halfshafted tb.....?

[1kwik6]

what exactly is done when this is performed? I've heard of, but never actually seen it.





I kinda feel stoopid askin' :tard:

[Flex]

You cut the upper portion of the throttle shaft off flush with the throttle bore. You can also use smaller button head screws to hold the butterfly on that are trimmed flush with the shaft. The leading edge of the butterfly can be knife edged and if you really want to go all out, the lower portion of the shaft can be trimmed. Leave meat around the screw holes though.

The first image is a stock 50 mm.

http://www.mustangmods.com/data/418/Stock.jpg

A modified shaft.

http://www.mustangmods.com/data/418/cutshaft2.jpg

A fully modded TB. Ledge before plate has been blended and bore polished.

http://www.mustangmods.com/data/418/3.8TBpol5.jpg

http://www.mustangmods.com/data/418/3.8TBpol4.jpg

[1kwik6]

What are the gains for something like that? It seems like it would be very minimal.

[Stone]

Nice pics, nice polish, Flex.

Seeing as how the stock 94-98 TB is soo tiny, there are some small gains to be had by doing this. After all its pretty much a free mod, can't beat that :)

[1kwik6]

Well, mine's a 2000. What did you use to cut the shaft?

[lemming104]

How do you get the shaft out of the throttle body? I managed to figure out that, if you unscrew the screws that hold the butterfly in, you can slide the butterfly out, but after that, I'm lost. I'm playing around with a spare 99+ TB at the moment.

[Flex]

Gaston,
Thanks. My skill with the camera leaves something to be desired. Hard to keep them from being a bit blurry. I think I shake the camera bit.

RGR and Mik posted it was something like %10-20 depending on how radically the job. Not huge, but as Gaston said, with a tiny little 50 mm on the early motor, every bit helps. Also, as the TB bore remains the same, velocity does not drop like with a larger TB.

I use a small cut off wheel on a dremel. Before removal, scratch the shaft with an awl where it enters the TB body on each side. Once the two screws are removed, slide the butterfly out slowly. Careful not to gouge the bore. You then unhook the throttle return spring and TPS. You may have to file down the bottom of the shaft where the screws exit as they can distort the shaft there preventing it from sliding out without damaging the bearings.

Now you can mod the shaft. Carful not to go too thin on the bottom or it could fold.

When doing the TB bore, make sure you mark the bore area where the butterfly touches the bore and DO NOT touch that area. If you remove material there, the car will always idle high and eratic. Go slow to avoid a mistake. I use different grits of flapper wheel to slowly take down the lip, finishing with a 320 so it will polish easy.

You can also taper out the mouth to reduce restriction from the transition of the inlet to the TB. The cast factory TB's all have a "ridge" at the mouth. You can feel it if you run your finger over it.

[Flex]

The 99+ are a 60 mm better TB as well.

[062stang]

i dunno if you can or not but can you take some more pics of the before and after shaft pics??

this seems like a pretty cool mod to do just because its FREE :D also is there any other FREE mods that can be done??

-umesh

[Flex]

I have a 99+ V6 60 mm, but it has the wrong linkage on it. The shaft is there though and I can disassemble it and try to do more of a "how" to type shot. Try to run you through the process so to speak. I'll try to get it up for later tonight.

[1kwik6]

I have a 99+ V6 60 mm, but it has the wrong linkage on it. The shaft is there though and I can disassemble it and try to do more of a "how" to type shot. Try to run you through the process so to speak. I'll try to get it up for later tonight.



Thank you..

[Full Tang]

this seems like a pretty cool mod to do just because its FREE :D also is there any other FREE mods that can be done??


Polish the runners of your upper and lower intakes, polish the MAF (don't remove the post, just smoothe down the ridges), build a homemade CAI, remove the trunk mat/insulation, do a test drive on a GT and steal the rear sway bar off of it :D

BTW Flex, DAMN that is shiny! I used 2000 grit (wet) to polish a spare 5.0 TB and it came out well, but not as mirror like as that. What'd you use for the final polishing?

[Flex]

Alright, here is some more.


