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The Internal Reaction (Ring) Gear shattered in 700R4 of my 1982 GMC 2500 4x4 with 98K miles.


http://www.geocities.com/pm67/m01horse01.jpg

I have inherited a 1982 GMC 2500 4x4 from my mother. I had automatic trans fluid replaced at 70K miles three years ago. Everything appeared to be normal.

Last week, I put transmission in "Drive", proceeded to step on gas pedal, and heard the most gawd-awful noise I had ever heard.

Local Buick/GMC dealership originally said that I shattered the Sun Gear and Shell in the transmission. I visited the dealership to take a look at the transmission for myself.

Now, I know why they call it the Sun gear. There are three planetary gears that revolve around the Sun gear. From what people have told me, it is very common to experience problems with Sun Gear and Shell. Actually, my Sun Gear and Shell were not damaged.

It was the collar ring with teeth that mate with the three planetary gears. It is offically called the "internal reaction gear". It is now in three pieces. The teeth on the corresponding "internal reaction gear support" were completely ground down.

Upon a closer examination, there was another problem brewing. At one end of the transmission case -- on the inside -- there is a channel for a seal. Something called "low reverse piston". It appears that this is another common problem. This channel becomes jagged and causes wear and tear on the seal. This causes reverse and manual low to fail. My transmission was no exception. My channel was very rough. I was told that the seal is supposed to be square. Mine was very rounded.

So, my parts lists, if I decide the have my transmission rebuilt by local transmission rebuilder...

New Transmission Case
New Low Reverse Piston Seal
New Internal Reaction (Ring) Gear
New Internal Reaction Gear Support
New and Improved, Stronger Sun Gear Shell

Question #1. Should I have my transmission rebuilt locally or should I purchase a rebuilt transmission or should I purchase a new crate transmssion?

Question #2. Where can I find a rebuilt transmission? a new crate transmission?

Question #3. I have never abused the transmission. Other than the problems that I mentioned, the transmission was very clean -- looked like new to me (as a person with no experience in transmissions). The truck only has 98K miles. Any thoughts as to what caused my transmission to let go?

Question #4. Anyone have any experience with...

TCI Auto
http://www.tciauto.com/Products/Maximizer/truck_transmissions.asp
GM 1984-93 700R4, 30-spline V8 371400

Bowtie Overdrives
http://www.bowtieoverdrives.com
 

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Internal reaction [ring] gear shattered in 700R4

The 1982 up to 1984 700r4 was engineered with many parts that were prone to failure. The rear ring gear underwent a different [better] hardening process,84 or 85,which helped to reduce the types of catastrophic failure you experienced.

They also came out with a larger input shaft,changed the pump,input sprag,and really just a bunch of updates. The 700R4 may be the most vilified transmission ever built. And by the way,that is a beautiful horse.

Should you get the trans built by a local shop? I own a trans shop,so I'm biased. The list of parts you posted is extensive.

There are advantages either way you decide to go,with a local shop,if they do a good job,great,and if there is a problem well, their close.

Many remanufactured transmissions come with fantastic warranties,including covering towing expenses,labor to replace or repair etc.

If you choose a local shop,ask around,local speed shops,custom exhaust shops and the like usually know or deal with the better shops in town.

Hope this info helps,Good luck!
 

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Discussion Starter #3
briscoe said:
The 1982 up to 1984 700r4 was engineered with many parts that were prone to failure. The rear ring gear underwent a different [better] hardening process,84 or 85,which helped to reduce the types of catastrophic failure you experienced.

They also came out with a larger input shaft,changed the pump,input sprag,and really just a bunch of updates. The 700R4 may be the most vilified transmission ever built. And by the way,that is a beautiful horse.

Should you get the trans built by a local shop? I own a trans shop,so I'm biased. The list of parts you posted is extensive.
I have a couple of local shops in mind. I just don't know what upgrades to ask for.

Because of all of the improvements made between 1984 and 1986, I guess that I should throw my old trans away and start fresh with a 1987 or newer.

I am learning as I go...

My old torque convertor is 27 spline (besides it is probably full of shavings). So, it appears that I need a 30 spline.

I read elsewhere that I need to start with a "K case". What is a "K case" and on what make/models are they originally found?

I read elsewhere that it would be a good "mod" to upgrade from 10 vane pump to 13 -- as well as increasing the size of passage in Sun gear. Isthis necessary? I drive the truck on 140 mile round trips on the Interstate -- 4 or 5 times per week.

Also, I am thinking of installing a larger ATF cooler. Any recommendations on any aftermarket brands??
 

