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Technisub "Grinta" pneumatic speargun

Thread Status: Hello , There was no answer in this thread for more than 60 days.
It can take a long time to get an up-to-date response or contact with relevant users.
I will do a total reconstruction.and I need technical parameters-
and manual dismantling.Thank you for your help
 
A manual will give you an exploded parts diagram and parts list, but will not tell you how to dismantle the gun, however the photos and text here should be all that you need. A pumping table would be provided, but the best approach is to pump the gun until you cannot load it, then let a small amount of air out to allow a margin for fatigue, after say two hours of spearing. The amount of oil should be about 15 to 20 ml, but depends on the length of your "Grinta". On this forum there is the manual for a Technisub "Ranger", have a look at that to ascertain the scope of the information provided by Technisub with their pneumatic guns. The "Ranger", despite its external appearance, has a small diameter tank buried in a rubberized plastic moulding that makes the gun look like a 40 mm OD tank.
 
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Here is a composite photo of the “Grinta” back in one piece after its examination. The gun shoots an 8 mm diameter spear of length 73 cm from tail butt to screw threaded tip, it having a busted trident on it when I first received it. From the rear of the hollow and open ended raked handle (which thus floods) to the nose of the muzzle the gun is 81 cm long and from the rear of the receiver (the inlet valve cap) to the front of the muzzle it is 75 cm long, hence the “75” in its designation. The muzzle OD is smaller than normal, so the gun will not take a Mares muzzle due to the restriction of the nose cone opening. The inner barrel diameter is 13 mm, while the barrel screw thread is 17 mm diameter (I did not note the thread pitch) and the muzzle body OD is 22 mm. The “Grinta” gun does not float, but apparently the longest “Jeans” model did, probably due to the extra tank length even though both models had the same size tank at 30 mm OD. The throttle system used to regulate shooting power may make the gun a sinker as it occupies a chunk of the tank volume, but I have not tried leaving it out of the gun as for me the throttle is what was of interest. Incidentally the “Taimen” magnetic control power regulator was tested, but apparently has some bugs as the revolving ported cylinder drags on the peripheral seals, but I have an idea how to fix that by incorporating fore-aft cylinder movement into the magnetic switch so that the revolving cylinder momentarily comes away from the seals and then slides back.


To my knowledge the 75 cm model was the longest “Grinta” available in the USA back in 1979 as shown by the attached table.
 
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I wonder if the tooling still exists for the "Grinta", particularly the injection moulds for the plastic parts, as I think with a few updates this gun would be a real contender today. A vacuum barrel, a buoyancy chamber equipped handgrip and a lightened throttle system to make it a floater and it would be like the modern, slim pneumatic guns such as the "Pelengas" (ECO version) with a very similar construction, e.g. pinned rear bulkhead, a grip handle that slides onto a cylindrical subsection (rear tank bulkhead) and a plastic nose cone. Line release is close to barrel, but underneath rather than on the side of the handle. Below is the "Pelengas 55 ECO" model.
I wonder if the Pelengas has a power regulator in the works. No sign of a safety though which otherwise helps when wrapping the shooting line to prevent unwanted trigger-line release interactions.
 
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I see that there is another version of the "Pelengas 55 ECO" with a more conventional grip being part of the rear handle/rear bulkhead structure as is the case with the guns we see from Italy such as the Mares and the Salvimar models. I don't know anything about this one as I have not been following the changes at "Pelengas" for several months.
 
What are the dimensions O-rings? tube Grinta
 

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Well your gun is a "Grinta 75 VP" and looks in much better condition than mine, which is a bit of a wreck, so do you really need to do anything to it at all? Anyway you can find the "O" ring sizes by measuring the existing rings (the ones in mine are flattened out of shape) or measuring the "O" ring seat diameters with vernier callipers. Then you measure the tube or tank ID and the width of the grooves in the seats which will give you the section width. Thus tube ID minus seat diameter should equal twice the section width, but with a slight compression when fitted this number will be a slight underestimate of the true section width (which is the rubber ring cross-section if you sliced the"O" ring in two) and the adjusted section width figure should be just under the groove width for the "O" ring to sit snugly in the groove. Your "Grinta" looks almost unused, either that or your camera has been unable to show any flaws.

