Idler gear bronze bushes

[panda911]

Good afternoon
I met an interesting retired engineer this lunchtime when I took the 1071S over to his house.
We discussed the water pump noises, he suggested adding a lubricant to the cooland to get rid of the water pump squeek.
The interesting bit was when he started talking about bronze bushes for the idler gear rather than needle roller.
Their Blackpool works had started having problems with the needle roller bearings which upon collapse tended ruin the casing around them and other bits.
They had made phosphor bronze bushes which pushed into the back of the GB and the front of the drop gear casing.
I came accross this in rebuild of Alfa racing engines Idler gear on the duplex timing chain.
Has anyone come across this in the mini drop gears?.
Thank you
BR
P

[Peter Laidler]

Interesting querie Panda..... During my enegineering apprenticeship- a real 5 year apprenticeship - in the 60's and thereafter, including a spell in a large workshop 'bearing inspection bay'*, our school of thought was that where there is 360 degrees of rotation, then bearings....., needles, tapers or balls were best. Lubricated of course, because by default, they are always 'loaded'
* some of these large tank wheel and wheel station bogie bearings were £1000 EACH!

On the other hand, for bearings that accommodate reciprocating parts/shafts AND bearings that accommodate shafts that DO NOT rotate OVER 180 degrees ( or is it 90? someone correct me if I'm wrong over the years.....), then bronze is best and gives the most area support through its whole 360 degrees. For instance, the rear swinging arm. Yep, I know....., the inners are needles but mechanically, nobody seems to know why - when lubricated bronze is best!

One of my Uni tutor group was a Timken sponsored student who was a gold mine of this and relevant info. Luckily for me, his son is still part of the manufacturers.....!

That's only what I have been taught, practiced and taught others. Certainly in your example, cased, lubricated needles are best. And it's well known that with bearings, it's like shopping at M&S**. You get exactly what you pay for
** asked by PM. M&S is a high quality English retail shop....
Any of the others come on board for comments, please.....

[Spider]

My own rule of thumb is basically, if it's high speed then it's usually low load (like Idler Gear Bearings), bearings generally work best. High load and low speed, bushes are best. Even NASA and Marrion Shovel company found this out the hard way

I feel the Idler Gear falls in to the former here. Bushings could be used, though, not my first choice, and if they were to be used, would really want an oil feed - while definitely possible, it's quite a fiddle.

The biggest single cause of Idler Gear Bearing failures is not the bearings themselves, but a misalignment between the flywheel housing and the gearbox case. In my view, the design here by the factory is far from ideal. Given their manufacturing tolerances, they should have made the Idler Gears with a dead axle, fitted bearings to that on which the Idler Gear would run, much like some of the straight cuts are offered today, though, years ago, JKD did do a Helical version.

These days, I align and match the Flywheel Housings to the Gearbox Cases and have found since doing this, bearing issues here have gone away. For some, I have also fitted taper roller bearings in to the Idler Gear.

[Peter Laidler]

Glad you came on board here Chris. And live oil feed is definitely a plus.

Back to Pandas querie now. To allow a bearing to collapse - or even near to collapse - is unforgivable, given the rumble that you'd hear early on.

Most mechanical woes are identified by the five senses. sight, feel, hear, touch and smell (was taught that water pumps contain all of those features.....)

Have a great week Chris, Pete the Pom

[CooperTune]

Having never run into bronze bushes for drop gears I have found cases that had been faced and a brass thrust made up. And for my vintage racer I machined oil impregnated bronze bushes for front upper control arms and rear swing arms. Buying blanks, I machined them taking small cuts holding an ice cube to the far side of work. Pressed in and honed in line with long king pin hone. I'm sure you know the welded rear swing arms had two steel backed bushings. Steve (CTR)

[SPO41]

A former engineering company and gearbox manufacturer here in Australia, KG engineering fitted bronze bushes to the laygear in straight cut 3 syncro race car gearboxes years ago.
They would also use bronze thrusts on the idler gear, and would press the shaft out of the idler gear, make a larger shaft and fit rollers inside the idler gear.
On some of the high HP cars, they would make straight cut idler gears, much wider than the std gear and eliminate the thrust washers.
I see no reason why bronze bushes could not be used to replace the roller bearings, but as others have said, they would require an pressure fed oil feed, and really they are unnecessary, the std idler bearing is perfectly adequate for most usage.

[BAD942B]

don't use std bronze, use a HD specialist material from Columbia Metals, Bedford then accurate machining of both bores bolted together to align properly then feed the bushes with plenty of oil, good lubrication is the key

[panda911]

Thank you for your comments.
Ingram Engineering in Blackpool did the work, owners name was Ben, think they went under in one of the boom and busts.
I am told that they were good engineers and wondered if anyone have come across their work.
BR

[MrNoo]

I have a 1300gt engine that I stripped down and the remote box idler had been bored out and a bronze top hat bush had been press fitted in, I can’t remember if the cover had the same but certainly the box did, it also had bronze crank thrusts that had been machined and then screwed to the centre main cap and block both sides.
I suspect the crank thrusts were a repair and also the idler gear bush. I flogged that engine half to death and never had any issues, I still have it sat under a bench in the workshop.
Unsure who did the work on it, it had been done prior to me getting it from the local scrapyard must be 30 odd years ago!

[panda911]

Thank Mr. Noo.
I have never seen one but have a small amount of experience fitting an oil fed bronze intermediate shaft bearing on a flat six that has now done
80k miles.
Original bearing is sealed ball race and a certain percentage fail by disintegrating and then blow ul the engine.
BR
p