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Author Topic:   I need help putting a 9" under a metric !
posted January 31, 2002 07:54 AM
I need to know the pinion angle, in my mind I was thinking 6 degrees.

This is how I was gonna set the rear-end.
1. Get the correct tire & rim bolted up the 9" then roll it under the car.

2. Set the rear of the car on jacks to the correct ride height.

3. Set the pinion angle and weld the trailing arm brackets.

Is this any where close? I'm lost for the most part.

posted January 31, 2002 12:54 PM
Hughes, While perhaps not impossible,it will be very difficult to set up your 9in. under the car. If you don't get it right,it will induce all kinds of chassis problems. You really need to jig it to do it properly. Here's some pointers that may help. First, before you remove the stock rear end,install the racing springs that you intend to run..............(There will be a difference in tube diameters between the two rear ends.Make a shim 1/2 of this difference.) Place this shim in or under the spring bucket/perch that you intend to use.......OK,with your spring,spring bucket/perch and shim installed,set your ride height. At this point,check and record your existing pinion angle.Next,remove your stock rear end. ON a steel table make some stands that will fit the tube diameter of the 9 in. Place the 9 in. on the stands and measure up from the table to the center of the axle.Remove the 9 in. from the stands and place the 10 bolt in the stands....Between the stands and the axle tubes,place some shims to get the 10 bolt axle center line to the same measurement you had with the 9 in.......(all we're doing here is making allowances for the different tube diameters)...............Ok,with this done,set the pinion angle on the 10 bolt at the same degree you recorded while it was in the car. Now you can jig the mounting points on the rear end. The lower ones are easy,the upper ones more difficult.There really is no "stock location" mounting of a 9 in. in a metric as the "stock location" of the upper arms is so close to the top of the 9 in. ,that you have to raise the mounting points in order to attach the arms.............So,your upper jig must be made in such a manner that it can be bolted to the 10 bolt and then raised up for the 9 in. while traveling in the same arc as the trailling arms travel. (at least for the first time,after you know where they go,you can jig your jig and make a new one that is solid and bolted to the table) Before you take the 10 bolt out of the jig,mark the lateral location on the table of the center of the pinion,and the ends of the axle flanges. Remove the 10 bolt from the jig and put the 9 in on it. You will notice that the pinion of the 10 bolt is offset about 1 in. and the 9 in will have a greater offset.The first thing you must do is determine the desired lateral location of the pinion. Ideally,you would like your yoke to be in the stock position laterally,but that may not be possible due to the different offsets. After determining lateral location,set your pinion angle. To do this,refer to your eariler recorded pinion angle,subtract this number from your desired pinion angle and set to this new number. Example; If your eariler recorded pinion angle was plumb,and you want you angle to be 6 degrees,set it to 6 degrees. If your earlier recorded number was 2 degrees set your angle to 4 degrees.This will give you 6 degrees once you install the rear end in the car. After setting pinion angle,install your mounting brackets to jig fixtures and weld to the housing. Many guys cut the lowers off the 10 bolt and install them on the 9 in.,which is a pretty easy deal. This is about as close as you can get to stock location mounting. There are improvements over this that can be made,but you would have to make a scale drawing of your car to determine anti-squat characteristics and adjust from there. If making the jig would be infeasible,I think you would be better off to hire this job out to someone with the equipment to do it,as it will be very difficult to do under your car. Hope this helps...........

posted January 31, 2002 04:28 PM
doesn't speedway offer a 9 in housing with all the mounts already on it?

posted January 31, 2002 04:54 PM
Thanks snowman, sounds pretty rough, I might consider my options

posted January 31, 2002 05:39 PM
Rocco,you may be right about speedway,I don't know. Most race shops have a jig,I bet you can have one done locally. I am certain there are speed shops on this fourm that supply them. Also, any fabricators here could easily do it. Awkwardjeff and Owlracer immediatly come to mind......... Hughes, It's not really that hard,one step at a time. It's just hard for a (brain dead) person like me to explain it. You really do need to make the jig though. Very difficult to do under the car............If I can help any further,let me know..........

posted January 31, 2002 06:43 PM
Hughes go to And checkout the housings they have. (REAL GOOD PRICE)

posted February 01, 2002 05:00 PM
Where are you guys buying the brackets? I hate to have to cut off the 10-bolt brackets and re-weld them to the 9" rear... Somebody has got to make weld-on brackets for this conversion as it seems really popular.

posted February 01, 2002 06:28 PM
coleman make upper lower bracket

posted February 01, 2002 10:39 PM
when mounting housing under car do you line the rrtire up with rf tire and stick the lr out?

posted February 03, 2002 08:45 AM
How about using clamp on brackets on tne lowers turn to get right angle clamp and then tack. Can change angle with out cuting the brackets off.

posted February 03, 2002 04:55 PM
I always try to line up the pinion w/ the tailshaft of the tranny, the rest can be done with offset wheels.

posted February 05, 2002 01:08 AM
In the Modifided tech fourm,under the subject Rear Trailing Arms,AwkwardJeff (resident genius,for the benefit of the new comers) discusses this topic further. He describes a simple jig and some more optimum pick-up points.I encourage anyone considering building a housing to view this information.

Concerning the lower mounts; using the stock mounts or the aftermarket mounts is the easist thing to do,But not the best. I use 2 1/2 wide, 3/16 thick strap. By making you own,you can gain more foward bite over what the stock mounts can provide......For the top mounts,I use 2in.wide, 1/8 thick strap and some 1/2 id tap tube for the bolts to go through,and 1/2 bolts.

MalibuChevy2 In general,I would say that yes,You are better off to have your right side lined up and any extra out the left side.But, lets look at your options. Ford made many different rear ends with many different widths and offsets.That is to say,the pinion is not centered between the axle flanges.How much depends on which one you have.

For example,if you keep your 9in yoke in the same lateral position as your 10 bolt yoke,your right side tire may not clear the frame.If that is the case your options are; get a different rear end,move the housing to the right,or use a different offset wheel. There are drawbacks to all these options....... Buying another rear end cost money,but finding one that would fit in the car and keep the yolks in the same lateral position while not being too wide would be best,probably not alot of those around........Moving the rear end to the right could cause driveshaft problems,Best to avoid this........Different offset wheel would not be bad in and of itself,but then you have to have more wheels and you could end up switching tires from rim to rim to get stagger.

Ok,I know your concern is the performance aspect of your tires placement,(as well it should be)But the right tire being in the "right" place won't make much difference if you can't keep a driveshaft under the car....................

My advice, keep the yoke in the same lateral position. Measure the rear ends to see what you have to do,consider your options,and go from there.

[This message has been edited by snowman (edited February 07, 2002).]

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