Technical Another 700R4 issue to be solved.

Hey all,
Had a 700R4 rebuilt with performance upgrades. $1200.00 in hard parts alone ( TransGo, Sonnax, etc...). Installed the transmission, adjusted the TV cable correctly at WOT, fluid level is correct. Went to drive it, put it in drive, 1st gear is fine shifts to second and very unresponsive / slippage, shifts to 3rd, 4th and OD and those are good. I then shift it manually from 1st thru drive and all gears work perfect. So it's acting like a manual valve body and am assured that when the shift kit was installed it was installed for full automatic mode. Fluid is red and no burnt smell.

Builder thinks it might be a governor issue, so we take out the modified stock one and put in a Corvette one which is a nice upgrade anyways. Go for another ride and while the trans is in drive, 1st is good, shifts to 2nd that's good too, cool. Actually not, now it won't shift to 3rd & 4th automatically or manually. So my "builder now thinks it may be a valve body issue. Anyone with knowledge have a clue what's going on ? This is starting to wear on me and don't want to go off on the builder, just get it fixed and on the road. Any help appreciated and thanks.

 

Take back to builder and say FIX IT !

 

He'll be here in a couple hours

 

What rear gear do you have in it?

 

4:11

 

Valve body is out and gone, will know more Monday or Tuesday.

 

Get a new builder!!!

 

I wouldn't dump the builder yet, everyone is human.
These transmissions are not like the older stuff, shit happens.
Low gears will change the shift point to real short if it was set for a car with modern gears.
I would look at band servo just for assurance, those can be tricky to install and cut a seal.
The valves in the pump can throw a curve also, half to take care in the choice when installing the shift kit.

 

Thanks saltflats, I'll pass that info along. The builder is a long time friend who does transmissions for a living. Also getting up there in age and sometimes stupid stuff happens, don't ask me how I know !

 

Yeah,,,don’t crucify the guy because of a little problem.
But,,,,it’s most likely a build problem,,,,,,so,,,,,,he needs to fix it .
It does sound like the valve body .

Tommy

 

I kind of agree with saltflat. Sounds like something in that servo. The same band applies for second as fourth but I think they do it through a different piston in the servo. Kind of weird that it changed with the governor. I’d be tempted to put the original governor back in and see what happens. It may be coincidental.

 

Have 4:11 rear gear but with a 29" tall tire that kills it to 3:70 and think that would be in the correct range for the Corvette Governor. As for now it's a waiting game and going to a car show today without a car....real bummer, later.

 

I did not know there were different governors, I thought it was the servo was different for the vette.

 

Servo and boost valve in the pump for sure are different for corvette

 

A bunch of sound advice above.....please post what was wrong after it gets fixed!

 

Still patiently waiting to hear back from my Transmission guy. He has the Valve Body. I'll let you all know what the fix was, once I get to that point.

 

My limited understanding is the Corvette governor is set to shift around 5300 RPM's at WOT when left in drive. I'm sure there are multiple variables to that.

 

So, here is my helpful calculator help for toady. If you want to know what your relative gear ratio is in the third member with a taller tire is, try this. All rear gear ratios are based off a 26" tall tire, in my case I'm running a 29" rear tire with 4:11 gear. To figure the final drive with this tire, divide 26 by 29 ( tire size difference ) so 26 ÷ 29 = .89655... now times that number by the gear ratio, .89655 x 4.11 = 3.684. So 26 ÷ 29 =.89655 x 4.11 = 3.684, the final drive of a 4:11 gear set with a 29" tall tire. Hopefully you can follow this and it helps somebody out in the future.

 

A 4.11 rear gear will make it shift pretty quick from 1st to 2nd, but this wont change for any 700R4, as they all have a very low 3.07:1 1st gear. What rpm it shifts at will be determined by your shift kit, and the springs in the governor. Lighter springs will raise the shift points, and heavier springs lower the shift points. This is for all gears, not just 1-2 shifts.

