700r4 won't shift at WOT
this is my first post here, although I've been reading for a long time.
I have a problem with my 700r4. After burning up the 3-4 clutches I've read a lot on the web about possible upgrades for my tranny.
I changed the following parts:
.500 boost valve
transgo TV kit (SK 700-Jr-A)
stiffer acc. springs
B&M TV plunger bushing
opened up a couple holes on the valve body plate (like the transgo paper said)
blocked line bias valve.
alto racing clutches, 9 stack in 3/4 pack
pressure regulator valve 2nd land grinded flat
kevlar 2-4 band
After that the tranny shifted good everywhere but at WOT the tranny never shifted. I want her to shift around 5500rpm but it revs much more. I have to let off the throttle to let it shift. When I push the throttle down again after the shift it will shift back to first.
Then I played with the governor weights and springs and put stiffer springs in it and put more weight on the original weights. But it didn't bring down the shift points. The weights are regular, not corvette parts.
I aslo tried to "adjust" the TV a bit but it had no effect on the high shift points at WOT.
Then I suspected the blocked line bias valve and removed the blocking pin. I left the red stiff transgo spring in it.
Today I checked the shiftpoints and they are still way too high. even with heavier than stock governor weights.
FYI, the original boost valve was only a .393 unit.
Please help me to fix the problem.
Before I changed the parts the shift points were at a normal 4000rpm or so.
maybe t.v. valve in the valvebody has got some trash in it.. or maybe t.v. linkage at the carb is wrong(too much travel), or t.v. is not adjusted correctly.
hows the shift points under normal acceleration? still need more info...
At MIN / WOT what are the shift points?
It sounds as though you have too much throttle pressure.
Thanks for the answers so far.
I'm using a quadrajet.
It has the bellcrank shown in the pic.
I checked the relation of the TV plunger and carb linkage with the pan off. At WOT the plunger is fully buried. At idle the plunger is a bit depressed.
I was told and read somewhere that this bellcrank would work with the transmission. Although Bowtie Overdrives offers an adapter for these.
My guess was also that the pressure is too high, so the governors pressure cannot overcome TV pressure.
The shift rpms at min throttle are pretty normal. 1-2 at 10-15mph, 2-3 at 25-30mph, 3-4 at 35-45 mph.
It also downshifts nomally.
I found it interesting that I cannot shift it manually in first. at 5500rpm I put it from L1 to L2 but it doesn't shift. With a lower throttle setting it will shift just fine.
From my limited knowledge of the 700R4, you definitely have a TV problem. I suspect it is either in the TV adjustment or in length of pull geometry. Looks like the QJet is for a TH 350 or 400. I assume the bracket attached to the carb's rear mounting studs is for the TV cable. I personally do not like the alignment if it is. Your shift points are not bad for partial throttle so the gov. weights are not far off. Your stated the TV plunger is a bit depressed at idle. I think it should not be depressed at all which means you need to lengthen the cable (more slack) If you can't get this, you will need to modify your bracket or move the front ball on the cable forward. You may want to PM Crosley because he is very knowledgeable of trannys.
trees, I also thought the problem is in the TV system, BUT even if my TV setting would be wrong, at WOT the plunger should be fully buried in the bushing, right?
Thats what it is now. Maybe the starting position is not right but the WOT adjustment is ok.
So the problem is maybe somewhere else. Could a dirty governor screen cause this problem?
I checked the valves in the valvebody for free movement. All were ok.
Could the B&M plunger bushing cause this problem? Its for high rpm cruising in OD.
get rid of the B&M sleeve for the TV .
these can cause poor shift patterns changes. They do not provide detent oil for a forced kick down out of over drive.
The TV bore where the Transgo Valve is could be worn enough that oil is bypassing and causing problems too.
Install the OE TV plunger sleeve and see what hapens.
I am curious what weights are in the governor.
Real light weights can cause late shifts . Some situations the engine will float valves before the tranny shifts if the governor weights and shift valve springs in the valve body are mis matched bad enough.
