How feasible is it to rebuild your own Tranny.

I was wondering how feasible it would be for me to rebuild a tranny. I know that it is relative to skill and possibly equipment. For the sake of discussion let me throw this at ya.

I was thinking... There are some used transmissions I see on Craigslist all the time. I am pretty good with mechanical things. I can do most average repairs and am not really afraid of diggin into things. I am an Electronics Tech/Computer Tech by trade and grew up farming. So I have good troubleshooting skills and mechanical ability. I learned from my father and the military how to read and follow manuals.

So really I just need a place to start. Maybe a list of required manuals, tech bulletins, diagrams or anything helpful. also a list of equipment that may be needed.

I realize that people spend a lot of time and money to train to do this work, so I don't mean to offend anyone. I don't think that just anybody can do that kind of repair. I do however, think that I can.

So.. Before I actually need to have my transmission repaired, I would like to see if it would be feasible for me to learn and rebuild one and have it ready to go.

My blazer has about 195k miles and now is making a whining sound. It shifts good, but it was rebuilt at 75k and then they had to go in again in about 3 months following. Since then though. we have put alot of miles on. I also just towed a boat (1800 lbs) for over 625 miles in some very hot weather. No Transmission cooler. ( I know probably not a smart move) I think the whine was there before though.

So anyway the wife loves her blazer and I really like it too. I will probably buy another since you can pick em up for pretty decent prices.

If I can learn the tranny rebuild it will save me alot of $$$$ in the long run I think.

What do you guys think? Just thought I would run it by to see what you pros think.

Thanks
:screwy:

their is alot of tech manuals available on line and diagrams of specific trannys all over including electrical schematics. the difficulty of rebuilding the tranny is in the type that you are working with and how old it is.

nowhere in your post do i see year of veh 2wd or 4wd i am guessing automatic because you say you dont have trans cooler. I would change fillter and fluid because auto transmissions can whine if fillter starts to clog. as far as rebuilding an automatic trans, they req special tools and expertize. i dont know what you ablity is or how much down time of veh you can afford to have but i have changed trannys and that alone is hard ive done some on ground ( not fun) i now have a lift and its still hard.

nowhere in your post do i see year of veh 2wd or 4wd i am guessing automatic because you say you dont have trans cooler. I would change fillter and fluid because auto transmissions can whine if fillter starts to clog. as far as rebuilding an automatic trans, they req special tools and expertize. i dont know what you ablity is or how much down time of veh you can afford to have but i have changed trannys and that alone is hard ive done some on ground ( not fun) i now have a lift and its still hard.


Thanks. All very valid points. I am definitely going to change the filter and fluid. Down time is kind of flexible, except its the Mrs vehicle. So you know what that means. It can't take too long. Couple of days the most. That is why I was thinking about getting a tranny in advance and rebuild it in my garage just so that it is ready to go.

I don't have a lift, just a spot in the garage or driveway.

Thanks for the input, Much appreciated.

Sorry Details on vehicle are as follows.

2000 Chev. Blazer LT 4.3
4X4 (3-Button), Auto
195k miles.

nowhere in your post do i see year of veh 2wd or 4wd i am guessing automatic because you say you dont have trans cooler. I would change fillter and fluid because auto transmissions can whine if fillter starts to clog. as far as rebuilding an automatic trans, they req special tools and expertize. i dont know what you ablity is or how much down time of veh you can afford to have but i have changed trannys and that alone is hard ive done some on ground ( not fun) i now have a lift and its still hard.

I must agree with you. I'm an old man but in the 60s I worked in a tranny shop, today with all the electronic shifting etc. Nothing replaces experience & correct tools. I got a shock a while back. A friend of mine owned an 05 Ford Explorer 4x4 with a 5 speed auto. There is NO DIPSTICK & NO WAY TO ADD FLUID without pumping it in through the cooler lines. But without a dipstick it has to be pumped out with a machine & refilled with the correct amount of fluid. That made me want to go out and buy one of those pieces of JUNK.

There are somethings to do inside it too and the aftermarket found this out.One is inside the direct drum,there are 5 black springs inside there and there is one thing to do with them: Do not put back in and throw them away.Aftermarket says to throw them away and GM says to put them back in.GM is 100% wrong and the aftermarket is right.They restrict the clutches from floating and will burn them right up.The aftermarket found this problem.

