Learn me GM 700r4 automatic transmissions

OK....this is in our challenge C4. I know a TH350/400 or Power glide is better for our application but budgetary restraints, ya know.

I've always been a manual guy but that ain't happening for challenge money. So I have a few questions.

1.) The car can run virtually any autoX course in 2nd given torque and gearing. When you put it in "2", it obviously starts off in low and shifts to second. However in low speed turns, when exiting, it down shifts back to low and screams it's guts out before up shifting. Even with left foot braking. Normal?

2.) If the above behavior is not normal, could it be a TV cable out of adjustment?

3.) If the behavior is normal can anything be done inexpensively to keep it from downshifting short of fully manual valve body?

Before you recommend shift kit be advised that tranny shifts solid, doesn't slip, etc.

AND PLEASE EXPLAIN IT TO ME LIKE I'M A 4TH GRADER BECAUSE I'M CLUELESS ABOUT AUTO TRANSMISSIONS/b]

Thanks in advance

That sounds normal for a c4 with a 700r4. Mine was like that, it liked to shift to 1 when 2 was fine.

In reply to Patrick:

Thanks, Patrick. I just wish it was like my 02 BMW 525 that has a manual shift mode. Aren't the transmissions somewhat similar?

Don't screw with the cable, other than o make sure it is correctly adjusted. Try to fool it, and the pressures drop with a corresponding drop in trans life.

You might be able to fudge the governor weights or spring a bit on that one, but I'm guessing.

There is a way to make 2 mean 2. Shift Kit. C5s are that way from the factory. I'm planning to replicate that function on an s10 i'm planning to v8 swap (it's already 4l60).

I've heard this complaint from old Corvette autorcross buddies so you're in good company but I didn't experience it with my 91, 92 or 95.

Maybe I had a lighter foot and didn't force a kick down.

I started the car in 1st, shifted to 2nd when needed and left it there unless 1st was called for (rare). Starting in first might have had something to do with it staying in second but I kinda doubt it.

If you have the 2.49 rear axle you could be getting the downshift due to the tall axle ratio.

Of these possibilities, the first and third seem most likely and the second less likely but worth trying.

In reply to conesare2seconds:

No, it has the 3.09 "performance" rear gear.

In reply to Ovid_and_Flem:

This is the TV adjustment procedure. It also includes setting up a TV cable from scratch, which you'll need when you swap to a carb, but for now just go through the adjustment procedure & see if it makes any difference.

the Trans-go valve body kit Is Super Simple to do (Heck I did One) and allows for Holding in the selected Gear. The spring and weight set for the Gov'na Is also as simple the instructions are in the Kits, Inexpensive too.

I'd look into a diy manual valve body. I know some of the other GM trans of that era could be done diy.

I built mine up the best budget bet is a transgo reprogrammer kit. I have a full manual reverse pattern valve body with quick silver rachet. There is a governor in side the trans that spins and determines shift points the TV cable should not be messed with. http://www.transgo.com/products.php?category_id=96&parent_id=31&product_id=169

Ok...first things first. Do you all agree that downshift out of slow corners is "normal"?

Second...the transgo shift kit just makes it shift more solid, correct? Doesn't really affect shift points?

Told you...Splain it to a 4th grader.

Transgo will allow you manually select your gear and hold it to any rpm with out it shifting. Other wise it will automatically shift at a certain rpm no mater what gear you are in.

In reply to Strictly_Attitude:

I think that's true on TH350/400 but not on the 700r4...I may be seriously mistaken tho.

Do the TV cable adjustment per the Art Carr link. This is critical for internal line pressures on the non-electronic 700R4's.

How slow is a "SLOW" corner in terms of RPM? If you're down or close to 1,000 RPM when you nail the throttle, the transmission will automatically downshift to the next lower gear. If the 700R4 is wailing up to 3,500 RPM, but not upshifting at that point, a rebuild may be just around the corner. (The FSM shows 1-2 upshift occurring between 30-53 mph at WOT depending upon engine load, rear axle, etc. You can check this out by going to an empty parking lot, cruise at 25 mph in second gear, nail the throttle, and see at what speed your 700R4 upshifts back to 2nd.)

