Competition Input Shaft / Launching Question

[CLAYTON]

I just got a triple disk 89% SunCoast transmission with all the bells and whistles except for the input shaft... I know I should of got that when I got the transmission. Thing is I bought it off a friend for cheap and I didn't have the money for the input shaft. I'll get it someday down the road. Coming from the stock 48re there are definitly some differences. It pulls great through the gears and the shifts are firm and fast. It's seems like when I stomp on the pedel from a stop it takes a couple of seconds before the truck takes off... like it's working harder before it builds boost. For example when it would have taken 1 second for the wheels to start spinning it seems like it takes 2 seconds now. Is this normal? Also when it was stock if I was going to race somebody I would put it in 4hi build about 5lbs boost and let it take off like a sling shot. Now I'm worried about snapping the input shaft. Am I still safe to build a couple of pounds of boost for a launch? What is going to snap my input shaft? And are 4 wheel launches out of the question without an upgraded input shaft? Thanks in advance



CLAYTON

 

[paulb]

I just got a triple disk 89% SunCoast transmission with all the bells and whistles except for the input shaft... I know I should of got that when I got the transmission. Thing is I bought it off a friend for cheap and I didn't have the money for the input shaft. I'll get it someday down the road. Coming from the stock 48re there are definitly some differences. It pulls great through the gears and the shifts are firm and fast. It's seems like when I stomp on the pedel from a stop it takes a couple of seconds before the truck takes off... like it's working harder before it builds boost. For example when it would have taken 1 second for the wheels to start spinning it seems like it takes 2 seconds now. Is this normal? Also when it was stock if I was going to race somebody I would put it in 4hi build about 5lbs boost and let it take off like a sling shot. Now I'm worried about snapping the input shaft. Am I still safe to build a couple of pounds of boost for a launch? What is going to snap my input shaft? And are 4 wheel launches out of the question without an upgraded input shaft? Thanks in advance



CLAYTON

From your description, I doubt that there is anything wrong with the trans. It just sounds like the symtoms of a tighter then stock TC.



As far as the input shaft. You really aren't taking anymore of a risk now then with the stock trans of breaking the input shaft. However, anytime you do a 4x4 launch with a stock shaft, you take a chance of breaking an input shaft. A lot of people say that you can launch with up to 10psi with a stock shaft, but there have been input shafts broken at that boost level. Before having my trans re-done, I was doing 5 psi launches and didn't break the input shaft. Now I launch with 15 to 20 psi.



Paul

 

[BIG C]

Ive never heard of a 89% triple lock from Suncoast. I always thought a triple lock relied on lockup and a 89% convertor relied on fluid coupling. I could be wrong though.

 

[CLAYTON]

Your right about them not selling a 89% converter. . I believe I have their 48 converter that they sell for my 03 48re. Had a guy drive it and told me it felt like a 89% efficient and not a 91% or 93%. It has great driveablility. Power seems to comes on strong around 1300- 1500 rmp range... Thats what I meant when I said 89% in my previous post to have something to compare it to. Guess I should have been a little more clear.



ON EDIT: All this transmission stuff is new to me. I'm still learing all the different odds and ends with them so any info would be helpful

 

[BCarmicle]

Launching @10lbs. of boost can be done with the stock input shaft but isn't a very safe practice.



I made 20+ passes launching @10lbs. without any breaks. When I did the twins I upgraded to a billet shaft. Now I have more insurance for launching @20lbs.



Factors to consider is how much power your putting to the ground and tire size. The more power you have the easier it is to break a shaft. Bigger tires also put more strain on the transmission.



You can probably still get away with doing 5lb. launches, but anything much higher than 5-10lbs. and I would suggest a billet input shaft.



Brandon