James Bailey

The very early 78 5 spds also had the front guide sleeve mounted to the CHASSIS they quickly moved it to the torque tube......the slots in the rear bushings was designed to be there (the 911s had none) so Porsche went out of there way to ADD the slots. I wonder why ????

Lizard928

Jim,
The difference between a GT and a sports car.
The elongation in the bushings takes a little more harshness out.

The reason for putting the front guide sleeve from the chassis to the TT was for a matter of installation.
They assembled the driveline outside the car and were able to simply lower the chassis over the assembly with no fuss. With that bushing mounted to the chassis, this was not as quick. If they could say 1 min by doing this they would.

James Bailey

Ah harshness equals a buzzing vibration .... I got it now. Good theory on the installation I am sure it has nothing to do with the known fact that the entire engine torque tube and transmission move around quite a lot with several Gs for force....

Lizard928

I have tons of miles, including track miles with this same shifter assembly.
There is no noise with stock bushings. Only with the bronze.

toofast928

So what's the final word on the bronze bushings for a street car. No play in the rear coupler means vibration/buzzing up the shift linkage?

Jadz928

Roger may have customer feedback, but it may be rather isolated incidents.
It's possible what we are reading here is the 5th percentile and the rest are just fine.
I suggest try it and see if it works on your car.
It's not hard to change out, and they're cheap.

Rob Edwards

+1. I put a set in and didn't like the buzz, so I swapped 'em out. It's a 30 minute job as long as you you're not above slitting that stupid rubber boot to get it out of the way quickly. A small 2-arm gear puller works best for pushing the pin out of the rear coupler.

toofast928

Hi Jim,
From the feedback that I'm reading its more like a 100% buzz/vibration complaint after the bronze bushings are installed. Which is probably the reason why Porsche elongated the holes to begin with. So I'm thinking maybe I should drill the bronze bushings to increase the ID but not to the opening of the OEM diameter.
Changing the oil is easy too but hate doing it twice in the same day.

SeanR

The buzzing is caused by the lack of the internal bushing part, that is on the factory bushing. It keeps the shift linkage from hitting the side of the assembly.

Rog just got his derilin ones in, I've got a test subject here I just need to find the time to install them, and test. Should have that done sometime next week.

BC

There is buzzing for a reason. If the buzzing were to get louder and louder, people would blame the TT.

Who has a brand new TT but also installed hard bushings and has vibration?

ROG100

I was not happy with the feedback on the bronze bushes. Fine for a track car but not a street car.
The 911 crowd use a plastic bush with out the elongated hole but the price is a little high for my liking.
I now have the new delrin version ready to test and will have a few for free trial if a couple of you are interested.
With all my team working flat out and Third Coast upon us it may be after TC before I can finish the fit tests and get them out.

Jadz928

The reason for 100% buzz feedback here is because of the thread title, mainly.
My understanding is Roger has sold alot of these (5O plus, Roger?)
How many have complained or sent them back?

I'm sorry, Sean but that is absolutely not the reason. That inside flange you are referring to is there to keep the plastic bushing from sliding out. The width of the bronze bush is the same as the plastic, thus both keep the rod ("T" joint) centered and isolated from the aluminum housing.

Mine buzzes. I'm also using the Lizard shifter, so I wouldn't consider mine "typical".

Also, I designed the bronze bushes, so I can let anyone know what was considered in their design.
FWIW, I have interest in them and don't make a dime from their sale, so no worries.

EDIT: I see Roger has chimed in. So I guess that is that.

Jadz928

I figured I give it one last go at the bronze bushings. See, I like their performance and never need replacing.
So I packed the coupler boot w/heavy grease. I mean I literally and liberally injected the grease to fill up the boot.

No more vibration! I did a s$&%load of full-band pulls, and mid-to-high rpm pulls. Nothing.
Tomorrow I'll be running the car all day, so I'll report back w/some more seat time.

Mrmerlin

the vibration is being transferred from the shift fork on the syncro to the shift rod in the trans then to the shifter selector, then to the shifter coupler.

The grease may be a suitable dampening medium for a while,
but i think the delrin bushes should be a better solution as they offer a bit more vibration absorption, than the bronze bushings do

As always with a new design, it may take a few tries and different combination of parts to get the perfect shifter

James Bailey

Might also mention that the cross pin to the coupler is an interference fit. Once you push it apart it will no longer be as tight /fixed in place when you push it back together with new bushings. I have had one fall out at the track ! a bit of fooling around a a nut and bolt made it drivable.