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Old 12-20-2008, 09:20 AM   #421
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Does this mean that when we upgrade our t bars we will need to alter our chassis? Sorry i dont have my car infront of me to se if those 2 holes are in it
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Old 12-20-2008, 04:14 PM   #422
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Does this mean that when we upgrade our t bars we will need to alter our chassis? Sorry i dont have my car infront of me to se if those 2 holes are in it
Yes you will need to enlarge the holes.
I'll get a measurement for you tomorrow.
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Old 12-20-2008, 05:45 PM   #423
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Here's a pic of the bottom of the chassis change.

The two holes next to the pivot ball screw are larger, and you can just see the button head screws in the t-bar. (the screws are not the official ones, they will be hex head and slightly smaller).
That explains why the new, replacement T bars are not counter sunk for flat head screws!! I first thought it was an error. That's too bad. All they did was eliminate the counter sinking on the T bar that was required for the flat head screws. This will make the T bar slightly stronger but does not fix the problem.

There are three holes in the T bar. The large hole in the middle for the pivot ball cup and the two holes for the screws on each side of the big hole. While switching to button heads adds a little more material to the T bar, the design of all three holes in a row across the T bar, makes a very weak unit. The Associated, CRC, HPI design is much better as it uses four screws and the holes are not in a row across the T bar. Much stronger. It would cost a lot of money for serpent to make new pivot ball cups molds, cheaper to buy Associated, CRC, HPI pivot ball cups for the kits or even cheaper to eliminate the counter sink and switch from flat head screws to button head screws which is what they chose to do. Understandably they do not want to increase the cost of the kit anymore than it already is.

Looks like I will be going forward with making my own T bars which will use either Associated, CRC or HPI pivot ball cups.
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Old 12-20-2008, 05:53 PM   #424
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Another note - are your sure theese larger holes in the main chassis plate won't reduce its rigidity in a heavy-loaded area where the rear pivot-ball is mounted?
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Old 12-20-2008, 05:59 PM   #425
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Another note - are your sure theese larger holes in the main chassis plate won't reduce its rigidity in a heavy-loaded area where the rear pivot-ball is mounted?
I have several different chassis with holes like that for other cars and I have never broken a chassis in that area. The T bar will break long before the chassis will.
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Old 12-20-2008, 08:01 PM   #426
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I have several different chassis with holes like that for other cars and I have never broken a chassis in that area. The T bar will break long before the chassis will.
guess who has a serpent?
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Old 12-20-2008, 09:31 PM   #427
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ok, so I am building the car. I am guessing the hub issue I heard something about is that there is a piece of material that didn't get machined off and screws up the diff action?
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Old 12-20-2008, 10:59 PM   #428
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ok, so I am building the car. I am guessing the hub issue I heard something about is that there is a piece of material that didn't get machined off and screws up the diff action?
Actually.... No.

There have been issues where the tread was pulled from the axle. We believe it is due to the nut running out of thread before the diff is tight. I suggest using a washer between the nut and the belleville washers that sit against the thrust bearing.

The newer kits have 1/8th diff balls which helps and the axle was slightly changed. But to be on the safe side use a shim. About 1mm thick is enough.
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Old 12-20-2008, 11:11 PM   #429
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Actually.... No.

There have been issues where the tread was pulled from the axle. We believe it is due to the nut running out of thread before the diff is tight. I suggest using a washer between the nut and the belleville washers that sit against the thrust bearing.

The newer kits have 1/8th diff balls which helps and the axle was slightly changed. But to be on the safe side use a shim. About 1mm thick is enough.
ok, well where the diff is notched on my diff there is flash that screws up the diff action. also the tbar screws aren't long enough, and the t bar pivots kinda suck, you can't tighten them for anything or they bind, and the t bar doesn't have full throw cause I have the revised tbar version not the new version. so the tbar isn't countersunk, but they still include countersuck fasteners and dont relieve the chassis.. = gay. This is like my 15th 12th scale and yeah for the most part its a rad car. but these things are all kinda dumb. and I have the 3mm ball version.. will probably just find some 1/8 balls so I can run other spur gears anyhow..
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Old 12-20-2008, 11:15 PM   #430
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That explains why the new, replacement T bars are not counter sunk for flat head screws!! I first thought it was an error. That's too bad. All they did was eliminate the counter sinking on the T bar that was required for the flat head screws. This will make the T bar slightly stronger but does not fix the problem.

