7MT hydraulic accumulator failure

[tdhyden79]

Dude, nice trail save! Kudos! Curious, how did you bleed it?

Bleeder valve is part of the QD at the bottom of the hose as it goes into the transmission. System is not really made to be easily field blead, apparently ford has a special setup to get the bubbles out. Two retaining clips on the fitting, one to remove it completely, one to slide it out just enough to bleed out it through a nipple. Once I got the part on, had my wife slowly push the pedal down, pop the bleeder, close the bleeder, slowly pull pedal up...repeat about 50 times. Still no pressure so had to do A LOT of full stroke pumps and half pumps while my wife taped the brake fluid reservoir and all the lines trying to get all the air to move up and out of the system. 100 pumps to break up the bubbles in the master cylinder and get them moving to the reservoir, stop for 10 minutes and let the bubbles rise up through the system, repeat- 100 vigorous pumps while she taps the reservoir and lines, wait. It took a out 300 pumps to get full pressure. The drive home was 900 miles, my wife was up to the challenge as I had to drive the truck and camper. She limited pressing the clutch as much as possible and tried to keep the brakes cool as the brakes and clutch share the same fluid. I refilled the system with Prestone full synthetic DOT 4 because it had the highest rating against thermal degradation. She kept it in 3rd gear while in the mountains to keep up torque for climbs and also to maximize engine breaking. Once we got to flatter ground she locked it in 4th and kept the RPMs around 2500. Luckily that little 2.3 is tough as nails and doesnt mind reving.

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[Brian_B]

I'm going to build a permanent fix, let me know what yall think...



Two of these as the broken part is female on both sides.

https://www.tickperformance.com/4an...gmwFgmvZAGeEKrukbq0kp0h14s2xDvQcaAuK7EALw_wcB



And one of these to join in the middle.

https://www.summitracing.com/parts/..._Y2kWQOYcAbMIMK7TI33Hew-RnqvILVRoCZskQAvD_BwE



should completely replace the plastic part

That could be just crazy enough to work, you bastard genius

 

[GI_Jo_Nathan]

Bleeder valve is part of the QD at the bottom of the hose as it goes into the transmission. System is not really made to be easily field blead, apparently ford has a special setup to get the bubbles out. Two retaining clips on the fitting, one to remove it completely, one to slide it out just enough to bleed out it through a nipple. Once I got the part on, had my wife slowly push the pedal down, pop the bleeder, close the bleeder, slowly pull pedal up...repeat about 50 times. Still no pressure so had to do A LOT of full stroke pumps and half pumps while my wife taped the brake fluid reservoir and all the lines trying to get all the air to move up and out of the system. 100 pumps to break up the bubbles in the master cylinder and get them moving to the reservoir, stop for 10 minutes and let the bubbles rise up through the system, repeat- 100 vigorous pumps while she taps the reservoir and lines, wait. It took a out 300 pumps to get full pressure. The drive home was 900 miles, my wife was up to the challenge as I had to drive the truck and camper. She limited pressing the clutch as much as possible and tried to keep the brakes cool as the brakes and clutch share the same fluid. I refilled the system with Prestone full synthetic DOT 4 because it had the highest rating against thermal degradation. She kept it in 3rd gear while in the mountains to keep up torque for climbs and also to maximize engine breaking. Once we got to flatter ground she locked it in 4th and kept the RPMs around 2500. Luckily that little 2.3 is tough as nails and doesnt mind reving.

Wow! Nice work, that's a hand full.

For what it's worth the Bronco shifts pretty well without the clutch if you rev-match and ease it in. Up is easier than down, but down is possible.

 

[tdhyden79]

Wow! Nice work, that's a hand full.

For what it's worth the Bronco shifts pretty well without the clutch if you rev-match and ease it in. Up is easier than down, but down is possible.

I wondered... glad to know.
I had an old 94 F150 and a 95 Geo Tracker back in the day that I occasionally had to drive like that because I couldn't afford to repair them! lol

 

[GI_Jo_Nathan]

I wondered... glad to know.
I had an old 94 F150 and a 95 Geo Tracker back in the day that I occasionally had to drive like that because I couldn't afford to repair them! lol

Yep! I've played around with my Focus like that and couldn't help but try it in the Bronco.

Definitely not the best thing for the synchros I'm sure, but in a pinch. Basically if you lightly tug on the shifter and feather the throttle going up it will pop in place if you get it right.

 

[oldcanoe]

Enough failures have been observed that it could be more than isolated manufacturing defects. Open question to those more in the know...could these failures be high cycle fatigue? Possibly sourced from the vacuum assist? Are there any photos of the failure points/surfaces?

