Balance shaft
Balance shaft
Hi All,
Well I'm getting back the enthusiasm that I need to rebuild the stripped engine thats sitting in my garage wth a very sorry for itself bike sat next to it. Anyway - the noises that were initially diagnosed by a local garage as main bearings going turn out to probably be the balance shaft on it's way. If you look carefully at the machined face of the shaft just behind the weight it is marked a bit...... apparently a sure sign it's going. Rather than spending about £150+ on a new shaft and bearings though, has anyone ever taken one to an engineering place and got the shaft turned down slightly and fitted an oversize bearing ? is it an option ?
Cheers
Ed
Well I'm getting back the enthusiasm that I need to rebuild the stripped engine thats sitting in my garage wth a very sorry for itself bike sat next to it. Anyway - the noises that were initially diagnosed by a local garage as main bearings going turn out to probably be the balance shaft on it's way. If you look carefully at the machined face of the shaft just behind the weight it is marked a bit...... apparently a sure sign it's going. Rather than spending about £150+ on a new shaft and bearings though, has anyone ever taken one to an engineering place and got the shaft turned down slightly and fitted an oversize bearing ? is it an option ?
Cheers
Ed
That is possible Edarter as long as you can get an oversize bearing ( what size is on it at the moment?). The other options are spray metal and then turn down to original bearing size. If steel then you can MiG weld the shaft drop into a lathe and turn down to bearing size. Whats the shaft made of ?
Hope that is some use
Lee
Hope that is some use
Lee
no idea what it's made of Lee - i would imagine plain old steel, not sure whether it will have been hardened or not though. Not keen on the spray metal option though - I think there would be a fair bit of energy going through this part. Welding up and turning it back down again may be a thought though...
Thanks
Ed
Thanks
Ed
Unfortunately guys, with respect, you're both out of depth on your bearing knowledge.
The shaft surface, where the roller bearing runs, is case hardened and ground to to size to an in-comprehendably high standard.
Trying to re-create the required hardness and finish that a roller bearing could tollerate is financially and practically nothing like viable.
Even the most superb of lathe finishes would destroy a roller bearing and the shaft in seconds.
The required harness could also not be replicated.
You'll need to purchase the new parts I'm afraid but looking on the bright side, it is unlikely you'll ever have to service this part again.
Andy.
ps. couldn't find 'in-comprehendably' in the dictionary but you get the idea.
The shaft surface, where the roller bearing runs, is case hardened and ground to to size to an in-comprehendably high standard.
Trying to re-create the required hardness and finish that a roller bearing could tollerate is financially and practically nothing like viable.
Even the most superb of lathe finishes would destroy a roller bearing and the shaft in seconds.
The required harness could also not be replicated.
You'll need to purchase the new parts I'm afraid but looking on the bright side, it is unlikely you'll ever have to service this part again.
Andy.
ps. couldn't find 'in-comprehendably' in the dictionary but you get the idea.
After paying out the £80 odd for a new balance shaft, which started rumbling after about 600 miles, I managed to find a way of repairing the old shaft, this has now done about 3000 miles & is still as quiet as a new shaft!
I contacted my local Bearing supplier & purchased a bearing sleeve, which measured 25mm outside diameter, 25mm long & I think it was 21mm inside diameter, cost about £3. This is basically a tube with a ground & hardened surface!
I then contacted a local small engineering firm with a Centre lathe, they were able to hold the Balance shaft in the lathe & machine the old bearing surface down to suit the bearing sleeve, they also had to machine down the 'Gear' end slightly to allow the bearing to slide over.
They commented on the fact that the machining was particularly difficult due to the hardness of the old bearing face & the fact that the shaft, by the nature of its purpose, was ‘considerably out of balance’ which stopped them running the lathe at the ideal speed.
The sleeve was then fitted using some bearing Fit Locktite, the sleeve had to have a chamfer ground on the edge as it fouled on the Engine casings.
I contacted my local Bearing supplier & purchased a bearing sleeve, which measured 25mm outside diameter, 25mm long & I think it was 21mm inside diameter, cost about £3. This is basically a tube with a ground & hardened surface!
I then contacted a local small engineering firm with a Centre lathe, they were able to hold the Balance shaft in the lathe & machine the old bearing surface down to suit the bearing sleeve, they also had to machine down the 'Gear' end slightly to allow the bearing to slide over.
They commented on the fact that the machining was particularly difficult due to the hardness of the old bearing face & the fact that the shaft, by the nature of its purpose, was ‘considerably out of balance’ which stopped them running the lathe at the ideal speed.
The sleeve was then fitted using some bearing Fit Locktite, the sleeve had to have a chamfer ground on the edge as it fouled on the Engine casings.
Great bit of ingenuity d5aul. I'll bear that tip in mind in case my balance shaft ever wears again.
Deffinately a job for the experienced tinkerer though.
The lathe balance issue, while trying to machine the shaft at an ideal speed, can be easily resolved by bolting a suitable counter weight to the lathe chuck opposite to the weight on the balance shaft. Its a common solution for machining unbalanced work pieces at higher speeds.
Did you find out why your replacement shaft failed so quickly?
I know they are a common weak point but they usually last many thousands of miles.
Andy.
Deffinately a job for the experienced tinkerer though.
The lathe balance issue, while trying to machine the shaft at an ideal speed, can be easily resolved by bolting a suitable counter weight to the lathe chuck opposite to the weight on the balance shaft. Its a common solution for machining unbalanced work pieces at higher speeds.
