The BSA A7-A10 Forum

Technical => A7 & A10 Engine => Topic started by: RichardL on 25.03. 2014 04:28

Title: Sticky Crank
Post by: RichardL on 25.03. 2014 04:28
Gents,

I'm distressed. The issue of "Sticky Rod" was solved to my great satisfaction and now appears ridiculously minor. Now that the engine is tight together and mounted in the frame (without top end), I have found that it rotates smoothly in the top half of the stroke and tightens up a lot in the bottom half, but can still be forced around. The rods are still free at the bottom. No bolts are installed in the front three chain-case holes. Have I made the end float too tight? A horrible thought, considering it would mean another near total tear down.

Any uplifting ideas?

Richard L.
Title: Re: Sticky Crank
Post by: RichardL on 25.03. 2014 04:40
Another thought: I might have been too heavy-handed when tightening up the crankcase studs. Is it possible I've compressed the crankcase casting 0.0005-0.001" My recollection is that the crank turned free when the case was assembled while fitting the shims.

Richard L.
Title: Re: Sticky Crank
Post by: KiwiGF on 25.03. 2014 06:28
is the primary on? i ask as the front 3 bolts and 2 inner bolts if too long can contact the crank, usually of course it would stop it turning altogether tho  *eek*
Title: Re: Sticky Crank
Post by: orabanda on 25.03. 2014 07:00
Richard,
Could be a mis-alignment issue between the main bearings.

What was your set-up procedure for line boring the timing bush?

The Other Dick
Title: Re: Sticky Crank
Post by: duTch on 25.03. 2014 08:32

 Well you do say the front three case screws are not in, but the bottom one of the two rear ones could cause grief As Kiwi says (if in the same place as plunger ones, I think the top one clears all?), I had a similar issue long time ago caused by that.
 Over-tightening maybe- if there was a gasket in there, which I think isn't normal...?
Title: Re: Sticky Crank
Post by: bsa-bill on 25.03. 2014 10:40
Had exactly the same problem with my last rebuild, The primary front bolts were catching but imagine my thoughts when I cured that to find it still stuck when put together.
The other Dick is correct (in my case anyway) I took it back to the shop, showed the problem to the desk guy, they did it again (with another new bush) and it was fine.
I've had a bit off stuff done at that (local) shop, all good apart from the last two ( crank and rebore) shame but I think the old guy's eyes are not what they were, however they put everything right at no extra cost (apart from the extra bush).

PS I'd check alignment before be tempted to take any action re shimming other than checking it, you could and up costing yourself time and money DAMHIK
Title: Re: Sticky Crank
Post by: RichardL on 25.03. 2014 11:18
Richard, Bill and all,

Well, the alignment procedure for the timing side bush was left to the machinist. I think he described a conical alignment center that set in the main outer race. I should have asked to see it because it's already feeling like an issue while I sit here typing. On the other hand, this shop is doing all types of very serious engine machine work (albeit, not BSA, specifically) so it's just hard to imagine that he did not understand the gravity of proper alignment. I suppose I should ask him if he did the work himself. I'm wondering, if it is alignment, why would it not be tight all around?

I notice no one is suggesting running-in as a solution. Also, no bites on the case-too-tight possibility. I guess I'll be torquing the studs to a lower value to see if it helps (oh, I hope it helps). I tightened by feel originally, but think I'll need to use a torque-wrench to get them evenly looser.

Thanks gents.

Rrichard L.
Title: Re: Sticky Crank
Post by: Seabee on 25.03. 2014 11:55
Richard, you might try adding your front three bolts and torquing them first.  It could be a slight case misalignment (skew) from not being torqued evenly all around.  I know it's a stretch, but easy enough to eliminate that as a cause.

Joe
Title: Re: Sticky Crank
Post by: muskrat on 25.03. 2014 12:28
G'day Richard.
When you measured for end float did you use bolts in the holes that are used as engine mounts as well as the studs. When you've mounted it in the frame these bolts may have closed it up a tad. I'm with you in thinking misalignment of the mains would cause stiffness all the way round.
Cheers
Title: Re: Sticky Crank
Post by: RichardL on 25.03. 2014 14:32
Musky,

In my final measurements I used more than just the four dead-ended studs, but can't recall which hole or how many. I'keeping fingers crossed for getting some relief by loosening-up on all studs and hoping there has been no plastic deformation.

Richard L.
Title: Re: Sticky Crank
Post by: bsa-bill on 25.03. 2014 14:48
Quote
hoping there has been no plastic deformation.

I stand to be corrected but think you'd strip threads before you deformed the crankcase, it is after all two bell shaped casting (extremely strong shape) clamped around the circumference of a mid join.
thoughts - was the timing side bush seated firmly square against the case before it was line bored, surely it was and have you tried it with the cushdrive fitted
Title: Re: Sticky Crank
Post by: orabanda on 26.03. 2014 01:57
Richard,
I wouldn’t attempt "running in". It is likely that the machine set-up wasn’t quite accurate enough.

