two Theoben Evos both have issues advice needed

**valboskie** · 23-08-2014, 01:40 PM

Hi there I missed on an evo for £100 last week with broken cocking lever and shoe .

I have managed to pick up a very nice one.
its very under powered though
Its doing 4.1fpe with superdomes in .22 its in great condition

I also picked up another one a few days later from the same guy.
It has some slight pitting to the action and some dings and scrapes to the stock.

it has issues
the cocking shoe is broken well that's what he thinks you break the barrel and it just flops theres no resistance
at all.
the allen plug at the back is missing that allows access to the valve.
does anyone know where I can purchase one of these .
are they a specialist part or will other allen bolts fit.

I have a brocock slim jim pump but im totally new to rammers does the good one at 4.1fpe just need pumped up.
Could anyone please advice me on what's wrong and where to check going by the information I have.
I have found a cocking shoe I just need the valve cover bolt.
the rough evo holds air in the ram I emptied it then pumped it up a little and all seems to be working.

The pump does not have a gauge does anyone know how much pressure each stroke of the pump produces
I don't want to over fill it.
and help and advice would be greatly appreciated
atb
david

**TORNADOS7** · 23-08-2014, 01:52 PM

Sounds to me buddy like the one that won't cock has been let down by some fool "probably in a botched attempt to pump it up, that or they've blown the seals" and cos they failed miserably they got rid of it, anyway take the stock off and have a look you'll soon see if it's busted !...

As for the other one it sounds like it just needs pumping up cos if it's holding enough pressure to produce 4+ fpe then there ain't much wrong with the seals !...

If it's a modern "Theoben HE" then I think I read somewhere that it's in the region of 6-700 psi, you'll find it on the internet or I think it's maybe on the "Best Fittings" website as they do the adapter to pump it up with !...

**JLB** · 23-08-2014, 03:34 PM

They also respond well to a spring conversion should you not want to worry about reliability in the future.

John

**rhyslightnin** · 23-08-2014, 05:31 PM

Originally Posted by TORNADOS7

Sounds to me buddy like the one that won't cock has been let down by some fool "probably in a botched attempt to pump it up, that or they've blown the seals" and cos they failed miserably they got rid of it, anyway take the stock off and have a look you'll soon see if it's busted !...

As for the other one it sounds like it just needs pumping up cos if it's holding enough pressure to produce 4+ fpe then there ain't much wrong with the seals !...

If it's a modern "Theoben HE" then I think I read somewhere that it's in the region of 6-700 psi, you'll find it on the internet or I think it's maybe on the "Best Fittings" website as they do the adapter to pump it up with !...

Start at 600 and work up slowly

**Stormdancer** · 23-08-2014, 05:44 PM

I have two, an old Theoben and a Weirauch one, I have had an Evo in the past too.

Impact airguns who took over the old Theoben works are just about to launch a new Gas ram model, they also do repair of the older models I am told.

May have spares available.

www.impactairguns.co.uk

**Martin(rockape)** · 23-08-2014, 06:07 PM

Originally Posted by Rammer

I have two, an old Theoben and a Weirauch one, I have had an Evo in the past too.

Impact airguns who took over the old Theoben works are just about to launch a new Gas ram model, they also do repair of the older models I am told.

May have spares available.

www.impactairguns.co.uk

That's correct they are going to be making break barrels and a single shot underlever, I was shown the underlever recently but no idea what the stocks will look like as they are or where still in development at the time.

As already said if your pumping more air into the ram do it bit by bit, just for reference my .22 SLR98 has about 51 bar but use that as a guide.

Regards

Martin

**valboskie** · 23-08-2014, 09:29 PM

here are some pics of the rough one
does anyone know if i can get a replacement allen bolt and o ring to cover the valve
if so where or what sizes do i need
atb
David
http://i833.photobucket.com/albums/z...ps3c95f57d.jpg
http://i833.photobucket.com/albums/z...ps51ae214b.jpg
http://i833.photobucket.com/albums/z...psd621344d.jpg
http://i833.photobucket.com/albums/z...psd3720ffa.jpg
http://i833.photobucket.com/albums/z...ps356f7fbb.jpg
http://i833.photobucket.com/albums/z...ps91cdc4c2.jpg

**valboskie** · 23-08-2014, 09:34 PM

**severnsider** · 24-08-2014, 11:54 AM

Originally Posted by valboskie

here are some pics of the rough one
does anyone know if i can get a replacement allen bolt and o ring to cover the valve
if so where or what sizes do i need
atb
David

You're not having much luck with your Theobens are you!

Fill valve blanking screw. 4mm is the size of the Allen key required to undo it, so either 4mm or 5/32" will be fine. As for the actual screw, 5mm is close, with a pitch of 0.80mm. The diameter of the screw thread is, as far as I can make out, just about 5.30mm/0.209" and 32tpi. I can't find anything close in BA, BSF or UNF.

Don't forget that the screw is bored up the centre so that it fits over the tit of the Schrader valve, and a tiny 'O'-ring sits around it.

Would you like a photo of it?

**severnsider** · 24-08-2014, 12:03 PM

Originally Posted by TORNADOS7

Sounds to me buddy like the one that won't cock has been let down by some fool "probably in a botched attempt to pump it up, that or they've blown the seals" and cos they failed miserably they got rid of it, anyway take the stock off and have a look you'll soon see if it's busted !...

As for the other one it sounds like it just needs pumping up cos if it's holding enough pressure to produce 4+ fpe then there ain't much wrong with the seals !...

If it's a modern "Theoben HE" then I think I read somewhere that it's in the region of 6-700 psi, you'll find it on the internet or I think it's maybe on the "Best Fittings" website as they do the adapter to pump it up with !...

At 4fpe it will be very easy to cock. If it was really hard to cock, then it will have been overpressured. Higher pressure (e.g. beyond 750-800psi) will, in all likelihood, cause the muzzle energy to fall and fluctuate as the piston seal starts to suffer.

700psi is a good starting point if it's a .177 or .20. Perhaps 650psi if it's a .22.

If you have found a cocking shoe, make sure that you don't damage/enlarge the hole that it fits into when you remove the old one. They are peened/expamded over a little on the underside and if you go at it with a hammer and punch you run the risk of enlarging the hole, whereupon your new shoe will be a sloppy fit. I have found it better to carefully remove the slightly-peened/spread area using a decent pillar drill and appropriately-sized bits before pressing out the old shoe.

**severnsider** · 24-08-2014, 12:04 PM

Originally Posted by JLB

They also respond well to a spring conversion should you not want to worry about reliability in the future.

John

Heathen!!!!

**valboskie** · 25-08-2014, 12:03 AM

i got the low power one all pumped up today its shooting at 10.7fpe .
i put 350 pellets through it and it was a joy to shoot .
accuracy wise i need more practice .
at first when i zeroed my hawke eclipse at 25 yards i was hitting the 15 and 20mm knock down no problem
i went out side and hit various targets out to 55 yards .
then the accuracy went after about 220 shots or so i carried on shooting till i got fed up so went to the indoor 25 yard range the zero had shifted 4 inches left.
it could just be the scope
im still very happy with the evos first outing.

i really need a dust cover screw for the other evo to hide the valve ,
if anyone has any info on the allen bolt i would be very grateful
atb
David

**Martin(rockape)** · 25-08-2014, 08:23 AM

Just give Impact airguns a ring mate, they will know exactly what you need.

Thread: two Theoben Evos both have issues advice needed

Thread Tools

Display

two Theoben Evos both have issues advice needed

Posting Permissions