Did you find out why your replacement shaft failed so quickly?
I know they are a common weak point but they usually last many thousands of miles.
Andy.
If they are \"roller bearing\" quoted by agermaney then you still can weld the shaft turn to say 3,000 oversize and use a crankshaft grinder to finish.
The hardness of this piece of steel will never be recreated but by time you have MiG welded it ground its going to be getting hard at that point.
Try your local engine rebuild shop they will have a crankshaft grinder Ford say Cosworth crank cant be reground due to the hardness which is ****ocks had mine reground and 40,000 miles later still going strong.
Nothing is never unserviceable.
Agermaney who mentioned HARNESS?
Go with d5aul`s idea sounds good to me
Lee
The hardness of this piece of steel will never be recreated but by time you have MiG welded it ground its going to be getting hard at that point.
Try your local engine rebuild shop they will have a crankshaft grinder Ford say Cosworth crank cant be reground due to the hardness which is ****ocks had mine reground and 40,000 miles later still going strong.
Nothing is never unserviceable.
Agermaney who mentioned HARNESS?
Go with d5aul`s idea sounds good to me
Lee
Fixing counterweight to the shaft may have been an option but there was no real way of fixing it!
Never did find out why the replacement shaft failed so quickly, I thought of trying for a refund but didnt think the supplier would entertain a refund seeing as the shaft was not fitted by a dealer, there would also be no way of prooving the returned shaft was not the original shaft.
Never did find out why the replacement shaft failed so quickly, I thought of trying for a refund but didnt think the supplier would entertain a refund seeing as the shaft was not fitted by a dealer, there would also be no way of prooving the returned shaft was not the original shaft.
Hi d5aul,
A machinist would nip a suitable counterweight between the work piece and the appropriate chuck jaw to provide the balance he requires.
I've done it many times. Anyway that's just for your interest, well done on a great fix.
On to you lee_p.
I detect quite a quite a defiant edge to your post but unfortunately you are even further out of your depth.
I served a four year apprenticeship at an engineering firm and during my college years I studied A level metalurgy. Because of this I feel an unfortunate need to correct you further, although, it's probably going to be a discussion I'll not find very rewarding.
I can confirm that the bearing we are discussing is most certainly a roller bearing and uses the shaft surface as the inner bearing face. You seemed unclear on this point having started your last post with \"If\".
If you tried to build the shaft with mig weld, the case hardening, which represents a very thin layer of material, would be destroyed and be replaced with relatively soft mig weld.
Turning and grinding back to the original diameter or beyond will clearly leave the newly formed bearing face as only soft weld material and not the original case hardened stuff.
You haven't fully thought this through have you?
d5aul's fix will indeed work if carefully done but your's deffinately won't.
As for your cosworth...Grinding a car crankshaft with hardened journals is possible and can give extended service. The white metal bearings that a car crank runs in are relatively kind and will not wear the crank quickly. After all, in grinding off the hardened outer layer, you crank has only been down-graded to a spec similar to most other car engines.
Needle rollers are much more aggressive when presented with less than perfect surfaces on which to run. They would mince the shaft surface in no time at all.
I have no objection to enlightening you lee_p, but stay clear of any scarcasm.........I don't know how much more egg your face will take.
Andy.
A machinist would nip a suitable counterweight between the work piece and the appropriate chuck jaw to provide the balance he requires.
I've done it many times. Anyway that's just for your interest, well done on a great fix.
On to you lee_p.
I detect quite a quite a defiant edge to your post but unfortunately you are even further out of your depth.
I served a four year apprenticeship at an engineering firm and during my college years I studied A level metalurgy. Because of this I feel an unfortunate need to correct you further, although, it's probably going to be a discussion I'll not find very rewarding.
I can confirm that the bearing we are discussing is most certainly a roller bearing and uses the shaft surface as the inner bearing face. You seemed unclear on this point having started your last post with \"If\".
If you tried to build the shaft with mig weld, the case hardening, which represents a very thin layer of material, would be destroyed and be replaced with relatively soft mig weld.
Turning and grinding back to the original diameter or beyond will clearly leave the newly formed bearing face as only soft weld material and not the original case hardened stuff.
You haven't fully thought this through have you?
d5aul's fix will indeed work if carefully done but your's deffinately won't.
As for your cosworth...Grinding a car crankshaft with hardened journals is possible and can give extended service. The white metal bearings that a car crank runs in are relatively kind and will not wear the crank quickly. After all, in grinding off the hardened outer layer, you crank has only been down-graded to a spec similar to most other car engines.
Needle rollers are much more aggressive when presented with less than perfect surfaces on which to run. They would mince the shaft surface in no time at all.
I have no objection to enlightening you lee_p, but stay clear of any scarcasm.........I don't know how much more egg your face will take.
Andy.
errr....cheers for the updates guys. Looks like it's a sleeve or a new shaft and bearings LT did say thiat there is no harm in running it as is until I cant take the noise any more - as the available funds were used up in buying the gaskets etc for the now unnecessary rebuild I guess I'll leave it as is for a while and tackle it again in a few months...
back over to you chaps for a spot of bearing tennis
LT did say thiat there is no harm in running it as is until I cant take the noise any more - as the available funds were used up in buying the gaskets etc for the now unnecessary rebuild I guess I'll leave it as is for a while and tackle it again in a few months...back over to you chaps for a spot of bearing tennis
ebay bottom end
had a look at it last night, it had loads of play in crank...
i needed one too.
i needed one too.
brmmmmmmmm brmmmmmmm