This first picture is just a 99+ style V6 60 mm TB. The shaft is clearly visible in the bore. That portion is what is going to be removed.

http://www.mustangmods.com/data/418/99TB.jpg



Here is a shot of it open. Looks a lot more restrictive than the modded TB in my first post. The long screws are obvious. They can be replaced with low profile button heads that are trimmed flush with the shaft. You can also see the shallow ridge before the butterfly. It is more pronounced on the 50 mm TB. It can blended into the body for a better transition for smoother flow.

http://www.mustangmods.com/data/418/99TBopen.jpg


Mark the shaft where it enters the TB on each side and also on either side of the butterfly. You can do this with a felt or scratch it with an awl. Do the same where the butterfly touches the bore as it is VERY important that you DO NOT sand into the bore there. If the plate cannot seal the hole, idle will always be high and eratic.

http://www.mustangmods.com/data/418/99TBmark.jpg



Now you will take the TB apart. Mark the plate so that you will remember how it was originally installed. Remove the 2 screws that hold the butterfly in place. Sometimes they are loctited so a little heat may help. Once they are out, hold the throttle open pull the plate out. Remove the TPS. The underside of the shaft will most likely need to be filed a bit where the screws came out as the threads pull out a bit and prevent the shaft from easily coming out. Once this is done, grab it by the linkage arm and pull it out. The spring and its rubber pad should come with it. Once it is free from the TB, gently remove the two o-rings so they will not be damaged. Your marks should be visible. Using a cutoff wheel in a dremel, cut through the UPPER part of the shaft. Not the threaded lower or you just made a fishing weight.

http://www.mustangmods.com/data/418/99TBcut.jpg

The lower portion of the shaft can be thinned as well for an extremely radical halfshaft. Do not go too thin and leave meat around the threads. Carefull as it will now bend easy. Once you are done, screw your plate to the shaft and mark the threads to where they need to be trimmed flush. The leading edge of the butterfly can be knife edged as well. DO NOT make it a razor sharp point as it will make it weak and prone to fracture. Leave a small flat lip.



The TB bore can be blended in as I said before. I use various grits of flapper wheel to take the ridges out from 80 up to 320 to leave only fine scratches behind. The 99+ Housing is thinner at the mouth but both can be tapered out to reduce the ledge between the inlet and the TB.

http://www.mustangmods.com/data/418/94-99.jpg

The thick mouth of the 94 style TB is obvious and makes for a fair obstruction to the air path


As a final step, I polish the bore and butterfly plate. I work an aluminum oxide paste into a course sewn buffer pad that is attached to a special arbor for dremels. It makes for a pretty mirror finish. If you want to go super radical, you could go through a finer paste as well like jeweler's rouge.


http://www.mustangmods.com/data/418/Buff.jpg


Make sure to clean away any excess paste that may have gotten into some of the passages. I find brake clean work well for this. The TB can now be reassembled. Make sure to place the butterfly in correctly and use some loctite an its attaching screws. Assemble the plate in the fully closed postion (adjuster screw backed out) to prevent a mismatch.

[062stang]

when doing this is there a SOTP gain in this mod by any chance, and how long does this take for say someone who knows alot about cars but has never done this type of mod?

-umesh

[mikael]

http://rpm-mustangs.com/porting/images/tbs-94halfshaftvs70mm.jpg

http://rpm-mustangs.com/porting/images/tbs-94halfshaft.jpg

There are a couple more pics. I countersink the screws so they don't
protrude at all. I hadn't really cleaned it up at that point. I use a carbide
to cut down and angle that ridge, then a cartridge roll throughout (except
the area where the blade touches) then a fine flapwheel throughout,
including where the blade touches but only enough to remove the glaze.
The worst part about the job is removing the screws for the blade and
for the TPS. They are quite often pretty firmly in there.

Edit: also I grab the protruding part of the screws from the backside
before disassembling with vise grips and twist to snap them off. That way
when you pull the screws out they don't tear up the threads.

[062stang]

http://rpm-mustangs.com/porting/images/tbs-94halfshaftvs70mm.jpg

http://rpm-mustangs.com/porting/images/tbs-94halfshaft.jpg

There are a couple more pics. I countersink the screws so they don't
protrude at all. I hadn't really cleaned it up at that point. I use a carbide
to cut down and angle that ridge, then a cartridge roll throughout (except
the area where the blade touches) then a fine flapwheel throughout,
including where the blade touches but only enough to remove the glaze.
The worst part about the job is removing the screws for the blade and
for the TPS. They are quite often pretty firmly in there.

Edit: also I grab the protruding part of the screws from the backside
before disassembling with vise grips and twist to snap them off. That way
when you pull the screws out they don't tear up the threads.

is there a SOTP gain to half shafting a TB

-umesh

[Flex]

I noticed it a lot top end on my 50 mm singleport.

[062stang]

hmm, then i will have to try this free mod when i install the intake spacer, along with a mild port and polish of the upper and lower intake.

-umesh

[Flex]

As mentioned, it is free, so why not. If you are capable of doing it then why not. Just go slow and be careful.

[RGR]

Nice polish Flex

But I have to say, for most DIY'ers the time invested
will far exceed the gain over a satin finish. Maybe a 1-2 CFM difference
(if my exhaust port flow testing is any indication...)

I countersink the screws too, use flatheads.
ALSO: Use loc-tite and I peen the back of the screws
to prevent fall-out and engine failure :)

[Flex]

Quick question for you Rob. Someone recently told me that our stock singleports heads max out for airflow at the factory .424 lift. You have done plenty of flow testing. What is your opinion?

