Group effort to illustrate 200-4r weak points

[Mike T]

There are always discussions regarding what part broke and I thought it would be nice to have a visual for those (including myself) that do not know exactly what part is being discussed.

With everyone's past experience maybe we can use this illustration to point out the problem part and add a brief description of the failure type (IE cracked,sheared,distorted) and at what power level.

I've pointed out a few and with everyone's help we can number and list parts known to be a problem.
Calibration failures could be listed too (IE low/high pressure damages this particular part)

1. Stator support
Splines strip

2. Selective pump washer
Small cracks can develop causing it to break/fall out. Will lead to damage of stator support retaining bolt due to metal to metal contact

3.Turbine/Input shaft
(failure type/description needed)


4. Over Drive ring gear
Cracks in spline area. Blocked 4th accumulator mod thought to be a possible cause.
(failure type/description needed)

5. Band pin
Shears off causing band to become inoperable.

6. Band
Lug area (where band pin attaches) can be damaged/torn off.
Apply end can be punctured by servo pin.

7. Direct piston
Distorts under high apply pressure.

8. Forward drum
Shaft shears

 

[INEEDAGN]

You're basically trying to create a more up to date and detailed version of the "strengthening the 200-4r" post that was a sticky for 15 years. I like it. I may not contribute much because much of what I "know" about hard part failures has been hearsay I've read on here. It all makes sense to me but I haven't seen/done it myself, except the idea that blocking the 4th accumulator is hard on the overdrive section. The two I've torn apart that didn't have active 4th accumulators had the common cracks in the splines of the OD carrier. They didn't "fail" but they were cracked. On that note I'm wondering how many of them ever actually fail even when cracked, because the back end of the carrier/spline area is solid and would seem less likely to actually fail even if the thin area of the splines is cracked. I'm sure I'll think of more topics of conversation if you want me to ramble incessantly.

 

[Mike T]

You're basically trying to create a more up to date and detailed version of the "strengthening the 200-4r" post that was a sticky for 15 years. I like it. I may not contribute much because much of what I "know" about hard part failures has been hearsay I've read on here. It all makes sense to me but I haven't seen/done it myself, except the idea that blocking the 4th accumulator is hard on the overdrive section. The two I've torn apart that didn't have active 4th accumulators had the common cracks in the splines of the OD carrier. They didn't "fail" but they were cracked. On that note I'm wondering how many of them ever actually fail even when cracked, because the back end of the carrier/spline area is solid and would seem less likely to actually fail even if the thin area of the splines is cracked. I'm sure I'll think of more topics of conversation if you want me to ramble incessantly.

Your input is exactly what I'm looking for as a group. Check the updated O/D ring gear info please point out any inaccuracies. If we have a theory and a majority thinks it's incorrect we'll edit it.

 

[Mike T]

Also I would like to show where the roller bearings are installed. From my own experience I see where the rollerized pump bearing would be beneficial.

 

[McHaggis]

Pump Slide. Break at the pivot point. I'm on my 3rd one in under 6500 miles. Not a HP thing but RPM/Pressure? 300psi at 6500-6800rpm. This last time I dropped 1st & 2nd pressure from 300 down to 275 psi with a PR spring so fingers crossed.

 

[Mike T]

Pump Slide. Break at the pivot point. I'm on my 3rd one in under 6500 miles. Not a HP thing but RPM/Pressure? 300psi at 6500-6800rpm. This last time I dropped 1st & 2nd pressure from 300 down to 275 psi with a PR spring so fingers crossed.

Was bitten by this type of failure too, I started to add it to the initial list but wasn't sure if it was a wide spread problem. Would really like to leave the entire pump assembly to INEEDAGN so when he completes the thread we can reference that.

 

[INEEDAGN]

Lol I oughta finish that one of the days huh? Much easier to do on the computer and the wife usually has it for work.

 

[FASTV6HENRY]

Hey Mike you can use my 2004R that i just pulled out of my car for illustration. All i ask is you give it back fully rebuilt.

