When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I have the typical throttle body shaft that with a lot of slop that sticks and binds. Well after very little info on the web, just one good write up here (thread : "Throttle Body Triage") I decided I would get my TB fixed. I bought a bushing kit from "Carb Junkys" off Ebay, 3/8 shaft kit.
Before I started
Grind the back side of the plate screws so they will come out. GM peened these so they wont come out. Torx T9 worked for me. Some say it's a T8 but a T9 fit tighter and worked great.
Grind off the end of the shaft where GM peened as well
Linkage plate off. The spring assembly comes apart but don't worry as it only goes back together 1 way.
cap comes off (PITA) then the nut comes off the shaft and it then pulls right out
A little cleaning
Reverse cut reamer slides in and stays on center because it uses all the shaft journals to keep it straight.
Reverse cut in the drill. A little tape to mark the depth you need
Drop in the new bushing and tap it in to get it fully seated
Bushing in and the shaft test fit. Zero wobble and smooth operation. Here I realized I had not cut deep enough for the new bushing as the shaft nut caused bind. I had to remove and cut a bit more, 1 wasted bushing.
Back together and shaft operates like new. I test fit the spring assembly and linkage. Need to decide if I'm going to drill & tap, JB Weld, or get it spot TIG welded back on.
So far a straightforward job, learning a few tricks that if I ever do another will make the job easier.
I will finish the job this weekend (hopefully) and post more pics. I won't be able to give a final update as I have the motor apart for a cam swap so it final assessment will have to wait for a bit.
Time for a Crown and Diet!
So far about $40 bucks for the tool and 8 bushings.
Pretty damn complete "how I did it" - it certainly looks as if it will pass the test. I'll pass on a suggestion for the lever retention. The drill/tap sounds good but then again you likely won't need to revisit so why ........
Pretty damn complete "how I did it" - it certainly looks as if it will pass the test. I'll pass on a suggestion for the lever retention. The drill/tap sounds good but then again you likely won't need to revisit so why ........
Maybe a "coin-toss".
I'm leaning to the drill & tap. Need to run to the H-Store in the morning and see if they carry a small bit and tap set.
Back together and shaft operates like new. I test fit the spring assembly and linkage. Need to decide if I'm going to drill & tap, JB Weld, or get it spot TIG welded back on.
here's a suggestion, or maybe some food for thought - drill a #26 (.147") hole down through the shaft about .3125" deep, and secure the lever arm with a .147" diameter rivet. since you'll have a press, friction, or an interference fit, you'll need to tap or press the rivet in place. I have done something very similar when restoring/rebuilding quadrajets.
"JoeC" mentioned Q-jet and brought back some recollection of a one-time fix, these steel "drive-rivets" but depending upon shaft composition maybe creativity should be limited. An Epoxy on the ID of the lever and maybe a drive rivet to finish and secure. Much might depend on the dimension of the head required for retention.
"JoeC" mentioned Q-jet and brought back some recollection of a one-time fix, these steel "drive-rivets" but depending upon shaft composition maybe creativity should be limited. An Epoxy on the ID of the lever and maybe a drive rivet to finish and secure. Much might depend on the dimension of the head required for retention.
Local availability of the steel "drive-rivet" I'd think very likely.
the factory finished end of the shaft is approximately .325" so any rivet with at least that flange diameter should suffice. once in place and secure, a couple small tack welds could be an option, and a little extra insurance.
the factory finished end of the shaft is approximately .325" so any rivet with at least that flange diameter should suffice. once in place and secure, a couple small tack welds could be an option, and a little extra insurance.
I like the drive rivet idea. I will have to check with the local hardware store to see if they have them.
Thanks for the ideas!
Car finally finished and back on the road. I ended up having the bracket welded on to the shaft at a local shop.
It runs great and the throttle is smooth as butter. I had put a BBK on the car for the past few years and finally decided to tackle this project. I like the easier feel of the stock throttle body as the BBK has a pretty stiff spring.
Does anybody else have this issue with their throttle body? I have extra bushings and the tool to do the job. It's not that difficult if your mechanically inclined and it makes a world of difference. I can pay it forward and send the tool and a few bushings if someone promises to send it back!
