[Chevy2Bad]

Hi all,

I recently received my 4 link backhalf kit from Checkered Racing. http://checkeredracing.com/4LinkBackHalf.html


I have been reviewing these writeups on backhalving Chevy Novas:
http://www.hotrodder.com/projects/backhalf/backhalf.html

http://autoweldchassis.com/Instruct.ivnu


I was a a little over-ambitious when I removed the rear subframe assembly a few years back. I just removed the entire rear subframe/suspension assembly w/o taking measurements and/or plotting where the axle centerline was in the car's stock position.

The two links above, both use different methods to arrive at the same end result. I understand the general procedure of backhalving, you want to keep the axle, the subframe, and the car itself all square, and level to one another...

But what I don't understand is what to do now that I have no stock subframe to go off of for axle position. I would think that this could just be ''eye-balled'' in the wheel well openings, front to back, and side to side..

EDIT:Also, should the front crossmember of the new subframe go in about the same position as the stock counterpart???

I have tried to make this post as coherent and logical as possible, however if I haven't done a good enough job, I will gladly attempt to clarify.

TIA

 

[Vin63]

While it is better to have taken a series of reference measurements of the stock rearend housing location, you can still complete your back-half project by droping a plumb and marking a series of reference points from the current chassis and then plotting them on the floor (provided the floor is level), using a string or wire pulled taught for the centerline - obviously it is essential that the car is level, you don't move the vehicle once you've made your reference marks and plotted your centerline. I would also recommend plotting your drive/ride height.

As far as locating the rearend housing, you can located where you want it, but you may have to go intially by a visual location and then make final measurements for square. This will help you determine the location of the frame and crossmember since I'm sure the 4-link kit has a specified length for the distance between the front link brackets and the housing link brackets. Good luck.

 

[Chevy2Bad]

Thanks! This is now starting to become more clear.

 

[luepke75]

Im doing a ldderbar tub job on mine. I took a few measurements before. According to my measurements the orignal rearend was off about 3/8" on oneside. I will be moving my rearend back abit for tire clearance issues. I plan on measuring from the front wheels (CW kit) to help get it squared up. Measure both sides as much as possible I am finding that these cars can very from side to side a bit. Keep in mind that any damage like mine minor rear quarter makes that a bad choice for measuring from.

 

[Vin63]

Im doing a ldderbar tub job on mine. I took a few measurements before. According to my measurements the orignal rearend was off about 3/8" on oneside. I will be moving my rearend back abit for tire clearance issues. I plan on measuring from the front wheels (CW kit) to help get it squared up. Measure both sides as much as possible I am finding that these cars can very from side to side a bit. Keep in mind that any damage like mine minor rear quarter makes that a bad choice for measuring from.

If you're talking about the rearend housing being 3/8 of an inch to the passenger side of center, that's not off...many rear-drive passenger vehicles, including our Novas, had the drive train offset to the passenger side about a 1/2 inch, or more in some cases. If you centered your rearend housing, did you also center the rest of your drive train?

 

[luepke75]

If you're talking about the rearend housing being 3/8 of an inch to the passenger side of center, that's not off...many rear-drive passenger vehicles, including our Novas, had the drive train offset to the passenger side about a 1/2 inch, or more in some cases. If you centered your rearend housing, did you also center the rest of your drive train?

Ok that solves that. I will check but I beleive it was to the pass. side. I have not put anything in yet still finishing the frame rails and sheetmetal. If thats normal I can base alot of the install off of the original leaf locations. I will be puting the leaf spring back in to aid in mock up of the ladderbars. Thanks for the info.

 

[Chevy2Bad]

If you're talking about the rearend housing being 3/8 of an inch to the passenger side of center, that's not off...many rear-drive passenger vehicles, including our Novas, had the drive train offset to the passenger side about a 1/2 inch, or more in some cases. If you centered your rearend housing, did you also center the rest of your drive train?

