VikingTrad3r

hi all, on my red z51 that i did a whole schwack of maintainence to stop her bleeding over the winter....


i believe that i have an issue with the transmission either governor, or tv cable related or fluid type. here is what we did to the tranny over the winter:

a fluid and filter change on the tranny by dropping the pan. used mobil dextron vi atf. this is what the parts counter guy told me to use.

changed the outer oring on the edit: servo cap because it was leaking.

changed the tailshaft seal and oring.

edit: i may have misunderstood what the governor is. is the governor the thing in the tailshaft? maybe we didn't put the tailshaft in correctly and the governor is not functioning correctly?

that is all we did to the tranny.

now, we have shifting issues with thE transmission:

shifting way to early and staying in too high of gear when it should be gearing down up a hill for example. instead of downshifting, it bogs out. i can really depress the pedal and get it to down shift.

note that the previous owner and i recently spoke and he told me that the guy he bought it from, who was the original owner, told him it has a shift kit. my understanding of a shift kit is a different set of governors, which is the correct way to adjust the shifting, usually a person wants shifts to be higher. our problem is the opposite...its shifting too early.

the early shifting is most noticiable at very slow accelleration and mid throttle acceleration. i get into overdrive at 25mph. when i stomp on it it seems like it shifts where it should.


i have studied up on the TV detent cable and i understand that it controls line pressure within the tranny's valve body. my understanding is that the more throttle is given, the more it pulls the linkage at the tranny, the higher the line pressure, the later it shifts, the harder it shifts. And when the tv cable is preset tight in the idle position, this results in a higher line pressure starting point, which should theoretically cause shifts to happen later and harder

then we have the governors, which my understanding is that the there weights and springs and as each of these governors rotate, centripetal force moves them out and they are supposed to change which gears are engaged because they all move at different amounts of force related to rotational velocity, which moves the weights etc. in other words the governor is supposed to govern which gear is active based on the line pressure based on the throttle.

i have much too low a gear, too early.

I *think* this is a new condition, but I didn't get much time behind the car before we parked it in my shop for the winter so i don't have much before/after experience with respect to before the work we did vs after the work we did.

i do however have an 87 z52, that shifts perfectly, and this 85 is way way different.

I have read that driving the car with a mal-aligned throttle valve cable is a bad idea, and i tried to adjust the tv cable as per instruction:

with car off, depress D locking button and pull the cable all the way towards the firewall. release locking button.

now go sit in car with car off and depress the pedal all the way.

done.

when i do this, my tv cable does not move. it stays all the way to the right, towards the firewall.

i note from the black wear marks on the tv cable, that the previous owner had the tv cable housing set to the left, front of vehicle, making the tv cable tighter, which would make it shift sooner and harder.

so....

am i on the right track here guys? i want to get this thing shifting perfectly.

did i put in the wrong fluid?

should i open the servos and pull them out to make some adjustments to the weights?

is it possible that the TV cable stretched over time and is just too loose? this would lower line pressure no?

how do i determine which it is?

thnx guys. VikingTrad3r.

for those who, like me, don't reallyknow what the tv cable is or how it functions, check out this vid.:

VikingTrad3r

more update:

shifts hard, all the time. fast/slow, shifts hard. does not waste any time. i assume this is the "shift kit" that is supposedly installed as told by previous owner.

in all cases, fast accel, medium accel (50% throttle), and slow accel...in ALL cases, it shifts too early, and shifts hard.

It has issues as well it does not want to downshift when i apply throttle. it would rather hang out and be sluggish in overdrive.

the tranny feels REALLY strong (i think its the hard shifting that is making me think this), and wow does this car accell so much faster than my 87.

i have a new chevy tv cable coming,

is there anything else i can do guys? pop the governor cap off and check its operation? if there is a shift kit installed should there be something done to the governor that i should look for?

thanks in advance. VikingTrad3r.

JD1964

The TV cable should be adjusted so that it is pulled all the way out as tight as a piano wire when the throttle is wide open. That means full depression of the TV valve in the transmission at wide open throttle.

If you cant achieve this then there is something wrong like a mis matched linkage part or perhaps even cable disconnected in trans end.

Grab the throttle linkage with your hand and open it all the way. Hold it there and pull on the TV cable with pliers. The TV cable should be tight and not move. If it moves out at full throttle, it's not adjusted right. It needs to be pulled all the way out tight when the pedal is floored.

JD1964

BTW, you stated that making the cable tighter would make it shift sooner. Its actually the other way around. When the TV valve in the trans is depressed further (tighter cable) it's telling the trans your foot is further down on the pedal and then hols the trans in each gear longer.

VikingTrad3r

Thank you John, i will try the piano string test at full throttle. thanks also for clearing ne up on the tight vs slack cable. i tried to get the tv all the way tight by having the housing pushed all the way to the firewall. it just wont make the shift happen later. this is why i started thinking it may be the gov.

i will try the piano wire test first and report back.

Cliff Harris

The shift kit in my 700r4 did not come with any governor modifications. It was just opening up some of the holes in the valve body spacer plate to increase the pressure to the clutches.

You should be able to pull the TV cable at the throttle body and feel the spring tension of the throttle valve. It's a pretty light tension, but should be enough to make the TV cable taut at the throttle body.

