TH400 lost 2nd gear

V-Twin

V-Twin

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Mar 23, 2008
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I have a problem with a TH400. It lost 2nd gear. I already had delayed 1-2 some time when cold and it had a 1-2 sec delay in picking up going from reverse to forward.
It has reverse and 1st and 3rd work fine, kickdown freewheels, Engine braking also works in 1st and 2nd.

It won't go into 2nd but will rev 1st until it slips briefly through 2nd into 3rd.

I suspect it's the direct drum clutch
 
V-Twin said:
I have a problem with a TH400. It lost 2nd gear. I already had delayed 1-2 some time when cold and it had a 1-2 sec delay in picking up going from reverse to forward.
It has reverse and 1st and 3rd work fine, kickdown freewheels, Engine braking also works in 1st and 2nd.

It won't go into 2nd but will rev 1st until it slips briefly through 2nd into 3rd.

I suspect it's the direct drum clutch
Click to expand...


I'll have to go with the intermediate clutch and sprag. Sounds llike the sprag is not holding. Get an early model 34 element sprag- almost bulletproof. You'll need the intermediate clutch drum too.

The sprag:
http://store.summitracing.com/partdetail.asp?autofilter=1&part=TCI-227900&N=700+115&autoview=sku

The Drum:
http://store.summitracing.com/partdetail.asp?autofilter=1&part=ATI-405681&N=700+115&autoview=sku

I would also look at getting the steel and faced plates for a 4L80E. The plates are all thinner than the stock 400 plates, You can get more surface area for the clutches..
 
sounds like lugs in case broke. if you have engine breaking in 2nd then kd band is working. the delays into rev and forwd sound like too much pump gear clearance.
 
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If I manually set it in 2nd so it won't shift to 3rd it the engine basically freewheels, there's little or no drive. When I mash the throttle the revs go up quickly and the car pulls a little but it's mostly a sensation of freewheeling.

I hope it's not the lugs, then I won't be able to fix it myself..drats!!!

I was hoping it was the clutches :( The fluid is clear, doesn't smell, is always on level. I never even abuse it either...I thought those TH400s were strong....they're junk LOL

It really feels like it's shifting in 2nd, freewheeling till the governor forces it to shift into 3rd.

I'll have to pull the tranny and tear it apart to make a proper diagnose then. :gurney:
 
V-Twin said:
If I manually set it in 2nd so it won't shift to 3rd it the engine basically freewheels, there's little or no drive. When I mash the throttle the revs go up quickly and the car pulls a little but it's mostly a sensation of freewheeling.

I hope it's not the lugs, then I won't be able to fix it myself..drats!!!

I was hoping it was the clutches :( The fluid is clear, doesn't smell, is always on level. I never even abuse it either...I thought those TH400s were strong....they're junk LOL

It really feels like it's shifting in 2nd, freewheeling till the governor forces it to shift into 3rd.

I'll have to pull the tranny and tear it apart to make a proper diagnose then. :gurney:
Click to expand...


I'm still gonna' stay with the sprag being broken. A 400 is a pretty strong trans, but with enough HP you can break them. Pull the tranny and rip it apart. You should be able to find the problem.:ill:
 
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