The BSA A7-A10 Forum

Technical => A7 & A10 Engine => Topic started by: t20racerman on 30.05. 2011 11:44

Title: My SRM conrod bolt nuts touch the casing and won't let the crank turn!
Post by: t20racerman on 30.05. 2011 11:44
Hi all

Just building up my 1959 A10 bottom end (after it has been off the road for 10 years  *sad2*) and I fitted my lovely new (actually bought them two years ago) SRM conrod bolts, new mains etc and started to assemble the engine... only to find that the crank won't turn all the way around as one nut on the big-end bolt on the timing side fouls the casing! It only just touches it, but nonetheless, the crank won't turn 360 degrees. The new nuts are longer and wider at the top than the original ones.
So, what to do:
 - Take the angle grinder out and just touch the outside corner of each nut to take about a mm of the edge?
 - Take the angle grinder out and grind the inside of the casing to make a bigger gap?
 - BOTH of the above?
 - Strip the cranks and try to take the top edge off the nuts in my lathe?
 - Try and source bolts from somewhere else that are shorter?

I really want to get this built up asap and my preference is I think for both of the first two suggestions. Anyone else had this problem? Any thoughts?

Thanks

Title: Re: My SRM conrod bolt nuts touch the casing and won't let the crank turn!
Post by: MG on 30.05. 2011 12:11
Yep, I had that happen recently. I went with your suggestion no.1, took the crank back out and filed a small chamfer on the ouside edge (no angle grinder reqd, just a good file). The original nuts have a smaller diameter lockingn ring on top, while the SRM (ARP) ones got the hex going over the full width, that's where the problem comes from.

When did you buy the bolts? I have reported the problem to SRM end February, and they promised to add a note to future sales. If they didn't do it, I am gonna have to drop them some bad bad notes....

HTH, Markus
Title: Re: My SRM conrod bolt nuts touch the casing and won't let the crank turn!
Post by: t20racerman on 30.05. 2011 12:14
Yep, I had that happen recently. I went with your suggestion no.1, took the crank back out and filed a small chamfer on the ouside edge (no angle grinder reqd, just a good file). The original nuts have a smaller diameter lockingn ring on top, while the SRM (ARP) ones got the hex going over the full width, that's where the problem comes from.

When did you buy the bolts? I have reported the problem to SRM end February, and they promised to add a note to future sales. If they didn't do it, I'm gonna have to drop them some bad bad notes....

HTH, Markus

Thanks Markus - will go and get my file out. It does seem like the best solution.

RE SRM - I have been buying random new A10 bits for the past 4-5 years so that when I did get the time/money to rebuild my bike, I wouldn't have all the cost in one go! I got the bolts about 2-3 years ago.
Title: Re: My SRM conrod bolt nuts touch the casing and won't let the crank turn!
Post by: Brian on 30.05. 2011 12:27
While we are on the subject of these bolts I recently bought a set of the ARP ones from SRM, they came with a slip of paper saying to torque them to 35 ft lbs which I consider way too high, BSA recomend 22. I emailed SRM several times to clear this up but they refused to answer any of my emails. I emailed ARP in the states and they recomended 28 ft lbs. Has anyone else had this with the ARP bolts ?
Title: Re: My SRM conrod bolt nuts touch the casing and won't let the crank turn!
Post by: MG on 30.05. 2011 12:33
Yes, Brian, the recommended torque is way too high.
I used about 25 ft lbs as a good compromise. These ARP bolts are designed for modern (steel) conrods, and obviously SRM just state their standard torque figures without criticism. I bet the original A10 alloy big ends will be pretty egg-shaped when tightened to 35 ft lbs.

Cheers, Markus
Title: Re: My SRM conrod bolt nuts touch the casing and won't let the crank turn!
Post by: Brian on 30.05. 2011 12:40
Thanks Markus, around 25 was what I had decided to torque them to when I use them.

I was very dissapointed with SRM over this. This was the first time I have dealt with them and when I ordered the bolts they where good but as soon as I had a querie they didnt want to know. I sent several e-mails with no reply. I wont deal with them again nor would recommend them to anyone else.

