Here is a pic of a home built 9 inch I did. I tried to take as many pics as possible etc and was thinking of maybe doing a how to, give axle dimensions and everything. I will be finishing the thing this weekend and installing it in the car. I have already test fit it without the tourque arm and the thing bolted up like stock.

Anyone wanna see more?

Oh yeah and I did have alot of time into this thing, alot of figuring out etc. However this one is for the g/fs camaro and the next one is for mine so the 2nd one should be easier.

 

Your torque arm mount won't be strong enough. Those 3/8" bolts won't handle the torque.

 

i have to agree with the above. After all if it was that easy then everyone would have one, and currie would be out of business.

 

I kinda expected the above response. The torque arm mount is coming off of 4 bolts. Furthermore this is going on a car with a stock motor with the rear blown mine will be different. I figured I would try it and if the studs rip out I will build one like mosiers setup a setup like that is easy enough to build and there is lots of room under there. My biggest problem is I am in a hurry to get this car outta the garage its in.

Also the tensile streght of a grade 5 bolt/stud 3/8s thick is about 9500 lbs from the info I can find.

Considering the max power that the stock motor will put out I'm thinking it should be adaquate. Anything done up I don't think it will hold.

I did run the numbers on it and yes the 3/8s studs are cutting it close but considering how much I have the mount spread out and the fact that Its coming off 4 studs It should be ok for a stock motor.

Worst case I try and break the thing on the test drive and I do. So I build something different.

Anymore input would be appreciated.

Oh yeah and it really wasn't all that easy doing the figuring building the jig etc.

Like I said if I was only building one it would be more work than it was worth. It might still be but I enjoyed doing it and the challenge of trying to figure the setup out.

 

I've seen 9-bolt mounts that are essentially a big ring, that slips over a 9 bolts, as a mounting point.

Do it that way & there would be enough strength. If needed, drill out the housing & put Grade 8s or even thicker (1/2"?) in there

 

Maybe post some more pics, because whats here doesnt really show much of anything, its really an interesting idea and one that i've wondered about before, so i really want to know how it goes.

 

where are you located crazycrocket?

tensile strength isn't the issue, shear strength here is. I can't tell how it's mounted based on that one pic. got any close up pics?
3/8" bolts should be plenty, with 4 of them at least. I want to see how it's done up though.

 

why on earth are you using a grd 5 bolt/stud? there is no reason for no using a grade 8 or better especially in this application.

Like stated, tensile in the stretching of the bolt, shear is the side to side strength. Again, grd5 is not a good idea.

Stock motor or not, i dont think the arm will be strong enough,

 

I'm not saying that it will or will not hold up. The thing is that if it doesn't then you might not survive the crash to make another one. If it breaks then the rear end can roll under the car and the results might be very bad.

Did you also make a bracket that mounts it to the pinion housing? If you had it on the studs and also on the pinion housing then it would be quite a bit stronger.

 

Well I've been thinking about this all day. Glad to see more input.

I ran the numbers again while at was at school lol I probably shoulda been paying attention in thermodynamics rather than doing car stuff but anyhow.

I think considering the above points I may redsign the torque arm.

Here is my reasoning

1. The studs will hold up in tension in shear, however since its hard to know how much of each it will have (its a sheer and tensile application) its hard to get a proper number on the safety factor. All I can do is guess and on suspension parts thats not the greatest.

2. I do have a concern about the rigidity of the pinion support where I am using two bolts and also the fact that the bolts could stretch potentially allowing more movement in the pumpkin/pinion support than I want.
This could pile up the rear end

3. I do not know if the sheet metal will hold up the to the load. I mean if the studs hold up that force is transferred to the sheet metal

4. What if the g/f wants a bigger engine in the car

5. I'm putting a 434 thats going to make around 450-500 ftlbs of torque in my car so I have to do ti different anyway

6. most of the time I spent on this torque arm mount is getting the postioning right so that the pinion angle isn't way outta wack and so the torque arm will bolt up.

