BSeery

Howdy,
I smoked my stock 350C transmission, and I guess it is time for the swap to the 700R4 -- just 1 or 2 years ahead of my plans.
What I would like is all / any input from the guys who have done this swap before.
Who did you get the tranny from? Where did you get the crossmember, how did the project go? Any tips or tricks? How does it run now? Was it worth it?

I have talked to both Bow Tie Overdrives and 4th Gear Inc and have gotten prices and all that. But I want to know what YOU guys think about the transmission. Also, I do have a set of 3.73 gears to install later. Would they work well with the 700R4? What rear gears are you using?

Any information would be appreciated.

Thanks.

gkull

After talking to Red 73 the best gearing for a 700 is @3.90 who ever you go with ask about 1/2 inch selinoid for oil to the lockup TC. Also ask to get the govenor factor set to what ever rpm you desire at WOT. Ensure that the 700 doesn't have any kind of 4-3 kickdown.

MIKER

Hey Brian,
Here is my generic cut-n-paste response. I need to update it but maybe you can find something useful in it.

In August 2001, I completed the installation of a 700R4 into my ’80 along with a new 383.
Not counting the price of my transmission (purchased used for $350. It failed 1700 miles later on Nov. 7th) here is a list of the things that I did and the parts that I purchased.

I took my used transmission to "Howards Transmissions" in Stephenville TX.
They installed the following
-Filter Kit. $25
-Lock-Up Valve Assembly. $28
-TransGo 3-4 Max Throttle Kit. $64
-Corvette Servo. $23
-Pump O-ring, Gasket, Bushing, and Seal $15
-Labor Charge. $150
They suggested that I go ahead and let the do a complete rebuild while they had the transmission in the shop but said to give it a try and that if it didn't work out, return it and they would rebuild it for $450. Now that the transmission has indeed "failed" I wish that I would have had them complete the job then but I was hoping to save $450 and not have any problems. It was a gamble that has only cost me the time spent on removal and re-installation.

-Dipstick tube and indicator for 700R4 from Bowtie overdrives ~$22.
-Adapter kit for TV cable to stock Rochester carburetor, from Bowtie overdrives ~ $45.
-Changed from electronic speedometer sending unit to a mechanical gear driven unit from Bowtie overdrives ~$45.
-Had the drive shaft shortened and new U-joints installed at
-American Drive Train Repair
2519 N.E. 36th Street
P.O. box 161427
Fort Worth, TX 76161
817-831-7878
Shorten and balance drive shaft. $49.50
((Dynamic balance @ Barney’s discretion. $29.00+ (not required)))
2-U-joints ($13.48 each) $26.96
Labor for replacing U-joints. ($8.75 each) $17.50
Total bill $96.18

-The drive shaft yoke from the TH-350 worked in the 700R4
-Modified stock cross-member. (moved the mounting pad ~2” back and moved emergency brake cable over away from the U-joints.)
-Modified the original TH-350 shifter bracket that mounts to the side of the transmission pan. (The distance between the pan bolts on the TH-350 were ~3 ½” apart and the pan bolts on the 700R4 are about 3” apart). We simply cut a 1/2" section out from the middle of the bracket and welded it back together.
-The stock speedometer cable is supposed to be able to reach the extra couple of inches required. I can’t verify this, I had to purchase a new one because my old one was broken. The new one came out about 12” longer than the old one. (almost too long) New lower cable ~$16.
-I will modify the shifter guide plate located in the console below the shift lever to allow placing the shifter into 1st gear. I’ll save this for another time because it is not critical.

I don’t know if the transmission lines from the TH-350 will work or not because mine were so butchered up from previous repairs that I am replacing most of them with new steel lines using compression fittings.
Here are more details regarding the steel lines:
For my 700R4 install I used part of the existing lines and added new sections to complete the job.
I purchased two separate pieces of new steel tubing and 4 brass compression fittings from NAPA auto parts.
From the radiator end: The original connections to the radiator consisted of short pieces of flared tubing (~3"). These short ~3" stubs were connected to the remaining length of the lines that connect to the transmission with short pieces (~3") of high pressure rubber tubing w/hose clamps.

