Author Topic: My SRM conrod bolt nuts touch the casing and won't let the crank turn!  (Read 5561 times)

Offline t20racerman

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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

1961 A10 - somewhat modified :-)
1980 TZ350 - lunatic Classic Race machine
1967 T20 Suzuki - heavily modified Classic Racer
1967 T20 Suzuki - pretty standard road bike
2007 KTM 660 SMC - fast and furious supermoto
Triumph 675 Speed triple
Ossa 250 and yet another T20 racer in bits both being built up

"If I had all the money back that I've spent on motorcycles... I'd spend it all on motorcycles!"

Offline MG

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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
1955 A7 Shooting Star
1956 A10 Golden Flash
1961 Matchless G12 CSR

www.histo-tech.at - Restoration, Repairs, Racing

Austria

Offline t20racerman

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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.
1961 A10 - somewhat modified :-)
1980 TZ350 - lunatic Classic Race machine
1967 T20 Suzuki - heavily modified Classic Racer
1967 T20 Suzuki - pretty standard road bike
2007 KTM 660 SMC - fast and furious supermoto
Triumph 675 Speed triple
Ossa 250 and yet another T20 racer in bits both being built up

"If I had all the money back that I've spent on motorcycles... I'd spend it all on motorcycles!"

Online Brian

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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 ?

Offline MG

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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
1955 A7 Shooting Star
1956 A10 Golden Flash
1961 Matchless G12 CSR

www.histo-tech.at - Restoration, Repairs, Racing

Austria

Online Brian

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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.


Offline MG

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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.
1955 A7 Shooting Star
1956 A10 Golden Flash
1961 Matchless G12 CSR

www.histo-tech.at - Restoration, Repairs, Racing

Austria

Offline t20racerman

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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.
1961 A10 - somewhat modified :-)
1980 TZ350 - lunatic Classic Race machine
1967 T20 Suzuki - heavily modified Classic Racer
1967 T20 Suzuki - pretty standard road bike
2007 KTM 660 SMC - fast and furious supermoto
Triumph 675 Speed triple
Ossa 250 and yet another T20 racer in bits both being built up

"If I had all the money back that I've spent on motorcycles... I'd spend it all on motorcycles!"

Offline RichardL

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I have found the best way to work with SRM is to telephone them directly. Gary for mechanical, John for electrics.

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Offline muskrat

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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
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Muskys Plunger A7

Online bsa-bill

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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)
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Offline muskrat

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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
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
Australia
Muskys Plunger A7

Offline fido

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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.

Offline t20racerman

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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.
1961 A10 - somewhat modified :-)
1980 TZ350 - lunatic Classic Race machine
1967 T20 Suzuki - heavily modified Classic Racer
1967 T20 Suzuki - pretty standard road bike
2007 KTM 660 SMC - fast and furious supermoto
Triumph 675 Speed triple
Ossa 250 and yet another T20 racer in bits both being built up

"If I had all the money back that I've spent on motorcycles... I'd spend it all on motorcycles!"

Offline tombeau

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I hope they're not building customers engines with those *eek*
Iain