Ok i need some help! i have broken a few 75mm throttle bodys. I have an good floor stop,.. and I have solid motor ,tranny mounts so there's is no movement in engine bay.My blow off valve is an tial so I got good venting. they seem to last about 10-15 hard passes and break when i shift(let off gas). I talk to a few fast guys and they seem to think it's my floor stop ,but i've even adjusted it to where it not 100% open, ........there' breaking under the booost pressure, but i don't see why, when i have very big blow off valve. I'm lost!!!!!! help

Humm... no problem out of mine so far *knock on wood*. I've heard stories of several people breaking the BBK's, but this is the first I've heard of broken accufab's due to boost pressure. I've made at least 30 hard passes on it and several dyno runs this summer, but I'll watch it closely for any problems.

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I have had the exact same problem, I too would like to hear from others that run mustang TB's. I have broken two accufab 75mm, and have made sure that the linkage was not pulling tight, to the point that the TB was not even opening all the way. They break when I let off the gas to shift, running 30psi.

I've read it...........did'nt see anything about broken throttle bodies. Or do YOU not think this is advanced?

I was refering to your typing and such. I really have no information on the throttle body issue.

How much psi are you running? That would probably be helpfull information.

Does anyone know if the throttle cable can be to blame for the broken shaft?

Can you post a picture of your throttle cable to throttle body connection? You probably need to add a throttle stop on the throttle body, unless you already have one. I seriously doubt boost pressure is causing the throttle butterfly shaft to break.

Well, don't have camera, I'll try to borrow one. I thought that it can't be boost pressure also, but 3 throttle bodies later, with good floor stops+ not opening fully(meaning not hitting throttle body stop) I don't no what else it can be

HighPSI91 (Wes Hess) has gone through 5+ TBs as well. He also had a well setup floor TB stop.

Part of the problem is the floorboard literally flexes. I didn’t believe him when he told me but I did it myself and felt the floor flex underneath my foot. Wes then watched the TB open a good deal more. So what he ended up doing was welding a HUGE plate to be his stop. Even putting my considerable weight on the gas I could not get it to flex.

The other part of the problem is the TB shafts are weak. So even if you go the extra mile they still wont last. Almost every TB out there is made by BBK. Accufab was supposed to be that one company out there that was that much nicer than everyone else. Wes broke his Accufab so bad that he sent pieces into the head. He had a relative of his fab up some super strong tb shaft for his BBK. He also said the Ford racing tb worked out well for him. But Im not sure what he is running now.

Bottom line is if you don’t have an aftermarket TB yet DON’T GET ONE. If you do have one you are going to have a lot of fabrication work to do. These are by no means a bolt on affair.

This is what Accufab said "Something is still not right. It may be the timing of the blowoff valve or some reversion back up the manifold. Here is what causes throttle shafts to break when used on other applications than what it was designed for.
Throttle stop is not adjusted properly.
Cable is not pulling throttle linkage straight.
Blowoff valve is not fast enough or big enough.
Nitrous or other backfire.

That's it. Those are all your options. The ONLY guys that break these are Eagle Talon or Eclipse guys. The shaft is steel already and made to do just what it is doing.

Either way you need to identify what the problem is and fix it. I can rebuild the throttle body. And I can look at it and tell you why it broke. Send it in".
john

Originally posted by Lee'sGSX
That's it. Those are all your options. The ONLY guys that break these are Eagle Talon or Eclipse guys. The shaft is steel already and made to do just what it is doing.

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That letter is Fing classic man. Tell him to figure out the problem and get back to us because he is right we all do break their shafts. At least they will talk to you BBK has god awful tech support.

After seeing what you guys deal with, it looks like I'm sticking with the good ole facshioned 60mm 1G throttle body.

