Best way to shorten OEM pushrods to Combat spec.

Hey Guys,

Or could you give me the spec for the Combat shortened Pushrods from Cup to ball
ex and int. if that is too much to ask. I can't find anything in the service notes.

Thanks.

follow the links , might get you there . https://www.accessnorton.com/NortonCommando/commando-valves-and-pushrods.16275/

Wrap the alum section of the pushrod in cardboard and clamp securely in a vice. Fold thin aluminum sheet metal around each jaw of a crecent wrench and tighten the crecent wrench onto the tapered part of the steel end. Hold the crecent wrench perpendicular to the pushrod and smack the wrench with a brass hammer to remove the steel end.

jseng1 said:

Wrap the alum section of the pushrod in cardboard and clamp securely in a vice. Fold thin aluminum sheet metal around each jaw of a crecent wrench and tighten the crecent wrench onto the tapered part of the steel end. Hold the crecent wrench perpendicular to the pushrod and smack the wrench with a brass hammer to remove the steel end.

Click to expand...

Please relate the second half - how to put them back on. I have quite a few good push rods except that the steel end is loose.

jseng1 said:

Wrap the alum section of the pushrod in cardboard and clamp securely in a vice. Fold thin aluminum sheet metal around each jaw of a crecent wrench and tighten the crecent wrench onto the tapered part of the steel end. Hold the crecent wrench perpendicular to the pushrod and smack the wrench with a brass hammer to remove the steel end.

Click to expand...

Thanks Jim
I'll try that method.
Cheers,

marshg246 said:

Please relate the second half - how to put them back on. I have quite a few good push rods except that the steel end is loose.

Click to expand...

I've always replaced them on a press. You must have everything in straight alignment before starting. The removal technique I stated using a crecent wrench will work but its crude. It would be better to make an aluminum bar with a slot that fit the steel taper of the pushrod end. Below is a photo of Ken Canaga's pushrod end removal tool. You would also have to split one of the blocks and add bolts so you could attach it to the steel pushrod end.

jseng1 said:

I've always replaced them on a press. You must have everything in straight alignment before starting. The removal technique I stated using a crecent wrench will work but its crude. It would be better to make an aluminum bar with a slot that fit the steel taper of the pushrod end. Below is a photo of Ken Canaga's pushrod end removal tool. You would also have to split one of the blocks and add bolts so you could attach it to the steel pushrod end.

Click to expand...

Am I right then that a loose steel part makes the pushrod useless?

marshg246 said:

Am I right then that a loose steel part makes the pushrod useless?

Click to expand...

did you ever try using loctite 609?
not sure how loose is loose?

CanukNortonNut said:

did you ever try using loctite 609?
not sure how loose is loose?

Click to expand...

Haven't tried anything, was just hoping someone knew. New stock pushrods are not overly expensive so I've always replace them when they will pull off. Most loose ones are just loose enough to pull off and I stick them in a box. Those looser than that get trashed.

The problem with loctite is that it breaks down with heat. Loctite 609 is only good to 300 deg and you motor will get that hot. Loctite 620 is high temp and good to 450 deg.

There is also

Vibra-TITE 19960 Hot-Lock Extreme High Temperature Threadlocker​

good for 2000 deg but I haven't tried it.

Might be the lenght required ?



Intresting to see those record breaking ' standard ' Z1's had ported heads ! . wonder what else was fudged .

Changing the barrels on my 750 I found a few loose pushrod ends. About half if I remember rightly. They'd only done about 15 000 miles since fitted brand-new.
I pulled the loose ends off with a mole grip. (Ally jaws in the vice and cardboard protection around the aluminium - much struggling and wiggling - but I got 'em).
I then used a centre punch to make lots of dents in the ends of the aluminium rods where they go into the steel end caps. The bumps around the punch marks made the end caps tighter. After that I cleaned them up squeaky with acetone and stuck them back on with Loctite 638.
To 're-fit' them I held them in the vice again. I struck the ball ends through a simple brass drift. I struck the cup ends through the same brass drift but I put a ball bearing in the cup first. ALSO I got an unwilling nipper to hold a weight against the other end.
My method was founded on the precept that it might save them and that if not, I'd just have to get new ones - probably just as shitty as these were when they were new.
They stayed straight - looked like new once polished and they've done about 7000 miles since.
But I can't promise they're not rattling about in there !!

Any machinists in the crowd with advice on how to reduce a slightly oversize pushrod tube enough to create an interference fit?

Not really to the subject raised but relevant me thinks! - ORIGINALLY THE PUSHRODS USED ON THE TWINS WOULD BE SOLID ALLOY WITH STEEL ENDS, THESE THEN EVOLVED INTO A SPECIAL RENOLDS ALLOY HOLLOW TUBE. (FIRST ARE PARALLEL, SECOND BARREL SHAPED), UNFORTUNATELY BY 1975 THE RENOLD COLD DRAWN TUBE BECAME UNAVAILABLE AND THE CAST PRODUCTION PUSHRODS ALONG WITH THE ALLOY ONES AVAILABLE TODAY WOULD RETAIN THE 'BARREL' SHAPE BUT ARE ACTUALLY SOLID. THE STEEL PUSHRODS WHILST BEING HOLLOW ARE STILL HEAVIER THAN THE SOLID ALLOY PUSHRODS. THEIR ADVANTAGE IS DERIVED FROM THE FACT THAT THEY ARE SUBSTANTIALLY STRONGER AND WILL ALLOW THE VALVE TO FOLLOW THE THEORETICAL TIMING DICTATED BY THE CAMSHAFT. - from RGM's pushrod description -

Reducing the size ?

Do you know any HVAC / Chiller engineers ?

Years ago ( 40 ish ) when I used to work on industrial chillers we had swaging and shrinking tools for thick walled copper tube ( imperial ) when wanting to change from one diameter to another without needing a “ fitting “ as a reducer

I guess if you know any chiller engineers they will likely have the equipment needed to do the job in just a few minutes

Similarly if you know anyone who has the equipment to make their own hydraulic hoses then thy also would have the equipment to do the job as well

Yes I’ve worked in a variety of industries

There's more discussion of pushrod lengths, making pushrods, materials, etc. in these older threads, if anyone is interested





Ken