Replacement throttle body butterfly screws and shaft o-rings?
 

I'm planning on having my throttle body ceramic coated along with my UIM and LIM and figured I would fully rebuild it/eliminate unnecessary components while I was at it. The problem I am having is locating new shaft o-rings and screws for the butterfly plates. Any idea of where I can get these parts?

I would recommend against that. The screws have the back threads "mushroomed" to keep the screws from working their way out - you don't want a screw to come loose and go into the engine!

The amount of work and the LARGE amount of potential problems from taking the TB FULLY apart to do this is really not worth the benefit.

See if it can be done without totally taking the TB apart, or just go another route. If you HAVE to do it, you'll want to find a shop that can PROPERLY install new plates and screws. I know RC Engineering did a number of bored out stock throttle bodies a while back, they did a nice job with larger throttle plates and properly installed screws. That might be a reference for you.

Dale

I completely understand the recommendation to not remove the butterflies if you don't have to and would recommend the same thing to most people. However, properly installing a few screws and staking them is nothing new to me, so it really isn't an issue.

Also, I'm not a big fan of ceramic coating or powder coating a part, then baking it in an oven with 20 year old o-rings installed, and then using the part without replacing the o-rings. The only way to do it right is to completely rebuild it at the same time and replace the necessary components.

I could always go about sourcing the o-rings and screws myself, but if the information is available and I could save a little time/effort that would definitely be a plus.

I once looked into countersinking the butterfly mounting shaft and replacing its screws with new ones that mount flush. It's been a back-burner thing for years now but I think I went as far as finding replacement screws with the correct thread pitch and a countersinking tool / bit. Those parts are probably buried somewhere in the garage... will try to find them and post the info.

Good point regarding the mushroomed threads, I wasn't aware of that. Do you think some good threadlocker would hold everything together with some chance of success? I wonder how threadlocker would hold up against the gunk that ends up in contact with intake piping? It seems like the charge pipes get oil on them, and throttle bodies and intake runners appear to have small droplets of fuel or possibly condensed water on them whenever I remove them. People running water/meth injection might want to account for that as well.

I'm interested to hear what you learn about the shaft o-rings... McMaster.com might be a good source.

I've made some headway with respect to the o-rings. I don't want to give out actual dimensions or part numbers until I'm completely sure they are correct and work, but here are some notes.

- All four o-rings used for the throttle body shafts are the same
- The o-rings used are double seal style (aka "quad" o-rings)....see picture below
- From first measurements, it looks like the oem o-rings are a standard o-ring size and readily available

I still need to take some more accurate measurements of the throttle body/shafts and do some o-ring stretch and compression calculations to verify they will work correctly. After I do that I'll post some results.

http://www.marcorubber.com/images/pictures/xring1.gif

That is what lock-tite is for.

While loctite could be used, I think there's a good reason the screws were staked/mushroomed. I think it was the Nissan Sentra SE-R, it had problems with screws working loose and getting sucked into the engine. Considering it's the ONLY fastener in the whole intake tract, it's worth being triple-sure it's not going where it shouldn't be.

Also, I do have to back up my original post by saying that's good advice for an average FD owner, for someone more advanced (which, being a MotoIQ reader and following the project) you're definitely in that category, I think you'll do just fine.

I would try and source new throttle body screws, re-using the original screws would probably be a poor idea. I have a feeling they're a relatively common metric screw.

Good find on the O-rings, I didn't even realize there were O-rings in there, but it makes sense.

Dale

I also don't plan on using loctite as the only method to secure the screws...just isn't a reliable enough method. I'm honestly considering tack welding them together instead of staking it. If I ever want to remove it, it's easier to grind off a tack weld than it is to remove a stake without damaging everything at the same time.

Also, new screws are pretty much mandatory. The factory screws are very soft and deform easily when pulling them out. I would imagine this is to make them easier to mushroom during assembly.

Bit of an aside. Can't remember whether it was the secondary throttle or the TB now, did notice at some stage, Mazda had changed the the fasteners used to retain the throttle plates from cheesehead(?) to countersunk....no idea of the year the switchover happened.

I'd suggest carefully grinding the backside of any of the screws with a tiny burr before any attempt to undo.

Resurrecting an old thread. Does anyone know where I can get a small throttle body butterfly plate screw for my ported throttle body? I had my throttle body ported by RC Engineering last year and was remounting the throttle body and noticed that one of the small countersinked Philips head screws had backed out about a bit. When I tried to delicately screw it in a tiny bit, it was loose and would not tighten. After removing it, it was totally stripped with flattened grooves. Good thing I checked it or my engine was going to eat a screw in a few months. I checked the other screws and they were loose but not stripped. I will use Loctite on all of them when I get a new screw for the stripped one.
Thanks of the help.
Mike

I would just call RC Engineering, let them know what you discovered, and ask that they send you a replacement screw. They should have plenty new and they should send you one for free at the very least.

If possible, loctite the screw AND mushroom the back of the screw where it goes through the shaft.

Dale