hey everyone, so i put my 455 in my 84 delta 88 4 door. I got my 400 long shaft transmission in it with my just temporary modified transmission crossmember in it- its the orginal single hump style. the only thing that i need to do to this car is run exhaust. i want to run dual exhaust all the way back. i cant find a double hump crossmember and was wondering what others may have done to make one or did they use one off a different vehicle, thanks.

 

Get a side to side measurement, and go to one of the biggest yards in your area, and ask if they have something that'll work.
A good counterman will find a earlier one that'll fit with modification.
If not, ask them to look up the number, and run it on the cross-county line!
I know I used a '65 chevelle crossmember on a '80 malibu, with about an hours work!

 

I used one out of a 90's caprice, and notched the front. I used a th400 with a 9" tailshaft as well.

I had to extend the frame on the passenger side.
Driver's side mounting holes line up fine.
Here's where it will sit.

Here's where you notch the front to fit the th400. It will line up with the rear hole.

 

thanks Chicago, thats info i needed

 

hey chicago, i know you know alot about this swap, i think i finally found a junkyard thats got the dual exhaust crossmember, its from a 94 caprice, i spent all day calling around and figured the only caprices that had dual exhaust was the 94-96 ones. since ive got to travel just a bit to get it, im going to go ahead and check to see if its got a posi rearend, if it does, will it work with my delta? thanks

 

I've asked the same thing before and I understand that it will physically fit. However, there are some modifications that need to be done. I believe the driveshaft has to be shortened. I think the brake lines need to be modified somehow, too. I'm sure it's been done and hopefully someone remembers what they did. Over 3 years here and I'm still blown away by the sheer amount of knowledge here.

 

The posi rearend will fit too, if it has drum brakes.
The disc brake rearends are more involved. You have to swap in a different proportioning valve and most likely break all of your brake lines trying to remove the old one.

1 problem you will run into with the caprice rear ends, the axle shaft bearing surfaces are usually chewed up, so make sure you are prepared to buy a pair of axles and some new tube end bearings if yours end up being shot.
OR work out a deal with the junkyard owner where you have the option to come back and get a different pair of shafts if the ones he sold you were junk.

Caprice 8.5 axle shafts have 30 splines, & your original 7.5 only has 26 splines, so they won't interchange.

 

As Henry K said, you will need a much shorter drive shaft. I figure you knew that laready though using a 9" tailshaft 400.

The 8.5 is about 1" longer in the front than your stock 7.5.

 

Google G-Force Performance Crossmembers. Give the tech line a call. Ill bet they have it or can make it?

 

thanks everyone, where i live there is no caprice crossmember but my dad thinks he found a guy thats sitting on alot of them from like 94-96 caprices. hes got the rearends too, there already out of the cars. ive actually already cut my driveshaft to fit the for the longer transmission, so ill go ahead and get the driveshaft cut another inch. having such a short driveshaft does this put any wear on anything? or change the angle somehow where it can hurt something when getting on it?

 

Awesome! If you've already modifield the driveshaft, you may want to do that last. You know the old adage "Measure twice, cut once". It may be short enough already!

 

yeah your right, im going to wait till i get the rearend in then check. it would suck to cut too much off lol. everytime i work on it i just think what kind of tire smoke this thing can produce. ive already scared some rice burners with it.

 

Gustav, I believe that you and I are doing similar things to our Delta 88s. Mine is a 1982 vintage and I understand that most, if not all, chassis parts will interchange between the years of 1977-1996 GM B-body vehicles.
I found a 1994 Buick Roadmaster in a local junkyard and snagged its 8.5 rearend. It's presently undergoing a change to a Detroit Truetrac limited slip differential with a 3.42 gear ratio. I removed the 11" drum brakes and am going to put on the 9" ones to match what my Olds now has. The axles I intend to have drilled for the Olds' 4.5 inch five bolt pattern (the Roadmaster has the 5" wheel pattern).
Error correction: As J-(Chicago) points out in his reply below, I made a mistake in stating that my 82 Olds has a 4.5" bolt pattern; it's actually 4.75". Thanks to J-(Chicago) for correcting this. I wouldn't want anyone to be misinformed because of me.

While I was removing the rear end from the Roadmaster, I noticed that it had true dual exhaust and that the transmission crossmember was double humped for the dual exhaust plumbing, so I grabbed that, too. I'm hoping that the factory Buick exhaust can be made to work on my '82 with minimal modifications.

Sounds like the mid-90s Caprice has the same crossmember as does the Buick. Good luck in finding what you need.

Rob

 

glad theres a lot of others here thats done this and know whats going on, people around my area didnt even think the 455 would fit, i knew it would. thanks for the info on the roadmaster RobS. ill look into those too.

 

Just a few pointers here. The midsize gm's have a 4.75" bolt pattern,
not 4.5" that is a jeep pattern.
I wouldn't want you ordering the wrong axles.
Also, you can run the 11 inch big brakes. You just have to pick up some drums from a 1989 custom cruiser. Those should come double drilled for both bolt patterns.
Bendix part number pdr0201

 

The caprice crossmember will sit about 1/2" higher. I didn't have to worry too much about it because I am running a double cardan joint and have fully adjustable control arms.

 

J-(Chicago),
Many thanks for the correction. I don't know why I put 4.5" in my post, I know better-- I must be getting old or something...

And a big thank you for the 11" brake information, especially concerning that dual pattern drum. I didn't know anything like that existed. And now to even have the part number-- behold the power of the internet!

Rob

 

i also want to say thank you for the brake info