700r4 surprise

[pantera928]

11 minutes ago, Gunslinger said:

The 700R4 was designed for a much heavier car than an Avanti...it has a very low first gear and upshifts almost immediately.  I had a 700R4 installed in the '70 I owned in place of a badly leaking PowerShift and while it certainly worked well...it took time to be able to keep from smoking the tires starting out...it was that touchy.  The trans was built by a transmission guy to match the GM 350HO crate engine being installed and an aluminum driveshaft.  You simply couldn't give it any amount of power starting out without breaking traction.  That's why the gearing of a 200R4 is better suited to an Avanti.  It just has to be built by someone who knows what they're doing.

That is what i have heard and why i am thinking of a 200R4. Just need to figure out what else I need to do to make it work

[mfg]

18 minutes ago, Gunslinger said:

The 700R4 was designed for a much heavier car than an Avanti...it has a very low first gear and upshifts almost immediately.  I had a 700R4 installed in the '70 I owned in place of a badly leaking PowerShift and while it certainly worked well...it took time to be able to keep from smoking the tires starting out...it was that touchy.  The trans was built by a transmission guy to match the GM 350HO crate engine being installed and an aluminum driveshaft.  You simply couldn't give it any amount of power starting out without breaking traction.  That's why the gearing of a 200R4 is better suited to an Avanti.  It just has to be built by someone who knows what they're doing.

Understood, however, I'll take the heavy duty 700R4 any day!!

[Jred]

On 1/14/2022 at 9:54 PM, mfg said:

Jred......Is the lockup torque converter functioning OK?

I’m going down a list of things to check while I learn up on this transmission. After reading up on the tv cable I noticed that the bracket looks diy and there’s too much slack in the cable. Also, the plastic clip that holds the tv cable in the bracket has broke and is held in place with a zip tie. Ha.
I believe this is why 1st and 2nd almost seemed like one gear before. First went into second at around 5-7 mph. What I was chopping up to a malfunction carb was intact, possibly, the tv cable. or just the nature of the 700 from what the members have wrote.
The Rochester four barrel has been rebuilt and running great. Still was getting the strange 1st/2nd gear and an occasion hesitation into what would be overdrive. 
Going to call summit and Monster transmission in the Monday to see what combination of bracket and corrector kit I will need to get the tv cable operating correctly. Hoping that will get the trans shifting properly. 
opting to wait on getting the center console to look correct at the moment. The letters and number line up relatively accordingly. 

Edited January 17, 2022 by Jred

[Jred]

On 1/14/2022 at 12:07 PM, silverstude said:

Unless you have an axle gear of 2:80 or the like,  1st gear in a 700 will take you around 15 feet before it shifts to 2nd.  I have a "built" 700R4, which was adjusted by  the tech's  at "Bowtie Overdrive", the axle has a 3:54 ratio .  Under normal driving, you do not want to have a cup of coffee in your hand when you start off.  Even moderately flooring it and you will be wearing the coffee after the abrupt  shift to 2nd.

 The gear spread in a 700 isn't the best and that's been discussed.   I always wondered why you can't start off in 2nd to avoid the " Atlas-Centaur 2nd stage" effect....

 

Good to know. That’s what was happening. 

[Dwight FitzSimons]

Re the THM200-4R trans:  I once read an article about a '63 Tempest drag car with a 455 Pontiac engine with something like 600 HP.  Because the 700-R4 has only a Chevy bolt pattern he had to use a 200-4R trans (which has a dual pattern).  The 200-4R was built to racing specs and held up behind that 600 HP engine.

--Dwight

[pantera928]

8 hours ago, Dwight FitzSimons said:

Re the THM200-4R trans:  I once read an article about a '63 Tempest drag car with a 455 Pontiac engine with something like 600 HP.  Because the 700-R4 has only a Chevy bolt pattern he had to use a 200-4R trans (which has a dual pattern).  The 200-4R was built to racing specs and held up behind that 600 HP engine.

--Dwight

Good to know. I will try to keep my engine under 600hp to be safe.🤣

Thanks

[silverstude]

Yes before you drive it, make sure that TV cable is adjusted correctly or you'll lose the trans in a hurry

[Jred]

Okay, new tv cable installed and adjusted. 
adjusted per instructions and a couple different YouTube tutorials. 
I actually feel the shift from 1st into 2nd now which is nice. Making adjustments per instructions and online tutorials the initial shifting was way to harsh at 18-20mph.

