700r4 swap

[81malibujoe]

Hey guys. haven't chatted with anyone for awhile. Hope u are all well!. My 81 project found a 7.5 3.73 posi in a field for a C note. Now, and I honestly did not think it would be a problem, is the 3000 rpm's @ 60 mph with the TH350. This just ain't gonna cut it. I have a 700r4 just waiting, with the B&M Shift improver kit and am getting all kinds of negativity on this swap. Tell me what to expect...please. I am hearing it will require massaging the floorboards to make it fit, & I am aware of the crossmember issue, it needs to go to the rear about 6 or 7 inches...is this correct...? What else should I expect? The guy that's gonna do the swap is trying to talk me into just swapping in a set of 3.08's into the 7.5 posi. I would prefer the OD route though. You guys are the PROS! That's why I'm here and not on.....CL!

Joe

 

[patmckinneyracing]

Ok this is the same issue I ran into. I put in a 7.625 rear end out of an 86' monte ss that has an auburn posi and 3.73 gears. I was running a TH350 and was doing about 3800 rpm at 70mph. I am now in the process of swapping in a 700r4 with a 2500 stall.

As far as the crossmember, it should take much mods to make it work. You don't have to move it or relocate it, its to my understanding that all you have to do is drill another hole in the mounting pad.

Second, you don't have to modify the floorboards at all. I know a friend of mine as well as many others on this forum who have done this swap and didn't have to touch or modify the firewall or floorboards.

With the 3.73's and the first gear being a 3.07, you will go through first gear pretty quick, but you have to think of it this way that most stock manual transmission have a very large first gear. The 4 speed in my 71' Roadrunner uses a 3.09 first gear. People will recommend using the 200-4r because the numerical drop between first and second gear is less than that of the 700r4. But you can compensate for this by getting higher in the rpm range before shifting to second.


What negative comments are people making?

 

[JBreu]

I just did this swap as well.......You will be very happy that you did it... I put the 700-r4 in my '84 Monte as well as 4.10 gears and I'm running 65 mph about 2200 rpm's. The 700-r4 will fit in there just fine with no mods to the transmission hump...I believe it's the 4l80 that causes those problems....You will need the stock driveshaft cut 3", if you have the th-350 in there now..... Either way you will need 49 1/2" from center of U-Joint to center of U-Joint. If you go with an 8.5 rear take another inch off.ALso if you are running a 4 bl carb, you will NEED the geometry corrector bracket and linkage bracket as well. I'm running a holley 4779 and got both brackets to my door from JEGS for about $50.00 ( Jegs Brand I used) I am going the non lock up route and have seen no issues....Good luck

 

[81malibujoe]

Pat and JBreu...thanx for the help. The neg commentaries are coming from people who are Ford, some Chevy, not G-bods tho, an Olds guy...for some reason they are old school I guess. They are firm believers in the TH350/400 and Glide trans. I personally think I've driven more miles in reverse than they have forward, and I know this is a popular swap. The crossmember thing is what gets me...Summit sells these brackets for around $70 I think that place the member where u need it for the 700r4 and this places the bolts back in the same holes as the th350...from what I am understanding. Jbreu, what is this geometry corrector u r talkin about, am lost on this. The trans and converter are from an 86 Camaro.

Joe

 

[81malibujoe]

Pat, forgot to ask you where you got the blue headlites? I like that. I imagine they are halogen?

 

[anakputa]

get a double hump from jegs, change the shifter and shorten the driveshaft (driveline shop will do it for $100 bucks or so) They even have a pamphlet describing the proper measurement process etc.. A Lockup controller unless the car already has a pcm and proper linkage at the carburetor. Then you will have to play with the kickdown/throttle cable adjustment so it will shift properly. I had did this swap, then blew up the 700R4, then I stuck a T5 in it. (Wish it was a T56) If the 700R4 is weak spend some money on it so it won't leave you stranded....

 

[patmckinneyracing]

The blue headlights I bought off ebay 4-5 years ago after getting tired of not being able to see down the road with the stock sealed beams. They are a projector headlight and swap right into the stock buckets with no mods. The bulb can be swapped out (H3/H4 bulb?) and it also has a smaller running light inside that was blue, but I swapped mine out for a pair of red bulbs. Gives the car a more sinister look at night when I go to the ricer meets. They now have halo headlights for our cars btw. Just go to ebay and type in 1980 malibu halo headlight or projector headlight and it comes up with a lot of hits.

As for the geometry corrector Jbreau mentioned, look at where the kickdown linkage mounts on your carburetor. There is a small bracket that mounts at that spot on the carb. On an edelbrock style carb, the bracket moves the mounting point for the TV cable lower than the stock mounting point.

If you go to bowtieoverdrives.com, they have a lot of useful information. Click on the link below, and to the left they'll have installation guides and parts used on all styles of carbs. This website provides almost all the info you need along with most of the parts. (http://www.tvmadeez.com/)

 

[jrm81bu]

The crossmember thing is what gets me...Summit sells these brackets for around $70 I think that place the member where u need it for the 700r4 and this places the bolts back in the same holes as the th350...from what I am understanding.

Joe

That sounds to me like the frame extension for use on the older models that don't have the secondary set of holes for the crossmember built into the frame. That is for use when putting in a 2004r transmission and using a stock 2004r crossmember.
You can either modify your existing crossmember(all I did was cut and move the mounting pad some) or better still(especially if you plan on dual exhaust) just buy an aftermarket crossmember. Check out Iceman's products. http://www.maliburacing.com/iceman/

 

[TURNA]

For an 81 Malibu/Monte..G-Body

Use your stock crossmember with these mods and your 700R4 will fit right in.

I had this in one of my 80 Malibus with an approx 400hp small block and a freddie brown 700R4

Never had a problem.

The 2 1/4inch hole in the crossmember is for trans mount clearance.

The egg shaped hole makes it alot easier to get the mount in the correct spot.

And just hammer down slightly the top on the crossmember to clear the tail of the trans.

No mods to your floorboad are necessary.

If you are having a problem with your floorboards and trans fitment, your body mounts are no good.

 

[JBreu]

"Jbreu, what is this geometry corrector u r talkin about, am lost on this."
Joe check this out:http://www.jegs.com/webapp/wcs/stores/servlet/KeywordSearchCmd?storeId=10001&catalogId=10002&langId=-1&N=0&Ntk=all&Jnar=0&Ne=1%2B2%2B3%2B1147708&searchTerm=geometry+corrector.
when I get batteries for my camera I could take a picture of this and the linkage n=brackets and send it to you or post it here....