 

[tdhyden79]

Enough failures have been observed that it could be more than isolated manufacturing defects. Open question to those more in the know...could these failures be high cycle fatigue? Possibly sourced from the vacuum assist? Are there any photos of the failure points/surfaces?

Here is a photo of the failed accumulator. There are 4 tabs that hold the body to the internal valve. All 4 tabs broke off allowing separation.

Enough failures have been observed that it could be more than isolated manufacturing defects. Open question to those more in the know...could these failures be high cycle fatigue? Possibly sourced from the vacuum assist? Are there any photos of the failure points/surfaces?

Here are a few pics of the failed part. There are 4 tabs that hold the body to the internal valve. The tabs broke off allowing full separation. I have ordered a new factory part, when I get it I will upload pics of the new complete piece.

 

[615_Bronco]

So is this another part I should order and throw in the Bronco?

 

[tdhyden79]

So is this another part I should order and throw in the Bronco?

A resounding YES! I have ordered the parts to replace the plastic piece with a full metal piece. Once I get it put together and verify fitment and function, I will post it here with links so it can be replicated.

 

[GI_Jo_Nathan]

A resounding YES! I have ordered the parts to replace the plastic piece with a full metal piece. Once I get it put together and verify fitment and function, I will post it here with links so it can be replicated.

Thank you! Really interested to also see if this changes the feel of the clutch, For better or for worse .

 

[mspeter]

A good spare to have. May go with the quick connects and the AN coupler.

Unlikely, but any thoughts if the OEM part had some impact or stress at some point; from installing up-fitter wires closeby etc.

 

[tdhyden79]

Thank you! Really interested to also see if this changes the feel of the clutch, For better or for worse .

Honestly, I'm used to performance clutches on sports cars, and hd clutches on trucks. The Bronco clutch has always felt loose, mushy, and unpredictable. The accumulator (failure point) and dual mass flywheel (heat generator) combined create a comfort-biased system at the expense of ruggedness and reliability. A Southbend Organic/Ceramic Stage 2 Clutch with a billet flywheel is in my future.

 

[tdhyden79]

A good spare to have. May go with the quick connects and the AN coupler.

Unlikely, but any thoughts if the OEM part had some impact or stress at some point; from installing up-fitter wires closeby etc.

No, It's tucked right against the firewall, but honestly, this is a part that should be built to take abuse. Actuating the clutch, even in normal stop and go traffic puts an immense amount of stress on the hydraulic system, upwards of 350 to 500 psi. In reality, having a plastic pressure vessel that is constantly seeing 0psi-350psi-0psi-350psi over and over aging, and is exposed to extreme temperature fluctuations because of cold ambient air and under hood heat, is only a matter of time before the plastic degrades and fails, in my opinion.

 

[GI_Jo_Nathan]

Honestly, I'm used to performance clutches on sports cars, and hd clutches on trucks. The Bronco clutch has always felt loose, mushy, and unpredictable. The accumulator (failure point) and dual mass flywheel (heat generator) combined create a comfort-biased system at the expense of ruggedness and reliability. A Southbend Organic/Ceramic Stage 2 Clutch with a billet flywheel is in my future.

Yeah mushy is definitely the right word. The Steeda clutch return spring helped a little bit, feels slightly more linear I think. I'm wondering if this will improve even further. And yeah whenever I need to do a clutch, single mass flywheel is for sure happening.

 

[crenca]

Honestly, I'm used to performance clutches on sports cars, and hd clutches on trucks. The Bronco clutch has always felt loose, mushy, and unpredictable. The accumulator (failure point) and dual mass flywheel (heat generator) combined create a comfort-biased system at the expense of ruggedness and reliability. A Southbend Organic/Ceramic Stage 2 Clutch with a billet flywheel is in my future.

Here is a short summary to add/expand on what @tdh1971 is saying:

https://outbacktravelaustralia.com.au/4wd-mods-tech-torque/dual-mass-flywheels-explained/

Yeah mushy is definitely the right word. The Steeda clutch return spring helped a little bit, feels slightly more linear I think. I'm wondering if this will improve even further. And yeah whenever I need to do a clutch, single mass flywheel is for sure happening.

I’m also interested in this as well. I never installed the Steeda spring because I suspected it would only have minimal effect. The question to my mind is how much this little damper/“accumulator” is responsible for the vaugeness/mushiness of the Broncos clutch. Even if it’s just 20 or 30% (with the dual mass flywheel responsible for the rest) removing it might be a significant improvement.

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