From the transmission end: I used about 12"of the original tubing from the transmission (in and out).
For the new section placed in between the radiator and transmission: Basically I removed and replaced the tubing between the 12" stubs from the transmission and the original lines which were cut near the fuel pump. I used a decent quality tubing bender. It was the first time I had used one and it didn't seem too difficult to use.
The original transmission lines had been routed below the starter which made removal of the starter somewhat difficult. I bent the new steel tubing section along a path that provided clearance for easy starter removal (followed the frame curve to below the A/C evaporator core housing and back out and up to meet the (~12") stubs coming from the transmission.
To sum it up: From the radiator> ~3" metal tubing> ~3" rubber hose> new section> ~12" stubs connected to transmission.

I know a picture would be better but I don't have one of the transmission lines right now so this was the best description that I could give.
All in all, the modifications for the swap weren’t nearly as bad as I thought that it would be. I worried most about the cross-member modifications but a talented friend using a welder, cutting torch and tape measure made short work of it.
I’m just guessing, but if you have all of the parts and access to the tools needed, I think that you could tackle it in one weekend with help from a friend.

As far as transmission selection, I’ve always heard to go with a 1988 or newer model 700R4. The prices can range from as low as ???$ for a used one up to ~$1200+ for a new or rebuilt one.
I'm running a 2200 RPM lock up stall converter. I paid ~$180 for it at the local shop.
Bowtie Overdrives sells a 1800-2200 lock up stall converter for all street applications. These converters feature brazed turbine vanes, Torrington thrust bearing, heavy duty sprag clutch, larger dampening spring assembly, carbon fiber clutch material and is fine line balanced for smooth operation. Price is $154.00

I currently have 3.08’s which are way too tall. I am changing to 3.73s.
I purchased my 3.73 ring and pinion gear from "Tom's Differentials" for $141 at http://tomsdifferentials.com/cat26.htm
I purchased the complete '80-'82 differential rebuild kit from "Bair's Corvettes" for $89 at http://www.bairs.com/page22.asp
Check out Smokemup.com to see what your new speed MPH vs. engine RPM would look like http://www.smokemup.com/utilities/calc/mph_range2.cfm
Bowtie Overdrives sells lot's of pieces and parts for the swap too!
http://www.bowtieoverdrives.com/68-81Corvette700R4.htm
Budman78 has provided this link for a business that also sells a modified cross member for the 700R4 swap. "Muscle Members" http://www.x-members.net/

(edit/modification = adding to cut-n-paste list)


[Modified by MIKER, 1:10 PM 11/15/2001]

Jvette73

If you want to just buy a tranny outright, i think BTO has the lowest price. About $1000 for tranny and convertor. I got my OD setup from BTO and the next closest price including convertor was between 13 and $1400. I got the other items i needed for the swap from them as well. Shipping from west coast to east coast was about $180 for everything. Im using the 200r but the overall idea is the same. In addition to the brake pedal vertor switch, get two toggles for full manual convertor controll. Runs great now. I think its worth it. I picked up an additional 4mpg plus 8 tenths in the 1/4 mi.

BSeery

Also, there is a company that was in an article about overdrive swaps in C3's called 4th gear.
They have the tranny, dipstick tube, tv cable, convertor for $1025 + shipping. Contact Don at 407-880-2882. They use a 1988 or newer tranny and do the correct build up (servo, kickdown, boosters) for the performance minded driver.

BSeery

I just talked with my local shop (guys I have used before and trust with my baby).
Here is how they 'splained it.

They would do the entire swap including having the driveshaft shortened, modify the cross member, move the brake cable, install the tranny, setup the upshift, downshift, and lockup --- for $1300-$1400 !! :D TOTAL!!

He said they would use either a 1987 or 1988 (wouldn't use a later one since they have electronic speedos), set it up with a 1600-1800 stall convertor, use a hydralic lockup (as apposed to the electronic contoled lockup), set up the TV cable, and use my existing shifter (to keep price down). They said that with the existing shifter, I would not have manual first gear (big deal, never used it anyway). If I want the manual first gear, then I will do the Shift Works shifter conversion.
They have done the swaps for Camaros and other custom street rods before and the customers have always been very happy with the lower first gear and the 4th gear AND lockup convertor.