Just another opinion. I have rebuilt trannys, engines, full restros, you name it. While it is not really hard if you have thee right tools and a good set of directions to follow, you have to decide if it is really worth it to you to rebuild it, or start rebuilding. For me, I have a rebuilder I trust and he will rebuild any tranny/torque converter for price of parts +$200, and that includes a 2 year warranty. I cant beat that. I can rip the tranny out, get it to him, get it back from him and back in the car in less time then I can take it out and rebuild it myself then reinstall. Hes a pro. Same with exhaust. I have a guy does exhaust for usually cheaper then I can buy the parts. I just had a friend come to me with a noisy exhaust. I looked at it and told him there was a hole in the muffler. I looked up a new muffler, stock, like he wanted. The lowest priced direct fit I could get was $79. I told him to take it to my exhaust guy, $45 later he had a new muffler installed.
So, if you want to do it, it is very possible to do. Just get good info and tools. But, you might be better off finding a pro and just taking care of the removal and install yourself.

my wifes blazer is 97 4x4 4.3 auto and although it has had some problems my code reader has been my solvation so i dont have a book yet or i would look up your trans. i think it may be a 4l60e which replaced 700r4 both good trannys but they like having full fluid levels they burn fast if you get break in line. i would drive up on ramps get top of line fluid no xtra crap in it just name brand then with filter gasket kit in hand drop pan change filter and only replace fluid i dropped out dont flush system. you say trans was rebuilt 120k ago so dont change all fluid. clean pan out and while its down look for metal on magnet in pan there will probibly be fine metal but no large slivers. just tell wife no hard of line starts 4 apx 2 weeks let fluid work in, also check level and top off as needed until it levels off this is only a safe guard.you say it shifts fine so maintan now or it may not later. let me know how you do. good luck

Check your local library. I've found good repair manuals and a video on rebuilding GM automatic transmissions (Darrell Young Racing Transmissions). It was a few years ago, but selection must be better now. As for your transmission whining you need to replace the pump. With no dipstick people often drive with low fluid levels, and the fluid provides lubrication to the pump. Sometimes if you catch it early enough and top up the fluid, the whining goes away. But if you've been towing a trailer or driving it too long after you hear the pump whine, your going to need a new pump at the least. And overfilling can cause the trans fluid to foam up, and since pumps don't work well with air, the trans will slip and you burn up clutches, bands and damage the pump. You can replace just the pump without rebuilding the trans, but first pull the pan and check for burnt black friction material from the friction plates and for small pieces of metal. Check the Yellow Pages, Google or ask a used car dealer for a transmission rebuilder near you and buy one directly from them and save hundreds over what a garage will charge for the same part (always take a better warranty over the lowest price). Install it yourself or find a garage that will let you bring in your own parts. There's usually an inspection plug and a vent. A GM dealer used the vent to overfill the trans (by 1 whole quart) on my sister's 99 Malibu claiming that's the first thing GM told them to do when customers have noisey, slipping or slow shifting transmissions and trans fluid level is at or dripping out the inspection port when trans is hot. It's funny because they got rid of dipsticks because they blamed owners and independant garages for over filling and damaging trannies.

These trannys are not that bad to rebuild. They are essentially the same units for many, many years, and are essentially the same as a 700R4, but with upgraded electronics. Special tools do help make the job easier, but it can really be done with some basic tools. You need though to get a good rebuilders manual. There is a good how-to on this website, in the how-to section here. I highly reccomend you read through that. I have done a few in my garage without any lift and have been successfull. I do reccomend some upgrades though, a better, heavy duty sunshell(the beast for example), if you do a lot of towing, upgrade the front and rear planets, from 4 to 5, better 3-4 clutches, etc, etc. There is no question, you can save money if you do it yourself, but, and the big but, is that are you willing to spend the time to do the job, and carefully put it back together. Because you really want to re and re a transmission once and you want it to last.

It's going to take a lot longer than "a couple of days" but it can be very educational for a first timer. I too, was an Electronic Technician before retirement and also shade tree mechanic. Look at this post http://www.automotiveforums.com/vbulletin/showthread.php?t=919716 for some of my experiences. I have about $500.00 in it and a whole bunch of time. Learned how those babies work, very ingenious. I highly recommend, highly, the DVD on how to rebuild one. You can make a bunch of the tools yourself if your handy. It's still working......

good luck

I have rebuilt a couple of trannies, and find it takes me several days - or a week or two - though I do it for fun as much as to save the $$$, so I dont spend hours each day on it. The stuff that is hard to fix is if there is a worn bushing that should be replaced, or if gears or bearings are worn. If the tranny was the usual situration of simply worn frictional surfaces (clutches and bands) and nothing gummed up the valve body (such as someone having put motor oil or antifreeze in it, then a rebuild is just following the directions in the manual. I dont have any special tools, and have been able to get by with C clamps and homemade jigs - where I needed to depress a spring to get a lock ring out, or back in.
One thing I insist on, is having a workbench that I dont mind getting oily, and enough flat counter space to string out the parts in the order-they-came-out. Having a digital camera and taking pictures of each stage in the disassembly can be a big help in putting it all back. I also have a torque wrench that reads in inch-pounds.
And I am a hobbyist - no formal training. If I can do it - probably any idiot can.