Mike (mangus)- Cucv 700 trans update?

[Adamlee]

Hey, curious...how'd the trans swap go? Did you get that done yet?

the 4-speed has got to be a great mod for the cucv. did you mention you also swapped gears?

Adam Lee

 

[mangus580]

I got the swap done the weekend before the 4th of July. Since then I have put 2 major trips on it. The tranny works very nice, although I need to come up with something a little different for the torque converter lockup. With my current setup, I have a toggle switch that turns off the lockup (as well as the brake pedal). This wouldnt be a big deal, but it locks up in 2nd, 3rd and 4th. Makes it lug pretty bad. When I switch the gears out finally to the 3.73's that I bought for it, I may not have as much trouble.

 

[devilman96]

Mike what did you use? 700?

If so you only want lock up in 4th which you can easily do with a PSI switch on the vlave body and leave your braking set up as is.

 

[mangus580]

Yup, the 700.

I know, I just havent wanted to dig into it yet..... too hot!

 

[MATT]

Mike, what all did you have to convert, fabricate or do to make this swap work?

 

[mangus580]

Its a straight forward swap. I replaced the tranny and t-case. Mounted the TV cable bracket, and wired up the TC Lockup. With the 208 t-case, the tranny t-case combos are the same length, therefore the driveshafts are the same. Some day, when i rip the dash apart, I will put the proper gear indicator plate in, but its not a big deal. D is just OD, 2, is 3, and 1 is 2, and well there is no spot for 1 right now

Oh yeah.. VERY important... I learned the 'hard' way. The flex-plate is different Really sux when you get the new tranny in place and find that out....

If you do this swap, make sure you use a 700 thats built for the diesel, and built to abuse. They arent cheap to buy in this manner, but if you have it done this way, it will last quite well.

Another thing I would suggest for 1009 owners.... CHANGE YOUR GEARS!! 3.42's or ideally 3.73's the 3.08's are just horrible all around to use.

 

[devilman96]

There is also a low pressure switch that you can use and or a lock up over ride kit that bypasses part of the pump valve body...

4th lock up http://www.allnitevans.com/astroproj/700r4/lockup.html
low psi lock up http://www.classicchevy.com/product.asp?pf_id=25-16&dept_id=1168

If anyone is interested I have a 700R4 that I built to brick $hithouse specs for a 400 HP small block... I ended up selling the engine but still have the trans (which I had forgotten about) sitting in the loft. Red Alto clutches, HP servos, etc... It would NOT be a smooth driver as it is made to hit rather than slip when shifting gears but thats what makes them last and hold up to HP and abuse. It is complete but I would HIGHLY suggest swapping out the valve body plate back to a stock configuration for a truck application.

 

[mangus580]

whats the difference betwene the 2?

 

[devilman96]

One will lock up in any gear when the trans psi drops past a certain point. The other goes on the 4th port and only locks when the 4th is pressurized. Stock GM's were set up for 4th lock up only when they first came out... I THINK that might have changed with the later style computerized jobbers giving 3 and 4 lock up but I am not certain.

I do know 4th / brake lock up is the thing of choice when cramming a 700 into a different application because of the lugging you were speaking of. Even with a high stall converter (which you wouldn't want in your truck) you would still get the lag. There are some tach driven jobs out there too but I'ma lost when it comes to those, let alone how to apply it to a diesel.

There is a formula for figuring TC lock up and I can not remember what it is (sorry) but you factor in your driving application, weight, gear ratio, tire (not wheel) size, trans ratios, cam lobe (power band) and HP in order to get a matched stall speed for the vehicle...

A lot of people go looking for a "stall speed" thinking the higher the faster it makes my car when buying a TC... Which usually leads to a car running slower in the end but its hard to convince the PBR weekend racers of that.

 

[Ambulancechser]

curious...

mangus...what stall speed converter ARE you running...from various sources i figured something like 1800 rpm or so.
after considering other routes,this is likely the best way to get a lower first gear and an overdrive into the m-1010...it will work with a 203/205 doubler rather well too.crawl gears and an overdrive.

 

[mangus580]

RE: curious...

I have no clue. It had some 'diesel' TC in the tranny when I got it. Although, its only a 3 bolt, not a 6.

Also... I should mention, finding the stuff to hook a 700 to a 205 t-case might be tough.

 

[Recovry4x4]

RE: curious...

700 to a 205 case is not really a challenge. Advance adpaters makes the correct output shaft for the 700 then all you need is the cast iron adapter from the 350/205 combo that was used extensively before 1974.

 

[mangus580]

RE: curious...

No, not hard at all

 

[rizzo]

RE: curious...

Mike the 700 is suposed to have a lower first gear. did you notice that?

 

[mangus580]

RE: curious...

Yes, very much

 

[Ambulancechser]

doubler...

not planning on hooking the 205 to the 700-r...the 700 is really a glorified thm-350,so the np-203 that was super common on thm-350 applications will bolt to the 700-r with a few mods.
the 203 accepts the out-put shaft of the 700-r.the mount to the thm-350 matches the mount to the 700.some machining of the bearing carrier of the 203 range housing and some holes retapped to metric and the 203 will bolt to the 700-r.
the 205 then bolts to the 203 range housing.
the last bit is the expensive part.about 700$ U.S. for the adaptor and 203 output shaft.

 

[mangus580]

RE: doubler...

the 203 would make for an interesting T-case

 

[Ambulancechser]

only one good part...

The 203 is widely considered junk.but it has one redeeming feature.it easily un-bolts into two parts...the front have is the useful side.throw the chain case away.
the range box(the front) is really just a 2 speed aux transmission.
high and low range.thats it.combined with the low of a 205,you get a little less than 4:1 reduction in double low.
and strong too...the combo will handle more power than a 6.2 could ever make.

 

[mangus580]

RE: only one good part...

Way cool... I never thought of the 203 as junk it was a great 'full time' t-case.

 

[Ambulancechser]

i guess...

i guess it depends on your point of view.the reason the 203 failed so often was the fact it was full time...which was the reason so many liked it.
chain stretch was the 203's achilies heel.that and poor maintainance.quite a few mechanics(using the term loosely)often failed to realize the correct oil for a 203 was ordinary 10-30 motor oil.
converted to part time,and correctly maintained,it was stong and durable.not as strong as a 205 though...which is why these days you can pick up a 203 for less than 50 bucks,and the same yard often wants up to 500 for a good 205
I bet for a beater truck though,a 203 would be a fine inexpensive choice.