TR6 Replacement throttle shaft bushings for TR6

[Brosky]

in order to make this available to those who may not see it in a clutch thread, I decided to have a separate posting for this information.

What you see on the right is the bushing supplied by the Big 3. Very difficult to install, to say the least. What you see on the left is the bushings that I have listed below, by the part number listing of every type of material that McMaster Carr supplies in the sizes needed on the TR6 firewall to fit the bearings in easily.

McMaster Carr Flanged Plastic Bearings to fit throttle shaft and firewall of TR6

All bushings are 3/8” ID X 5/8” OD X 1/8” Flange Thickness X 7/8” Flange Diameter X ½” or ¾” Length

Depending on whether you get a 1/2" or 3/$" length, the parts will need to be shortened to end up with a total length of about 1/4" after the shoulder.

I have taken the liberty of dropping the ridiculously priced medical grade materials from this list.

Plastic Type Length Load (P Max) Speed (V Max) Load at Speed (PV Max) Temperature Range Specifications Met

Delrin 1/2" 1,000 1,000 2,700 -20° to +180° F Not Rated 2705T21 3.38 Each
Delrin 3/4" 1,000 1,000 2,700 -20° to +180° F Not Rated 2705T22 3.49 Each
Nylon 1/2" 400 360 3,000 -20° to +250° F Not Rated 6389K414 4.18 per Pack of 1
Nylon 3/4" 400 360 3,000 -20° to +250° F Not Rated 6389K415 4.59 per Pack of 1
MDS-Filled Nylon 1/2" 300 60 3,000 -40° to +220° F Not Rated 6294K213 3.84 Each
MDS-Filled Nylon 3/4" 300 60 3,000 -40° to +220° F Not Rated 6294K214 4.10 Each
PEEK 1/2" 8,500 400 3,500 -148° to +480° F Not Rated 6627K108 16.22 Each
PEEK 3/4" 8,500 400 3,500 -148° to +480° F Not Rated 6627K109 21.22 Each
PTFE 1/2" 500 100 1,000 -350° to +500° F Not Rated 2706T21 4.52 Each
PTFE 3/4" 500 100 1,000 -350° to +500° F Not Rated 2706T22 5.10 Each

Please refer to Dale's excellent pictorial .pdf file a few posts below, that include all needed instructions for installation.

Good luck and smooth accelerating from here on in. Plus that infernal rattling noise over bumps will go away. /bcforum/images/%%GRAEMLIN_URL%%/banana.gif

 

[Soup]

thanks Paul, doesn't sound aweful, just need to take my time.

Soup

 

[Brosky]

It's really very easy. I just wanted to make it a step by step for those not familiar with the car.

Make sure that you can get the bushings so you'll be ready when the time comes. That's why I gave you various options in case they were out of one number or the other.

 

[Soup]

Order placed!!

Waiting for three (just in case) at 4.10 each

Getting my ducks in line and actually getting a little anxious to get this project underway. Need some warmer weather which is sure to be around the New England corner. Will be doing the job with a friend who is a very good American made mechanic. He's not real familiar with the British stuff but these Tr6's seem pretty straight forward.

Need to get that Gunst in the mail tomorrow!!

Soup

Gotta go before this site gets me a divorce, actually wife is real good :>)

 

[Guest]

I have a brass solution that's dead easy too. I wrote it up - I'll post the writeup here for completeness.

Throttle Shaft Bushings

If you ever tried to replace the throttle shaft bushings, you’ll know what a difficult job it is. I started off with the usual poly bushings from one of the big three, but installing them nearly drove me crazy. I tried all the usual suspects – boiling water, grease, slicing them –and nothing worked for me. I must have spent two to three hours on one side, and ended up with nothing to show for my trouble.