You are aiming for 0.0015" clearance on the crank journal. If the set-up is say only 0.002" out between the machined housing for the drive bush and the timing bush centre, then the crank will be tight like you describe (if it turns!).

The most accurate methodology is to set up off the main bearing bore (in the LH case) so that radially and axially there is zero concentricity (no run-out).
Then bolt the RH case to it (undersized bush installed), and machine to 0.0015". The bore of the timing bush is then perfectly concentric with the bore for the drive side bearing.

This job is commonly done in a horizontal borer (or mill), but mine are done in a lathe.
I made a jig out of an old aluminium bellhousing (used to mount a hydraulic pump onto an electric motor; it didn’t cost me anything).
The forum won't let me paste the pics; sorry!

Richard
Title: Re: Sticky Crank
Post by: RichardL on 26.03. 2014 02:47
The forum won't let me paste the pics; sorry!

Richard, and all,

Huh, can't post pictures? I seem to recall seeing your setup in a previous (years ago) post. I appreciate the effort spent in explaining the right process, but maybe, just maybe, things are going to be OK for me and my engine (if this was a Vincent, I would have so enjoyed saying "me and my shadow").

When I got home today I intended to start loosening things up until the stickiness went away, starting with the new dynamo pulley. Lo and behold, when I put the socket to the idler nut the crank seemed to turn over more freely. Not exactly sure why, though, last night I had poured a quart-and-a-half of oil into the crank case to be sure everything was well and fully lubricated (even though I had used assembly lube). After turning the engine over many times via the idler nut, I'm beginning to think I might be OK, and what was seeming excessive tightness had loosened up. I have posted a video on YouTube to show this and, hopefully, you and the gathering hoard will confirm my pending happiness.

 https://www.youtube.com/watch?v=ufQyjM_EpPQ&feature=youtu.be

(by the way, the white crap on the floor is the oil absorbent that I through down after forgetting that oil would come out the chain-case front three holes.)

Looking forward to all comments. Don't worry if they are negative, I'm well past the jumping off my workbench phase.

Richard L.[/size]
Title: Re: Sticky Crank
Post by: KiwiGF on 26.03. 2014 05:49
hi maanosound, I thought you had just the crank spinning in the cases, but youve got the barrel on and timing on as well, could the stickiness be caused by something other than the crank eg an oval mag gear, or dynamo belt?
Title: Re: Sticky Crank
Post by: muskrat on 26.03. 2014 06:18
Umm, your turning the crank backwards  *ex*.
Yes a bit hard to track a sticky with all the ancillaries bolted on.
Cheers
Title: Re: Sticky Crank
Post by: WozzA on 26.03. 2014 07:55
 *eek* It had me stumped why the pistons were not going up & down when you turned it over...  *eek*   *dunno*
Then I realized your got plastic bottle bottoms stuffed in the boars...   *smile*
Maybe it's COKE dribbling down the barrels making it sticky...   *whistle*
Title: Re: Sticky Crank
Post by: bsa-bill on 26.03. 2014 10:28
Quote
Umm, your turning the crank backwards

Way to go if you don't want the idler pulley to pop off *smiley4*

Yep quite a lot of stuff to cause resistance there, belt drive, new pump?, Maggie and so forth

as a matter of interest have you fitted a 357 cam ?
Title: Re: Sticky Crank
Post by: duTch on 26.03. 2014 10:29
Quote
me and my engine (if this was a Vincent, I would have so enjoyed saying "me and my shadow").
Was thinking the same thing- Harry Nilson?

Hmmm, a couple of things do concern me...

Quote
the boars...   
Maybe it'the boars...   
Maybe it's COKE dribbling down the barrels making it sticky...   s COKE dribbling down the barrels making it sticky...
   Wozza, are you a pig farmer..? You crack me up...!

 Richard, are they high or low compression drink bottles...?

 I agree with musky, good eyes buddy- I couldn't tell straightup which way it went, maybe doesn't matter much but I'd take the idler out and should turn easy without a wench...?

The only other thing bothering me is-
Quote
you and the gathering hoard will confirm my pending happiness.

 We the hordes are watching with great interest...!!!
Title: Re: Sticky Crank
Post by: WozzA on 26.03. 2014 11:20
Hmmmm..... I C what u mean Dutch...   *smile*
I KNEW I shouldn't have watched Deliverance B4 posting ...   :o
Title: Re: Sticky Crank
Post by: RichardL on 26.03. 2014 11:42
Kiwi, Yep, I should have mentioned the state of assembly when asking for opinions and advice, though the barrels without pistons would not be at play.

Musky, I knew I was turning in the wrong direction and figured it didn't make a difference but, before it loosened-up a bit, the idler nut was unscrewing when turning in the correct direction. Even though I just got out of bed, I ran to the garage to check if the turning was any different in the correct direction. I does seem a tad easier. The only thing I can think of as a reason is the new SRM oil pump. Oh man, I hope there was no "Under no circumstances should you turn the pump in the wrong direction" instruction.

Wozza, They were well-dried water bottles, which work better in sows. I knew I should have checked the spelling of "horde" while assuming no one would mind being called part of one. But really, who among you would not admit to being a bit of a hoarder, particularly of BSA parts.

