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-   -   Project street rod Bronco (http://www.hotrodders.com/forum/project-street-rod-bronco-181896.html)

77bronco_ed 07-30-2010 04:36 PM

Project street rod Bronco
 
Maybe this forum is better suited for my question.

I would like to start a project street rod truck. I would like narrow/tub.

I realize that purchases are unique for each application.
However I have a chance to pick up some parts from a fellow that is not going forward with his project.

I have a spare frame that I would like to do the modifications on, and later transfer the body to. Without having the body prepared to start stuffing tires under and measuring for widths I will need to approach it via measure ments.

I want to see if it is possible to use the rear end that he has narrowed already. He also has the wheels and tires that I would like to use.
At this point I believe with a few quick measurements that the current set up appears to be about 4 inches too wide.

Even if I can't use everything I still would like to pick up many of the parts that he is selling. (- the rear housing?)

I will do this to an old style Bronco... right off the bat the stock frame is straight above the rear axle, I'll need to c channel to allow the truck to sit lower.

To stuff `18 tires I will need to offset this C channel by one inch inboard. I also would like to make sure the wheels are centered in the rear uncut wheel well so I may need to move the axle back around an inch or so...

I would like to mock this up on paper (cad) once all is determined go forward.
Can anyone that has done this chime in... Need to understand the approach others have used.

I also want to convert this to mustang II type suspension in front. For all the modifications the fabrications would be easier without the body to worry about.

It appears that it may be more difficult to attempt this on just a frame. Maybe this is not the best approach? Is it best to have the body unmounted and set back on the frame along the way to be used as a constant reference?

Thanks,

-Ed

77bronco_ed 07-30-2010 04:58 PM

Since posting this the other day I gave it some thought.
I thought that I could begin by putting the vehicle in the garage on stands similar to the anticpated height. Using a square to follow the contour of the inner quarter and lay this out (draw) on the garage floor. I can do this to follow the frame and any other points of reference ie center of axles,etc...

Once I have points of measurement I can easily figure out where the tire needs to be for clearance to the quarter panel. Then measure in the wheel and width of tires and lay this dimensions also on the floor.
Account for the disk brake roters and then I believe I have the appropriate rear end width.

I can mark up all new width dimensions for the frame in addtion to where I want the new Axle center line.

Once finished grab all measurements and put them on paper or in the cad drawing.

This should give me all of the x/y dimensions
I want to keep the inner wheel wheels looking as stock as possible so I believe I can just measure up from the frame to just under the wheel tubs so that the frame will remain under the inner fenders. (I realize that I will have to split and move inboard perhaps they may need to be widened as well.

With all the dimensions I can modify the extra frame to get it set for the body.

Does this sound like a realistic approach or can anyone provide advice that may be easier? I guess I'll need to do some heavy searching to see if there are builds that show how it was done.

Thanks,

-Ed


Perha

start measure back from the inner quarter reference line indicating the dimensions of the wheels

the floor markings I can begin

big gear head 07-30-2010 07:38 PM

The first thing that you need when narrowing a rear end is the car (or truck). The next thing that you need are the wheels and tires. You need to put the wheels and tires under the car and get them into the correct position and measure between the wheel mounting surfaces to get the total width of the rear end. Subtract the thickness of the brake rotors or drums. This is the easiest and most comon way to do this. You can start with the rear end, but you must make some carefull measurements to get the wheels and tires right.

If you want to use these used rear end parts then you will have to get another set of wheels and tires to fit. You might be able to send the axles back to the manufacturer and have them cut down some more and resplined, then narrow the housing again. Be sure to get the pinion offset correct for the car that it will be going in.

77bronco_ed 07-30-2010 09:14 PM

I do have the truck, and the wheels and tires will be here early next week however it will not be as easy as tucking the wheels under the truck to determine the rear end size. Just to get the tires under the truck modifications will need to happen.

The Wheel wells and frame would need to be cut just to get things under the truck.

My goal is to use a spare frame and do all the modifications to the frame. At a later time I would cut and set the body on the completed drive train.