I wonder if 70mm would hold up better?? I'd hate to go back to stock with my 3inch piping and all ,but I can't keep buying throttle bodies and risking my motor like that too!...........I emailed shepherd and he said he has never broken one! But he also runs the 70mm so maybe.............I duno. Thank you guys for the replies.....Lee

Alot of it could have to do with how you have adapted the throttle cable. What you should be doing is setting up the TB on the car, and welding the stock style mitsu throttle pully? from your original throttle body to the new aftermarket one. If you dont have it positioned correctly (i.e. rotated too much in one direction, by just opening the throttle to full throttle you may be flexing the shaft enough to break any Throttle body. What I would reccomend doing is adjusting your throttle cable (where it tensions on the intake manifold) see if that helps. If it was due to the floor flexing, i think you would see this sorta thing happening on more and more stockish vehicles.

Originally posted by Lee'sGSX
I wonder if 70mm would hold up better?? I'd hate to go back to stock with my 3inch piping and all ,but I can't keep buying throttle bodies and risking my motor like that too!...........I emailed shepherd and he said he has never broken one! But he also runs the 70mm so maybe.............I duno. Thank you guys for the replies.....Lee

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Shepard runs the 75 mm mustang throttle body just like I do

It really would help if we could see the installation of your TB. But Acufab is right about contributing factors. You must make sure that your cable is pretty much 100% straight. Another useful thing can be a throttle stop at the throttle body in addition to the stop on the gas pedal.

Bottom line: this is NOT an easy mod…

I am glad that I do not have to worry about that just yet .

Leon
RR

Originally posted by GRNDSM
It really would help if we could see the installation of your TB. But Acufab is right about contributing factors. You must make sure that your cable is pretty much 100% straight. Another useful thing can be a throttle stop at the throttle body in addition to the stop on the gas pedal.

Bottom line: this is NOT an easy mod…

I am glad that I do not have to worry about that just yet .

Leon
RR

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the 75mm accufab unit that I have has a throttle stop built in, so unless you are not using the 75mm mustang one, I cant imagine that youre having a problem with this, maybe you needa mash on the trouble making pedal a little less hard?

Well i changed the spring in blow off valve to a much lighter one and whola! After many,many high boost shifts no more breakage!And it blows off with very little effort now;not like before. By the way it only broke after a shift not while slamming the gas. They make 3 springs for the tial 11psi, 9psi, 7psi, I had the 11. And they are made for differant manifold vaccums. With cams and sheetmetal intake I had very low vaccum, so my tial did'nt open quik enough and after a few hard shifts the butterfly just could'nt take the beating and would break. So if anyone has had the same problem using tial blowoff valve and sure they have the throttle linkage right and good floor stop look into the spring! (forced performance has them) Lee

>By the way it only broke after a shift not while slamming the gas.

This does not make sense... You ether slam the throttle during a shift or you keep it open. If you are keeping it open, there are no forces on the throttle plate/shaft. So you must have been slamming it.

But it was probably a combination of closing/openning the throttle and the force from the boost.

Leon
RR

Originally posted by GRNDSM
>By the way it only broke after a shift not while slamming the gas.

This does not make sense... You ether slam the throttle during a shift or you keep it open. If you are keeping it open, there are no forces on the throttle plate/shaft. So you must have been slamming it.

But it was probably a combination of closing/openning the throttle and the force from the boost.

Leon
RR

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I think what he was getting at is that it was the boost that was breaking the throttle plate, cause his tial wasnt opening easily enough, so he probablly experienced some compressor surge when the throttle plate shut. Down grading the spring however isn't necessarily a bad idea, doesnt really hurt anything, it's still gonna hold boost regardless.

I meant it broke after letting off the gas, not while full throttle. But so far so good I drove it out today gave it a little hell.....everythings still good. I'm a very happy man for now!

Still holding strong Just wanted to keep ya'll posted.

so did you use the 9 psi or the 7psi spring on your tial?
I am having the same problem scared the $h!t out of me.
thanx glad you figured that out.

Are any of you guys running an ISC or using the throttle blade opened a little for the idle? I am in the middle of putting my car together and and trying to figure out what to do about that.