I figured there had to be a better option, so started looking around to see what others had done. I was directed to this article: https://www.britishcarforum.com/bcforum/memberfiles/3948-NelsonRiedelArticle-accelshaftbushings.pdf

Needing to get this problem fixed, so I could continue with the ‘real’ change I was trying to make, I ordered pretty much everything recommended there, and I think I found a pretty neat solution in the end, one that I take no credit for inventing, but that I still think is worth sharing.

You will need the following parts:
McMaster-Carr - 6338K461(x2) and 6435K13(x2).
(Probably) a new coil washer (Moss 315-060).
A letter W drill bit.
A flex head Dremel with the pink 5/8" grinding wheel.

First, drill out all 4 of the McMaster Carr parts with the letter W drill.

Next, dismantle the entire throttle shaft assembly. You have to extract the pedal and shaft. (Note: when you start to disassemble it, make sure you have the relative lever to shaft position marked). Clean the shaft and straighten it - you are sure to bend it taking off the lever if it is anything like the state mine was in.

Hone out the two holes in the bulkhead for the bushings with the Dremel. I used the pink 3/8” wide grinding wheel, which was exactly the right size for these bushings - ymmv here, so before going crazy make sure they are a press fit at each end. Use the Dremel, or a file. Don't do what I did first - crack one of the bushings trying to ‘drift’ it into place. This is just so much easier.

Re-assembly is as follows:

Put the throttle shaft through the hole in the firewall at the driver’s side. Push it 4-6" into the engine bay.

Thread the bushing onto the shaft, flange side outermost. Thread one of the two collars on.

Push the shaft through about 80% of the way. Put the lever back on, then the coil washer, then the collar and finally the bushing, flange side inwards.

You should now be able to fit the two bushings into their holes. Once they are in place, Use the collar to push against the on the driver’s side bushing to locate the pedal appropriately. The coil washer between the lever and the collar will hold the collar against the bushing on the passenger side.

It turns it into a really neat (neat as in tidy) setup, and took less than an hour to do both sides. I wish I’d known about this from the start – I’d have saved all the time I wasted messing with the rubbers.

One final thing - the hole for the bushing on the passenger side in my firewall wasn't exactly perpendicular to the shaft. This means the bushing isn't flush to the bulkhead all the way round. I noted that there is signs of repair under the firewall in this region, so again, ymmv.

I used epoxy to locate the bushing, using the shaft as a guide to keep it aligned while it set. It's now square to the shaft, firmly attached to the firewall, and I can forget about it for the next 30 years.

 

[Brosky]

Alan,

Sounds like a good solution as well, but I can't get the pictures to show? Is it just me?

 

[brdave]

I don't want to get beat up in here but one day I asked a local british mechanic about replacing these bushings. He apprenticed in the old country in the days that things were fabricated on the spot if necessary to make repairs. He suggested obtaining some rubber or nylon tubing, slitting it down one side and sliding it over the shaft to where the bushing was. I felt there may be some merit in such a solution but have yet to have completed the repair. Wish I had thought about changing these bushings when I changed the clutch this winter. Oh well!

dave

 

[Brosky]

Dave,

He was partially correct. The reason that I went with the "flange" bushings was to have an easier method of driving them into the holes it the firewall and to provide a measure of protection over a sleeve type from possibly sliding out.

 

[Tinster]

I am hoping this is the pdf file on how
to install throttle bushings:

Cool!!!! the pdf format works!!

dale /bcforum/images/%%GRAEMLIN_URL%%/banana.gif /bcforum/images/%%GRAEMLIN_URL%%/banana.gif /bcforum/images/%%GRAEMLIN_URL%%/driving.gif

 

[Brosky]

Dale, that is an excellent job!! Thanks very much.

 

[Soup]

The McMaster Carr bushings arrived today.....that was fast.

The Gunst Bearing was finally mailed back today.....that was slow.

Copied all the above info for reference when things get under way in the near furture, maybe next week. Still to much melting snow and sand on these CT roads for me to want to drive the car to my friends so we can get started.

