GTC 340

#1
Just got one of the GTC 340 copies of a comet/salsbury 340. I took it apart to see how it compares with the originals and it is a very close copy. Looks like they came over on a slow boat as it was a bit corroded and had moly spray all over it on the sheaths, so I cleaned up everything and started to get ready to assemble. The screws holding the axles for the weighted rollers are cheap so I am waiting on some new ones but otherwise looks just like my real ones and it is rated to 8500. Rollers weigh 51 grams (steel) and there are no 51 gram ones in the original salsbury charts just 55 gram steel ones are the closest to it. . I did not measure spring wire diameter but will go back out and measure. IMG_20200728_110006.jpg IMG_20200728_110200.jpg IMG_20200728_110212.jpg DSC02087.JPG DSC02086.JPG DSC02093.JPG
 
#3
Only one of mine has the steel shaft and I bought it from arc when they were making them. None of my dragbike drivers have it but only one has much time on it. I‘m sure it was an issue or they would not have made them but they sure work great for me with or without the steel splines. Did you ever break a stock one or know the history of who was breaking them?
 
#4
are they going to also make the driven? i still have my driven unit,but never use it. always went with the 7inch comet in the pass.
like to try it someday...:scooter:
 
#5
Only one of mine has the steel shaft and I bought it from arc when they were making them. None of my dragbike drivers have it but only one has much time on it. I‘m sure it was an issue or they would not have made them but they sure work great for me with or without the steel splines. Did you ever break a stock one or know the history of who was breaking them?
i ran a brand new cast unit with 3800 stall springs with a long keyway in it. 4 passes and it slit wide open. i think if a guy uses only2200- 2500(stock) stall springs it will hold up longer. engine just doesn't produce enough torque to damage it.
i bought a all billet unit before they went to half steel and billet aluminum.
billet unit started to so fractures in it .so that one became my half steel/aluminum project build driver unit.
really think if someone started to sell these performance parts again they would do real good. we know juggernaut has it's problems and know one wants to fix that.
the only problem with the 340 unit the driven needs to run inbound unless you can run the driven as a floater unit so it stays align correct(belt)and most bikes are only setup for outbound driven units.
 
#7
Wonder if arc would make another run of them? The made the half steel splined part.
if i remember right they got rid of that old cnc machine that they made thoses parts with and the program with it. if you ask me they weren't smart about saving info. i see in one of there arc videos they use a billet pulley(340 unit) with a hole drilled into it as a crankshaft stopper when setting up there engine.:eek: if i wanted to invest some good amount of money$$$$ i could get a guy to make these parts on a cnc machine,but i am talking about alot of money at first. i have work for over 30 yrs having cnc machines in are work environment and setup time programing..etc.. cost alot of money. for arc to do it....cheap but they ain't going to do it.
 
#9
Perfect! I'll call hunter and see if maybe they still have some buried. I tell them someone is repoping them maybe they would consider a run of them.
 
#10
Delray it did come with a driven. I post pics after I finish the driver. The driven unit does not have the multiple holes to vary the spring tension and adjust the upshift. Its easy to drill them using the one I have with all the holes as a guide.
 
#11
Delray it did come with a driven. I post pics after I finish the driver. The driven unit does not have the multiple holes to vary the spring tension and adjust the upshift. Its easy to drill them using the one I have with all the holes as a guide.
ok cool, here is my original 340 driven with a 3/4 keyway bore if you would like to compare it to you new remake unit. little shelf life,but it does look to be in real good condition.
340 driven1.jpg
340driven2.jpg

340 driven3.jpg
 
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#12
Perfect! I'll call hunter and see if maybe they still have some buried. I tell them someone is repoping them maybe they would consider a run of them.
if hunter new how strong the minibike market is.
i think he would,but those guys at arc are all about gokart racing. sure they still help the minibike guys out and all. but no clue on guys having problems finding a torque converter that can hold up with a strong clone motor.
goodluck ole, i hope you can convince him?
 
#13
No good he found a couple of billet sheaths but no posts. He confirmed that the stock ones would split on the Jr dragsters with too much power.. He said people broke the steel posts by tightening the screw think that holds it together. I have about 5 salsbury/comet 330,340 units including one with the steel post. I took apart the driven and the retainer and moveable sheave look the same but the other sheave with the post was either steel or iron and pretty heavy. The originals say comet industries or salsbury on them but this has nothing printed anywhere on it.
 

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joshua. c.

Active Member
#14
interesting to see one of these finally come out, they have had them listed with prices for years now. I would like to see a driven unit to accompany the driver. from what I've read the driven is better than a comet version due to better tunability. so dose this use the thicker current size belt or the thinner older style belt?
 
#15
The driven that came with it has a cast iron fixed section unlike the real salsbury/ comets which are aluminum. Also it only has one hole for the spring so it is not adjustable as it comes but it’s easy to drill extra holes.
 
#17
wops sorry i overlooked your earlier the post about the driven. I wonder why they made the driven hevier with a steel or cast iron fixed section. do you think they misunderstood the information about the drivers spline falures on these and beefed up the wrong part?
 
#18
not sure if you notes or not ole on my salsbury driven it has the 5holes for spring adjustment and the whole thing is cast aluminum.
like to really try it out. need to run it inbound and i don't think any my bikes would work correct with it.
5holes.PNG

on my 7inch comet 20series has 4 holes. i like the 7inch because it helps with the gearing. also would like to run a spacer on the driver if possible. that too could help the motor/correct gearing for the type of short drags i do.
4holes.jpg
 
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#20
boy is it bad! I think overall the GTC driver is a good piece for a copy but the driven not so much. It is horribly out of balance. I took a video of it on a shaft with bearings in v blocks but it is a avi and It says its a unsupported file. It would be a OK unit for a mild build but the way mine is I bet it would vibrate and higher speeds. There is a rib where the heavy spot is do I will start milling some of it away.
 

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