Adjusted for the shift to happen at around 15mph and the it’s seems much happier. Those with the 700r4 installed, what speed are you shifting at? @silverstude it’s definitely a head jar/no cup of coffee while moving from 1st-2nd  

 

Edited January 21, 2022 by Jred

[silverstude]

The next item to assure is the lockup solenoid functionality.   A run of the mill 700 will lock up the converter in 2nd or 3rd.  In 4th, the converter must lockup or the oil will cook.   4th is overdrive and puts quite a strain on the converter, creating loads of heat,  so an oil cooler  and knowing the lock up works, is a primary concern.     You can tell the lockup is functioning by a 2-300 rpm drop. 

 

[mfg]

3 hours ago, silverstude said:

The next item to assure is the lockup solenoid functionality.   A run of the mill 700 will lock up the converter in 2nd or 3rd.  In 4th, the converter must lockup or the oil will cook.   4th is overdrive and puts quite a strain on the converter, creating loads of heat,  so an oil cooler  and knowing the lock up works, is a primary concern.     You can tell the lockup is functioning by a 2-300 rpm drop. 

 

Not sure about that...i took manual control of the lockup converter on my '83 over fifteen years ago, and rarely use the lockup feature if I'm not on the highway.....never hurt the 700R4 or its converter!

[plwindish]

I had a 200R4 rebuilt and installed in my '76 in 2011 after having the 400 motor also rebuilt.  Dan Booth had the rear trans mount needed along with the TV cable, shift rods and the plastic AOD gear indicator plate for the console shifter. The combination has worked well over the years. The 3:31 rear gear "born" with the car is still intact, interstate cruising at 75 mph is right at 2000 rpms. The first three speed gearing of the 200R4 is the same as the Turbo-hydramatic 400 the car originally had and also the same length as the THM 400 trans, needing no driveshaft alterations. 

[pantera928]

34 minutes ago, plwindish said:

I had a 200R4 rebuilt and installed in my '76 in 2011 after having the 400 motor also rebuilt.  Dan Booth had the rear trans mount needed along with the TV cable, shift rods and the plastic AOD gear indicator plate for the console shifter. The combination has worked well over the years. The 3:31 rear gear "born" with the car is still intact, interstate cruising at 75 mph is right at 2000 rpms. The first three speed gearing of the 200R4 is the same as the Turbo-hydramatic 400 the car originally had and also the same length as the THM 400 trans, needing no driveshaft alterations. 

Paul

I show that the 200 4R is 3/4" shorter than the TH400. THat did not cause you any problems? Did you do the conversion yourself?

[silverstude]

19 hours ago, mfg said:

Not sure about that...i took manual control of the lockup converter on my '83 over fifteen years ago, and rarely use the lockup feature if I'm not on the highway.....never hurt the 700R4 or its converter!

I tried quite a few ways to manipulate the lockup and protect the innards.  Currently have an SPDT switch on the dash to leave it on (auto) or turn it off altogether.  It's also wired so it only locks up in 4th.  Add to that a temperature sensor on the oil pan.     From everything I've read, if the oil temperature exceeds 260 for any length of time it will deteriorate  the soft parts and clutches in short order, especially the ones in the 4th gear (OD) servo.   Even with an internal oil cooler in the radiator and an external  cooler in front, plus forced air ducts into the bell housing, there's no stopping the temperature climb if the lockup is off.  If drive it without the lockup and it's in 4th,  you can actually see the temperature rising and it comes on fairly quick, especially in the summer.  Once the switch is on, you can actually watch the temperature drop and it does this much quicker than it rises.  

  My 700 is supposed to be a HD build and said to be bulletproof.  It has a 2200 RPM stall converter if that makes any difference, but I would think a higher rpm stall would allow for less resistance to flow which causes the heat.   So far, the only complaint is that 1st gear jump and no way to avoid it.   

