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Trans pulls down motor?
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DRR Sportsman
posted
Fresh TH400. Launches fine thru 1st, fraction of a second into 2nd motor pulls down noticeably (not a bog) for a fraction of a second then picks up again. Feels like tire rub so I changed to a narrower section slick but it does the same thing except last night it twisted my drive shaft in half and tore up my steel floor real good.
Any ideas?
 
Posts: 459 | Location: Lakewood, Co. | Registered: January 22, 2007Reply With QuoteReport This Post
DRR Pro
Picture of 27Keith
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Does your converter have a sprag ?


2018 Dragway 42 Top Champion
 
Posts: 2032 | Location: out there | Registered: March 31, 2004Reply With QuoteReport This Post
DRR Sportsman
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No sprag. New converter.

This message has been edited. Last edited by: SS427IMP,
 
Posts: 459 | Location: Lakewood, Co. | Registered: January 22, 2007Reply With QuoteReport This Post
DRR Sportsman
Picture of RB72Duster
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Maybe I'm not thinking about this correctly but how does a trans binding twist the drive shaft? Sounds more like a rear issue.
 
Posts: 182 | Location: NE Ohio | Registered: October 11, 2009Reply With QuoteReport This Post
DRR Sportsman
Picture of CURTIS REED
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quote:
Originally posted by RB72Duster:
Maybe I'm not thinking about this correctly but how does a trans binding twist the drive shaft? Sounds more like a rear issue.


I was going to ask the same question



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Posts: 688 | Location: KIEFER, OK. | Registered: August 17, 2007Reply With QuoteReport This Post
DRR Pro
Picture of Mike Beck
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Unless the trans locked-up internally there is no way it can bend the driveshaft going down the track.......

And there had to be skid marks from the rear wheels locking-up, or that driveshaft was on it's way out to begin with.
 
Posts: 1629 | Location: South River, NJ | Registered: June 19, 2007Reply With QuoteReport This Post
DRR Sportsman
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Drive shaft might be a separate issue although I thought it would go at launch, not 2nd gear.
Rear seems ok, spins freely, no noise.
Shaft splines (internal)are chewed up a little, haven't had time to check tailshaft splines or if trans moves freely in neutral.
Let's forget about drive shaft for now, what would cause motor to pull down in 2nd?
 
Posts: 459 | Location: Lakewood, Co. | Registered: January 22, 2007Reply With QuoteReport This Post
DRR Pro
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quote:
what would cause motor to pull down in 2nd?


A bind up in the transmission will cause that.

On the power flow, do you know if the low-reverse band is applied in low gear?
 
Posts: 2582 | Location: Boon Docks, FL | Registered: March 22, 2005Reply With QuoteReport This Post
DRR Sportsman
Picture of sr4440
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I had a 3 speed transmission that had some severe shift overlap, when you put it on jack stands and ran it thru the gears it would STOP during the 1-2 shift. Going down the track it felt like a bog.


Joe


Without data, you’re just another guy with an opinion.
 
Posts: 1120 | Location: TEXAS | Registered: February 07, 2003Reply With QuoteReport This Post
DRR Sportsman
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quote:
Originally posted by Trans Lady:
quote:
what would cause motor to pull down in 2nd?


A bind up in the transmission will cause that.

On the power flow, do you know if the low-reverse band is applied in low gear?

Don't know but I'll find out!
 
Posts: 459 | Location: Lakewood, Co. | Registered: January 22, 2007Reply With QuoteReport This Post



DRR Pro
Picture of Mike Beck
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I have a TH350 that would throw us curve balls from time to time. We would lose exactly .1 and never feel it do a darn thing!

Could go 10.90 on a few passes, then 11.00, then another 10.90. Chased this a long time. Changed convertors, no change. Rebuilt the engine, changed compression, changed cam, still same thing happened.

Finally did a glide and the car was now perfect.

Trans owed me nothing, LOT'S of passes on it, just find it strange that it could do that yet we never felt a thing. Data logs did show a slower acceleration rate 1st-2nd and 2nd-3rd on the slow passes.
 
Posts: 1629 | Location: South River, NJ | Registered: June 19, 2007Reply With QuoteReport This Post
DRR Sportsman
Picture of RB72Duster
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I would have the trans inspected at the very least. With driveshaft breakage, many times there is also damage to the trans.
 
Posts: 182 | Location: NE Ohio | Registered: October 11, 2009Reply With QuoteReport This Post
DRR Sportsman
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After closer inspection bell housing is cracked all around and one trans mount ear broke off Frown .
Trans shaft splines look OK though Smile.
Oh, and motor not frozen Smile.
 
Posts: 459 | Location: Lakewood, Co. | Registered: January 22, 2007Reply With QuoteReport This Post
DRR Pro
Picture of Mike Beck
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quote:
Originally posted by SS427IMP:
After closer inspection bell housing is cracked all around and one trans mount ear broke off Frown .
Trans shaft splines look OK though Smile.
Oh, and motor not frozen Smile.


Sorry to hear that. Years ago a u-joint cap came off in the burnout box then all he!! broke loose! Got a new driveshaft made, got a new tailshaft for the Dedenbear case. Was changing it at the track, went to tighten the bolts on the new tailshaft and thought the trans was spinning. It was hot and humid, thought I was dizzy......... I try again, and the case is moving!

I get out of under the car, look down at the trans, and see a crack completely around the entire trans!

Just had that case recertified too. It was DESTROYED!

That was over a $3000 burnout! Smile
 
Posts: 1629 | Location: South River, NJ | Registered: June 19, 2007Reply With QuoteReport This Post
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