Title: Re: My SRM conrod bolt nuts touch the casing and won't let the crank turn!
Post by: MG on 30.05. 2011 12:48
I can understand that you are disappointed, Brian.
I have emailed them some questions and remarks in the past, and always got a reply and good advice. Sometimes it would take them a few days to respond, but that's something I can live with.

Basically I am very happy with the quality of the parts they supply, never had any problems there. The only thing that I found really annoying so far was parts running out of stock and SRM being unable to give any RELIABLE/RELAISTIC dates for delivery. So I agree, their customer service could indeed be better.
Title: Re: My SRM conrod bolt nuts touch the casing and won't let the crank turn!
Post by: t20racerman on 30.05. 2011 15:32
Just as a follow up, the file did a good job and the nuts now clear the casing nicely. The bottom end is assembled and I look forward to getting this bike running again.  *smile* *smile*

On the subject of torque setting - I did try the 37ft/lb setting first, partly so as the instructions with the bolts said to tighten them up twice to this torque to get rid of any residual stretch, which seems to make sense. Once at this setting, the conrods wouldn't move freely at all on the crank - they were both really stiff. I thought 22ft/lb seemed a bit low with such decent bolts, 37 far too high, and settled on 27ft/lb. The rods rotate very freely at this torque so it should be OK.
Title: Re: My SRM conrod bolt nuts touch the casing and won't let the crank turn!
Post by: RichardL on 30.05. 2011 20:42
I have found the best way to work with SRM is to telephone them directly. Gary for mechanical, John for electrics.

Title: Re: My SRM conrod bolt nuts touch the casing and won't let the crank turn!
Post by: muskrat on 30.05. 2011 20:44
Ah yes, what a horrible feeling, what the #@%* did I do wrong.
I swapped a A7SS crank for a LJ A10 and had the same problem. I was surprised that there is so little clearance in there.
Good to see you got it sorted.
Cheers
Title: Re: My SRM conrod bolt nuts touch the casing and won't let the crank turn!
Post by: bsa-bill on 30.05. 2011 21:27
I got some bolts from Mike Cheyne (spelling) that he had made, he discovered this too and sent me replacement nuts that had the bottom of the nut rounded off, fixed it fine thanks again Mike if your in here
Now this might seem/be obvious and I apologise now if this offends anyone but it is possible for one of the rod bolts  to catch the bottom of the crankcase where the raised bit for the oil return is when the barrels are off, this does not happen when the barrels are on (because the top of the rod is always travelling perpendicular)
Title: Re: My SRM conrod bolt nuts touch the casing and won't let the crank turn!
Post by: muskrat on 30.05. 2011 22:06
G'day Bill,
             mine touched at about 7 O'Clock looking from the drive side. I think there would be small differences in the castings so mine caught there and another one might catch at another point.
Cheers
Title: Re: My SRM conrod bolt nuts touch the casing and won't let the crank turn!
Post by: fido on 31.05. 2011 07:57
Good to hear the A10 is coming together. You will no doubt remember when we took your engine bits down to SRM in my topbox, for the timing side bearing job. The firm was a far cry then from what it is now.
Title: Re: My SRM conrod bolt nuts touch the casing and won't let the crank turn!
Post by: t20racerman on 31.05. 2011 09:30
Good to hear the A10 is coming together. You will no doubt remember when we took your engine bits down to SRM in my topbox, for the timing side bearing job. The firm was a far cry then from what it is now.

I really don't remember that....  I vaguely remember going there and looking around inside, but that is about all. It was down in Cardiff docks then.