They are going to start on Friday of this week and said they would be done by late monday - early tuesday.

I hope this works out as well as they expained it. :( (<- me worrying)

Budman68

Here's a good link for a cross member. http://www.x-members.net/
They are half the price of BTO. There are alot of add on pieces that add up. My swap budget is $800. and I am rapidly aproaching that.
What I have spent to date.
Tranny core $50.00
Kit $120.00
Rebuild $200.00
I still need
Converter $129.00
Crossmember $90.00
Shift plate kit $90.00
Dip stick/cover $40.00
Cut Drive shaft $60.00
Beer $21.00
That's the scoop so far.
Budman

MIKER

I am using a '92 700R4 / 4L60. It came with electronic speedo. It is very easy to change to mechanical. You just have to replace the electronic carrier with a mechanical carrier unit and install a gear on the output shaft. I did it myself and it only took ~10 minutes. ~$45 part from BTO.

I believe that I have read on the forum where others have simply filed an additional notch into their shift plate located in the console. This allowed manual operation of first gear. This is a free mod.

Once it is all done, you won't be dissapointed.

cbyrd74

Hi All. New Guy Here.

I did the 700R4 Swap in my '74. Here are a few tips and tricks.

1. When you get the driveshaft shortened have them (driveshaft shop) change the front yoke to a 350 style. It will give you more room in the driveshaft channel.

2. Be sure to install the coolent lines while the trans is on the jack. Alot easier that when bolted up. If not have some Crowfoot Flarenut wrenches.

3. If possible install the dipstick tube on the trans before you place the trans in the car.

4. Be sure to have a good torque wrench for pan bolts.

Thats my experiance with the swap. I really like the 700R4. Makes the car much more drivable and fun. I bought the whole shabang from Bowtie and it does make the swap easy.

Chris


[Modified by cbyrd74, 9:24 AM 11/15/2001]

BlueShark29

I did this swap on my '81 two years ago, when I installed the 383 engine. I have 3.08 rear gears, but with the torque of the 383 I find them adequate. I agree with everything that MIKER says, as I encountered the same things, and did almost exactly as he did. I have an electronic switch to lockup the converter only in 4th gear, and the brake switch to disengage lockup. The only problem with the 3.08 gears in my car is that in town I have to manual select 3rd gear, but I drive high speed on the Interstates most of the time, so this is only a minor problem.
I believe the 700R4 swap was the best thing I could have ever done to this car, as a driver. Even with the 383 engine, I am averaging 24-25 mpg.
I hope this is of some help.

MIKER

I just modified/edited my first post in this thread adding more information to the "cut-n-paste" swap info. I know it was already too long but for someone contemplating the swap, the more information the better.

Jvette73

Blueshark29, do you have a toggle switch to overide the convertor? if you install a toggle in the powerline to the tranny you can flip the toggle and prevent the convertor from automatically locking in 4th gear. This allows you to cruise at lower speeds in 4th gear so you dont need to pull the stick into 3rd. I can cruise as low as 30mph in 4th with the convertor lock overidden. I have 3.90 gears and just like you, if i allow the convertor to lock in 4th it makes the car chug too much. Even with 3.90's, I dont lock the convertor unless im doing a steady unobstructed 50mph minimum. When I unlock the vertor in 4th, it allows me to use all 4 gears in slow speed traffic. I also have another toggle that allows me to have the vertor lock automatically in 2nd and 3rd as well. this toggle is connected to the second pin on the tranny. The only time i lock the vertor in 2nd and 3rd is for drag racing. With the convertor locked in 2nd and 3rd, there is no power loss to the convertor slip. 2nd and 3rd become direct drive more like a manual tranny. I picked up an average of 2 tenths better 1/4 E.T. with the vertor locked in 2nd and 3rd. I do my burnout thru 1st and 2nd gear with the vertor unlocked. Right before staging I flip the switch that locks the vertor in 2nd and 3rd. The vertor is always unlocked in 1st so the car can be held still in gear without stalling. When you punch it off the line, the vertor will lock as soon as its in second gear. It will remain locked thru the 2nd to 3rd shift. It makes a noticable performance difference to me. I unlock the vertor when heading back to the pits or else the car will buck and chug when locked in lower gears at part throttle. My mini toggle switches fit nicely under the ashtray lid on the console. There is some advantages to having full controll over when the convertor locks. A couple a $3 switches and some wire is all it takes. :)

