New guy with some chassis questions

[Hairball II]

Hi guys I just picked up a pretty rough 76 vega hatchback for $400. A guy who I work with and myself are going to bust out the plasma cutter and welder pretty quick here to start making room for a 4 link and 2x3 rails. I was wondering what width rear you guys are running in your tubbed cars. I have a 12 bolt as well as a 9" that I can use. I talked to a guy at the track yesterday and asked him a few things about his car. I really liked the stance and look of the car he said the rear was 42" backing plate to backing plate and He was running 29.5x11.5x15 slicks in the back. The only problem was I forgot to ask him the backspacing and rim width. Anyways I was wondering if you guys had any advice before I get started n this project.

Kevin

[Topgun]

My advise is to get the wheels and tires your gonna use then figure out where you need the rails in accordance to that.

[Hairball II]

Sounds good. I actually just found a 42.5" 12 bolt rear. How do I determine what back space rear wheels I need to get?

[Topgun]

Well, you still need to determine the size of tire your gonna run.

[Hairball II]

Probably 29.5x12x15

[greg72]

As Topgun said , before you start narrowing the rearend or buliding the rear frame you should first decide on the tires and the rims.

Once you HAVE the tires mounted on your rims, cut out the stock rear suspension and floor, etc. Place the mounted tires in under the car and then begin to carefully take all of your measurements. this is a real good time to remember and pay homage to the saying " measure twice , cut once" !

As far as back spacing, in a case like this where you are building the rearend , frame, etc to work with the rims you bought (see first paragraph) , I prefer to have the center of the rims almost perfectly centered. i.e. 6.5" Backspacing on a 14" wide rim. I feel that this allows for a longer bearing life, as opposed to having too little backspacing with a lot of weight hanging off the end of the axle. But this last part is just my opinion.


Here is a link to my cardomian site , page 6. it shows some of what I am talking about.
http://www.cardomain.com/ride/2171469/6

Or you could get a pre-made kit like this one:
http://artmorrison.com/layout.php?y=rea ... r/&x=index

Then after that is done measure what you need for tires and rims to fit the car.

[Hairball II]

Nice car greg! Just wondering, do you know what width your rear is backing plate to backing plate? And your rim size and back spacing?

Thanks, Kevin
P.S. did you find a 6-71 yet?

[greg72]

sorry Kevin i just say your post today.

I don't recall what the dimensions of the rear end are. It was narrowed back in 1989!

Unfortunately the car is tucked away in my garage and i won't be able to get to it for a little while.

I will check tonight for the receipt for the rear wheels....it should have the Centerline part number on it ...from that i will be able to determine the backspacing.

And yeah for some ridiculous reason i have saved the receipts....however I have stopped adding them up!

[greg72]

Kevin, the wheels are 15x15 with 7 1/4" back spacing.

and no I haven't gotten my 6-71 yet (well I actually had one a while ago but sold it because I wasn't ready to use it yet )

[chevyart]

you should just listen to what the guys are telling you to do and not worry about what the other guy has. every car can be different , depending on where you put the frame rails on the inside and where your inner rear quarter wheel wells are. those are the 2 major clearing points. cut out the stock floors and wheel tubs and any other sheet metal in the way and then get your rims and tires ( maybe even borrow a set close to the size you think you need and put them into the area where they are going and then start measuring for height and sise to side clearance. it it best(if possible) to use an equal backspace as it takes away unnecessary strain on the azles where the shaft meets the round hub. too much backspace is hard on this exact point and alot of time this causes axles to shap right there, almost for sure if they are not aftermarket. just to let you know . my 67 nova is completely tubbed out with 14 inch slicks and i have ample space on the inside by framerail and outside by wheel well opening on quarter, and it just happens to give me an axle flange side to side distance of exactly 43 inches, but i didnt pick that size, it just came out to that by doing the job the way the other guys and myself just explained. i will bet that the 43 inch 12 bolt rear will work in your size car (vega) , using about a 111 to 12 inch slick and a rim with equal backspace, if you want, and you should, you can get ford type axle ends(bolt on type with no c clips and get the safety axles, and if necessary have it slightly narrowed at the same time)( they have to cut to put on new ends) good luck chevy art