Yup, bike coming on - will hopefully have bottom end in the frame this afternoon. Sadly the gearbox layshaft and bushes are pretty badly worn and I may have to send it off to SRM who claim "2-3 weeks" to get it done - I was hoping for quicker than that...  I'll post a query on here on a new thread for advice to see if there are any quicker alternatives, or spares for sale.
Title: Re: My SRM conrod bolt nuts touch the casing and won't let the crank turn!
Post by: tombeau on 31.05. 2011 12:00
I hope they're not building customers engines with those *eek*
Iain
Title: Re: My SRM conrod bolt nuts touch the casing and won't let the crank turn!
Post by: SRM on 08.06. 2011 12:26
Hello A7/A10 forum
we are concerned that owners maybe having problems with the ARP product supplied by SRM
specifically the ARP bolts supplied as OE replacement for standard rods.
The ARP bolts SRM supply are shipped with the bolt-specific instructions that come directly from ARP. I have been in contact with ARP who have confirmed that the bolt 14AG2.600-1, should be used in accordance with the supplied instructions.
As reflected in this forum, this is not always an effective solution for you guys so I have spoken to Geoff Dewhurst, SRM workshop manager, and he has measured a set of standard conrods, at various torque settings, to find out what was happening. The rods distort by about 0.001? at 37ft/lbs at a perpendicular to the joint face.
The original rods would have been torqued to 22ft/lbs and the big-end face honed to finish, in an ideal world the conrods would be assembled and torqued to the new ARP specification and the big-ends re-honed to suit the new bolts.
As owners probably prefer a straight fit Geoff pragmatically advises the following;
?We have found that in some cases these bolts (ARP) torqued to 37ft/lbs, may distort the con rod end-cap, resulting in a restriction of free rotation, accordingly, SRM recommend reducing the setting to 28ft/lbs with an application of thread-lock on the final tighten, remember the bolts must be tightened and relieved twice with tightening to final setting on the third attempt?
Geoff also adds;
?These bolts were originally for a Triumph application but are advised by ARP to work well on BSA rods. Check for clearance on the scavenge pipe casting (timing side crankcase) on the A10?.

We would like to assure owners that all correspondence with SRM is answered, our internet address changed approx 18mths ago to www.srmclasssicbikes.com and we apolgise if any emails were lost in this process.

If you would like specialist advice the SRM department heads are;
Jon Jolley, Electrical and wheel building                  jon@srmclasssicbikes.com
Geoff Dewhurst, Engineering and workshop            geoff@srmclasssicbikes.com
Gary Hearl, Stores and parts/model specific info      gary@srmclasssicbikes.com

SRM now have a dedicated department for new product design and development and we are working steadily to eradicate specific issues with any products we supply.

Regards

Patrick
Title: Re: My SRM conrod bolt nuts touch the casing and won't let the crank turn!
Post by: Topdad on 08.06. 2011 13:01
i got my box done by SRM and they quoted 2-3 weeks but it was returned within 2 weeks and a great job, hope yours is done as well and as quickly, Bob Hebdon.
Title: Re: My SRM conrod bolt nuts touch the casing and won't let the crank turn!
Post by: muskrat on 08.06. 2011 13:13
G'day Patrick, welcome to the forum.
                                                  Thank you for taking the time to investigate and report on the con rod bolts. Well done.
I never tried your tighten & relieve method and (touch wood) have never had a failure. But I will take that on board for next time.
Never too old to learn something.
Cheers
Title: Re: My SRM conrod bolt nuts touch the casing and won't let the crank turn!
Post by: MG on 08.06. 2011 16:07
Hi Patrick!

Good of you (and SRM) to join us, great to have you here for direct communication/discussion. I hope you will be available here in the long run? I suppose you can get a lot of valuable feedback from this place.

Cheers, Markus
Title: Re: My SRM conrod bolt nuts touch the casing and won't let the crank turn!
Post by: A10Boy on 08.06. 2011 18:17
Yes, Hello Patrick.
How about making some nice new Thick Flange barrels, or even some AJS / Matchless 650 cranks?  *smile*
Title: Re: My SRM conrod bolt nuts touch the casing and won't let the crank turn!
Post by: t20racerman on 08.06. 2011 22:35
I'm very impressed that SRM took the effort to come on this forum and reply to my thread about the bolts. That is the sign of a good company, responsive to customer needs.
 *smile*

I've been using them on and off since 1985 or so and have always been impressed with their service (Main bearing conversion) and spares (loads!)
Thanks for responding guys, and in my own independent testing of the big end bolts I found that 30 ft/lb still caused a tiny bit of restriction, but 27 ft/lb (which I settled on) was perfect.
Title: Re: My SRM conrod bolt nuts touch the casing and won't let the crank turn!
Post by: SRM on 09.06. 2011 10:26
Thanks for the warm welcome gents, my department (Manufacturing, design, marketing) is a recent addition to the SRM business and I know I will be learning a great deal from owners such as yourselves.