Alex, if the geometry on the carb is incorrect, you can not get the TV cable set correctly. I suspect you need a larger radius on your carb linkage to allow the TV plunger to sit higher in the bushing at idle and arrive at the fully depressed position later in the throttle position. There are some good links to this discussion some where in the knowledge base so maybe you can do a search to find it. I have cone some "hunt and peck" work when building the brackets to make a non 700R4 carb work, but have never taken the time to write down the correct radius and bracket lengths. I'll try to take some measurements in the next few days and send them to you.
Crosley, am I not correct in assuming if shifting is good with partial throttle that the gov. weights are about right? Also, would it be safe to disconnect the TV cable for a short, one time WOT acceleration to see if the tranny up-shifts OK ?
Crosley, thanks for responding.
I will change the plunger bushing to the old one and let you guys know.
The gov. weight are the stock ones with the yellow and green spring from the B&M kit (medium). I even added more weight to the inner weights by welding material on them. But that also didn't lower the WOT shiftpoints.
trees, when I installed everything, I based my carb linkage info on the following on Sumners Homepage
The linkage I use is shown in fig.17. The text says that this was a factory setup. The centerline radius on my carb measures 1.1". I also measured the angles and came to the same.
Sounds like governor pressure is too low in relation to TV pressure. Classic 700 problem, esp at WOT. I agree with Crosley, try the OE TV plunger sleeve. Also, look hard at the governor and the bore in the case. The OD of the gov lands must be smooth and consistent. Memory tells me .805 is the desired OD, i might be off a little on the number. Check the gov drive gear and retainer pin. If the gear is loose, it will leak gov oil and cause upshift concerns. It must be a mild press fit to seal in the end of the gov. Also, many times when the gear is replaced, the new one is scored by the pin hole (inside burr) when the gear is pressed into place. NO BURRS. Check the gov head (weight area) to see if it is loose on the gov shaft. Seen this a bunch also.
The TV and gov oil circiut on 700 can cause hair loss. If you could see me you would know. Mostly, gov springs change WOT shift timing, weight changes low speed. They DO work together which adds to the complication. After you have checked all the above stuff I would make a significant spring change to the gov.
If you want to tune individual shift timing, then you change shift spring weight. Keep us informed how changes go. Sometimes what seems insignificant to you may hold the key for others.
I just came back from the testdrive with the original TV sleeve.
It didn't change the WOT shifting in any way.
I also checked again the shift points at min throttle because the numbers I gave you before were what I thought and not after a testdrive.
Well, 1-2 at 7mph, 2-3 at 15mph, 3-4 at 30mph.
I guess this comes from my heavier than stock inner governor weights.
The governor looks very good with smooth lands and tight gear and head. I didn't change the springs yet. The original springs were very light. Now mediums are in it. The gov. valve is also not sticking.
You pros need to help me with my problem, cause that was it with my transmission knowledge.
Have you checked the governor valve for for equal clearance?
Hold the governor by the gear and let the body hang down.
Look inside and you will see some clearance at the land of the valve.
Now depress the counterweights.
The clearance at the other end of the valve should be equal or close to equal.
Have you ever switched governors and given it a try?
I am still interested in the correct geometry of the TV cable.
Something just rubs me about that. Did you try a minimum adjustment? As in leave it connected but back it right off.
I used to enjoy challenges like this but after so many the hair starts to disappear. I am nearly bald now.
OK, in order to get back to normal shift points at min throttle I changed the weights to lighter ones. Now I have the 1 and 2 weights and the green and blue springs (a bit stiffer than before) in the governor. I thoroughly checked the function of it again but could not find anything wrong.
I will try my luck tomorrow with a minimum TV adjustment as stu suggested. I'm a bit scared with messing with the TC cable so much because that was the reason the clutches burned up in the first place.
Just as an aside.
Is it the correct governor?
Could be that's what F'd it up before.
Yes, the same governor worked before in this trans and produced normal WOT shift around 4000rpm. Since then I'v put less than 1000 miles on it.
I don't have another governor to test. Mechanically it seems OK.
|All times are GMT -6. The time now is 08:47 PM.|
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2015, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
Copyright Hotrodders.com 1999 - 2012. All Rights Reserved.