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Rebuilding a transmission...


Guest Anonymous

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Guest Anonymous

Welp, it apperes as if I will be using the '74 Nova motor that's in the Camaro after all because the Impala motor needs the same done to it, but it's just not as bad yet...but it IS getting there, which means I have $200 to spend on rebuilding it, which means I also have a bad Turbo 350 that I am told needs rebuilt. Anywho, here is my question. Since this transmission needs rebuilt BAD, it doesn't work (obviously). Could any of you give me a general idea of what is involved in rebuilding a transmission? Would it just be cheaper and more worth my while to buy an already working transmission from someone? Excuse me if this is a really stupid question, but I'm not very experienced with this kinda stuff, and you guys are the first ones that came to mind when I was thinking of someone to ask.

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Take the plunge now and get an overdrive tranny. I picked my 2004R up at a JY for $50. It needs to be rebuilt 'cause it slips a little, but if you are going to rebuild anyway.....

The 2004R is the same dimensions as the TH350, except the mounting is further back (ala TH400). Otherwise if you can find one, get a 700R4, from the newest car possible. Around here they are pretty scarce because all the taxis and hotrod guys snatch them up quickly.

Tim

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it all depends on what you are using it for,

i like the 350 and 400 trans for some all out street racing type stuff, they are seriously cheap, and geared well, the overdrive is always nice though, i run a muncie fourspeed and i love it, bearly any freeway use for me though, that long first gear, gotta love it...

if you building a freeway commuter, overdrive is best,

Leonard

muncie baby, muncie

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Since you posted a picture of you wearing a Slayer T-shirt, I feel I must respond icon_biggrin.gificon_biggrin.gificon_biggrin.gif

 

Anyway,

I just pulled apart a GM 700-R4 for the first time this past winter. I bought the "Haynes" book from the Local Auto Zone ($20) and it covered about 95% of the rebuild. The inside of the 700R4 wasn't as ugly as I had expected it to be, but it is fairly mechanically complex. Take your time and invest in a good set of snap-ring pliers. It took me a good week of after-work-wrenching to totally disassemble my trans and put everything back together.

 

On a plus note, I do believe that B&M sells a rebuild kit with very detailed step-by-step instructions for the backyard mechanic. However, they only offer these instruction for the 2 and 3 speed transmissions. Nothing for the overdrive units. If you decide to keep the 3 speed, bonus! But I do suggest that you heavily look into an overdrive. I've driven a Z with both the 3 speed and the overdrive. That extra gear was well worth the additional cost.

 

-Andy

 

[ October 22, 2001: Message edited by: Andrew Bayley ]

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Guest Anonymous

So what exactly does overdrive do anyways? I know a little about it, like how for every (for instance, lets say the overdrive gear was .75) .75 times the motor turns the driveshaft turns 1 complete turn, right? Is it better for gas mileage? If that's the case, this motor only gets about 7 miles a gallon, so I don't think overdrive would help much icon_biggrin.gif

 

I'm not really concerned about how cheap the car would be to maintain, I just want the poor thing to get running...It's been sitting in my driveway for about 5 years unmoved, except for one time a few winters' ago when my grandma's truck slid on the ice and smashed the taillight out...They were ugly taillights anyways lol. Even if it costs a fortune to keep running, I suppose it's better than having it not run at all...

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James,

Not only will you get much better gas mileage, but with the motor revving lower, there will be less stress on it (read lower maintenance and better reliability)and also the car will be smoother (running at lower revs) and quieter on the freeway. If you go on a long drive, you will be gratefull icon_biggrin.gif .

You WILL wish you had put in an OD unit if you don't now, so do it now and save some money and time. I can appreciate wanting to get the car running ASAP, but it will be a shortcut you will regret.

When my daily driver 240 had the 4 speed manual in it, I kept trying to grab 5th gear because the engine was trying to climb out of the bay. With the 5 speed it is MUCH better.

 

Tim

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Guest Anonymous

Welp, looks like I am going to have to talk my dad out of the 700R4 he was going to put in his Camaro in place of the Turbo 350. And the 700R4 actually works too icon_smile.gif

 

So what are the differences between the Turbo 350 and the 700R4 aside from overdrive?

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You are going to need a four speed shifter and a shorter driveshaft. Some of the aftermarket shifters can be adapted to 4 speed operation. Look in a Summit catalog, I seem to remember them selling something like that. Also, the 700R4 is about an inch and a half longer than the 350. Besides that, it's just a bolt in job.

 

-Andy

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TV cable, and the trans mounting point is further back, but if you havent put the trans mount in the Z yet, then that is moot. Also the shifter needs to be able to shift to 4 forward gears, not three. I think that's it? icon_smile.gif

Tim

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James,

I don't think it is physically longer than the 350, just has the mounting point further back. I have a 700 empty casing in the garage at home, I can measure if no-one else pipes in here.

I know that the yolk splines are the same as the 350 though icon_biggrin.gif

Tim

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Stay away from the pre 83 units(700r4) they are way weak and have a 27 spline torque converter. the later ones are 30 spline and cheaper. You will also need one from behind a v-8 not a 4.3l 90 degree v-6 they look the same but are very different. I would also get a ATSG manual any trannyshop will get you one also a good video is made by technical video

16325 E. Lincoln Dr.

Fall Creek WI 54742-4813

1-888-785-2604

Keith

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quote:

Originally posted by James M:

Hmm...Is the gearing pretty much the same then?

 

 

Hrm, good question. The 700R4 is a 4-speed overdrive, and not a 3-speed like a TH350. That 4th gear is just fantastic for highway driving, plus you'll save your engine by using it. If you were only going to use your car for drag racing, then the TH350 is great, otherwise you are much better off with the 700R4. Good luck!

 

Davy

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quote:

Originally posted by James M:

...Excuse me if this is a really stupid question, but I'm not very experienced with this kinda stuff...

 

James, you are smart enough to post this question in the proper forum, so I think you are smart enough to rebuild your tranny! icon_biggrin.gif

 

If you really want to stay with the 350 tranny (overdrive ones are by far better for any amount of street driving IMO) you can get books on rebuilding and buy a kit on how to do it. I have no idea about prices on the parts since I'm a manual kind of guy, but I suspect rebuild kits from Summit and the like are relatively cheap--it really depends on how extensive of a rebuild you are talking about. At some point, you really might be better off buying a 2004R or 700R4 like Tim said.

 

Davy

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I am recalling these numbers from memory so I might be off a little:

 

TH-350:

1st - 2.52

2nd - 1.51

3rd - 1.00

 

TH-700R4:

1st - 3.08

2nd - 1.71

3rd - 1.00

4th - 0.70

 

Also, the 700R4 is physically longer than the TH350 by about an inch anf a half. The TH400 is the same length as the 700R4, but not the TH350.

 

-Andy

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This is out of Lingenfelter's book:

P.glide

1st 1.76|1.82

2nd **

3rd 1.00

4th **

 

350

1st 2.52

2nd 1.52

3rd 1.00

4th **

 

400

1st 2.48

2nd 1.48

3rd 1.00

4th **

 

700R4

1st 3.06

2nd 1.63

3rd 1.00

4th 0.70

 

2004R

1st 2.74

2nd 1.57

3rd 1.00

4th 0.67

 

4L80E

1st 2.48

2nd 1.48

3rd 1.00

4th 0.75

 

Here you can see that the 4L80E is just a TH400 with an overdrive. You can also see the different gaps between the gears of the 200 and the 700. All else being equal, this would make the 200 the better choince, for drags anyway.

Tim

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