[RGR]

not true.

Intake flows over .500 unported and exhaust
tops out around .500 unported.
both increase w/porting

[Flex]

Thanks. I have seen flow data on this site and others that showed that and just wanted confirmation. I guess someone is just posting bullshit data for god knows what reason.

[matthewneuharth]

i know its been said before. but don't forget that my DIY TB flowed 430cfm@25 inches of water. if it would have been @28inches it would have flowed more. and also that was before i finished the TB. i did more to it after i flowed it and then never went and got it flowed again.

[Flex]

What is a DYI TB?

[matthewneuharth]

What is a DYI TB?

a DIY TB is a do it yourself. i took the stock 95 TB and halfshafted and ported it. it flow 430cfm@25inches of water. more than a 3.8l can use.

[cgrant26]

Good tech stuff here. This should go to the tech write-up area.

[Flex]

I guess that it would depend on the 3.8.

[matthewneuharth]

I guess that it would depend on the 3.8.

well a N/A one will never need that much. and a forced induction car will be forcing it. so thats were the extra air woudl come from.

[Flex]

I have seen a few claim (including SSM) that the 50 mm TB is the biggest hindrance to singleport performance. If you think about it, a 2.3 had a 50 mm TB. Several people who have gone to a 5.0 style 60, claim a noticeable performance gain in a worked singleport.

[RGR]

455 CFM @ 28" water is what it would be.
ANd it was his first attempt :)

[Flex]

Is that with the factory butterfly?

[matthewneuharth]

well i have considered putting on a 60mm tb. since i work at a mustang shop. they are free. hell we got like a million of the stock ones laying around. i even ported the upper intake tb hole to 60mm. so that if i do put on a 60mm. it will fit right. so one day i might just slap on one and strap the car down on the dyno at work and see if its a gain or not.a nd they would be back to back pulls so there would not be any difference in weather or other crap. also think of it this way. if you had a carbed 3.8l. would you put on a carb that was 600cfm if you did not need it. or would you go with the smaller carb for better booster signals?? i know carbs are different from fuel injection. so i am not comparing the two. but look at the dyno #s that i have gotten out of a stock tb. so i would say that its flowing enough air for my car no problem. and i don't see SSM's cars making much more power than i am with the bigger tb. and yes my tb has the stock butterfly in it. i did not bore the tb and put in a bigger butterfly.

[RGR]

IMO a "too big" TB will only show gains at high RPM
as most bigger TB's do even if needed. The BBK is
only a 56mm which is either cuz they wanted it
to match a maxxed-out crossover tube size
or 56mm is what a hot 3.8 wants... probably
the former reason.

[cgrant26]

well i have considered putting on a 60mm tb. since i work at a mustang shop. they are free. hell we got like a million of the stock ones laying around. i even ported the upper intake tb hole to 60mm. so that if i do put on a 60mm. it will fit right. so one day i might just slap on one and strap the car down on the dyno at work and see if its a gain or not.a nd they would be back to back pulls so there would not be any difference in weather or other crap. also think of it this way. if you had a carbed 3.8l. would you put on a carb that was 600cfm if you did not need it. or would you go with the smaller carb for better booster signals?? i know carbs are different from fuel injection. so i am not comparing the two. but look at the dyno #s that i have gotten out of a stock tb. so i would say that its flowing enough air for my car no problem. and i don't see SSM's cars making much more power than i am with the bigger tb. and yes my tb has the stock butterfly in it. i did not bore the tb and put in a bigger butterfly.

Any chance of getting one of those free TB's from you? Let me know what it's worth to ya. :deal: :D

[Flex]

cgrant26
Those TB's still need an adapter plate and the linkage modified to work on the 3.8 upper.

[cgrant26]

I was actually just looking for something to practice on. I most likely wouldn't be considering fitting to my engine. Also, just out of curiosity, are the 94-98 TB shafts the same diameter/length as the 99-up ones?

[Flex]

The shaft diemeter may be the same, but the bore is 50 mm on the 94-98 while 60 mm in 99+ so it would not be the same. The housing on the 99+ is way thinner and better set up as well.

[matthewneuharth]

TTT

[V6tooslow]

what exactly is done when this is performed? I've heard of, but never actually seen it.

I kinda feel stoopid askin' :tard:

I did it few weeks ago. It took only 20 min. I didn't notice any gain though.

[Natedog]

What year is your car?? I did it to my 98 and I noticed it up top, almost as much as or more than my CAI. So it isn't huge but definately significant enough to feel a difference. I have heard for the 99+ it is not really a noticable gain since they start with a bigger TB anyways.

[V6tooslow]

2000 V6