Whats The Knock On The THM250?

[kingcolbert83]

Ok before you read this please dont leave responses like its garbage just get a 350. I am aware of how easy it is to get a 350 and its popularity.

I have been reading and the thm250 trans is basically the same inside and out as the 350. Difference is the adjustment band on the outside of 250. From reading it says the 250 is lighter version of 250. Basically in stock form they where saying 250 torque and 350 torque respectively. A 350 can be built to handle loads of torque and horsepower depending what is all done to it right?

Lets say a 350 is built to handle 750hp. How much would the same 250 handle? Why wouldnt the 250 be able to handle the same amount if you use the same parts. Now before you say whoa there they are two different beast. We had a 350 trans at school being rebuilt and the rebuild kit was made by transgo. On the side it said th250/350. This would mean that some parts would be or wouldnt be used depending on the trans. I also went to autozone and looked at different kits and they said the same thing.

So what is the knock on the 250? Is the 250 the stepchild that is hidden under the big brothers shadow? I see no reason why the 250 couldnt be made to handle about as much power as the 350 if using the same quality parts. And of course in stock form the 350 is better because it used better parts but I'm talking bout both completely rebuilt using the highest quality parts.

A derivative, the THM250, was introduced in 1974 in Chevrolets as a Powerglide replacement. Internally, the THM250 is a THM350 without the intermediate clutch pack with a band adjuster similar to the Powerglide. It was later reintroduced in 1979 as the THM250-C in the wake of the failure-prone THM200/200C.

I got the last paragraph from wikipedia.
http://en.wikipedia.org/wiki/Turbo-Hydramatic#THM350

 

[CutlassGrandNational]

Wow no responses. I think you just pissed a lot of people off who like to knock on things like th250's and building up stock buick 3.8l's to handle turbos. Hahaha!

 

[jrm81bu]

Internally, the THM250 is a THM350 without the intermediate clutch pack

Not sure how it works without that particular clutch pack, but less clutches=not good. One of the things guys do is install extra clutch discs to give it more holding power. Even to the point of clearancing other parts to make room for more clutches.

I'm curious about this too, however i've never seen a 250. There may be not enough of them out there for whatever reason to not be considered as a good candidate. :?

 

[custom442]

http://craig.backfire.ca/pages/autos/boxchevy/th250

"with the high availability of TH-350 transmissions at low cost, swapping the TH-250 out is the easiest, cheapest, and therefore best way of sending a lot of torque to the rear of the car. "
-- this is the point I keep trying to make for you, I found a 550$ racing th350. You can't build a th250 for that amount to handle that kind of power, and can probably find a stock/rebuilt one in good condition for less than how much I paid for mine

It isn't about how the th250 can take the torque, it's about the cost of doing it

 

[kingcolbert83]

I have a th250 already in my car. If I didnt have it then I would go out and get a 350. What i was trying to say is from my research and experience the th250 is basically the same trans as its bigger brother. I can go out and buy a 350 but it be cheaper if I already have a 250 and rebuild that. Depending on what type of rebuild I do I truly believe the 250 can handle 500hp and some torque which is really more than enuff for a street car. Just like a motor can handle power if the internals are beefed up. Yea it may not handle 600hp monster but who really drives that on the street daily?

I can get a 350 built already for bout 500 but I really dont plan on going the route of buyin when I can rebuild myself regardless of 250 or 350.

I read that page also. It really boils down to is that I dont see any reason a 250 cannot handle the same if not lesser streetable power without breaking something, when using the same quality and strength of parts since the only major difference is ability to adjust the outer band.

Now if somebody was putting a trans in their car then by all means yes put a 350 in it but I already have the 250 and dont see enuff difference and arguement not to rebuild what I already have and be able to handle some power.

 

[Blake442]

Well, I think the point that is being stressed is that while they are quite similar, the TH350 is stronger in stock form than a TH250, naturally making it a better starting point.

You said so yourself that the only difference is fewer clutches...
In a world where more clutches is good... Why take a step backwards like that?

You seem to have already made up your mind though, and are just looking for people to tell you what you want to hear...
Looks like the only way you'll know for sure is to try, so go ahead and use your TH250. Let us know how it works out.

 

[kingcolbert83]

I know the 350 would be a better trans, but for my power numbers and me already having the 250 I didnt see enuff reason to not reuse it. If I didnt have it already then I would of course spring for the 350. Just wanted to see what peoples input was compared to what I have read and from experience.

 

[custom442]

I can go out and buy a 350 but it be cheaper if I already have a 250 and rebuild that.

Let me try and explain this once more. But it won't help because you didn't post this topic for advice, you posted this topic to argue. You can buy a rebuild kit for around 150$. Your th250 will still only handle 250 torque.

You could scrap your th250 for 15$ or try to get more out of some sucker who thinks it's a good transmission... and buy a good stock/rebuilt th350 for 300-400$ and call it a day

I very much doubt you can build the th250 to the same specs as a th350 for the same price as a nice used one, and save all that work and headache if somethin doesn't work with your rebuild... will it work for a mild engine? Yes of course, but the first time you drop an engine bigger than a 305 in there with some real parts you can say goodbye to your rebuilt th250

Depending on what type of rebuild I do I truly believe the 250 can handle 500hp and some torque which is really more than enuff for a street car.

Like I said before, if you've got the cash, let us know. And I'm absolutely positive your th250 will do fine on any car under 500 torque. Even a th200 can last fine behind an engine with 500 tq. But the first time I go footbraking it with a real stall I'm gunna hear a big bang :shock:

My question is why did you post this topic if you've already convinced yourself? Why not just say you'll be doing mild driving and avoid all this confusion.




I can make a 1.8 L fwd civic faster than a big block/4 link 1/8 mile car... but how much $$ would I be spending and how much more would break before it's over.

 

[custom442]

Here's another idea if you're interested. There are always engine/trans combos on craigslist, people trying to sell their whole used stuff together. Why not find a combo in good running condition for around 600$. Keep the trans and sell the motor for 600$ obo.

That way you spent less or about the same on a used/rebuilt th350 than you would've spent on a rebuild kit for your old th250... you might even make some money if you can hustle and sell the th250 for 50-100$...

 

[jae]

I have to agree with Blake and the others, the TH350 is stronger out the gate, can be made even stronger for not much coin and there's a ton of them out there, making them again, relatively cheap. But if you have your heart set on the TH250, which seems like you do, then by all means grab that $150 transgo TH250/350 shift kit, have at it and let us know how you make out.

I don't think you're really going to get anyone here to tell you what you want to hear instead of telling you what we've experienced in the past. Not trying to give you crap or anything, believe me.

Guessing you're in school (your mentioning the 350 being rebuilt) this may be the best time to do that "what-if experiment". Rebuild your 250 using the shift kit, performance parts and put it to the test. You can probably get a deal on the parts, save a ton on not having to buy the special clamps & tools, and have help rebuilding it. Then put the hammer down on it and see what happens.