ARP rod bolts

[Rocket Racer]

http://arp-bolts.com/kits/ARPkit-detail.php?RecordID=1242

a balancing specialist mentioned ARP rod bolts to me yesterday, which appear to be available for BSA's subsidiary triumph 650 bonnies.
Would triumph rod bolts be likely to be common with BSA rods?

[Brian]

You can buy ARP bolts for the A10

http://www.srmclassicbikes.com/catalogue/index.php?target=products&product_id=30

I have a set in my '61. When I bought mine they came with a slip of paper saying to torque them up to 36 ft lb or some similar spec, I ended up contacting ARP's tech department and they recommended 28 which is what I did mine up to.

[Rocket Racer]

Just what I wanted to know! many thanks.
I love this forum  

Order placed!

[Clive54bsa]

Rocket racer, I bought some ARP rod bolts for my '61 Super rocket,. installed them as instructed, installed the crankshaft, bolted the case half together, install the pistons and the barrel. turned the crank over by hand, and clunk the crank would only turn about 300 degrees in either direction. It turned out to be the nut of the rod bolt hitting the inside of the case. So I had to tear the motor down and put the old rod bolts in.and had no further problem. Not much room inside there.
Clive

[bsa-bill]

Hi Clive
I bought some custom made rod bolts from a well known Mike in UK, he wanted some made for his own use so got a batch made, I might of had the same problem as you but he had found the problem before I used the bolts and sent out replacement with the bottom of the nuts shouldered (if that's the right term) just about a 1/8th or so square section taken off the outside bottom corner.

I've had no problem with them, rather different method of torquing up though, came with special lube and IIRC instructions were to torque up to required setting and then slacken off, repeated three times to same setting, came with stretch measurements too which I checked and were spot on.

Felt like a real engineer doing al that

[KiwiGF]

Tim (aka rocket racer) are you using standard rods? ( I ask as torque settings will vary depending what rods are used, and whilst you will know that someone reading this in years to come might not!)

The issue with nuts hitting cases seems to be a question of luck, I fitted "lightning" brand billet rods from Thunder Engineering of the UK, with ARP bolts, to '56 cases and they did not hit, but others like the post above have found they DO hit.

I oiled the threads but felt nervous doing it, it seems more natural to use threadlock given there are no lock washers etc......

[muskrat]

I had the nuts hit the cases too, but it was std BSA large journal crank, rods and bolts into a '57 A7SS case. Domed the nuts a bit to give about 60 thou clearance and problem solved.
I was told once that the std A7/10 rods only had a life span of 60,000 miles.
Cheers

[Rocket Racer]

Tim (aka rocket racer) are you using standard rods? ( I ask as torque settings will vary depending what rods are used, and whilst you will know that someone reading this in years to come might not!)

The issue with nuts hitting cases seems to be a question of luck, I fitted "lightning" brand billet rods from Thunder Engineering of the UK, with ARP bolts, to '56 cases and they did not hit, but others like the post above have found they DO hit.

I oiled the threads but felt nervous doing it, it seems more natural to use threadlock given there are no lock washers etc......

I too have has problems in the past with rod bolt nuts fouling the cases. Am in the process of doing two motors and hope to use the ARP bolts in the race motor which they may not fit using modified T140 rods with steel caps. However my '61 SR build which will have std rods can always use them...
My balancer is looking to make the crank balance variable just in case I want to experiment, given my motor is short rod, not in a standard frame and dragging a racing sidecar along, so not necessarily a std build 

[jjbsa]

Hi,  I've also used the ARP bolts for A10 rods, the ones that SRM used to sell.  They were a lot better than the originals and hugely better than aftermarket rubbish that I've seen .  I also had trouble with them fouling the inside of the cases, but this was correctable with filing.

You may be surprised to read this, but the billet rods sold by Wassell are extremely good.  They are actually made by R&R, one of the top USA performance products companies specialising in conrods (drag racing and Nascar etc.).  These rods use 3/8" bolts made by ARP and are torqued to 50lbs ft and so will handle a lot more rpm than anything with a 5/16" bolt.  The junction face between the rod and the cap is also serrated.  I know the Thunder rods have a good name but these are also a very good product.

[chaterlea25]

Hi All,

You may be surprised to read this, but the billet rods sold by Wassell are extremely good

There was a problem with the centre to centre distance with these some time ago
I dont know whether this is still the case?????

John

[jjbsa]

I hadn't heard such news and I'd be grateful to know more.  Can you supply any details?  My motor built up OK.

[chaterlea25]

Hi jj
If my memory is correct the Wassel rods had 6.5in centres where as the BSA is a little shorter than this
I dont have the actual figure to hand at the mo. it led to the top of the pistons touching the head

Dont mention Wassel carb jets to me utter SH*TE !!!
nowhere near correct size, on both needle and main jets


John

[coater87]

 Old thread, same case hitting problem.

 After reading this I mocked up the motor with the new rod bolts, and they barley hit.

 For you guys that modified the rod nuts, how did you do it? I can chuck them up in the lathe and either dome them or shorten them, but I have no idea how hard these nuts are and I hate to ruin one.

 So the question is, did you use a lathe or a grinder to modify the nuts?

 Lee

[chaterlea25]

Hi Lee,
I would thread them onto a suitable sized bolt / stud thats held in the lathe chuck
Chamfer the outer ends of the offending nuts, and see if this will give clearance
If more is required shorten them a little at a time,
Only take metal from the outer end of the nuts, I would worry if you faced the flange you could go off square to the threads
An insert tool should have no bother with the material

John

[coater87]

An insert tool should have no bother with the material

John

  Thats what we were thinking a few weeks ago with a keyed shaft (interrupted cut just like a the nut) that needed cutting. We almost ran out of inserts getting that done. Between the hardness of the shaft and the keyway pounding them too, the inserts didnt have a chance.

 I will report back with the results.

 I wish I had a tool post grinder, and someone elses lathe to use it on.

Lee