Trans Upgrade Parts Recommendation

[badbajawa]

I've got a 68RFE with what seems to be OD clutch slip.

It will go into 5th and 6th but as soon as any load is applied it throws P0735.

I was towing about 15k 2 weeks ago, at the top of the first grade it threw P0871 as it upshifted coming out of load, but the whole timing of it was strange so I cleared that and went on my way.

The rest of the 800 mile trip it got progressively worse.

Phone research lead me to believe it was probably cross leaks as it had one bad incident and wasn't the same after.

Trans had apparently went into a sort of limp mode and I was only getting 1st and 4th and I hit a construction zone in a steep climb towing 15k with 38s and stock gears and it was stuck in 4th gear at 25 ish miles an hour and 103 degrees outside.

As you can imagine it got hot like really hot trans was over 260 for a solid 6-7 minutes.

We fought heat the entire way even as it cooled outside it didn't matter.

Anyway we got a second truck to tow the trailer home and I now unloaded at this point got to be really familiar with just hoping it stayed under 220 degrees.

Fortunately the fluid and filters were changed about 1k before the trip.

Anyway got it home added these parts:
Mag-hytec pa
Sonnax line booster
Sonnax accumulator piston kit
Sonnax accumulator plate kit
Bonded separator plate
ATS thermal bypass valve and speed sensors

It now runs great in 1-4 I'm pretty convinced the thermal valve locked closed and the heat took things out.

It's is however still slipping 5th and 6th it's pretty distinct that's it's clutch slip where it wasn't easy to tell before.

So now the trans needs to come out and I'm wondering what other parts I should put in it while it's out.

Kinda considering doing the pre assembled and clearanced Revmax input drum and then a standard rebuild kit for the remaining clutches and seals.

Will be going to DRD tuning and probably doing deletes since most of the cost will already be spent on the tuning.

I have no intentions to make big power with it or anything but I am wondering what other parts I should be considering both for longevity and to handle the added line pressure.

I think I have heard something about ballooning torque converters.

Anyway any advice would be much appreciated.

I'll reach out to DRD in the coming days as well.

Thanks guys.

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[IGOTACUMMINS]

I've got a 68RFE with what seems to be OD clutch slip.

It will go into 5th and 6th but as soon as any load is applied it throws P0735.

I was towing about 15k 2 weeks ago, at the top of the first grade it threw P0871 as it upshifted coming out of load, but the whole timing of it was strange so I cleared that and went on my way.

The rest of the 800 mile trip it got progressively worse.

Phone research lead me to believe it was probably cross leaks as it had one bad incident and wasn't the same after.

Trans had apparently went into a sort of limp mode and I was only getting 1st and 4th and I hit a construction zone in a steep climb towing 15k with 38s and stock gears and it was stuck in 4th gear at 25 ish miles an hour and 103 degrees outside.

As you can imagine it got hot like really hot trans was over 260 for a solid 6-7 minutes.

We fought heat the entire way even as it cooled outside it didn't matter.

Anyway we got a second truck to tow the trailer home and I now unloaded at this point got to be really familiar with just hoping it stayed under 220 degrees.

Fortunately the fluid and filters were changed about 1k before the trip.

Anyway got it home added these parts:
Mag-hytec pa
Sonnax line booster
Sonnax accumulator piston kit
Sonnax accumulator plate kit
Bonded separator plate
ATS thermal bypass valve and speed sensors

It now runs great in 1-4 I'm pretty convinced the thermal valve locked closed and the heat took things out.

It's is however still slipping 5th and 6th it's pretty distinct that's it's clutch slip where it wasn't easy to tell before.

So now the trans needs to come out and I'm wondering what other parts I should put in it while it's out.

Kinda considering doing the pre assembled and clearanced Revmax input drum and then a standard rebuild kit for the remaining clutches and seals.

Will be going to DRD tuning and probably doing deletes since most of the cost will already be spent on the tuning.

I have no intentions to make big power with it or anything but I am wondering what other parts I should be considering both for longevity and to handle the added line pressure.

I think I have heard something about ballooning torque converters.

Anyway any advice would be much appreciated.

I'll reach out to DRD in the coming days as well.

Thanks guys.

Can't go wrong with Revmax friend.

God bless,
igotacummins

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[Crshanta]

If it was me, I would call a couple of transmission shops like Revmax or Suncoast. They should give you some ideas what to check and have a better educated opinion on what is failing or failed.

Other than the trans you may want to consider an axle gear starting with a 4.

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[badbajawa]

Yeah it's time for the re-gear for sure thinking 4.56's. Randy's ring and pinion is close got a quote back at $3300 so I've got to decide if I'm doing them myself or shelling out for that as well. I won't delete without it though.

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[TexNeck]

I was going to say you need to regear or put a fully built trans in to handle the tires or downsize tires. Either way is expensive

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[RATLIN'HP]

Gears, gears, gears! I agree with the regear comments LOL.

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[badbajawa]

Does anyone disagree with 4.56 for the 38s? I don't think it's going too far but open to opinions

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[RATLIN'HP]

Does anyone disagree with 4.56 for the 38s? I don't think it's going too far but open to opinions

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That's what I'd choose.
Here would be your 65mph rpm with 4.56, and with 4.10 for comparison.
This would be in 6th gear with the 68RFE.

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[badbajawa]

Yeah I've been playing with calculators all afternoon glad my numbers match yours. I'm between 4.30 and 4.56 right now leaning towards 4.56.

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[Crshanta]

4.56 And 38 would be about same as 3.73 with stock sized tires. I do not envy your position of looking at trans, gears and supporting part changes. Good luck

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