page62

Now that my 200-4r is installed and configured according to the supplier's specs, I've noticed that it likes to drop into 4th whenever you let off the throttle --- and stay there until you give it at least half-throttle! In the city I find myself dropping the car into third (non-OD) and keeping it there.

Your comments would be appreciated! :yesnod:

dman535

I think that you need more TV. It sounds like your trans is short shifting. There is a pretty sunstantial difference in geometry from a kickdown to a tv cable. If you are not gettiing enough tv, it will drastically shorten the life of your transmission.

MIKER

I'm not a transmission guru by ANY stretch of the imagination but I worked with my transmission builder to calibrate the shift for my 700R4. I learned a little but helping set up this ONE transmission hasn't fulfilled my desire for more knowledge about the automatic overdrive transmissions.
When these transmissions are installed into the original vehicle at the factory, it is calibrated to shift properly based on the weight of the car and the HP/torque rating of the engine in use. The original calibration "recipie" is going to need changes after it is installed into a completely different type of vehicle.
Initially, my trans was stepping into overdrive WAY too soon under light throttle (~25 mph). Now under light throttle it goes into O.D. at ~45 mph.

I'll take a stab at describing my understanding of some variables:
Changes to the governor weights and springs will move all shifts UP or DOWN collectively.
To individually adjust the 1-2, 2-3, or 3-4 shift points you change you change the spring on each individual shift valve. Lighter spring for shorter (quicker) shifts and stiffer for higher (later) shift points.
Based on relation to throttle position, the T.V. will fine tune the shift points by sending a pressure signal to the governor valve which in turn alters it's opening and closing rate.
I might have screwed up this explaination in one way or another. I suggest that you find a trans guru who will tutor you through the shift calibration process. The transmission will feel a LOT better once it is set up correctly.
I think that a lot of 2004R and 700R4 converts are not as satisfied as they should be due to poor shift calibration.

rhoeven

Like dman said, you need more TV.
I have a 700R4 and assume you also installed the carb tv-adapter. By setting the adapter, you can change the shifting characteristics of the tranny.
With the tv cable connection point at the adapter in 6 o'clock position (at the carb) you have the greatest relative tv cable pull at low throttle, i.e hardest and latest shifts but if you start out at the 3 o'clock position you can figure yourself that you need more throttle travel to get same tv cable pull distance. In the latter case, shifts are smooth at low throttle and will shift to higher gear much earlier. The total tv cable pull distance remains the same from idle to WOT since the tv adapter radius doesn't change.

My tranny shifts into OD at exactly 46 mph under minimum throttle .

Hope this helps.

Roger

Ingar, Norway

There is an ongoing battle in your trans between pressures created by throttle position and car speed.
The TV valve creates a pressure that is exposed to one side of the shift valves (controlled by throttle position via TV cable, more throttle = higher pressure).
The other side is exposed to pressure from the governor (controlled by car speed, higher speed = greater pressure).
According to which is highest, the shift valve will move, causing a up or down shift.
So to get this correct you might have to adjust both the TV cable and/or govenor springs/weights.
In addition, as Miker said, the shift valves also have springs that affects them.

Most probably you need to start with the govenor.
And its critical that the TV cable is correct as this also controls pressure to the clutches. To low and you fry them.

On a TPI body, the connection point moves between 5 and 8 o'clock position, with a radius of 3cm. The original Qjet attachment is very close to this.
But roger, what you said about movement is not correct, if you change the clock position, the pull length might change if radius remains the same.

I have an article at my page (700r4 conversion) that gives some more info.

page62

I installed the TV Made EZ system on my QJet. A pressure gauge was used to set cable tension.

Shifting is much better than using a TV cable with the stock configuration on the carb. Shifting is nice and firm, and pressures are OK. The car only drops into 4th when using light throttle. Car downshifts with no problem at half throttle or less. During moderate acceleration the shift points are very good. So basically I rate my tranny's performance "pretty good."

In town, I find it best to leave the car in 3rd gear.

My lesson learned: It takes a lot of tinkering and fiddling to get everything just right. Plus there are some annoyances: stopping minor leaks, fixing stuff that breaks during disassembly (like the exhaust manifold flange). But it's worth it! :yesnod:

Ingar, Norway

Page62: Do you know the clock position and radius for the Qjet attachment (with the bracket) that you find work best?

page62

Not yet. Right now it's in the middle. My mechanics want the transmission to "break in" a little and let the cable stretch (which it will). Then I'll readjust...perhaps in a week.

But the people at Bow Tie Overdrives told me there is not that much difference between 3 o'clock and 6 o'clock

Markm10431

Mine likes 3rd a lot

Ingar, Norway

>But the people at Bow Tie Overdrives told me there is not that much difference between 3 o'clock and 6 o'clock

That sounds really strange..

page62

Mine likes the downshift from 4th to 2nd (which it is supposed to do) a lot...

Larry B.

As a former C-4 owner (700R4) and a graduate of automatic trans trade school I can tell you something that will save your 700r4 from early death. NEVER EVER use OD unless you are cruising at speed above 65. At low speed the engine will be lugged in OD (4th). Lugging the engine is a transmission killer. The more power you are making the harded that is on the transmission. O.D. is a .7:1 ratio. The 3-4 clutch pack is one of the parts prone to early failure (common). Using OD also runs the planetary gears 100% of the time due to the .7:1 ratio. In 3rd the ratio is 1:1 and everything inside the trans is spinning at the same speed. Planetary failure almost never occurs in the non OD transmissions but is rather common in transmissions that are driven in OD. In my 92 with a 3.07 rear...by the instant MPG onboard computer, the mpg was 28 at 65mph in 3rd or 4th. There was NO milage improvement until around 75mph and then it was only a tenth or so. You decide.... A few pennies more on gas or mega bucks on trans overhaul.


[Modified by silvervetteman, 6:50 PM 9/12/2002]

page62

Are you suggesting locking out OD until you get on the freeway?

Larry B.

Absolutely... Never use OD in town ..

page62

I can do that (and I already was for the most part)...thanks for affirming what I thought!!! :seeya

Larry B.

Glad you understand... think about it as a manual five speed.. You would never use fifth at 35 or 40mph...


[Modified by silvervetteman, 7:20 PM 9/12/2002]

BSeery

Something I have been trying to tell my wife for 5 years now :rolleyes:

CWUin82

Back in the 80's I had a neighbor that was on the local Police Dept. He was telling me that the patrol cars were eating up the transmissions, they were using overdive 24/7 until someone figured out ( after numerous replacements) that you can't use overdrive in city traffic.

MIKER

Does this "lugging", cause part of the problem due to the low input rpm to the pump causing low line pressure? Low line pressure during high load obviously being a bad thing becaue of slippage and heat buildup.
I just trying to get a better understanding of these things.

Larry B.

Miker.. It is just a matter of physics.. putting power in but the car cannot respond very well due to the very high gear. The weak link breaks... in this case it is the 3-4 clutches or the paneteary gears. If you have a manual trans car that has a clutch going bad, it will slip in 4th gear or going up a hill.(high load conditions) This same bad clutch may seem fine in the lower gears. You are also correct in the fact that line pressure is somewhat lower but the biggest factor is just high loads. Most newer vehicles owners manuals tell you to not use OD if you are pulling a trailel, in all city driving or in hilly areas.