700r4 surprise

[Jred]

When I bought the 1970 Avanti last year I assumed it was the original transmission. Well I saw the previous owner last month and he mentioned that the transmission was a 4spd. I thought maybe he had misspoken or was talking about another car of his but low and behold it is a 700r4.

Are there modifications that can be done to the center console to allow for me to manually shift into first? Something that looks stock? I know my junebug shift knob doesn’t look stock but I’m so curious how the tires will smoke in 1st gear

 

[Mel]

Dan Booth addresses this on page 40 in issue 191, Summer/Fall 2020.  Further, he has the parts for the conversion.

[wildfelr]

RQB3263/81/305  Sounds like a good way to mess up a perfectly fine Avanti  cruiser...... sorry thats just my opinion....3263 now has a 700 and ive never had the urge to spin the tires ..... with a 305 it probably wouldnt do it anyway.... best wishes and good luck ...... BILL

[Gunslinger]

For a 700R4 it needs a different shifter quadrant...that has the original 1-2-D-R-P design for the Power Shift.  The 700R4 has one that's 1-2-3-D-R-P.  With a 700 the shifter will not line up properly when in gear.  Dan Booth has the correct parts.

[pantera928]

I think what you should really do is just put an original transmission in it and send me the 700 R4 and drive shaft for my Avanti. 🤣

Just a thought!

Seriously, what a lucky find.

[Jred]

Thanks all. Just put in a call to Dan. 

[silverstude]

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....

 

[pantera928]

48 minutes ago, 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....

 

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.

[Gunslinger]

A 200R4 has a better gear selection and can be built to take punishment but normally doesn't come that way.  If the driveshaft has to be modified, take the opportunity to get an aluminum driveshaft...it saves weight and reduces rotating mass making for better performance.

[pantera928]

5 hours ago, Gunslinger said:

A 200R4 has a better gear selection and can be built to take punishment but normally doesn't come that way.  If the driveshaft has to be modified, take the opportunity to get an aluminum driveshaft...it saves weight and reduces rotating mass making for better performance.

Well, the 200 R4 is my first choice but i would still like to find a write up rather than reinvent the wheel.

Thanks

[mfg]

10 hours ago, Jred said:

Thanks all. Just put in a call to Dan. 

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

[Avanti83]

A little Google goes a long way. https://transmissioncenter.net/shop/swap-to-a-700r4-from-a-th350-th400-200-4r/

[wildfelr]

RQB3263/81/305    3263 HAS A 2.72  original rear gear and makes for a wonderful cruiser with the 700 I installed  5 yr ago... If you have this combination dont change a thing just cruise and enjoy.... at 70MPH im tacking 1750 perfect...a 305 will last forever at that rate...... I also installed a Crane torque cam  (RV) etc as to 305 can always use a little help down at the low end.... If you can install the trans you can fab the trans mount yourself and not buy anything.....as far as the quadrant is concerned you  dont need to make any changes there either...yes the lever wont align up perfectly but you can count to three (clicks) youve saved another 100 bucks and it will work just fine.......  I wrote on this some time ago so check out my posts and also are pics of my fabed trans mount...   BILL in Fl ....386-466-6434 ......happy cruising

 

[mfg]

7 hours ago, wildfelr said:

RQB3263/81/305    3263 HAS A 2.72  original rear gear and makes for a wonderful cruiser with the 700 I installed  5 yr ago... If you have this combination dont change a thing just cruise and enjoy.... at 70MPH im tacking 1750 perfect...a 305 will last forever at that rate...... I also installed a Crane torque cam  (RV) etc as to 305 can always use a little help down at the low end.... If you can install the trans you can fab the trans mount yourself and not buy anything.....as far as the quadrant is concerned you  dont need to make any changes there either...yes the lever wont align up perfectly but you can count to three (clicks) youve saved another 100 bucks and it will work just fine.......  I wrote on this some time ago so check out my posts and also are pics of my fabed trans mount...   BILL in Fl ....386-466-6434 ......happy cruising

 

Good deal Bill!...I have that same 2.72 rear gear in my '83, years ago I was thinking of changing it out to a 3.31....but I'm glad now I left it alone...Happy Cruising!

[pantera928]

8 hours ago, Avanti83 said:

A little Google goes a long way. https://transmissioncenter.net/shop/swap-to-a-700r4-from-a-th350-th400-200-4r/

Nice write up but still looking for a 350 swap to a 200 R4 rather than a 700 R4.