For the simplicity of it I am thinking of maybe going to a moser style setup. I have 2 days this weekend to get it done. I am hoping I can buy some pipe and a tap that is sufficiant. I will then cut a pattern out of some 1/2 inch or 3/8s steel plate I got laying around.

I do thank everyone for the input constructive critisism is always appreciated even if sometimes I seem defensive (we all have times where we don't nessicarily want to accept the reality of having to change some work)

Hopefully after the weekend I can give you guys some more pictures and go through how I got the housing ends on straight etc. (I didn't use a jig and if I could do it again for the 80 bucks in metal I would, however the people I do know who have lathes did not seem willing to help me out, so I used a laser and it took about 4 hours to get lined up straight and tacked, then another 2 to get it square)

Anyone else with more comments are welcome to let me know what you think.

 

It would have been easier and safer to install another third gen diff.

Looking at that mount, I can see all kinds of problems. As mentioned above, the shear forces on those 3/8 bolts will probably break the bolts in no time. If it was that easy to install a torque arm, there would be lots of threads saying that's how you can install a 9" under a third gen.

Also mounted to the pinion support, the torque force of the torque arm from acceleration and deceleration will distort the case and probably take out the pinion bearings if the bolts don't break first.

If the engine is stock and you don't think it will produce enough power to worry about it, why go through all the trouble and overkill to install a 9"? Even with a 434, a 10 bolt can withstand more power than most people will admit. I abused one into the low 11 second range with a BBC without it breaking.

Personally, I wouldn't trust driving on the street with a torque arm mounted like that.

 

Under load only two of those bolts are going to be under tension.

 

Umm guys? You didnt' read my very last post.

As far as a 10 bolt lasting. With a 434 seriously man why would I bother? This rear end that I'm replacing blew with a stock motor. So why continue using something that is proven to break by many people. That would be like keeping my t-5 because some guys have luck and get one that doesn't break.

I can't believe I have to justify myself around here for building something that obviously very few people on this board have the will or the ability/tools to do.


So as said I'm going to slightly change the design. All the work has been done to get the thing to line up with the correct pinion angle etc so its not going to be hard to convert.

 

here is link to pictures of a moser axle with it's bracket.

https://www.thirdgen.org/forums/orga...hlight=moser+9

you can weld up your own to look like this......you seem to have enough fabrication skills.

realistically, those bolts aren't ever really in shear, just tension. 4 3/8" grade 8's might be fine, just under worse case scenarios, you might have trouble......

I think you'd have to have some serious HP to deflect anything in the casting. If that was the case, any rear axle with anything hanging off the nose, like any rear in these cars, would have serious pinion bearing issues....if you can say anything about ford rears, they are beefy, even the 'crappy' 9" ones...

remember, in a stock suspension, one 2 bolts push the car around.....the two in the lower control arms.....connected to 4 flimsy pieces of sheetmetal

 

Umm I dunno if this is possible but maybe you should weld the torque arm to the removable piece of the 9 inch. I guarantee those those little bolts cant hold the torque arm. I you want it to bolt on you should look for a way for it to mount to all of the bolts around the housing.

 

[quote=crazycrocket;3912881]
I can't believe I have to justify myself around here for building something that obviously very few people on this board have the will or the ability/tools to do.
quote]

Above all else we are trying to look out for your saftey. This bracket of your may work just fine, but if it doesnt, and breakes, you will have a real problem on your hands.

 

I got no problems with that. Like I said I'm open to suggestion.

Just get frustrated with the negativity on this board at times it seems like there are no points for trying.

Also as mentioned about the grade 8 bolts from all specs on grade 8 bolts they are only something like 12 to 15% stronger. Thats not much.

Believe me I am looking into this seriously. I did have my reservations about diong it this way but someone who was older and more experiance in fabrication was and is telling me its fine. Apparently I'm building a mountain out of a mole hill. However I do take this seriously which is why I am changing my design.

I've got er figured how I'm going to do a mosier style mount now without having to find thick enough walled tubing to tap or having to machine tubes as it looks like they have done, or having to find the thread inserts.

