4L70E Sprag "weak link"
11-12-2006, 07:04 PM
#1
11 Second Club
Thread Starter
4L70E Sprag "weak link" Few Questions for the Trans Guys (and anyone that knows more than I about the inner workings is more than welcome to put their $.02 in here as well!!).....
I just read another thread with a guy's TBSS trans died, GM replaced a " broken sprag" and that same part has been the culprit in many "trans is dead" threads..
when is the most pressure or "vulnerability" of the sprag??
is it worth replacing with a stronger sprag?
would you know which one that would be, does someone offer one? GM told this last guy they are now using a hardened sprag as this part has killed many 4L70E's....
I just installed Sonnax Servos, New TCI converter, Cooler, & Pan... I would hate to have this weak link kill my 5k mi old trans...
is it worth dropping the trans now and getting that area addressed or will it break down over time?
thanks for any advice, i am sure others are thinking along the same lines as myself..
I just read another thread with a guy's TBSS trans died, GM replaced a " broken sprag" and that same part has been the culprit in many "trans is dead" threads..
when is the most pressure or "vulnerability" of the sprag??
is it worth replacing with a stronger sprag?
would you know which one that would be, does someone offer one? GM told this last guy they are now using a hardened sprag as this part has killed many 4L70E's....
I just installed Sonnax Servos, New TCI converter, Cooler, & Pan... I would hate to have this weak link kill my 5k mi old trans...
is it worth dropping the trans now and getting that area addressed or will it break down over time?
thanks for any advice, i am sure others are thinking along the same lines as myself..
11-12-2006, 07:17 PM
#2
We cryo the input sprag races in our level 5 units. Seems to work well but the input speag is the weak link. We do update the sprag element from the skf to the borg warner. I think in a tb ss 550rwhp is about all the 4l70e is going to take. We are working on some new parts for these units to see how far we can push them. The input sprag is the part that worries me! Vince
11-12-2006, 08:17 PM
#3
11 Second Club
Thread Starter
thanks Vince, sad thing is alot of these blown trans trucks are close to stock...
Does a highStall TC create more risk of it breaking? and driving around normally is it bad on anything (trans wise) to rev the engine to 3k to get out into traffic (alot of quick turns and such) or should I drive "slower" with a highstall? above 45 it locks the converter and drives like stock, but all these 30-40mph streets make me wonder if it's hurting anything..
PS trans temps on a 70f afternoon never went above 171f (beating it down on DR's)and were mostly in the 150's, at idle 143 (cooler & deep/finned pan) is that good, or should I look to cool it off more?
Does a highStall TC create more risk of it breaking? and driving around normally is it bad on anything (trans wise) to rev the engine to 3k to get out into traffic (alot of quick turns and such) or should I drive "slower" with a highstall? above 45 it locks the converter and drives like stock, but all these 30-40mph streets make me wonder if it's hurting anything..
PS trans temps on a 70f afternoon never went above 171f (beating it down on DR's)and were mostly in the 150's, at idle 143 (cooler & deep/finned pan) is that good, or should I look to cool it off more?
11-12-2006, 08:43 PM
#4
Trans temps look good. I think if you manually down shift the sprag takes alot of abuse. The stall tc will effect the input sprag to a degree but it is more of a load issue from what I have seen. That is why rwhp/tq I believe 550 is kinda the # to stay under. We are doing some testing with a couple tb guy's at this point. How big of a stall are you running?
11-12-2006, 09:17 PM
#5
11 Second Club
Thread Starter
I am running a new TCI MaxEffort StreetFighter 3200 (in the SS with the LS2 it's a little higher, 3400 or so) with a 2.6:1 STR here's what was said about it..
if that helps you understand what kind it is...
I've been talking to our rep at TCI about converters for the Trailblazer SS. As many of you know, I'm currently running the I6 Trailblazer converter, and it certainly woke it up some. With the vehicle being so heavy, the biggest advantage I could see an aftermarket converter having besides added stall speed is a high stall torque ratio (STR) for the heavy vehicle. The higher STR would not only help the 60' out, but it will also make the converter feel a little more streetable vs. the same stall speed torque converter with a lower STR. What TCI has come up with are two additions to their converter lineup that will work VERY well for the TBSS!
*TCI MaxEffort 3400, 2.6:1 STR
*TCI MaxEffort 3900, 2.7:1 STR
Both torque converters have a maximum positive angle on the impellor fin angle for best efficiency on the track. With the maximum efficiency of the converters, along with the high STR for a hard hit off of the line, they will make for excellent performing converters! Both converters will come standard with an anti-ballooning plate on the top and a ground, heat-treated impellor hub. They are using the stator from their competition converters to achieve the high STR's. The converters will both be very reasonable in price, too! The MaxEffort 3400 will be $499.99, and the MaxEffort 3900 will be $539.99. The converters are not recommended for towing. For those of you wanting to retain some towing capability, you can opt for the billet cover. It will use a wider clutch for lockup. The billet cover option will add $230 to the price of the converters. Again, if you are not looking to do any towing the billet cover will not be needed.
These converters will be ready to ship within 10-14 days. It's not surprising that I'm going to be swapping converters in the next 10 days or so. I will be trying out the MaxEffort 3400 with the billet converter. I am going to get track results from the I6 converter first so we will have something to compare it to.
*TCI MaxEffort 3400, 2.6:1 STR
*TCI MaxEffort 3900, 2.7:1 STR
Both torque converters have a maximum positive angle on the impellor fin angle for best efficiency on the track. With the maximum efficiency of the converters, along with the high STR for a hard hit off of the line, they will make for excellent performing converters! Both converters will come standard with an anti-ballooning plate on the top and a ground, heat-treated impellor hub. They are using the stator from their competition converters to achieve the high STR's. The converters will both be very reasonable in price, too! The MaxEffort 3400 will be $499.99, and the MaxEffort 3900 will be $539.99. The converters are not recommended for towing. For those of you wanting to retain some towing capability, you can opt for the billet cover. It will use a wider clutch for lockup. The billet cover option will add $230 to the price of the converters. Again, if you are not looking to do any towing the billet cover will not be needed.
These converters will be ready to ship within 10-14 days. It's not surprising that I'm going to be swapping converters in the next 10 days or so. I will be trying out the MaxEffort 3400 with the billet converter. I am going to get track results from the I6 converter first so we will have something to compare it to.
11-12-2006, 09:57 PM
#6
It sounds a little loose to me. I know these tc's are a new line from tci. I really haven't heard good or bad from any of our customers. Like anything else time will tell how they are going to perform and hold up. We use the vig's and have had very good luck with them. Next to no failures with very good results. We don't require the customer to by a tc from us with a trans. We really leave that up to the customer. Good luck to you with your new setup. If there is anything we can do for you in the future, feel free to contact Chuck or myself. Vince
11-12-2006, 10:13 PM
#7
11 Second Club
Thread Starter
Originally Posted by Vince @ FLT
It sounds a little loose to me. I know these tc's are a new line from tci. I really haven't heard good or bad from any of our customers. Like anything else time will tell how they are going to perform and hold up. We use the vig's and have had very good luck with them. Next to no failures with very good results. We don't require the customer to by a tc from us with a trans. We really leave that up to the customer. Good luck to you with your new setup. If there is anything we can do for you in the future, feel free to contact Chuck or myself. Vince
I know Matt from TuneTime has been speaking with you guys, so I am sure I will be using your parts/Services in the Future..