Dutch,  Could you imagine the chiding I would take if I let the rods clank against the cylinder walls? Good idea about removing the idler gear. I was on my way towrd doing that when I discovered that turning over seemed not all that bad.

Bill, No 357 cam, but what matter with no head? Yeah, new oil pump and new dynamo belt drive.

Richard L.

Title: Re: Sticky Crank
Post by: bsa-bill on 26.03. 2014 12:05
Quote
Bill, No 357 cam, but what matter with no head

Some folks have had 357 cam catch on the edge of the cam tray, was not the case in mine although I wouldn't like any body parts of mine to be caught in there  *eek*

Anyway glad it's turning, not long now till you put the SADDLE BACK (pigs  get it)
Title: Re: Sticky Crank
Post by: duTch on 26.03. 2014 13:00

 
Quote
not long now till you put the SADDLE BACK (pigs  get it)

      no...?
Title: Re: Sticky Crank
Post by: RichardL on 26.03. 2014 13:15
I looked up "saddleback pig", so, no ? there, and no banjos show up at the end  when I view the video. Anyway, if I looked up "banjo motorcycle" I'd probably come up with some pipe fittings.

Richard L.

Title: Re: Sticky Crank
Post by: muskrat on 26.03. 2014 13:29
Were you thinking Razorback? Saddleback was the name of a girl I once knew  *eek* *bash*
Cheers
Title: Re: Sticky Crank
Post by: RichardL on 26.03. 2014 14:25
Well, the teams that play for the University of Arkansas are known as the Razorbacks. "Saddleback" is , indeed, also a breed of pig (and the name of a mountain range in Arizona).

Anyway, back to the crank, one of my thoughts was that if was turnable (as shown) with the disadvantage of the larger idler gear, it is probably loose enough. But, I'm not taking anything for granted. I will be working it a lot more before a final decision, one way or the other.

Richard L.
Title: Re: Sticky Crank
Post by: Topdad on 26.03. 2014 14:35
'Scuse my ignorance but surely if it was sticky and about to ruin all of Richards hard work not to mention what it'd do to his present happiness, then it would be even harder indeed even impossible to turn over with all the ancillaries fitted ? and has it now turns over with them fitted doesn't it mean that he can proceed with confidence?
 *smile* *smile*  Trying my best here Richard but honestly it must be worth moving forward now!! I've had a rotten week so far and obviously missed something but how did we get into pigs? , BobH
Title: Re: Sticky Crank
Post by: RichardL on 26.03. 2014 17:19
Bob,

Thanks. I am just on the edge of proceeding without much more concern for it, but I will do a bit more spinning the crank to reinforce my confidence.

Hmmm, how we got to pigs? I had mispelled "horde" as "hoard". Wozza countered with "bore" (as in cylinder) as "boar" (as in hog), etc, etc, etc.  Oh my, how a bunch of old guys will distract themselves.

Richard L.
Title: Re: Sticky Crank
Post by: RichardL on 27.03. 2014 01:35
Gents,

Allow me to share the jubilation and spare you the video (unless you want one, of course). Got home and hooked-up my 1/2" drill motor to the splined crank end via a 15/16" 12-point deep socket (a near-perfect fit) and the right adaptors. She turns over just fine in the CCW (correct) direction. Turned easily enough to prime the pump and push oil out of the return.

I wasn't imagining it when I felt the significant stiffness at the bottom of the stroke, but working the moving parts seems to have done the trick. I do recall SRM mentioning that the pump would be stiff at first, but hard to believe it could have been that stiff.

Regardless of the cause, I am happy and relieved. (All you members out there who are superb BSA mechanics may have forgotten the feeling.) Only miles will tell if I've created a durable engine.

Thanks all for your advice and good words. It's probably a matter of minutes before I ask for more.

Richard L.
Title: Re: Sticky Crank
Post by: muskrat on 27.03. 2014 08:33
Good news Richard. It's a good feeling only surpassed by the thrill of the first kick start.
Good luck with it.
I also spin fresh motors like that.
Cheers
Title: Re: Sticky Crank
Post by: duTch on 27.03. 2014 09:33

 Well I'm glad you explained the pigs/boars Richard- it was doin' my head in with the banjos and all from the "sticky Rods', so I did some forensic research, but found your explanation *good3* and figured when you get the seat/saddle back on, just think of Wozza and your 'boars'.....  *whistle*...is that what you had in mind B-Bill....??
 
 A suggestion for future reference- I have an old spare cush sleeve from a S/arm model (different to plunger), and the spline on that will accommodate a gearbox sprocket, thought an old sprocket could have a handle attached to crank a new bottom end - if yea know what I mean....?
 Sounds like you got it sorted, so that's good- hope it stays that way
Title: Re: Sticky Crank
Post by: WozzA on 27.03. 2014 13:05
Were you thinking Razorback? Saddleback was the name of a girl I once knew  *eek* *bash*
Cheers

I think I knew her sister....   Turtle      *whistle*