BlueShark29

Jvette73,
No !! I do not have a manual over ride switch for the lock-up, other than the brake switch, to diengage the converter. When I had my tranny rebuilt, I had the extra clutch pack and a Fairbanks servo installed. These items make the shifts very positive/firm, and I have just learned to drop the gear to 3rd for in-town driving. I do, however, like your approach to the problem.
With my setup ( the 383 is quite torquey, and the cam selection, I am using a Chevy S-10 4.3 V6 torque converter, stall around 2400 rpm), and this seems to work most of the time.
Thanks for the info. I may adopt those switches in the future. :yesnod:

Jvette73

Yur welcome Blueshark :)

BSerry, you said they'll do the whole swap for $1300 to $1400!!! Man thats a deal and a half I say!!! Hopefully they will provide you a good warantee with that. Its a lot of work. It would be nice to have them responsible for proper operation and longevity of the setup. Does that include a shifter mod as well. Although the shifter mod is not totally nessisary. The shifter mod was worth it for me because my trans will shift to early on full throttle if left to shift automatically. The extra detent on the shifter mod lets me hold it in first to a higher rpm. I filed an extra notch in the detent to prevent a mis shift into 3rd. I just shove the shifter forward and it stops right in second. To shift to 3rd, I depress the button slightly to get the shifter lock past the added detent.

BSeery

Yeah that comes with a 1 year 12,000 mile warrenty plus all the adjustments and setup that it may need. If I want a longer warrenty they have it available. They are willing to stand behind their work.
We are going to leave the shifter stock for now and see how that works.

Jvette73

If everythings like you say, thats an awsome deal! I wouldnt hesitate to go for it. I had that much in parts alone for my swap, and I did all the labor. Like I said before...it was alot of work. Almost sounds to good to be true. Good deal man. Go for it!!! :cool:

Stingy74

I paid $1159 Canadian for my build up, plus the $750 lock up convertor (for which I overpaid). I think it costed $75 or $100 for the driveshaft shortening and $99 American for the shifter kit from Ecklers. Anything else extra I did myself in which there was no cost. If I can recall, the throttle valve cable was included as well as the stick and tube. Oh, and the cable mount bracket from Holley for a Holley was $20 Canadian or so. And the custon made tranny mount was $40 Canadian. Now that i've confused you with Canadian and American prices, i'll break it down into American money.

Tranny and rebuild:$1159=$724
3000 stall L/U: $ 750=$468
Shaft Shortening: $ 100=$ 66
Ecklers Shifter Kit: $ 99=$ 99
TV cable bracket: $ 20=$ 13
Tranny mount(custom) 40=$ 26
4 stuff I may have forgotten to list here: $100

Grand Total: $1496 American Dollars

I did the install myself and also gathered all the parts myself. I didn't buy any install kits or anything from anybody. Also, take into account that a stock tuned convertor (1800-2000) is included in the price but I didn't use it because I allready had the fancy one. So in reality, take $468 away from the grand total. See how much I saved by doing things myself? Alot more cost effective than some of the turn key kits out there, allthough i 'm sure they are top rate top quality setup's.

dman535

A few things when I did my 700r4 swap.

1. You can files a small portion of the shifter gate to allow first gear access. I aquired a shifter plate from an 82 CE and it shows a D-3-2 pattern, 1st gear is just not labeled.

2. There is a port in the valve body that is used to signal 4th gear has been engaged by the transmission. I used this switch, attached to a relay to provide a 4th gear on ly lockup. Its further tied to a 3 position toggle switch. full time lock-no lock-4th gear only lock. It makes it real handy for mild traffic on the expressway.

3. I used a stock remanned convertor for an 86 C4 Corvette. It gives about 2200 rpm stall and runs about $60 from any trans supply house.

4. I had a shift kit installed, corvette servo, 4th gear override, etc. 2nd gear hits real hard :)

5. Overall best mod I have made to the car. with a 3.55 gear I turn 2900 RPM at 85 mph and usually pull 16-18mpg on the freeway, assuming I can keep my foot out of the kitchen.