainyness. If it is grainy, it probably is sintered. As I said, look at it with a magnifying glass or use a lens off a camera.

Next time you need a bearing buy one from the places I mentioned. Unless you have a reamer or are very good at lathe work, it's difficult to bore exactly to size.

Also, I expect that sintered material would not give long shavings and probably break off into chips because it is not a homogeneous material but made up of small grains.

[Disturbed1]

dads a machinist - so lathe skills are top notch

hard to compensate for the reduction in internal bore

the input shaft spigot measured 16.97mm

the spigot bearing measured up 0.06mm interferend fit OD and a 17.04 ID measurement

buy the time it got smacked in, that id went to 16.98mm.

so had to machine it out that tiny bit extra to gain the clearance i was recomended (17.03mm)

[allencr]

sintered bronze material with the pores etc

didnt soak it in oil over night though - is that necc?

IIRC the replacement Lucas starter & generator sleeve bearings had a little note about soaking it in hot oil sor a specific period of time. I used a propane torch to heat them up and then gave it a few oil can squirts.

A needle or ball bearing spigot/pilot can be semi-spectacular when they fail, but a sleeve bearing will just slowly wear out and not cause a very noticeable problem like a sudden seizure will.

[petergoudie]

You certainly went to a lot of trouble to get that size right plus you must have some good tools to measure those internal diameters. However, next time buy one from those places I mentioned and all the tolerances are built in plus the allowance for the compression fit.

I once made some bearings for a washing machine and got caught with the reduction in bore after they were fitted.

Also, I have some reservations about using a needle roller bearing. You would have to be sure the gearbox manufacturer had hardened the shaft to accept the higher point pressures from the needles. There is a chance the shaft could fail quite quickly otherwise.

[petergoudie]

Also, as a bit of trivia, Bugatti cars of the 20's & 30's used roller bearings throughout the engine. That includes the crank, big ends and camshafts. As a result, the engine was quite noisy because of the lack of damping. I remember reading a description where it said the engine sounded like a bucket of nuts & bolts being poured down a metal drain pipe.