I'm thinking of getting some 3/4 inch bolts (with 3/4 inch shank), cutting the heads off em, inserting them into a 3/4 inch ID tube and welding them in the tube at one end and through a a few holes in the side. Then installing the 3 tubes like the mosier setup. Only rather than having holes that bolts run into I will have studs that the mount slides onto and then nuts hold on tight. If trimmed to the right length it should be just as clean of a setup.

I do see a few downsides to this.

1. being its harder to remove the mount, I'm hoping to avoid this by not blocking off the oil fill hole in the side of the diff
2. The threads are likely to be stripped in removing the mount and installing if one is rammy


There is however an advantage
I can use a lock washer or jam nut to keep this all together

Also the 3/4 inch shank should allow me to get a very tight fit on the torque arm mount.

If anyone sees any other potential problems with this let me know.

 

There's negativity because you wanted opinions and we told you what you are doing isn't safe. If I or anyone else tells you what you're trying to do will work fine and it fails, we're legally or morally responsible for the results.

I'll offer opinions or suggestions to things people want to do but it's still your choice to make if it will work or not.

You could have asked if driving around with 1 or 2 wheels nuts would work to hold the wheel on. Simple answer, yes. Common sense answer, no. Your mount will work fine if you're granny driving around but any sort of hard acceleration or hard stopping could break the small mounting bolts at any time. There's a lot more stresses on the suspension than you're aware of.

If making a mount like that was so simple, companies like Moser would have offered a conversion similar to it. The Moser mount is made of 1/2" plate steel and is attached to the diff with 3 large bolts. I'm guessing 3/4" but they may be 5/8".

 

And what do you think about new proposed idea? Is it going to work horribly because there are studs rather than tapped holes or is it going to pass?

 

its actually cast steel/iron, and its a beefy piece. Bolts are at least 3/4, fine thread.

crazycrocket, If you were to make a mount, like mosers, using the bolt studs rather than threaded tubes, it would go together fine, so long as the studs dont interfear with the torque arm. Also, when you weld a hardend bolt, it looses a lot its strength.

15% difference in strength from grd5 to grd 8 IS significant, we are not talking peanuts here.

Im pretty sure you can buy short pieces of think wall tubing pre-threaded from various preformance places, southwest speed, coleman, probably even mcmaster-carr.

 

i have been thinking of doing this as well. has anyone here ever tried the currie bracket? http://www.currieenterprises.com/ces...E.aspx?id=1595pretty logical to me. is this still not beefy enough for a higher horsepower application?

link fixed.

 

Fix the link but yes, that is the better way to mount it. Currie lists it as using two 5/8" bolts not 3/4" as I previously thought. That's the same mount they use on their bolt in third gen diff. The only weak link with that mount is your welding ability to weld the tubes to the 9" housing. I'd recommend a 220V MIG or stick welder.

I wasn't aware Currie still offered the bracket. I thought they stopped selling them separately a few years ago.

 

Ok I got 3, 3/4 inch grade 8 bolts today and some steel tubing that is relatively tight. I am going to see if maybe I can get away with grinding one side of the bolt head so that it slips in and out of the tube but won't turn when i tighten the nut on it. Otherwise I will have to weld on it a bit however I'm thinking since I only nee 5/8s and I got 3/4 all should be super strong now.

All I gotta do is get home this weekend and adapt the mount that I have to go off the tubes and the 3/4 inch bolts. Slap some paint on everything to make it look purdy, take some pics and throw it in the car.really the worst part will be converting my current mount but I got lots of metal for that.

 

I really do not think people here have the lack of tools or skills or even possibly knowledge!
It becomes more of a safety issue. we have had TQ arms break before from major build companies it is called fatique....
I commend you for your will to make a TQ arm mount in your own shop but stronger parts should be in your build. Since you have access to material you should make a TQ arm to compliment your mount,the factory TQ arms are wayyy too flimsy..

here is the best of the best
http://www.madmanandcoracing.com/

 

looks sweet! good job on the diy