4L80e No engine braking

[WannaBe1Ton]

I did a lot of reading on another thread about a diesel guy who said he had no engine braking with a 4l80e and it seems similar to my issue.

My truck is 1991 K2500 HD 350TBI with 4L80E and 3.73 gears.

I built the engine last year and my uncle built the transmission like 5ish years ago. The truck didn’t belong to me till this year. When i’m driving and drop it to third I can feel a very noticeable resistance. RPMS raise, truck starts slowing down, exhaust note changes. If i drop into second, instead of the rpm’s raising more and slowing down. I just go to a bit above idle (low 1k rpm’s) and i feel no resistance. Anyone know what would cause this?

 

[Supercharged111]

Whatever's causing my dually to do the same, but it does that in every gear but 1st. My guess for me is smoked overrun clutches AND a smoked intermediate band. Since yours does it in 2nd, your intermediate band is likely not playing ball either. I wonder if these issues can exist in the valve body? I.E. check balls mashed into the plate, blown through, etc?

 

[texas tough]

if your dropping it from 4th to third, this is supposed to happen. if u are going from 4th to second, the coast clutches are letting it roll so you dont tear **** up. why all the dropping of gears, ? are u climbing hills, trying to be hot rod man? just put it in drive and leave it alone.

 

[Supercharged111]

if your dropping it from 4th to third, this is supposed to happen. if u are going from 4th to second, the coast clutches are letting it roll so you dont tear **** up. why all the dropping of gears, ? are u climbing hills, trying to be hot rod man? just put it in drive and leave it alone.

You do realize we drive trucks, and sometimes like to do work with said trucks, right? I drop gears all the time with a trailer out back. There are plenty of legit reasons to deviate from "just put it in drive and leave it alone". I'm here for an answer to his question, not to debate the merits of engine braking. Let's keep this on track.

 

[GoToGuy]

Read up on trans braking. You may exceeding the allowed downshift and the transmission being smarter, may be overriding your gear selection. I'm not saying there your wrong, or could be a mechanical problem. Have looked in your owners manual, trailering, engine braking operation? There is information you may not be aware of.
Do have headlight warning chime? Did you you know if you rotate the cluster lights to off it silences the headlights on warning?
In 4th at 45 mph versus 2nd at 45 . Hmmm.
What speed is redline in second?

 

[Spareparts]

Well according to my speedo (might be off) im hitting 70 mph in second logging data for HPTuners.

 

[Supercharged111]

Read up on trans braking. You may exceeding the allowed downshift and the transmission being smarter, may be overriding your gear selection. I'm not saying there your wrong, or could be a mechanical problem. Have looked in your owners manual, trailering, engine braking operation? There is information you may not be aware of.
Do have headlight warning chime? Did you you know if you rotate the cluster lights to off it silences the headlights on warning?
In 4th at 45 mph versus 2nd at 45 . Hmmm.
What speed is redline in second?

Faster than 45 no matter what gear he has. Exceeding the limits would merely prevent a downshift in the first place. I don't believe the OP is mistaken with his observations because again, my dually does this as well but it also drops out in 3rd and 4th. As far as I know, overrun clutches and bands are all that there is to allow for engine braking since every next year overruns the previous with a sprag.

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[WannaBe1Ton]

if your dropping it from 4th to third, this is supposed to happen. if u are going from 4th to second, the coast clutches are letting it roll so you dont tear **** up. why all the dropping of gears, ? are u climbing hills, trying to be hot rod man? just put it in drive and leave it alone.

Yeah i tow car trailers and frequently have excess of 2000 pounds in the bed. the area i live in has a lot hills and i’d prefer not to have my brake drums smoking the whole way down. i’m also not worried about wear on my transmission. it’s built to do this. if it wears out… i’ll just rebuild it lol.

 

[WannaBe1Ton]

Read up on trans braking. You may exceeding the allowed downshift and the transmission being smarter, may be overriding your gear selection. I'm not saying there your wrong, or could be a mechanical problem. Have looked in your owners manual, trailering, engine braking operation? There is information you may not be aware of.
Do have headlight warning chime? Did you you know if you rotate the cluster lights to off it silences the headlights on warning?
In 4th at 45 mph versus 2nd at 45 . Hmmm.
What speed is redline in second?

I went pretty slow when testing this. shouldn’t have been going to fast especially considering it actually did drop to second. it just goes to idle if i’m not on the gas. the owners manual tells you to downshift to decend hills if you are well loaded up. no headlight chimes.

 

[tayto]

I would check the seal on the 1-2 servo