A shift kit will not affect the shift points in the 700R4. It just reduces slippage to the point that the shifts are very firm.

Converting the valve body to manual shifting is recommended for an auto-x only vehicle. This mod requires a working tach to take full advantage of the manual shifting capability.

I am stating this as a fact not an opinion if you took a peek at the link I posted it has this written FEATURES: Optional Stick Shift; or Gear Command with automatic upshifts; Holds 1st, 2nd and 3rd at any rpm. Backshifts to 3rd, 2nd and 1st at any rpm; Competition, Off road And Pro-street;

Ok...seems that transgo offers a 'shift kit" or a "reprograming kit" that accomplish different things.

So confusing.

Strictly....not questioning link info. Appreciate your input. The link info is referring to reprogramming ki not shift kit....2 different products from my online research.

Hey mrbeach...good to see you hanging around these parts. By low speed corner I'm thinking 2000-2500 rpm or less. And it will up shift almost immediately at 3000 to 3500 with a solid shift and no slippage...just light up the tires.

Shift kit = firmer shifts, less slippage.

Reprogramming kit = firmer shifts, less slippage, manual shifting from gear to gear

Your downshifting on slow corners as you described sounds normal to me. (See previous post re: 1-2 upshift speeds at WOT.) Winding out to 3,500 RPM (just above peak torque) is normal for a Vette 700R4.

The Transgo reprogramming kit sounds like what you need plus you don't have to remove the transmission to install it. (Review the installation video on the link page Strictly_Attitude posted to see if you feel comfortably with the installation procedures.)

I am stating this as a fact not an opinion if you took a peek at the link I posted

I posted it too..

Shift kit is a vague term. People generally associate it with making vehicles shift harder but the majority of kits that actually get installed nowadays actually address a lot of durability/reliability issues and whatever effect it has on shifting is secondary to that. A lot of shift kits are catered towards reliability and give OPTIONS to change actual shift timing or firmness based on customer desire. At the extreme end of shift kits are 'full manual' conversions that disable automatic shifting of any kind and let you stay in whatever gear the shifter is placed in no matter what. This has upsides and downsides. See the time that i flipped a lifted CJ7 because i accidentally bumped first while trying to diagnose a misadjusted shifter linkage. It drug the tires, slid out and immediately tipped over. A stock trans wouldn't have allowed you to reengage 1st at that MPH. But there are upsides as well and for an autocross car, avoiding a downshift while you are already at the edge of your traction circle is a big upside.

Vigo wrote:

I am stating this as a fact not an opinion if you took a peek at the link I posted

I posted it too.. Shift kit is a vague term. People generally associate it with making vehicles shift harder but the majority of kits that actually get installed nowadays actually address a lot of durability/reliability issues and whatever effect it has on shifting is secondary to that. A lot of shift kits are catered towards reliability and give OPTIONS to change actual shift timing or firmness based on customer desire. At the extreme end of shift kits are 'full manual' conversions that disable automatic shifting of any kind and let you stay in whatever gear the shifter is placed in no matter what. This has upsides and downsides. See the time that i flipped a lifted CJ7 because i accidentally bumped first while trying to diagnose a misadjusted shifter linkage. It drug the tires, slid out and immediately tipped over. A stock trans wouldn't have allowed you to reengage 1st at that MPH. But there are upsides as well and for an autocross car, avoiding a downshift while you are already at the edge of your traction circle is a big upside.

I definitely recommend a aftermarket shifter as part of the installation. A b&m quick silver and the transgo reprogrammer kit would be a nice combo. I installed a tci full manual in mine with reverse pattern and engine braking when I built my 700r4 up. But I feel if you have to use the 700r4 in any form of racing that kit should be the minimum modified. Just my 2 cents.

In reply to Strictly_Attitude:

So are you saying minimum mod for competition should be TCI or Transgo?

I have spoken with TCI a few months back. Ironically they are headquartered here in mississippi. They're kit is a bit pricier than transgo but if it weren't a challenge car, I would use them since they're right up the road.

I miss spoke and did mean the reprograming kit, so sorry you can still do this yourself,sometimes the spring colors are hard to differintiate ?(see) but you can do it. 300 or better for them to do it doesn't work for me. and the GOOD Servo not the Vette servo replacement.