I'm running 29" tall cheater slicks, and a 3.73 posi axle. I'm not sure I'd want a lower gear as it already shifts fairly quick from 1st to 2nd. But if I raise the 1-2 shift, the other shift points all rise too, and I like it going into 4th around 45-50 mph as it does now.

 

Yes ,I had to play around with the springs and weights on the governor on my Willy's I had. Shifted way too soon, and took three tries to get it where I wanted. The valve body will be back Thursday and a different original style governor is going back in with modified weights and springs. Three sets of eyes were on the valve body and shift kit ( TransGo ) this time with 110 years of experience and all checked out, I was told. Just hoping for the best and a car that can be driven. At this point maintaining my cool is the biggest trick. 20 years ago it would have been ugly.

 

MOST of the time on a new build the builder will use vaseline or trans gel in some spots. must be warmed up to melt. some guys are in a hurry and don't follow basic procedures.

 

running my 700r4 has shift kit , by pass the computer with pressure switch kit with 373 gears and it kicks hard in second...

 

Not much new to report. The valve body was removed, double checked and re-installed. Shifted from 1st to 2nd and that was it, manually or automatically. Changed the governor to a stock one, still have only 1st and 2nd automatically but have all four gears and O.D manually and good gears at that. Adjusted on the TV cable to no avail for 3rd or 4th gears. I have the correct geometry bracket installed on the Holley, so one less thing that could be wrong I guess. New plan is to replace the VB with a stock one to see if we can get all four gears automatically with that. At this point, who knows and I'll be calling around on transmissions tomorrow to see if anybody can ship one out faster than 8-9 weeks, which was the first shop ( Phoenix Transmissions ) I tried. Car show season is getting short and here I sit....

 

Have you had a pressure gauge on it?
Did you check the pressure regulator valve and TV boost valves in the pump?

 

Pressure gauge will be on it Tuesday, as far as the pump, wouldn't the transmission need to come out to check the pump ? Again, not what I do or really in my wheelhouse. If it's a dumb question, so be it.

 

The valves in the pump are attainable with the pump in the transmission.

 

It sounds to me like it is still a valve body issue. If you have the skills to remove the VB and totally dis-assemble it that is what I would do. All the valves are steel and they get constantly slammed back and forth and will stick. You can't start sanding on them as that will cause pressure loss issues. So you need a good core or all new valves. I did a 4l60e a few months ago for a young guy who was on his 3rd trans from a shop and it took 3 VB until I got one you could even remove the valves from. You watch these hacks on Youtube they show beating a separator plate back flat were a check ball is stuck instead of replacing the plate , really . It is nice to have a spec chart giving the od and length of the springs in the VB so you know what you are working with. If buying a VB the only one I would trust would be a SONNAX and I am sure they are several hundred dollars. Here is a file that would be worth your time reading on building a 4l60/80e which is the electric version of your 700 . It also covers the 700 . https://www.uscars.biz/uscars/extras-documents/ATRA_GM_4L60-4L60E_(700R4)_Rebuild_Procedures.pdf

 

I’m no transmission guy to be up front but have had three 700r4 behind sbc. And everyone required some messing with to get set up. My latest build is a 383 700r4 456 rear 31.5 tall tires in a old truck.
I don’t understand the way it shifted after you reinstalled the valve body. So in drive what gears do you have 1 2 only but you said you had 3 4 manually how’s that work or am not reading it right.

 

Everything was double checked by my buddy who built it and does this for a living. I don't know the history of the trans before I bought it and then had it built. I know we purchased a TransGo 700 2&3 reprograming kit for it and he doubled checked all the surfaces and hole sizes that got modified for a full automatic install. All the valves moved freely and I witnessed that and nothing needed to be sanded to move. However, not knowing the history of the VB, the plan is to install a known good stock one to see if we get all 4 gears with that in automatic mode ( Drive ).

 

You were reading it correct. put it in drive I have 1st and 2nd gears but no more shifts after that point. Yet you can manually pull the trans into 1st and manually get a good shift manually into 2nd, 3rd, 4th and you can feel the OD lock up.