You might want to try brass.
Photography by J.G. Pasterjak
With our engine, transaxle, oil system and even exhaust installed in our soon-to-be-V6-powered 1991 Toyota MR2, we’re down to small details and reconnecting previous bits where they need to go.
Unfortunately, since we had a little fire in that very same engine bay, the work isn’t turning out to be as easy as plugging and playing. We’re still finding the occasional charred bit that needs to be dealt with to function properly.
One of the more notable of these well-cooked bits is the bell crank for our the E153 transaxle. It serves as the interface between the shift cables and the transmission.
[How to bolt a Toyota V6 engine to a 30-year-old MR2 transmission]
Of course, our shift cables were crispy as well, so we replaced those with a fresh set from MR2 Heaven–we’ve used them before to great success–but this bell crank would have to be dealt with as well.
The metal bits were fine. Sure, they were a little sooty, but that would come off with some light scrubbing.
But the rubber and plastic bits were basically done.
The rubber boots were mostly dust caps: not critical to function, but nice for longevity.
But the important bushing that allowed the pieces to rotate smoothly at their connection was dead forever. It was made of a very hard–and clearly non-fireproof–plastic. When operating properly, it allows the two-piece bell crank to translate the shift cable actuation into both horizontal and rotational motion.
So we set about cleaning up the bell crank and fabricating the pieces needed to put the assembly back to work. This included polishing the “cube,” the end of a rod that rides in a channel on the transmission actuation levers and moves the gear selection in and out, parallel to the orientation of the car.
A smooth cube theoretically makes for less friction in this channel. Certainly looks nicer, too.
Replacing the burned-up bushing was trickier. As far we could find, Toyota doesn’t specify any sort of replacement bushing for this assembly. The bell crank assembly itself appears to be NLA.
Our first attempt was to make a bushing out of acetal plastic, but by the time we machined it to the proper size, it just didn’t have much structure to it. The stock bushing was much stiffer, even though the wall thickness was only a few hundredths of an inch.
Still, the acetal was smooth and fit nicely, giving the bell crank smooth motion when moved by the hand.
Unfortunately, that didn’t translate into smooth motion on the car. With the bell crank installed, there was binding in both directions of shift lever movement. With the cables disconnected from the bell crank, they operate smoothly from either end. And the bell crank can also be grabbed by hand and used to shift the gears through both rotational and horizontal movement.
But when everything is connected, we think, there’s just too much side load on that soft bushing and it’s smooshng up and binding.
So, back to the drawing board.
We currently have an assortment of other materials on hand to experiment with. We’ll keep you apprised as to our progress.
Once we get this shifter sorted out, we’re literally down to installing the wiring harness, wiring supplemental gauges and switches, adding fluids and firing up. Hopefully when we do, we’ll have five easily accessible forward speeds to choose from.
Our shifter bell crank was pretty char-broiled. The metal was sooty but undamaged under the char layer. The plastic and rubber bushings and dust covers were toast, though.
This primary hinge bushing was burnt and heavily worn. This appeared to be the most critical junction in the assembly, as it needed to rotate smoothly and retain alignment.
While we were in there, we removed any roughness and corrosion from this metal cube, which locates the shift mechanism laterally with the selection levers.
After some lathe time with acetal plastic, we reassembled the bell crank and … still crappy. It articulates fine on the bench but not so well on the car. Further experimentation is needed to figure out exactly what we’re missing here.
You might want to try brass.
RacerX makes those bushings of you haven't come up with a solution yet.
https://racerxfabrication.com/mr2-celica/transmission/e153-linkage-bushing
Seems like Delrin would work well there.
It would be nice know what the bushing was made of originally. Y'all have some clout and maybe a shout out to Toyota from yuz guys might actually get an answer. Original parts from our 90's Toyota rides are disappearing from the factory 'catalog' at an alarming rate. Some other manufacturers (Toyota included) might want to pull a page out of Porsche's and Mercedes' playbook and maintain select parts for older performance vehicles that are still loved and maintained by their keepers AND can be sold for top dollar to said proverbial keepers of the flame. It's not a typical practice for high volume manufacturers, but it seems to generate a bunch of coin for the Stuttgart based folks.
In reply to tgschmid :
Sorta related, I’m about to drop the 911’s engine for some work. While it’s out, my mechanic said we should replace the bell crank bushings–along with some other “while we’re in there” things. I had several options to order from including, IIRC, factory Porsche.
In reply to tgschmid :
There is a Toyota Heritage program that has made available select items for the 2000GT, and a few Supra bits. I think some AE86 parts may have been done as well. Unfortunately, the parts that have been made available... I'm really not sure who is asking for them. It's starting to become a joke.
GameboyRMH said:Seems like Delrin would work well there.
There's no such thing as "too light." There's "tires too skinny," "not enough downforce" and "underdamped."
Yeah that's what I ended up using.
Surprise teaser for the next update: we figured out the issue. It was tertiarily related to the linkage, but more related to be being dumb.
I'm currently trying to get my 2GR MR2 shifter sorted out, so I'm following your progress. Mine has an E153 and shifts, but you can't shift quickly and the feel is terrible. I'm doing the adjustable shift cables from MR2 heaven first, along with the shifter fork bushing and shifter base bushings. Hopefully that sorts it out, but if it doesn't this will probably be the next place I look.
zordak said:You might want to try brass.
I've actually had pretty good luck with sizing brass from spent shells after I've gone shooting.
Could it be geometry rather than material?
If the two parts twist relative to each other through the range of motion, having the center hole rounded rather than cylindrical { )( instead of || } might free up the angular motion without making it sloppy.
Displaying 1-10 of 10 commentsView all comments on the GRM forums
You'll need to log in to post.