Okay that is interesting, and something I certainly did not know.. What is the reason behind the offset, if any?

 

[Jim W]

Okay that is interesting, and something I certainly did not know.. What is the reason behind the offset, if any?

When these cars were built, two guys named Clyde and Sherman always put the rear ends in. Clyde was a big ol fat guy and was always on the left side. He needed a little more room to work. About 1/2'' usually.

Jim

 

[Vin63]

Okay that is interesting, and something I certainly did not know.. What is the reason behind the offset, if any?

It was primarily done to help clear the left-hand drive steering assembly, and throttle and shift linkages.

 

[Chevy2Bad]

It was primarily done to help clear the left-hand drive steering assembly, and throttle and shift linkages.

Ohhh. I guess I didn't notice the offset when I drug the deuce home. The idiots who had my car prior to me swapped in a 9" and if they did that like the rest of the car, it was half ∂$$ at best, so it might be better to do it this way I dunno.

 

[Chevy2Bad]

Clyde & Sherman? Haven't heard about those guys in years! I remember Clyde was killed in a bar fight down by the plant gate. Sherman did time for armed robbery and mail fraud. Guess he's gone now too...

 

[Chevy2Bad]

Status Update

I have managed to make some progress today, I'm taking a dinner break and hoping it is cooler once I return to my shop.

The car was probably level enough just sitting on the jack-stands, but I took some more time to get it closer to "perfect" with a combination of shims and strategically placed weights.

I have plotted a centerline for the car based upon a measurment from the firewall, and one from basically the taillight area. Seems ok so far.

I have plated the inner-rocker panel with steel to reinforce the area where the front crossmember of the subframe assembly welds.

The plan at this point is to measure the overall axle housing width of the 9" that came with the car, and align the car centerline with the centerline of the axle housing. Aligning these two centerlines will hopefully give me a symmetrical placement for the axle from side to side.

Any legitimate comments and/or thoughts would be appreciated

 

[Vin63]

I normally drop a series of plumb bob points off of the chassis from fixed locations and the corresponding opposite side locations to mark the centerline. Just because I'm sure the car has seen some flex in the chassis over the years. How many jack stands are supporting the car, and where are they located? Since it sounded like you had cut out the rear pan of the car, is the rear valance supported by stand(s), too, so that the rear half of the car is not sagging?

Just an FYI, I located my rearend housing back one inch from stock.

 

[Jim W]

I normally drop a series of plumb bob points off of the chassis from fixed locations and the corresponding opposite side locations to mark the centerline. Just because I'm sure the car has seen some flex in the chassis over the years. How many jack stands are supporting the car, and where are they located? Since it sounded like you had cut out the rear pan of the car, is the rear valance supported by stand(s), too, so that the rear half of the car is not sagging?

Just an FYI, I located my rearend housing back one inch from stock.

Screw the chassis, make the wheels happy. These old cars have chassis holes/measurements all over the place
The 4 wheels of the car don't know or care where the body is above it.
Get the four wheels set square, at the wheel base you want, check tire clearance's and start welding.
Kind of like a tube framed car, the frame is built first and the body goes on after everything is set in place.

Jim

 

[Chevy2Bad]

I normally drop a series of plumb bob points off of the chassis from fixed locations and the corresponding opposite side locations to mark the centerline. Just because I'm sure the car has seen some flex in the chassis over the years. How many jack stands are supporting the car, and where are they located? Since it sounded like you had cut out the rear pan of the car, is the rear valance supported by stand(s), too, so that the rear half of the car is not sagging?

Just an FYI, I located my rearend housing back one inch from stock.

4 jack stands, 1 under each front framerail, and 1 for each side of the rear portion of the rockers. There isn't enough weight in the car for the rear portion to sag, it's pretty well stripped down.

Thanks for the info about setting the axle back. I suspect I will do similar.

At what angle did you set your axle pinion????