There are three holes in the T bar. The large hole in the middle for the pivot ball cup and the two holes for the screws on each side of the big hole. While switching to button heads adds a little more material to the T bar, the design of all three holes in a row across the T bar, makes a very weak unit. The Associated, CRC, HPI design is much better as it uses four screws and the holes are not in a row across the T bar. Much stronger. It would cost a lot of money for serpent to make new pivot ball cups molds, cheaper to buy Associated, CRC, HPI pivot ball cups for the kits or even cheaper to eliminate the counter sink and switch from flat head screws to button head screws which is what they chose to do. Understandably they do not want to increase the cost of the kit anymore than it already is.

Looks like I will be going forward with making my own T bars which will use either Associated, CRC or HPI pivot ball cups.
hey, hook it up with the pattern for that. Cause if they didn't have this lil Tbar issue I would have rated this kit a lot higher my friend. . overall good designs. kit is 80% done.. gotta make some tbar mods tho which kinda pisses me off.. jakes cars were great like that (daydreaming)
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Old 12-21-2008, 04:53 AM   #431
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After switching to the 2mm t bar i havent really broken anything other than a front body post, and thats running mod and 10.5. I am using the countersunk t bars and although i broke my original thick t bar over the rear pivot and i do see the weakness i dont think its as bad as you are making out. Also to note that i had no build defects or axles falling apart in my kit
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Old 12-21-2008, 10:27 PM   #432
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hey, hook it up with the pattern for that. Cause if they didn't have this lil Tbar issue I would have rated this kit a lot higher my friend. . overall good designs. kit is 80% done.. gotta make some tbar mods tho which kinda pisses me off.. jakes cars were great like that (daydreaming)
Don't worry about the T bar, Patrick. Just run the car. It is so easy to drive that you will not hit anything and break a T bar. If you are using the thick, 2.0mm T bar, then you need to place the orange shims under the pivot balls. This should give you enough clearance for the button head screws so they don't hit the chassis. The T bar is really the only flaw in an otherwise outstanding design and even with that, it still works great. I am working on a new T bar that will use the Associated, CRC, HPI, four screw pivot ball cups. As soon as I get them I will send you a few to try.

As for the diff, just use 1/8th balls and a cone washer on the outside bearing just like all of the other 1/12th cars and everything is wonderful. What Serpent tried to do is make a Slapmaster device which did not turn out just right. I have not given up on that piece but I might just throw a Slapmaster unit on the car and be done.

We raced today and I TQ'd by two laps!!! I had a four second lead in the main with less than a minute to go and was lapping the fourth place car for the second time when he punted me off of the back straight and back onto the infield behind the second place car. Even with that I almost caught him for the win. You will be very happy with the car.
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Old 12-21-2008, 10:35 PM   #433
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It is so easy to drive that you will not hit anything and break a T bar.
you forget who you are talkin to? pm me your carpet setup

I am going to make an associated tbar for it with my dremel lol
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Old 12-22-2008, 02:58 PM   #434
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As for the diff, just use 1/8th balls and a cone washer on the outside bearing just like all of the other 1/12th cars and everything is wonderful. What Serpent tried to do is make a Slapmaster device which did not turn out just right. I have not given up on that piece but I might just throw a Slapmaster unit on the car and be done.
Did you use the kit supplied balls for the diff?
If so I'm 99% sure your problem is not with the thrust bearing.

Use 1/8th balls and the diff should work perfectly. We've had some issues withthe thread running out prior to setting the correct tension. But I've not seen or hear anything being wrong with the thrust bearing setup.
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Old 12-22-2008, 05:10 PM   #435
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Did you use the kit supplied balls for the diff?
If so I'm 99% sure your problem is not with the thrust bearing.

Use 1/8th balls and the diff should work perfectly. We've had some issues withthe thread running out prior to setting the correct tension. But I've not seen or hear anything being wrong with the thrust bearing setup.
The first thing I did to try and fix the problem was put 1/8th balls in the diff. While that helped a little, it still binds up and when you take the diff apart, you can see galling on the back side of the orange aluminum cup where the thrust bearing race is rubbing. I think the aluminum cup is not deep enough and it is bottoming out on the end of the graphite part of the axle. I did try and remove a little of that part of the axle and, again, while it did make it a little better, it still binds. I thought maybe when the hole was drilled in the end of the axle for the set screw, that it expanded the graphite and is causing the cup to bind. I sanded down a little of the graphite and that also made it a little better but it's not perfect. I think it's a combination of a lot of tight tolerance issues. I will keep working on it.

Don't get me wrong. I love this car!! As with any fine piece of racing hardware, it takes a little massaging to make it perfect.
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