VikingTrad3r

John, i am now convinced the tv cable is setup correctly. the cable will not move any further out from where the throttle body link will go. so its correct. the OTHER thing is that i reached down with both hands and moved the throttle body out and the cable actually ratcheted out to allow it to move all the way (i put some lube on it yesterday maybe that helped it be able to ratchet). that means it was a bit too tight. that should explain the hard shifting. higher line pressure right? anyway, it should be good now. so now lets see if we can sort out why it shifts too early....

Cliff, I can confirm that i do feel the tension of the spring down in the TV valve pulling back. it is fairly light pullback but it does feel right compared to how i see it on the videos i have watched. so that seems correct.

Based on your comments, and from my reasearch online, it appears that the term "shift kit" can mean anything from drilling your own holes on the valve body to allow for different pressures, to adjusting the servos, to adjusting the governor weighting to change where the shift occurs.


In my case, the shifts are strong, just at the wrong points. far too early, at least compared to my 87, and compared to my 2006 denali xl for that matter. And it also seems like the down shifts take far too long to kick down. My limited understanding tells me i probably need to pull the governor and inspect it, and reduce the weights. (we are talking by like a gram).

Anybody with tranny experience able to help me understand if I am on the right track? I suspect the governor may not be operating correctly.



First things first though, now that I got some actual ratcheting from the setting of the TV cable, and I can verify we are nice and piano wire tight, and that it will not move further past the throttle body linkage....i will go try driving the car and see if we are fixed. if not, i suspect the governor.

thanks in advance for all help guys! I will take it for a rip at lunch and see where we stand.

VikingTrad3r

also for those who want to learn about what the governor does, and what a "shift kit" can entail, here are some vids i ahve watched.

velsuk

I had the same symptoms on my -88 with the shift kit. I took about fingernail size chunks off from the corners of the big governor outer weights(2 pieces/weight). Did the trick, shift points are where I want them to be.

VikingTrad3r

how did you remove the fingernail sized chunks? and were you meaning the entire size of a fingernail or the size of fingernail clippings when a person clips thier nails. thnx.


i really want to get on this and get her back on the road so if i dont hear any advice from others soon ill just go ahead and do it.

to summarize the research i have done, first ensure the tv canle is correctly dialed in by using the correct reset procesure, then go to the governor to adjust your shift point. there may be alterations to the stock shift loints when a shift kit is installed, and you should adjust the governor in this case.

the part i have not completely dialed in yet is exactly which weights do what and what the difference is between the weights and the springs.

Cliff Harris

Here are the instructions for the B&M governor calibration kit:

http://www.bmracing.com/bmnew/pdf/9500558.pdf

velsuk

I used a 5 inch grinder and 0,8mm cutting disc. I cut the corners of the weight off 3 mm from the hole and enough material was left to keep the weight together. About the size of a little fingernail. A special factory light outer weight has just the frame of the weight shape, so you can cut quite a lot to change the light throttle shifting. With inner weights and springs you can make adjustment for harder accelerating.

Sorry about the bad language. I live in Finland and my english and garage skills are self made. American iron since 1993.

VikingTrad3r

thank you velsuk. so you ground a small amount of the outer "heavy" weights. Did you grind or remove any of the smaller inner weights as well?

I am thinking i'll just order a b and m gov adjustment kit like what cliff showed but im curious.

velsuk

No, just the outer ones. Inner are original and the springs too, I reckon. I have one light spring and the other is significantly harder. If I wanted to change the part throttle and harder acceleration characteristics, I would change the harder spring to next lighter spring on a kit next. If you have a good lift, weld a big nut to the gov cup, so you can make changes in 15 minutes.

Sticking valves are my next project. You can not be too accurate with the valve body. I rebuilt my own trans last winter and had to drop the valve body again because of sticking tv. Aftermarket valve did not return freely enough and some other valves still tend to have too much friction and delay on harder driving. Working on 700r4 is cheap and one dont have to be professional for basic tuning.

VikingTrad3r

well guys i decided to call a few tranny shops just to ask their opinion.

amazing. they all said, "your tranny needs to be rebuilt, bring it in".

well....i dont' know....just because the shift points are off does that mean i need a $1500 rebuild?

the one guy did have a good point though....he said that when trans get worn out, they allow "blow by", a laymens term for not as much pressure as there is supposed to be because its leaking around seals and such. i guess pressure activates the valves so i suppose i see his point.

he also said that if your TV is adjusted as tight as possible, and you are still getting early shifts (tighter tv should jack the shift points is what he said) then you either have a diesel suburban governor in there, or you need more work because the governor is exceeding the tv pressure really easily, which causes the shift early.

clear as mud all of this.

and to muddy the water even more, the PO said there was a "shift kit" installed. no idea what kind or what type.

has anybody else done as Velsuk has done? installed a shift kit then had to adjust (lighten in his case--and maybe mine) governor afterwards? Like if a shift kit is installed, does one definately have to adjust the governor?

I am close to taking my 87 governor out which shifts great and putting in the 85 to see if i get 'normal' shift points. Maybe they are different.

velsuk

Shift points are basically the same with and without the shift kit. But the throttle position is different on light acceleration because of the lack of slipping and the shifts tend to happen way too early with non slip trans. Cold tranny shifts nearly as stock with the kit.

All cars and trucks tend to have different kinds of tech combinations. Governor is one of the cheapest and easiest to modify and you can always go back stockwards.