A10 pushrods

[Greybeard]

Last year I had a very nasty experience with light alloy push rods - see first photo below. So I would not use them again. The other point was rub marks along the rod which indicated to me that theyhad been flexing.

I then bought a set of original type rods. Wassell make. They were dreadful, the ends were not properly machined - see second photo. They were sent back to supplier. Would not buy rods made by them again.

Finally got a set from SRM which were delivered the day after I ordered them. Top quality. Heavier than standard ones. No rub mraks evident to indicate flexing and I am very pleased with them.

My experience with replacement ally pushrods was identical. I even had to smooth the end caps by putting them in my drill chuck and shape them with emery cloth. When one broke I bought SRM steel ones; expensive but presumably reliable and well made.

[duTch]

 

The ends were bored for the hardened endcap rest of rod was solid.

 i'll say that sucks for starters, and suggest a cap over the ends would be better 

  I bought Dural rods from somewhere, maybe Kidderminster(?) and ends were F***ed, and had to do similar to GB;

I even had to smooth the end caps by putting them in my drill chuck and shape them with emery cloth.

 ...but having done that, have done +10K miles, and having checked the clearances occasionally not too much to worry about (so far)

[Klaus]

I use selfmade alloy pushrods form VW Beetle in all my engines with no problems. They are lighter than the origininal steel ones.
The SRM are in douple the weight and not usefull for racing.
I have a set from this heavyweight SRM pushrods, not long used. If you have interessed to get these let me know.

Cheers Klaus

[mikeb]

the queston has been covered really, tho heres the notes i made on the topic, copied from various:

• standard steel pushrods: 171.5 grams for a set
• parallel alloy pushrods: 127.5 grams for a set

(but i didn't record the weights of mine - some folk measure their differences as less)

• Dural ones flex like noodles at high RPM's. 
• dural push rods - the problem with them was noise. Also don't use on iron head due to different expansion
• chrome molly - More accurate valve timing at high rpm's more than offset the valvetrain weight penalty

I also wondered about higher lift cams and heavier springs loading up alloy rods and flexing them more.
so my conclusion-
steel for road use. maybe alloy if you are a racer or red-liner (tho maybe steel too)
suck it up and pay the srm chrome-molly premium for no -post-purchase regret (or re-machining). worked for me.

[Joolstacho]

Now I'm scared Mike! How do we know that the dural ones 'flex like noodles" at high revs?
Then "alloy if you are a racer..." ?
(And can I bear to swap mine out for the original BSA steel ones? Hmmm).

[mikeb]

How do we know that the dural ones 'flex like noodles" at high revs?

read this thread which summarizes someones testing: http://www.britbike.com/forums/ubbthreads.php?ubb=showflat&Number=195842
unless you treat your bikes like Klaus or RR or muskrat you may be overthinking this - if I had original ones that were straight I'd put them back in.

PS my notes are a onenote file with just cut and paste snippets from various sources when I'm stuck with a problem, so i don't have all the sources, but i do have that one . reading the original and making your own decisions is way better than following my random views.

[Tomcat]

Push rods do flex, engine manufacturers use overhead cams for that reason (and valve train weight). I've often wondered if a 'pull rod' would have been better than a push rod? 

[muskrat]

I've never had the luxury of high tech (or low tech for that matter) measuring equipment. I use seat of the pants method. My tapered alloy work better than the straight alloy. The alloy being lighter allow the motor to rev up quicker. I have a hill, hit the bottom at 60 and see what I get before the police radar post at the top!!! (my turn off is 100 yards short of them  ). I luv grapefruit the missus don't.

A  Does any one know for sure what the total length and radius of the original A7 and A10 pushrods was
Cheers
lost a lot of data with last computer crash

[Black Sheep]

Pushrods can and do flex. My uncle put a strobe light on his Rudge so you could observe the external pushrods flex - and they certainly did.