 

[Vin63]

I would suggest at least 6 jack stands: a pair under the very front of the car (front subframe and radiator support junction); a pair just behind where the front subframe bolts to the body; and a pair under the body in front of where you made your backhalf cut - just to make sure nothing is sagging or under tension. Also, the unsupported rear sags more than you might think - I always support the rear valance with a pair of tall adjustable (screw-type) stands, as well.

My car's driveline is inline with the crank, so I adjust my rear pinion angle with 4-link adjustments. You'll have to determine your pinion angle according to your driveline dimensions (crank height, etc.). Good luck...sounds like a cool project. Be sure to post photos of your progress.

 

[Chevy2Bad]

I would suggest at least 6 jack stands: a pair under the very front of the car (front subframe and radiator support junction); a pair just behind where the front subframe bolts to the body; and a pair under the body in front of where you made your backhalf cut - just to make sure nothing is sagging or under tension. Also, the unsupported rear sags more than you might think - I always support the rear valance with a pair of tall adjustable (screw-type) stands, as well.

My car's driveline is inline with the crank, so I adjust my rear pinion angle with 4-link adjustments. You'll have to determine your pinion angle according to your driveline dimensions (crank height, etc.). Good luck...sounds like a cool project. Be sure to post photos of your progress.

I have the front subframe already removed from the car. But, the four jackstands are in the places you mentioned; just behind where the front subframe would attach to the unibody, and in front of the backhalf cut, under the rockers. I did experiment with a 5th stand under the rear taillight panel area, but I couldn't get the car to sit level with the 5th stand there. The car has basically every piece removed at this point, trunk lid, doors etc, so it is extremely light and 2 guys could easily pick up the car and move it around.

I copied this image from Real McCoy's Nova backhalf site.

This is basically how mine is currently setup, except with the front subframe removed and the jackstands positioned under the front, right behind where the subframe would bolt in.

I was thinking the four link adjustment would be the way to dial in the desired pinion angle when the time comes, but I figured it couldn't hurt to ask for clarification. I will most gladly post photos, I'll wait until I have something that resembles a Chevy II a little more though, or at least when I get this backhalf all tacked in place.

Thanks for all the replies from everyone, it has been very helpful for a first-time ''backhalver''.

I was wondering, can anybody post some pics of a side shot of the rear axle, I'm trying to get a better visual of what I want my axle to look like as it sits in the wheel-wells.

 

[Chevy2Bad]

Axle too wide

Well I don't know how I didn't notice this sooner. But the Ford 9" which came with the car, is too wide to clear the quarter lips.

What's a fair price to pay for having an axle narrowed? Provided that I supply the axle housing.....

 

[Miller's Garage]

You can run roll bar tubing that will bolt through the tailpan and sit it flat on the ground to support the rear of the car once you have the four main points level too.
I usually brace the door opening from the qtr window area to the kick panel area and the side to side between the qtrs at the qtr window area before cutting the floor out to prevent movement, you don't have to use heavy tubing, I use 5/8 square, the movement is less on a post car, but hardtops will move around with the weight of the roof and qtrs without the floor strength.
I usually mock up the wheels/tires being used in the wheel wells so it looks right in the wheelwell for height, centerered to the opening and width to the qtrs, put a 1/2 round tube throught the center of the wheel side to side, then drop a plumb bob to the floor and that gives you rear end centerline, measure up from the ground to figure out the ride height, measure between for rear end width.

Hope that helps :devil:

 

[jer66nova]

offset

Okay that is interesting, and something I certainly did not know.. What is the reason behind the offset, if any?

Angle of the driveshaft helps prevent binding of u joints some cars do it verticle others do it left to right ,horizontally on my car front cross member of four link is located 27" inches forward of the rear axel to locate axel housing centered back into original location I made reference marks on the garage floor after getting car squared up and level and before cutting any thing off I used s&w race cars frame and 4-link you can look at and print instructions off their website. nphnp:yes::beer1::chev: