TH700 : succes and TV cable adjustment.

Gilles · March 30, 2004, 04:21:13 AM

This week-end I finished to install the TH700 in the roadster. It works perfectly and I am very happy!

I was worry a little as it was my first automatic transmission rebuild. This transmission is a early 87 TH700R4 from a 2 wheels-drive truck. I used a Transtar rebuild kit and a Transgo-kit (the cheapest one)
The engine is a 73 350 Chevy in stock form except the headers, Edelbrock SP2P maniflod and Edelbrock 600 cfm carb.

I studied the Bowtieoverdrive web-site and print all the information about the TV cable adjustment. I prefer to explain here the way I understood it and tried it.
If I'm wrong you can correct me and if I'm right maybe this can help someone.

I modified the TV cable bracket on the carburetor to be able to adjust the radius between the accelerator shaft and the pivot point of the TV cable. In fact I bolted an home-made bracket with long holes to the carburetor bracket. This way I can modify the TV cable travel.

In every cases the TV cable should be pull at full travel when the accelerator is fully depressed and is what I did with all the different adjustment tested .

I know it can be dangerous for the transmission to not have enough oil pressure at light throttle. This oil pressure is regulated by the throttle valve.

So I started with a safety half inch of preload TV cable movement when at idle. That means a relatively short TV cable travel, or a small radius on the caburetor bracket. The result was too late and hard upshift at light throttle. But I was happy to found the transmission able to work

At this point I increased a little the carburetor bracket radius, to increase the TV cable travel. With result to have a smaller preload TV cable at idle. It was better but still too late upshift.

I increased again, time to time a little the TV cable travel, always adjusting the cable at full travel when at full throttle.

I found after a tenth of test driving that with a quart of inch of preload TV cable the transmission works perfectly.
Only a very little of more preload makes too late light throttle upshift.

So my conclusion is that the oil pressure at light throttle can't be more and the TV cable is properly adjust.

But I don't have a pressure gauge to test it as recommanded and maybe it's a mistake?

I installed also a relay kit to have the lock-up working with the carbureted engine. But I can't feel if the lock-up engage or not.

If I compare with the former TH 350 it's very good to automatically down-shift 2 gears when necessary, even in first gear at low speed. But the shift are a lot smoother, maybe too much. It was a hard shift-kit in the TH350.
The best thing is the engine rpm drop in overdrive.

I also enjoy a lot the newly installed Gennie-shifter. I bought it one year ago during my trip to California directly from the man who make them... in his two car garage!

Gilles

GPster · March 30, 2004, 07:21:22 AM

When I first saw your question I thought there would be trouble. Our knowledgeable automatic transmission consultant knows more about satalite dishes and doorbells than television cable systems. If you've rebuilt an automatic transmission then I suppose you're ready to re-build a 235 into a 216 and make it 6 years older. This is the type of sense I make with only one cup of coffee. GPster

1FATGMC · March 30, 2004, 08:19:06 PM

It sounds like you have it adjusted properly, but I have the dimensions for the proper attachment location on the bellcrank on the carb on my site.

One way to check if it is right is to take off in first with moderate gas and then when it upshifts to 2nd floor it and it should downshift back to 1st. I adust the adjuster one way until it doesn't downshift and then go the other way one click at a time until it does downshift.

If you have a tach it is east to see if it is locking in 4th. When you are going along at a steady speed give it quite a bit of gas, but not enough for it to downshift into 3rd. The rpm's should just creep upwards in pace with your increase in speed. If the rpm's jump 200-300 then the converter is flashing and is not locked up. With no tach get off and on the gas quickly in 4th and see if it acts like a standard transmission. You should feel or hear the converter flash if it isn't locking.

I can do all of this, but I can't rebuild one, so I'm impressed that you rebuilt yours.

c ya, Sum

700R4 Info

Gilles · March 31, 2004, 02:00:51 AM

I should have look at your web-site before FATGMC! I just printed the 700R4 info to have it in my garage!

I found a similar draw as yours on another web-site for the TV cable bracket but it doesn't works exactly on my car. Maybe it's because the Transgo kit contain a throttlle valve piston different than stock.

For the lock-up I'm sure know it doesn't works. As I see on your page info I put the pressure switch provided with the relay kit on a wrong port of the valve-body. This way I know what to do next week-end : drain the transmission, remove the oil pan and correct this mistake.

To rebuild this transmission was certainly the more difficult (but very interesting) mecanical thing I did in my life. I used the ASTG book and followed lane by lane the instruction. I worked 2 hour at a time after my regular job, I couldn't be concentrate enough for more long. It took 30 hours to do the job, but I was extremely carefull : to brake one part even a small gasket means for me another order from outside the ocean.
Fortunetly there is for a few weeks a new company near Paris specialised in American automatic transmission that sells Transtar kits.

Gilles

1FATGMC · March 31, 2004, 02:18:28 PM

Quote from: "Gilles"
For the lock-up I'm sure know it doesn't works. As I see on your page info I put the pressure switch provided with the relay kit on a wrong port of the valve-body. Gilles

You can thank Tony (Crosley) for the valve-body pictures.

good luck, Sumner

Gilles · April 05, 2004, 03:03:55 AM

Saturday I put the lock-up switch on the good port of the valve-body.
Now the lock-up works! It makes a big difference.
With the drop on rpm and noise I have to be careful and have a look at the speedometer.

This transmission works good but there is a little thing strange. In neutral or in park I can feel the transmission engages slightly. It's almost unnoticeable, but while stopped in neutral on a very flat surface, if I accelerate the car moves a little. I don't know if it's normal, or if there is a pressure leak inside the transmission, or not enough play in some friction discs? This thing makes me a little worry.

Gilles

Dave · April 05, 2004, 07:59:11 PM

Quote from: "GPster"When I first saw your question I thought there would be trouble. Our knowledgeable automatic transmission consultant knows more about satalite dishes and doorbells than television cable systems. If you've rebuilt an automatic transmission then I suppose you're ready to re-build a 235 into a 216 and make it 6 years older. This is the type of sense I make with only one cup of coffee. GPster

I called my cable guy and he told told me there wasnt any adjustment for my tv?
No wonder I got satelite its got more buttons..
Dave