Re the "thick flange A10 barrels", I won't be breaking any trade secrets to hint that we do have such a project "in the pipe" but as with most of our projects
we have to balance the financial return against the investment as projects like this are not cheap. Our international partners and distributors seemed luke-warm about the thick-flange-barrels and so maybe you guys can give me an idea/feedback about how many sets are potentially required?

Re the ARP bolt issue, a fuller tech explanation will be available on the SRM website under "Technical" by the end of the week

thanks again for the positive response
Title: Re: My SRM conrod bolt nuts touch the casing and won't let the crank turn!
Post by: muskrat on 09.06. 2011 13:24
G'day Patrick,
                   I'd be in for 2, and while your at it another '54 alloy head with SR big valves  *whistle*.
Cheers
Title: Re: My SRM conrod bolt nuts touch the casing and won't let the crank turn!
Post by: A10Boy on 09.06. 2011 15:54
Yup, subject to price, I think there would be a demand, lots of the originals are now on +60 or fitted with sleeves.
Title: Re: My SRM conrod bolt nuts touch the casing and won't let the crank turn!
Post by: LJ. on 09.06. 2011 17:51
A good indication to the price of newly made barrels would be to see just how much originals are exchanging hands on ebay! There are an awful lot of A10s still out there on the roads and many owners are not engineers, often we are asked where and whom can do rebores, of course SRM can undertake this.

Would be nice to have a 'package/kit' consisting of new barrels, pistons, rings etc for the average guy to do his own work. I'd certainly be up for one if they became available!
Title: Re: My SRM conrod bolt nuts touch the casing and won't let the crank turn!
Post by: muskrat on 09.06. 2011 20:49
Even better would be to make them alloy and offer 750 kits just like the trihard ones!!
I'll take my pills now.
Cheers
Title: Re: My SRM conrod bolt nuts touch the casing and won't let the crank turn!
Post by: Tomcat on 15.06. 2011 10:24
A good indication to the price of newly made barrels would be to see just how much originals are exchanging hands on ebay! There are an awful lot of A10s still out there on the roads and many owners are not engineers, often we are asked where and whom can do rebores, of course SRM can undertake this.

Would be nice to have a 'package/kit' consisting of new barrels, pistons, rings etc for the average guy to do his own work. I'd certainly be up for one if they became available!
  The kit sounds good to me, my barrels need fins welded on, a rebore (or liners) and then a couple of piston assemblies.
Title: Re: My SRM conrod bolt nuts touch the casing and won't let the crank turn!
Post by: jjbsa on 18.06. 2011 10:29
A very interesting thread, and helpful to me!  I bought a set of the ARP bolts a couple of years ago, and only got around to using them on a newly ground -.010" crank early this year.  They touched the crankcase and the crank would not spin.  So I clamped the crank with the rods in in a vise and carefully filed off the interfering bit, with the nuts at the bottom so the filings would not drop down next to the rods.  Like another contributor, I had already found that approaching the full original SRM-quoted torque on the nuts started to make the rods show a resistance to turning freely on the crankpin, so I backed off a bit when they became free again, though the torque was still over the 28 foot pounds now quoted as correct.  Now fortunately the rebuild still isn't complete, so having in the meantime discovered the forum and read all this about about excessive torque I will take out the motor and retorque the big end nuts as stated in this thread.  I am impressed that SRM have joined in the discussion in a positive way.  Perhaps they might consider contacting people who have bought these bolts, mentioning the updated data for them - many sales must involve email where that could be done without much effort, after all.