[mfg]

1 hour ago, silverstude said:

I tried quite a few ways to manipulate the lockup and protect the innards.  Currently have an SPDT switch on the dash to leave it on (auto) or turn it off altogether.  It's also wired so it only locks up in 4th.  Add to that a temperature sensor on the oil pan.     From everything I've read, if the oil temperature exceeds 260 for any length of time it will deteriorate  the soft parts and clutches in short order, especially the ones in the 4th gear (OD) servo.   Even with an internal oil cooler in the radiator and an external  cooler in front, plus forced air ducts into the bell housing, there's no stopping the temperature climb if the lockup is off.  If drive it without the lockup and it's in 4th,  you can actually see the temperature rising and it comes on fairly quick, especially in the summer.  Once the switch is on, you can actually watch the temperature drop and it does this much quicker than it rises.  

  My 700 is supposed to be a HD build and said to be bulletproof.  It has a 2200 RPM stall converter if that makes any difference, but I would think a higher rpm stall would allow for less resistance to flow which causes the heat.   So far, the only complaint is that 1st gear jump and no way to avoid it.   

Great info!......maybe I've just been lucky!!

[Avanti83]

2 hours ago, mfg said:

Great info!......maybe I've just been lucky!!

Considering you said you drive mostly city miles I would think it wouldn't be a problem as most converters lock up around 40 mph IIRC. I do the same thing with my 2004R, just engage the converter lockup switch at highway speeds.

[mfg]

8 hours ago, Avanti83 said:

Considering you said you drive mostly city miles I would think it wouldn't be a problem as most converters lock up around 40 mph IIRC. I do the same thing with my 2004R, just engage the converter lockup switch at highway speeds.

Yes, mostly all city driving....hitting the highway really is a rarity with me.

[Jred]

Update. 
 

Got the Avanti out for a longer drive today. Everything thing seems great. 
city driving seems to be shifting as it should and the freeway is nice. Over drive comes in at about 65/70. Loving it. 
thanks for all the info everyone. 

[pantera928]

4 minutes ago, Jred said:

Update. 
 

Got the Avanti out for a longer drive today. Everything thing seems great. 
city driving seems to be shifting as it should and the freeway is nice. Over drive comes in at about 65/70. Loving it. 
thanks for all the info everyone. 

What kind of RPM are you turning at those speeds? Do you know your differential ratio?

[Jred]

3 hours ago, pantera928 said:

What kind of RPM are you turning at those speeds? Do you know your differential ratio?

Next up is getting the tach fixed or replaced. May hook up a temporary tach in the meantime
 

I should have counted the teeth when I replaced the diff fluid and axle seals but never did. Any other way to tell?

Edited January 24, 2022 by Jred

[Jred]

Photo for posterity 😍

[pantera928]

Well, your diff should have a tag on it showing the ratio and the O/D ratio on a 700 is .70. Figure that in with the tire diameter and that will give you what you should have.

Calculate RPM for Given Speed(MPH), Rear Gear Ratio, and Trans Gear Ratio (purperformance.com)

[Gunslinger]

The tachs used in Avantis…especially Studebaker…as well as earlier Avanti IIs…were notoriously inaccurate.  The faster the engine revved the greater the error.  The same goes for the speedometers.

[Jred]

1 hour ago, Gunslinger said:

The tachs used in Avantis…especially Studebaker…as well as earlier Avanti IIs…were notoriously inaccurate.  The faster the engine revved the greater the error.  The same goes for the speedometers.

I was noticing that for the speedometer today when comparing gps to the speedo. 
many recommendations on after market setups. Considering replacing all the gauges. 

[Gunslinger]

In the '70 I owned, I replaced all the gauges with AutoMeter units.  The gauges are all a standard diameter so you have lots of choices out there.  

[Raybader]

On 1/14/2022 at 4:00 PM, pantera928 said:

I probably asked this before but did you put the 700 R4 in yours?

I am trying to locate a true guide for how to put a 200 R4 or a 700 R4 in an Avanti II. 

Since it has been done, I am hoping someone has documented the procedure somewhere.

I didn't document putting the200 in my 78 (RQB2651). Just had to change the yoke on the driveshaft. Transmission mount lines up perfectly if your car has a TH400 originally. As stated by others, Dan Booth has all the parts needed to correct the shifter issues. DM me if you like.