An example of taking measurements in a systematic manner is shown here:
https://forums.deeperblue.com/threads/o-rings-especially-trigger-pin.97289/page-3
 
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Well we will need a bit more info than that as I cannot see what is wrong with it and I cannot read your mind, so we need a fuller description of any problems. If it does not hold air pressure then you are going to have to pull it apart and measure all the seating dimensions where the "O" rings sit. I did not replace any "O" rings as the gun still held pressure, but I did break one of the inner barrel circlips even though I used the correct size circlip pliers for their removal, so I suggest you don't remove them either unless it is absolutely necessary. Basically if you wish to restore the gun then you have to be prepared to do the work as I have not bothered measuring all the "O" ring seating dimensions as the gun is not being put into service until I can figure out a way to make it a "floater", but with the throttle system still in place. I have plenty of "sinker" guns, so I don't need another one!
 
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Might I suggest that you contact Tomislav (Tromic) and Marko about having a vacuum muzzle made for your "Grinta". Like you he lives in Croatia and although I don't know if you both live in the same locality, it will be much easier than if you were living in another country. He may be interested in seeing your gun as until you posted I have never seen another one. That said there must have been hundreds made, if not thousands, but my guess is that they were discarded in preference to the floating 40 mm diameter tank models soon to be made by Technisub as they eventually caught up with Mares and Cressi-Sub. Here in Australia we only saw the "Jeans" with the elevated non-concentric inner barrel, much else was the same as the "Grinta", but they were never popular and I never met anyone using one.

I have taken the liberty of wiping the arrows off your photo and using it as a "type" photo, but I can remove it if you like or you may even wish to create a better one. We can see on the stickers that only "Grinta" appears on the tank, not 75 VP and that designation is only known (by me anyway) from the catalogue entry.

 
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Today I upgraded- Technisub grinta:
new O-rings
new pistons (cressi SL)
new bushing dum ping(custom production-Synthetics)
new shaft+pum(cressi)
all right..I go into the water to try!!
 
Let us know how you go and what the gun feels like with respect to its handling underwater, apparent weight in the water and ease of aiming. So you have a new damping bush on the original anvil, or a matching Cressi anvil for the Cressi piston? New shaft is of same diameter 8 mm? Good luck with the hunt using probably the only still working "Grinta" in Europe!
 
A Technisub Conquest gun on eBay, this one has a white grip which I have never seen before. A later model probably.

Technisub Conquest 26” Speargun | eBay

Find many great new & used options and get the best deals for Technisub Conquest 26” Speargun at the best online prices at eBay!
www.ebay.com.au
 
You can see the Conquest Booster is built pretty much along the same lines as the Sten as Technisub had finally gone to a bigger tank diameter of 40 mm. The trigger has the same forward finger projection that is used to free the line release arm located in the front of the trigger guard frame, something used on the previous small tank pneumatic models. The very first one of these I saw was black with lime green trigger and other highlights, but it was basically a “me too” gun from Technisub. Technisub used a slightly thicker taper on their spear tail, so you need one of those to use the gun, however change to a Salvimar or Mares piston and you can use those shafts which all have the same tails. The shock absorber may need changing but I suspect the piston nose shape is the same on all of these later models using plastic pistons. Possibly the same company made all these Italian pneumatic guns under contract.

US Divers was the distributor of Technisub gear in many countries and when they quit spearfishing it blew the bottom out of the Technisub gun market. US Divers had decided to go green and embrace scuba diving rather than "bloodthirsty hunters".
 
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Technisub guns I found were always more expensive than other brands, although you did not seem to get much extra for your money. Unlike Mares and Cressi-Sub their distributors did not appear to carry spare shafts, or if they did then they had them hidden somewhere. Without spare spears your gun is useless and many don't bother to go past there and give up and the gun goes into the wall cupboard. At one stage as the pneumatic guns all began to gravitate towards the same basic layout used in the Sten it was thought that they would switch to the same spear tail, but this never happened. Spare tails for the different makes used to be available from specialist retailers, but not so many today. You were completely sunk if your gun used GSD shafts with a small metal ball on a spigot for the tail, a design that Technisub used in the past with their Jaguar family of Classic layout guns.
 
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