...I bought a bushing kit from "Carb Junkys" off Ebay, 3/8 shaft kit.
Do you have more info on that tool/kit ?
I couldn't find it on their web site.
Is this it: http://www.ebay.com/itm/Throttle-Shaft-Bushing-Repair-Kit-Carburetor-3-8-Piloted-Reamer-8-Bushings-NEW-/331695360667?hash=item4d3a958a9b&item=331695360667&vxp=mtr
Sorry I haven't folowed my own thread in a few days. Yes that is the kit I used. No issues with the purchase and it shipped quick. Nice reaming tool. I can send mine to you with a few bushing if you will return it.
What's your mailing address and who do I make the check out to? Great work!
Do you have a Throttle Body that needs work? Tear it apart and send me the body and I'll install a new bushing. The most difficult part was getting the tiny screws off the blades. Had to grind off the back a bit and use red locktite when reinstaling.
Nice work and write-up Pace. Makes my "triage" look like such a hack job Guess I shoulda bought the kit. Definitely follow up with how you retained the throttle linkage. I have zero experience with those drive-rivets. Looks like an interesting option.
Do you have a Throttle Body that needs work? Tear it apart and send me the body and I'll install a new bushing. The most difficult part was getting the tiny screws off the blades. Had to grind off the back a bit and use red locktite when reinstaling.
This is a really great post. Thanks a lot. My 96 shaft is loose, and been debating whether to try to rebush, send it away for a rebuild, or buy an aftermarket. I guess mine is also 3/8? going to take it apart shortly and measure, then order the reamer & bushings from carbjunkeys. This will save me a lot of $. Rebuild & rebush by dr.injector is $179.50....Again, thanks a lot
i am bumping this post to keep it in the minds of tpi owners. ive just spent a considerable amount of time trying to track down my high idle that would come and go. i could set the minimum idle correctly, but the tps would flutter back and forth two mv. (tunerpro rt). Eventually gooding throttle resulted in the idle hitting 1300 and the tos at 0.63mv (from the 0.53 i set it at).
the car has 220k miles in gritty conditions. i have 1/16 play in the shaft and the vacuum from the engine would actually pull the blades in after goosing the throttle a couple times and it made setting the minimum idle impossible. the iac would close to positition zero, but there was no controlling the idle up to 1200-1300 once the shaft was dislodged rearward in the bore.
Furthermore, because its very tempting to simply replace the tb, i learned that 85-88 throttle bodys are different in the cable attachment area.
years ago i picked up a like new 52mm bbk for $5, its unfounately an 85-88 design and my triage patient is a 90.
So the bushing it gets!
THANK you op for taking the time to post up these pics.
Resurrecting an oldie but looking to bush my TPI TB in the exact same manner. It was mentioned that the shaft was tack welded to the linkage plate which is my preferred approach. Is this confirmation that the shaft is, in fact, steel? The peened end at the linkage plate has a gold appearance suggesting brass. However, when ground down with the internally metallurgy exposed, it appears to be silver like steel in the picture. Can anyone confirm if the shaft is steel, not brass? I've got an '87 Vette with vacuum leaks at both ends of the shaft and a welder friend. Don't want to start cutting apart without confirmation. Thanks.
Resurrecting an oldie but looking to bush my TPI TB in the exact same manner. It was mentioned that the shaft was tack welded to the linkage plate which is my preferred approach. Is this confirmation that the shaft is, in fact, steel? The peened end at the linkage plate has a gold appearance suggesting brass. However, when ground down with the internally metallurgy exposed, it appears to be silver like steel in the picture. Can anyone confirm if the shaft is steel, not brass? I've got an '87 Vette with vacuum leaks at both ends of the shaft and a welder friend. Don't want to start cutting apart without confirmation. Thanks.
Yes mine were steel. It has held up great since I originally did this write up.
04-08-2016, 10:43 PM
Throttle Body Shaft Rebush
Makes my "triage" look like such a hack job 
Guess I shoulda bought the kit. Definitely follow up with how you retained the throttle linkage. I have zero experience with those drive-rivets. Looks like an interesting option. 