Soup

 

[14dna]

Dale
I'm not sure if I should be going to university to get my teaching degree or you. Excellent job, that will help lots of people. And thanks to Paul, who sends bushings all over North America.
Dave

 

[Brosky]

After smashing and burning my fingers trying to do it the Big 3 way, I decided to do what should have been done from the factory in the first place. I hate to see anyone else go through that ordeal, but now I'm out of bushings, which is why I posted the part numbers for M/C.

 

[mrv8q]

Thanks to all for this comprehensive procedure. All questions I had just reading Paul's excellent description were answered w/the PDF/pix. After ordering the bushings, I'll pull my carbs, and dive in... unfortunately, everything else will remain in place. Hopefully I'll be as successful as the others. Thanks again!

 

[Brosky]

Kevin,

Why are you pulling your carbs? Did I miss or forget a previous conversation? I'm getting old, ya know!!

 

[mrv8q]

Hey, Paul, I've got a nasty leak out of the rear carb. I bought a carb book from TRF, and someone posted a 3*part PDF on ZS rebuilding. I'm hoping it's a simple float or jet adjust! Just finished ordering the bushings from MC. Thanks for posting the part numbers...made it a snap!

 

[Brosky]

Well, Kevin, that answers that. Good time to do the bushings as well.

Good luck and if you need us, we're here!

 

[mrv8q]

Well, I replaced my throttle shaft bushings today, not too terrible a job. Since I was replacing them w/ the engine and carbs in the car, I deviated a little from Dale's PDF. I used the McMaster- Carr PTFE 2706 T21 bushings. It was a good thing I ordered 3 bushings; 1 fell out out of a hole and disappeared into the 7th moon of Neptune's orbit.... I mean completely off the face of this earth! I still don't know where it is.

I wound up mashing that 1st bushing pretty good before I lost it; there just isn't much room there to knock the bushing into the holes. Also, for whatever reason, the passenger side's hole was smaller than the driver's side. My fix for the tight confines was to notch a small groove in the bushing, w/ the same Dremel grinding wheel I cut it down with to begin with. This gave me a little give when I pushed the bushing into the hole.

My other fix was to use a flare wrench to tap the bushing in on the driver's side;

I wound up not cutting that one the 1/4 inch recommended. My only other piece of advice is to make a good mark on the shaft where the linkage sits. I may adjust mine a touch more, as the accelerator pedal may sit just a touch high...

Thanks to Paul, David and Dale for all the work and PDF, it was most helpful.... now, onto the carbs!

 

[Tim Tucker]

Since each British car should be built differently, I tried my own little twist to your approaches. I used McMaster-Carr 6338K461 and 6338K465 both of which are SAE 841 bronze flanged-sleeve bearings for 3/8" shaft diameter. The former is 1/2" the latter is 1". I cut the former down to 1/4" in length and threaded the latter to accept a 5/8-18" threaded lock ring or jam nut (it too will be cut shorter). Since I could not find an acceptable jam nut at MC, I order a 8509A33 lock ring - MISTAKE! They are for drill bushings and are left hand threaded. Since I will be taking it all back out when I paint, I re-threaded it right hand and installed it anyway. I used an adjustable reamer to get the proper ID as well as to hold the bushing will I filed it to the proper OD to fit the hole in the TR6's body. The setup works very well. Much better than the NO bushings I had. I also cursed far less than I would have if I had tried to install the hard bushing I was shown. I honestly don't see how those can be installed. Thought I would share.
Tim
parts:

on throttle shaft:

Have a Happy New Year!

 

[TheSearcherMan]

I think you will find, if I remember right, that is, if you want the carbs to go to full throttle, the accelerator will sit high. If you lower it, I don't think you get full throttle. I got used to it, now it seems normal. Also,I was somewhat terrified about what I had heard about putting in the standard bushings. It's not that bad. I actually did it twice. I still think the standard linkage is fine, if you have it on right, and adjusted properly.