You make an interesting point. "Be sure to get the pinion offset correct for the car that it will be going in."

It sounds like you are saying that just because it is a ford and you are using a ford rear does not necessarily mean that the pinion offest is correct.

Broncos come with Ford 9" however If I went with a used housing that was already narrowed it could be cut with an offset to match another vehicle type correct?

This is definetly something I did not know.


Thanks,


-Ed

Overdriv 07-31-2010 09:57 AM

A couple of tips I can think of is;

Establish your vehicle centerline and axle centerline and make all measurements from that.

After the vehicle is level front to back, side to side, Plumb-bob to the floor and mark, from two like points on the front of vehicle and two like points on the rear of vehicle. Make your centerline on floor from these reference points. Transfer the centerline to the vehicle and mark it.

A common laser found in the lumber yards is a big help when transferring the centerline to the vehicle. Make sure you level the laser!

It is a good idea to drill 1/8" holes in several places along the centerline to permanently locate the centerline for future use.

Find center line of the front spindle, usually the lower ball joint grease jerk is damn close as an example. Plumb-bob this to the floor on both sides. Measure back your intended wheelbase with marks on floor, both sides, measure for squareness with front marks and put your axle centerline on the floor. Transfer this to the vehicle with 1/8" holes in a couple of places if you can.

Now you have your vehicle center line and axle center line. Make all measurements from these lines and keep your world square, you will not go wrong.

If you have wheels and tires coming, how did you arrive at the correct back-spacing for the wheels? If these wheels are with the parts you will be getting, it might be easier to get different wheels with different backspacing rather than shorten the housing/axles, etc.

Overdriv 07-31-2010 10:09 AM

In my opinion it is better to center the pinion with your vehicle, mandatory for drag or hi-performance, but the housing can be centered for better looks in a custom show car type application, etc.

If you will be using a very short drive shaft, better center the pinion.

77bronco_ed 07-31-2010 03:53 PM

Thanks for the measuring and pinion tips...

There is no way that I can use the wheels and tires I want without narrowing the housing. I am going for Pro street type of truck. The wheels/tires combo were selected on appearance and the deal I got.. The rear housing will need to accomodate. 18" wide Sportsman S/R radial and Centerline warrior wheels


As the other fellow said many folks buy the wheels they want and work backwards to figure out the appropriate width for the rear. Same here, only want to do the drive train on a spare frame and transfer the body onto it once the drivetrain is complete. The fellow I am purchasing many parts from has a housing but I will not be able to use it unless I narrowed it further and bought new axles.
So I am not purchasing it... Once parts arrive I can determine the width I need.

In the mean time, I figure I would try to get some advice ;)

Thanks

OneMoreTime 07-31-2010 06:01 PM

it is your choice however if I had in hand a rear already narrowed that was close enough then I would use it..the idea of scribing a center line and center lines of the axles on the garage floor is a good one..i use a plumb bob to line with to the center but then I am an old guy..also measure from suspension mounting point when squaring the chassis as frame rails can be a bit off..

Sam

68NovaSS 07-31-2010 06:44 PM

Browse the Project Journals and Photo Albums, there's lots of information and pictures there.

Here's a link to my Photo Album, I show back-halving an older Nova, for 18.5 tires. Not the same as a Bronco, but gives some ideas for the frame rails.

http://www.hotrodders.com/gallery/sh...00/ppuser/4147

Overdriv 07-31-2010 09:13 PM

Quote:

Originally Posted by 77bronco_ed
Thanks for the measuring and pinion tips...

There is no way that I can use the wheels and tires I want without narrowing the housing. I am going for Pro street type of truck. The wheels/tires combo were selected on appearance and the deal I got.. The rear housing will need to accomodate. 18" wide Sportsman S/R radial and Centerline warrior wheels


As the other fellow said many folks buy the wheels they want and work backwards to figure out the appropriate width for the rear. Same here, only want to do the drive train on a spare frame and transfer the body onto it once the drivetrain is complete. The fellow I am purchasing many parts from has a housing but I will not be able to use it unless I narrowed it further and bought new axles.
So I am not purchasing it... Once parts arrive I can determine the width I need.

