The BSA A7-A10 Forum

Technical (topic titles must be descriptive) => A7 & A10 Engine => Topic started by: Topdad on 23.01. 2018 15:33

Title: Thunder conrods
Post by: Topdad on 23.01. 2018 15:33
Afternoon fellow mentalpieces , sure I followed a post about Thunder conrods just before christmas , I've searched without luck so can anyone confirm quality/ suitability for an A10 ,My con rods are the weakest link in my motor so may change 'em this year but don't want any more messing about than the rebuild so look forward to hearing what you guys think, regards Bob
Title: Re: Thunder conrods
Post by: JulianS on 23.01. 2018 16:14
Fitted a pair of Thunder rods in 2010 done about 20000 miles no issues.

Very nice product.

You might need to widen the cutouts in the cylinder to provide sufficient clearance.

They are made to correct between centre dimension, not the slightly over standard 6.5 inches as some others have been made to.


This is the original thread;

https://www.a7a10.net/forum/index.php?topic=12464.msg97788#msg97788


Title: Re: Thunder conrods
Post by: Topdad on 24.01. 2018 11:31
Thanks Julian. *smile*
Title: Re: Thunder conrods
Post by: RichardL on 24.01. 2018 12:27
I have 'em. They were given to me to make up for some inferior work by a shop that will not be named (because they made ammends). In this case, the inferior work was honing the big ends of my original rods for "clean up" without skimming the landings (and without me asking for this service), resulting in bearings that didn't fit. (That was just one of three problems.) When I received the rods, my first thought was, "Damn, he didn't send the small-end bushes." To my surprise, no small-end bushes required. The gudgeon pin runs in the unbushed billet aluminum small-end hole. As mentioned in a previous post, there is no oil hole for the left-side rod, so I drilled one. I won't go into if that's justified or not, because it has been discussed ad nauseum in many other posts and topics. Been good for over 4000 miles.

Richard

 Edit: PS, Yes, I did need to open the skirt notches just a tiny bit.
Title: Re: Thunder conrods
Post by: Greybeard on 24.01. 2018 13:29
I briefly visited their site but could not see prices. How much are these rods?
Title: Re: Thunder conrods
Post by: Topdad on 24.01. 2018 16:43
Hi GB spoke to them yesterday . Inc VAT £331.20 a pair which is a fair bit cheaper than SRM 's. however can't say I'd look forward to messing with the cylinder skirt gap ,not sure thats in my comfort zone !so once I've the pennies saved I'll decide .
Thanks for the reply Richard ,i will bear in mind , Bob
Title: Re: Thunder conrods
Post by: JulianS on 24.01. 2018 17:00
My Thunder rods came with the oil hole.
Title: Re: Thunder conrods
Post by: Greybeard on 24.01. 2018 18:08
My Thunder rods came with the oil hole.

They are very pretty!
Title: Re: Thunder conrods
Post by: gt6uk on 24.01. 2018 18:11
I bought a pair last year and mine came with the oil hole. It seemed a shame to hide them inside the engine.
Steve.
Title: Re: Thunder conrods
Post by: JulianS on 24.01. 2018 18:31
Side view.
Title: Re: Thunder conrods
Post by: KiwiGF on 24.01. 2018 19:23
Hi GB spoke to them yesterday . Inc VAT £331.20 a pair which is a fair bit cheaper than SRM 's. however can't say I'd look forward to messing with the cylinder skirt gap ,not sure thats in my comfort zone !so once I've the pennies saved I'll decide .
Thanks for the reply Richard ,i will bear in mind , Bob

I felt the same ref skirt gap/notch, but it really is as simple as marking the new notch out with a marker pen then taking to the barrels with an angle grinder, grinding 2 maybe 3mm off each side of the notch, I then put a very small chamfer on the new (sharp) edges using a file. 10 mins work at most  *work*

If you wanted to get technical I’m sure it’s possible to measure the clearance of the new rods, possibly avoid grinding altogether, but didn’t want to risk scratching the new rods during a trial fit, so just measured out how much thicker they were than the standard rods, and took that much off both sides of the notch.

I ended up with a notch only slightly less than the width recommended in the instructions anyway.
Title: Re: Thunder conrods
Post by: berger on 24.01. 2018 19:54
I thought same as steve when mine came last year , I just wanted to look at them, they had the oil hole and another surprise my girlfriend pointed out. they were made 6 years to the day of the anniversary of my death [thankyou trainee French paramedic and nhs] with a bit luck they will be on a crank and in some cases this summer
Title: Re: Thunder conrods
Post by: fastharry on 03.02. 2018 09:49
I am biased as Steve is a good friend of mine, we raced Harley Sportsters in the same team for Windy Corner Harley Davidson and a good few years on Rotax Super Mono's. He is a fine engineer, and his products are high quality at very reasonable prices, They are used in race engines all over the world. I have fitted several sets in Triumph race engines with no problems.
Title: Re: Thunder conrods
Post by: magicflem on 11.04. 2018 09:41
R&R Racing Products (USA) Billet alloy racing con rods are the way to go.
Regards,
Kim                  
Title: Re: Thunder conrods
Post by: Tomcat on 12.04. 2018 11:06
Just re built the Commando engine and fitted new Thunder rods. They are 1000% better than any 50 year old alloy con rods.