Help Me Stop Slipping Please.

[BC847]

Hey folks, I hope everyone is having restful holidays (if there is such a thing).

I've run into a bit of an issue with my heap's transmission. I'm wanting to correct it (them) before the trans toasts itself . . . . if it hasn't already.

Not quite a year and a halve ago, I rebuilt my A518 non lock-up transmission including Alto Red/Koleen Steels and ~
- The rear clutch-pack (forward). Went from an OEM of four clutches and steels to five of each.
- The front clutch-pack (direct) There I went from an OEM of four clutches and steels to six of each.
- The front band was changed to a solid type.
- A 4.2 to 1 ratio lever for the front band.
- An upgraded overdrive piston retainer.
- A new rear band.
- Tricked out multiple seal servos.
- Upgraded the OD direct clutch to 23 single-sided friction elements.
- Upgraded the OD spring and it's associated plate.
- The OD clutch itself was upgraded to six clutches and steels.
- A full TransGo kit.
- Suncoast converter.
- A supplemental fan assisted cooler with in-line spin-on filter.

- Bunch of other crap.


It's been doing well till recently when I installed twins (HT3B/HX35 hybrid). Prior to the twins I was running about 395HP / 725ft/lbs (#2/uncorrected). With that (and a little W/M) I could make a pass at the local tracks and not have any issues with the trans.
Adding the twins has taken me to about 406HP / 840ft/lbs (#2/uncorrected). Turning on the not yet tuned for the twins W/M takes it to about 405HP / 900ft/lbs (uncorrected).

With that the trans is slipping on engagement of the gears during a full power pass (13.90 @ 97.78 in the quarter).

I've stopped racing the mess till I can sort out and correct the slip as I don't want to ruin things.

- Would I be correct in thinking that I can raise the hydraulic pressures and stop the slipping? If I recall the TransGo install, in setting the pressure regulator, I turned the screws in three turns from flush out of a possible maximum of five turns (assuming more turns in means a higher pressure).
- Is it possible I should have used the 5 to 1 band lever instead of the 4.2 to 1?


What'cha reckon?

Thanks, David.

[KTA]

I would recommend not going to the 5-1 lever. I do wonder what is your current line pressure? Also make sure your throttle cable is adjusted properly. I would recommend setting your line pressure to be about 200+ in 1st gear idle with the throttle cable manually pulled to full throttle position. When I was at the track I would always run it tied like that, then un twist tie it and let it function normally for regular driving.

[Redneckintraining]

so how bad would shifting be at those pressures on a DD? I have a 727 but it doesnt want to shift into third until it warms up a bit.

[BC847]

I'm embarrassed to say I've no clue what my pressures are as I haven't checked with a gauge. I 'spect that'll be the next tool.

I've often wondered why my mess never banged when shifting from one gear to the next. I attributed it to the non lock-up converter.

Is there a particular PSI range I need to look for when getting a guage? (I'm fixing to go start reading the trans manuals regarding pressures).

Thanks folks.

[Richie O]

Do the shift kits make the chirp when they shift in the 727's and 518's. I had plenty of turbo 350's that would spin when they shifted. My dad even had a 1986 caprice police cruizer with a transpak shift kit and it would chirp 2nd and 3rd. There were not many cars that could get away from him in that one.

[PToombs]

Richie, it's all in the setup. IIRC, you could have firm solid shifts, or hard tire chirping shifts. Depends where the line pressure was set internally.

[peobryant]

Thats what I have always been told, Pete. The higher the line pressure, the harder the shift.

[VEfreak]

I would recommend not going to the 5-1 lever. I do wonder what is your current line pressure? Also make sure your throttle cable is adjusted properly. I would recommend setting your line pressure to be about 200+ in 1st gear idle with the throttle cable manually pulled to full throttle position. When I was at the track I would always run it tied like that, then un twist tie it and let it function normally for regular driving.

what's wrong with the 5-1 lever? If i'm not racing how should i set my line pressure?

[KTA]

The 5-1 applies too agressively for a low rpm high torque diesel. They are much more prone to breaking bands and bending struts and the 4.2 is plenty to hold the power and it does it in a more controlled manner.

[cummins king]

Also you torque converted if its not tight then it will slip alot, and when my new tranny shifts, its a good hard one, what the way you want it.

[Philip]

so how bad would shifting be at those pressures on a DD

It would shorten the life of the trans quite a bit. The clutch pack piston seals would most likely let go. They do not like much over 180 PSI against them.

With that the trans is slipping on engagement of the gears

Which gears is it slipping in???

There are two clutch packs in the trans. The rear clutch is used in all forward gears. The front clutch is used in 3rd & 4th only.

[BC847]

With that the trans is slipping on engagement of the gears

Which gears is it slipping in???

There are two clutch packs in the trans. The rear clutch is used in all forward gears. The front clutch is used in 3rd & 4th only.

Philip, it's kinda hard to tell as it only occurs during a WOT pass at the track. I don't know that it's slipping as I leave the line (1st gear). My best guess is it's happening going to third and OD which has a diagnosis lean toward the forward pack.
As has been established, I need to put a pressure gauge on it and see what's going on there as well as drop the pan to see if I've already toasted things.

I've just got to get to it.

Thanks folks.

[Philip]

If you drop the pan. Go ahead and drop the valve body and do a air pressure test. This will tell you if it has blown a seal or sealing ring.

[SNOOT]

Is your truck making alot of heat and no go on the top end? Is there any kind of leaking on the front seal. What flex plate are you using?

I ballooned a RV no name converter last year. After this happened I lost my MPG and the truck ran hot from heat exchange to the tranny cooler. The converter leaked so bad that it let the truck rev out and made lots of extra drive pressure and heat.

Don't know if you can check it in the truck here are a couple pictures of mine when I built the new tranny.