In the mean time, I figure I would try to get some advice ;)

Thanks

Well that's cool, but it might not work out depending on the back-spacing of your wheels.

You will have to determine the overall outside measurement, outside tire bulge to outside tire bulge that will fit in the wheel wells where you want them. Then set your mounted tire/wheels that far apart and measure the distance between the wheel centers to determine the overall width of the rear end, axle flange to axle flange, including the brake rotor or drum, etc.

Also you must know what the inside measurement is from inside of the tire bulge. Leave yourself about 2" between the frame rails and each tire bulge. That will tell you how far apart the frame rails can be.

If the back spacing is to much on your wheels, you may not have enough room for the suspension components.

Take your time and think it out. The cheapest, the easiest, and the best route to go are rarely the same.

big gear head 08-01-2010 02:32 PM

The pinion offset on all Chevy car rear ends is 1/2 inch to the right of center. I'm pretty sure that the Bronco has more pinion offset than that. Many people are using the Explorer 8.8 rear end in their projects, which has a lot more pinion offset than 1/2 inch. The drive shaft doesn't line up with the tunnel in the floor. Just check the pinion offset in a stock Bronco rear end and try to keep it the same on the new rear end.

77bronco_ed 08-02-2010 08:59 PM

Quote:

Originally Posted by Overdriv
Well that's cool, but it might not work out depending on the back-spacing of your wheels.

You will have to determine the overall outside measurement, outside tire bulge to outside tire bulge that will fit in the wheel wells where you want them. Then set your mounted tire/wheels that far apart and measure the distance between the wheel centers to determine the overall width of the rear end, axle flange to axle flange, including the brake rotor or drum, etc.

Also you must know what the inside measurement is from inside of the tire bulge. Leave yourself about 2" between the frame rails and each tire bulge. That will tell you how far apart the frame rails can be.

If the back spacing is to much on your wheels, you may not have enough room for the suspension components.

Take your time and think it out. The cheapest, the easiest, and the best route to go are rarely the same.

Outside bulge to outside bulge...I was going to allow .5" of clearance from inner wheel lip per side. Do I need to add anything extra since they will not be under the weight of the vehicle?

2" clearance bulge to frame, that sounds like quite a bit... I was thinking 1" was conservative. Why so much? there should not be any items protruding from frame rail near tires. I'll need to move the frame inboard at least 2.5" per side inboard.

backspacing is 5" on 15 inch wide rims


-Ed

77bronco_ed 08-02-2010 09:03 PM

3 Attachment(s)
Quote:

Originally Posted by big gear head
The pinion offset on all Chevy car rear ends is 1/2 inch to the right of center. I'm pretty sure that the Bronco has more pinion offset than that. Many people are using the Explorer 8.8 rear end in their projects, which has a lot more pinion offset than 1/2 inch. The drive shaft doesn't line up with the tunnel in the floor. Just check the pinion offset in a stock Bronco rear end and try to keep it the same on the new rear end.

OK... I'll keep the pinion offset location to original rear.

I am getting excited, still wrapping up my 4x4 Bronco and already rolling into next project.
74 waiting in line...

Prostreet similar to look I am going for but... I want to chop the top and only have a slight rake.(Keep quarters as original)

77bronco_ed 08-02-2010 09:21 PM

I keep hemming and hawing on the approach.

Do you think that I should reconsider doing this on a spare frame?
Would it be much safer doing the rear while the body is mounted?

-Ed

SSedan64 08-02-2010 10:33 PM

Quote:

Originally Posted by 77bronco_ed
Outside bulge to outside bulge...I was going to allow .5" of clearance from inner wheel lip per side. Do I need to add anything extra since they will not be under the weight of the vehicle?

2" clearance bulge to frame, that sounds like quite a bit... I was thinking 1" was conservative. Why so much? there should not be any items protruding from frame rail near tires. I'll need to move the frame inboard at least 2.5" per side inboard.

backspacing is 5" on 15 inch wide rims

-Ed

The Rear suspension has to articulate also, not just up & down. Think about when you jack up just one side of a car.


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