 

[bison]

The biggest problems I see are with direct oil and apply. The direct clutch capacity isn’t favorable to a high output application. High output is 9 sec power in a 3500+lb car. There’s simply not a lot of surface area for that clutch to apply on a ratio change under power. This problem is compounded by leakage on the direct oil circuit and by using warped pressure plates. The pressure plate and apply ring area can easily be updated for performance but oil to that area can still be a big problem. Leakage at the pumps boost valves is also a big problem and will cause reductions in line pressure when hot. For hard parts the intermediate shaft is very prone to failure as well as the OD planet. The OD planet damage I see is often caused by too large of an orifice for 4th oil. The spline area on that planetary is very weak. Input shafts break occasionally but not typically in 10sec or slower cars. Detail on the pump and direct oil circuit pays off huge when dealing with a 30 year old transmission that is nearly impossible to acquire usable hard parts from a supply house in a timely manner. Most direct drums aren’t acceptable for high performance and pump assemblies are typically crap as received from a supply house. You can throw all the soft parts you want at a trans but having parts that aren’t up to the factory spec to begin with the transmission will fail rapidly in a performance application


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[Mike T]

Lol I oughta finish that one of the days huh? Much easier to do on the computer and the wife usually has it for work.

Tell her you need it to Christmas shop

Hey Mike you can use my 2004R that i just pulled out of my car for illustration. All i ask is you give it back fully rebuilt.

Little short on skills at the moment

 

[Mike T]

The pressure plate and apply ring area can easily be updated for performance but oil to that area can still be a big problem. Leakage at the pumps boost valves is also a big problem and will cause reductions in line pressure when hot.

The unit I had a slide/rotor failure in is showing heat in the direct clutches, two of the frictions have dark circles that appear to be the shape and size of the apply ring.

Is the boost valve leakage typically between the bore and valve?

 

[SS/GN]

Good topic and the leaking boost valve is a problem, even with some of the "big" units. There used to be ones that were o-
ringed.

 

[Steve V]

Good topic and the leaking boost valve is a problem, even with some of the "big" units. There used to be ones that were o-
ringed.

Sonnax still sells the O ring boost valves, I use them in almost every unit needed or not cheap insurance.

 

[INEEDAGN]

The biggest problems I see are with direct oil and apply. The direct clutch capacity isn’t favorable to a high output application. High output is 9 sec power in a 3500+lb car. There’s simply not a lot of surface area for that clutch to apply on a ratio change under power.

Does the mcclay billet direct drum increase the dimension between the snap ring groove and the apply piston/ring? I know there's only so much to gain there before you run the clutches off the forward drum but there has to be some gain there, even if it's gained by allowing a thicker pressure plate at the top. Not only that but it should be able to dissipate heat a lot better than the stock drum. Then there's the rotating inertia in first, etc. I went total nerd when I saw that drum but none of my builds will ever be able to justify it.

 

[bison]

Does the mcclay billet direct drum increase the dimension between the snap ring groove and the apply piston/ring? I know there's only so much to gain there before you run the clutches off the forward drum but there has to be some gain there, even if it's gained by allowing a thicker pressure plate at the top. Not only that but it should be able to dissipate heat a lot better than the stock drum. Then there's the rotating inertia in first, etc. I went total nerd when I saw that drum but none of my builds will ever be able to justify it.

I have no idea. Never used one. We need an iron drum like the 400. It would be better for 1-2


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[bison]

Good topic and the leaking boost valve is a problem, even with some of the "big" units. There used to be ones that were o-
ringed.

There are o ringed ones but not enough size for some builds. I’ve tried to add grooves but haven’t been successful yet. The bore is too sharp and the o ring can’t protrude much or it gets nicked


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[achalmersman]

Wait did someone say something about a billet direct drum? I wasnt aware of any direct drums avaialable new. I have 2 NOS direct drums for future use but does anybody have info on this mclay direct drum?

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[~JM~]

http://scottmcclayengineering.com/200-4r-drum.html

 

[achalmersman]

http://scottmcclayengineering.com/200-4r-drum.html

Its aluminum? Wonder how that would hold up. Anyone with experience?

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[~JM~]

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