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700r4

probably the easiest solution is to buy a gm srta trans with 3yr/50k warranty and usually you will get a later model trans with better pump(13 vane)input shaft(larger)better servos and you can take it to any gm dealer in the nation for repairs if need be.be sure to have the factory trans cooler flowed for correct volume,i believe it is 2qts.a min.replace or flush to aquire the correct flow rates,make sure t.v. cable is adjusted properly to give proper upshifts and pump pressures to allow positive band engagement during 1-2 shift and holding of band in 4th. :thumbup:
 

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Internal Reaction [ring] Gear shattered in 700r4

You will be racking up over 36,000 miles a year,is that with the horse trailer?

A reman trans with a long warranty must be seriously considered. Now having said that,the problem is,if you go with a GM trans or someone like Jasper reman you are not going to get the really good updates which will help this trans live.

If your pulling that trailer that many miles a long warranty may be the best choice.

If you have it built,these parts are a good start-87,up trans,13 vane pump,wide 2-4 band,beast sun shell,transgo jr shift kit,transgo no yo yo kit[has good pump guide rings] then you should get a kit that increases the number of 3-4 clutchs,a good 5 pinion rear planetary,should consider a 5 pinion front planetary as well,not sure about your budget though. A good cooler is a must,synthetic fluid will raise the heat tolerance.

Other well informed trans people will probably post their ideas as well,so hopefully you can make an informed decision.
 

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Mr. Excessive
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On a different note, if (as you stated) your converter is full of metal shavings, then the rest of your lines, factory cooler (on the radiator) and any aftermarket cooler may well also be full of metal shavings.

These should be flushed very well. Another bit of cheap insurance is a magnetic inline filter on the return line to the transmission that will capture any shavings not cleaned out by the flush. I also used a magnetic drain plug and full synthetic Amsoil's Tourque Drive fluid that is designed for heavy trucks and is superior to Amsoil's standard synthetic fluid, offering severe service and allowing an extended drain interval (150K miles). The cost was an extra $8.50 for 2 1/2 gallons (0.85 a quart).

I rebuilt my own transmission (TH350) and it gave me the opportunity to strengthen the weak areas (larger/more shaft bushings, hardened parts, etc.) and increase the clutch packs to their maximum. I did have to get a piston shaved at a local machine shop, but it only cost me $30 and allows an extra steel and friction to be used for 25% more holding power.

This tranny lives in a rock crawler 4X4 and will be severely abused!

Good luck!! :mwink:
 

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Discussion Starter #7
briscoe said:
You will be racking up over 36,000 miles a year,is that with the horse trailer?
Besides the truck, I inherited my mother's horse farm, as well. The last few months, I was driving the truck -- without the trailer -- back and forth between my home and her farm at the furious rate that I mentioned earlier. I don't plan to continue that pace for much longer. I expect to put on another 15,000 miles next year. I plan to use the horse trailer about once a month -- on round trips of 240 miles or longer.


briscoe said:
If you have it built,these parts are a good start-87,up trans,13 vane pump,wide 2-4 band,beast sun shell,transgo jr shift kit,transgo no yo yo kit[has good pump guide rings] then you should get a kit that increases the number of 3-4 clutchs,a good 5 pinion rear planetary,should consider a 5 pinion front planetary as well,not sure about your budget though. A good cooler is a must,synthetic fluid will raise the heat tolerance.
Thanks, this is the kind of information that I am searching for. Still, I have no idea what is a good trans cooler. Is OEM GM good enough?
 

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Discussion Starter #8
conestogaman said:
Another bit of cheap insurance is a magnetic inline filter on the return line to the transmission that will capture any shavings not cleaned out by the flush. I also used a magnetic drain plug and full synthetic Amsoil's Tourque Drive fluid that is designed for heavy trucks and is superior to Amsoil's standard synthetic fluid, offering severe service and allowing an extended drain interval (150K miles). The cost was an extra $8.50 for 2 1/2 gallons (0.85 a quart).
I wasn't aware of magnetic inline filters. I have a magnetic drain plug for my oil pan. I never thought of adding a drain plug for the transmission. I have been just dropping the pan when the time comes to change ATF. I am using Amsoil engine oil in my other vehicles. I have owned several vehicles that made it over 175K miles without any transmission problems using just regular Dexron II/III. Looks like I will be using Amsoil Torque Drive ATF in the new transmission.
 

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Mr. Excessive
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I have used the regular Amsoil ATF with good results too. The Torque Drive is for severe service in large truck automatics and gives a 150K mile drain interval (in the big trucks) so should be awhile before I can come close to those miles...

The inline magnetic filter I got from my tranny parts supplier and is a Magnefine (www.magnefine.com). I reused a 3 qt. Caterpillar cooler from a dozer for my rockcrawler and decided the $12 was cheap insurance.

Usual disclaimers apply.
 
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