Of course a lot could be figured out from this article.

Thanks

[silverstude]

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.

Yes, this was in the late 90's before the 200-4R was even being spoken of.  If I had my "druthers....".  My 700 is from a late 80's state trooper trans that was reworked by Jasper Engines and Transmissions.   Still has a cable speedo...

[silverstude]

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.

The 700-R4 is a bit longer than a 200-4R, other than that, it bolts right up to a 350.  The only thing I ran into was 1) the two exhaust pipes right after the head pipes had to be reversed so get the wider sweep  around the trans pan. 2) fabricate a rear trans mount 3) get a new drive shaft.

The shifter quadrant I used is from a late 90's Camaro and I put a floor in the console to mount the shifter quadrant to.  The quadrant has the electrical switching for parking brake solenoid, neutral safety switch, back up lights, etc. so that was all in one package.   You can use the quadrant from a later 80's Avanti II which also used the 700 and the only change to the interior was the plastic shift indicator plate showing 123DNRP.  I preferred the Camaro unit because it isolated the shifter from the exhaust heat. 

The only thing I remember that was a PITA was that some of the bolts on the 700-R4 were metric mixed with SAE.... a real GM pleasure.. 

Edited January 16, 2022 by silverstude

[mfg]

One of the nicest things about my '83 Avanti is the factory 700R4 O/D transmission.....Always very dependable, all I've done to it over 28 years is change the fluid and filter perhaps five times...This Avanti has just just shy of 450,000 miles on it now. (New Goodwrench 305 engine in 2010)

Two modifications I did make many years ago are an auxiliary trans cooler fastened to the bottom of the radiator core support, and a simple toggle switch to 'interrupt' the torque converter lockup circuit, giving me manual control of it.  (I had felt the lockup converter automatically engaged at too low a road speed, causing some engine 'lugging' around the city.

[wildfelr]

RQB3263/81/305......I dont understand the fascination with the 200r4.....please explain to me the advantage over  the 700.....if it is availability and the overdrive then I think you will be happier with the 700...... ON ANOTHER NOTE.....does anyone know of a disc brake conversion for the original 81 rear end ?I dont want to change out the whole thing and loose my 2.72 rear gear.... Bill on a cold, wet, nasty morning in Florida ....thanks

 

[wildfelr]

RQB3263....... I also installed an aux cooler so trans heat does not going into the radiator...... there are pics here somewhere of that install along with the trans mount....BURRRRR..... BILL

[wildfelr]

RQB 3263.....I will attempt to post pics of t-mount and cooler install....wish me luck

[wildfelr]

RQB3263 the t-mount is now bolted underneath the X member not as pictured...to gain clearance for the speedo cable ...works fine 5 yrs cost nothing ...BILL

[Avanti83]

2 hours ago, wildfelr said:

RQB3263/81/305......I dont understand the fascination with the 200r4.....please explain to me the advantage over  the 700.....if it is availability and the overdrive then I think you will be happier with the 700...... ON ANOTHER NOTE.....does anyone know of a disc brake conversion for the original 81 rear end ?I dont want to change out the whole thing and loose my 2.72 rear gear.... Bill on a cold, wet, nasty morning in Florida ....thanks

 

Bill

I suspect the fascination with the 200 boils down to 1-size, smaller than the 700 and 2- The 700 has a much lower 1st gear to get heavy cars and trucks rolling with those under 3:00 numerical gears. Personally, Avanti Motors thought the 700 was fine for their cars, my 83 came with one so they can't be that bad.

Turner makes a rear brake setup for the Dana but I don't know if it fits the later ones. He says it fits the Fairborn flanged axle set up however. 

Google up Dana rear disc conversion and you'll see there are a ton of aftermarket suppliers for Jeep rear disc conversions and those should fit Avanti's if they fit similar years. When I rebuilt my 44 in the 1974 I used the rebuild bearing and seal kit from a 72 IH Scout II

BTW,  -3 F when I got up this morning so sorry to hear about your cold spell. 😉

Missing that great Florida BBQ though.

Bob

[mfg]

wildfeir....Those side air scoops you made up to direct cool air to the transmission fluid cooler are quite innovative!....Very nicely done!

[Gunslinger]

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.