Flipped input sprag?
Thread Starter
TECH Junkie
Joined: Mar 2002
Posts: 3,019
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From: memphis tn
Flipped input sprag? Hammered my new transmission for the first time last night hard takeoff then hit the rev limiter no first to second shift.The builder said I flipped the input sprag.He went on to tell me he had installed a heavy duty racing sprag and that it should't have happened.What the heck does an input sprag do and is it common for them to break?
On The Tree
Joined: Jan 2003
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From: Pontotoc, MS
Re: Flipped input sprag? A forward sprag or 'input sprag' holds the forward clutches. This clutches are applied in every forward gear. The sprag allows the clutches to spin in one direction but not in the opposite direction. If you break or flip this sprag then you should have reverse and manual first ONLY. The sprag usually flips when it is loaded and then unloaded quickly as you described. It is common problem. Make sure to ask for a sprag that has a double cage. Some high performance sprags are single cage.
Kevin Steele
TCI
Product Engineer
Kevin Steele
TCI
Product Engineer
On The Tree
Joined: Jan 2003
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From: Pontotoc, MS
Re: Flipped input sprag? The 4L60E will live. My truck weighs in at 3962 lb. with me. I run a 700-R4. I drive my truck on the track and run then drive back home. Have you weighed the truck or are you just looking at the weight on the door? As far as a stronger sprag... there is not one. What times and mph are you see in your truck?
Kevin Steele
TCI
Product Engineer
Kevin Steele
TCI
Product Engineer
Thread Starter
TECH Junkie
Joined: Mar 2002
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From: memphis tn
Re: Flipped input sprag? It's a Tahoe weighed 5450lbs with me in it turned 13.28@101mph a Memphis Motorsport with 7.5lb boost tried 9.5lb boost and blew rearend and transmission at the startline.
Thread Starter
TECH Junkie
Joined: Mar 2002
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From: memphis tn
Re: Flipped input sprag? It did't flip the sprag it tookout a 5 pinion rear planet,a heavy duty reaction shell,a hardened input shaft and broke the spider gear on a Eaton heavy duty posi on street tires.Any suggestions?
On The Tree
Joined: Jan 2003
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From: Pontotoc, MS
Re: Flipped input sprag? Dude, you can do one of two things. Put that pig on a diet or get a built 4L80E. I was thinking MAYBE you were looking at the weight of the truck on its door. 13.20 @101 at 5450 lbs. 
Kevin Steele
TCI
Product Engineer
Kevin Steele
TCI
Product Engineer
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Thread Starter
TECH Junkie
Joined: Mar 2002
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From: memphis tn
Re: Flipped input sprag? I suggested a 4L80E to the transmission shop on the front end he said it was to much trouble and now they have built the 4L60E 3 times in 4 weeks.They guaranteed I would be happy and cashed the check,the ***** in there court now,do you have any suggestions?How much trouble is it to change to a 4L80E?I like the closer gear spacing. If I had done it on the front end I would have installed a 4.10 gear.Won't a built 4L80E shift into 4th gear under full throttle?I've also had 2 different TCI convertors in the truck that the builder has blamed for my problems.The transmission shop has been dealing with Gary,maybe it's time yall got involved.
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Joined: Jan 2003
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From: Pontotoc, MS
Re: Flipped input sprag? What problems have been caused by the converters? Are they rebuilding the tranny for free (warranty?)? The 4L80E would require a flex plate, converter, drive shaft, and TCU. The TCU is to run the trans it would be easier than trying to find some to reprogram your current computer.
Kevin Steele
TCI
Product Engineer
Kevin Steele
TCI
Product Engineer
Thread Starter
TECH Junkie
Joined: Mar 2002
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From: memphis tn
Re: Flipped input sprag? The first convertor was a TCI3500 that was flashing to 5200rpm I spoke with Gary about the convertor,at the insistance of the builder,Gary said that yall didn't really know how your convertors would respond in a truck as heavy as mine he advised me to park the truck until the convertor could be replaced and said he sent a convertor with less stall I was charged for the install by the builder.The second transmission with the revised TCI convertor seemed ok but ate the pump within 10 miles of leaving the shop,leaving me on the side of the road.The builder claimed the convertor had caused the problem.The third transmission was put in with my old Yank 3000 that the builder had advised me earlier not to reuse,ran great until the streets dried and I hammered it the first time.I told the builder I did'nt care who caused the problem I just wanted the truck fixed.I'm not trying to place blame but I paid way to much money for my truck not to be fixed.They have the transmission dissassembled out of the truck right now I have'nt driven the truck more than 5 days in the last month.
Thread Starter
TECH Junkie
Joined: Mar 2002
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From: memphis tn
Re: Flipped input sprag? Is the problem with my combo with the amount of power or the weight?It looks like your truck is making more power and living with a 700R4 which is basicly the same transmission as the 4L60E.The 5450lb weight I gave was with no spare tire,about 3 gal of gas and everything not bolted down removed from the truck.
TECH Enthusiast
Joined: Mar 2002
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From: Memphis, TN
Re: Flipped input sprag? How long did the stock trans. last? You might have to put a new stock one in an settle for mid 13's and dependability.That's still one hellova sleeper,and faster than 95% of cars and trucks on the road.You just want be doing any 1.7 60's.Just a thought.Good luck with your problem.Jim
Re: Flipped input sprag? If you blow a pump right after a rebuild maybe they did not flush all the gunk out of the lines or the converter... That should not happen I would not blame a new converter.