Re the thin flange barrels: I don't think they are as bad as people say.  In the '60s I ran a home built RGS lookalike that would do 13.66 1/4 miles in road trim at NSA sprints and that had thin flange barrels.  I suspect that flange cracking on thin flange barrels came from the two halves of the crankcase not aligning perfectly at their top face and putting the flange on the barrels into too much stress. I have seen a number of crankcase sets that didn't align well - the ones on my bike had a step of about 2 or 3 thou until they were skimmed.
Title: Re: My SRM conrod bolt nuts touch the casing and won't let the crank turn!
Post by: muskrat on 18.06. 2011 12:51
G'day jjbsa,
                I blew 3 barrels off my '57 SS, cases were spot on. I think 13.5;1 comp and 8000 rpm had a bit to do with it !! *eek*
Cheers
Title: Re: My SRM conrod bolt nuts touch the casing and won't let the crank turn!
Post by: jjbsa on 21.06. 2011 09:16
8,000 is a lot of rpm!  That's Chris Vincent territory.  I'm sure thick flange barrels would be a good idea for that! 
Title: Re: My SRM conrod bolt nuts touch the casing and won't let the crank turn!
Post by: muskrat on 21.06. 2011 09:38
G'day jjbsa,
Didn't make them for the 500. Now it's an A10 and 10.5:1 I still through bolt the thick flange barrels. Once (or trice) bitten.
Cheers
Title: Re: My SRM conrod bolt nuts touch the casing and won't let the crank turn!
Post by: MG on 03.07. 2011 20:23
Richard, I'm really disappointed with you.  *sad*
I wrote a serious word of warning about enlarging the cutouts in my engine rebuild thread here:
http://www.a7a10.net/forum/index.php/topic,3195.0.html (http://www.a7a10.net/forum/index.php/topic,3195.0.html)

Do I have to assume you are not reading my posts with the necessary attention and wholeheartedness???

*Lol*, just kidding. But yes, SRM, and obviously also Thunder rods are a bit wider than the original ones and will indeed hit the spigots (I think Thunder Engineering make them for SRM anyway, but memory might be misleading me now).
So watch out there!!!!!
This is another case for SRM to maybe add a small note on delivery (hint hint nudge nudge).

Best wishes, Markus

P.S. Welcome Cherry Tree!
Title: Re: My SRM conrod bolt nuts touch the casing and won't let the crank turn!
Post by: RichardL on 04.07. 2011 04:34
I, too, am disappointed in me. I will turn in my key to the librarian's water closet and my personal copy of "Guide to the Dewey Decimal Classification System" autographed by Melvil Dewey and handed down through my family for generations.

I have to say, I missed or don't recall your post. If, indeed, I did I see it, I should have given my compliments. Very nice job.

Now, the coincidental and really bad thing is that I have those same rods and knew nothing of widening the notches in the skirts. I got the rods as no-charge replacements for my original rods that the machine shop screwed up by honing out the big-end O.D. without milling down the   landings. Because of this circuitous means of acquisition, I did not get any warning about the skirts (as noted on the mapcycle.com website, I just learned). On the other hand, I haven't heard any banging in the bottom end (restraint boys!), nor has the engine blown up in the 2000 or so miles since the rebuild. It's either luck or trouble on the horizon. I don't think I need to dismantle to find out.

I also appreciated your balancing charts and will use a translator when I have time to evaluate the data. It's possible that I flew over the balancing discussion because the same awkward shop that screwed up the rods was also charged with static balancing my crank and I would have figurered "it's all too late". The fact is, I have no way of knowing if they actually balanced it or forgot about it. Even if they balanced it, it would have been with my old rods, not the billet replacements. The good news is, I'm loving the way my bike is riding right now. Uh oh, jinxed myself, here comes the curse.

Richard L.

   

Title: Re: My SRM conrod bolt nuts touch the casing and won't let the crank turn!
Post by: MG on 04.07. 2011 07:27
 *lol*
Don't be too hard on yourself, it's all forgotten.  *beer*
Thanks for the kind words, the engine is still going strong, so t'was a successful operation.

I've come across a wide variety of these slots, depending on the machinist or his beer consumption the day before probably. Some are bigger, some are smaller, and sometimes they won't even be aligned exactly along the centre line of the spigot.
So you might be lucky to have a set that allows the rods to move freely, machined after closing day of the pubs in Small Heath. If there wasn't any noise when turning the engine over you will probably be okay, fingers crossed.