Upgrading throttle linkage bushes

[Tim D.]

Hi all,

Currently have the car stripped down and in for a respray. This has given me time to look at the state of the various ancillaries that i had to take off the car. So usual suspects have been rebuilt e.g. Heater, instruments.... Now I'm looking at the throttle linkage.. its the underslung one as the car is a CP. Had previously replaced the linkages that link the crossbar to the throttle bodies with the ball jointed ones from Moss. But looking at the cross shaft itself the nylon? Bushes it runs in look shocking. The DPO has obviously replaced them but to do this he has cut them to make them easier to fit..

Anyhow don't know that I like the nylon as a solution. I have seen some people have replaced them with needle bearings but this looks pretty involved. So I have bought some oilite flanged bronze bushes. Amazingly they fit not only the cross shaft (which they should!) but the outside diameter makes them a good fit in the brackets that support the cross shaft (and they only cost 4 quid!). I still need to work how to secure them to the cross brackets (but i have some ideas!).

My question is, to replace the centre bearing I would have to remove one of the cams on the shaft. This means grinding off a weld which should be easy. I could then replaced the bush but I would have to re-weld the cam back in place. I am guessing that this would have to be done with the cam perfectly placed with respect to the other cams to ensure that the throttles act in synchrony.

 

So my question is... has anyone done this? And did you use some form of jig to ensure that everything went back OK..

 

Cheers

Tim

PS if I can get this to work i'll write it up and put it on the blog!

[Steves_TR6]

Sounds interesting Tim

 

I'm contemplating fitting the moss throttle linkages as there's some slack in the rearmost linkage on mine.

I'd also like to replace the bushes which look quite loose.

This will be done in conjunction with wrapping or zircotec coating the tubular exhaust manifold in an attempt reduce under bonnet temps.

 

One thing leads to another with a TR!

 

Good luck with the oilite bushes, look forward to seeing the result!

 

Steve

[TriumphV8]

The soft bearings are one reason that the CP is not that

precise as it should.

The midle bearing can only be fitted in a good quality

if the shaft is separated.

Otherwise it has to be cut and fiddeled in or better made from

nylon and fix it after being pushed in position because its much

stiffer and can not be pushed into that original holder.

 

I made the whole spindle from axle parts from RC cars,

providing a precise shaft and needle bearings for it

to run directly on the shaft.

 

 

Not that much work as it might look.

A good job for these winter days.

[Waldi]

I may not understand this, but I recently fitted 3 new PU bearings on the countershaft of my CP.

They came from TR shop and are a perfect fit.

The outer ones go in easy, and I did give one cut with a sharp knive in the middle one and managed to get it in, while I had the countershaft on the bench. Nice smooth oparation now, with very minimal radial movement. Moss part no: 138490SP.

Waldi

[JJC]

My thread "countershaft bearings" also covering this at the moment. I don't think the central bearing was on our car when it left the factory. But I could be wrong! The engine was untouched when I got it and I certainly haven't removed the bearing. Maybe someone with one of those unused untouched CP cars could have a look. JJC

[Tim D.]

Replaced my outer bushes with oolite bushes. Top hat shaped off the shelf and fitted perfectly.

Tim

[Trever the rever]

I too have just bought 3 PU bushes from Moss. My centre one is missing (as said was it ever there!) and the other two look awful. Reading the posts, I'm not in the game of serious mods and like Waldis post. (parallel evolution kicking in here!). Cutting the centre bush and making fit seems like a realistic way forward. Waldi, did you use a lubricant to assist in fitting the bush?

 

Regards Trevor

[Waldi]

Hi Trevor,

I made a cut with a sharp (Stanley) knife, just one cut.

It took some convincing, but went in easy.

The warm wheater (temperature) will help, or some lube.

Dont recall if it was needed.

Cheers,

Waldi

[Trever the rever]

Great Waldi, thanks again! Earlier posts seem to suggest these bushes were suspect and hard to fit. Looks like these later ones are pretty good.

 

Regards Trevor

[barkerwilliams]

I'm thinking of this on my car. But when I balance my cylinders there are slight differences between linked pairs of throttle bodies. Has anyone split the shafts to allow individual cylinder adjustment?

 

Alan

[TriumphV8]

Alan you can not split the shaft because there is no space.

I did see such a manifold what got full rework.

Each inlet got its own spindle that was turned by 90 degrees

so sitting from top of manifold to bottom.

Each had a lever to a linkage that connects them all.

And this main linkage had six individual provisions to set each throttle lever.

A lot of work to build and even more work to set that wonderfull artwork!

 

You can simply remove airbox, apply full throttle and grab the two throttle plates

with two pliers and turn them against each other with force in the required direction.

Unfortunately the spindles are from brass and the point where they turn and the point

where the spindle breaks are pretty close together.

 

Anyway the good function of PI relys on proper setting of the plates so perfect bearings

and prefect setting of spindles is so essential.

 

At the carbs you simply apply a bit less power if there is a mismatch but at PI also

the mixture quality is affected that some will run lean and some run rich.

Edited July 13, 2018 by TriumphV8

[Waldi]

Hi Alan,

Splitting the shafts will add to complextity as Andreas pointed out and reduce the stability (or do you name that rigidity?) of the shafts.

For proper adjustment of the butterflies per TB, it is best to remove the TB from the car, and first give it a good clean.

I also cleaned the bores at the location of the seats, but others disagree with that. My reasoning is it should be clean to properly set the small gap on each butterfly; a layer of cokes/black stuff is not helping with that.

Others find the sooth layer provides a seal; each to his own I guess.

Then check the spindle for wear and binding at each orientation, but especially at closed and almost closed position. If the play is too much, renew the spindle.

In my case (I installed 3 new spindles) that reduced the clearance sufficiently, it is mainly the spindle that wears.

I re-used the butterflies but used new screws.

I first installed one disc, adjusted it visually to have a nice half moon when fully closed, and put the scews in finger tight.

Then did the same with the 2nd disc and finally made both moons equal and as small as possible.

Then fixed all 4 screws for a final check.

After ok, I removed the screws one by one and did the final tightening with loctite, one screw at a time in order not to disturb the discs.

Regards,

Waldi

[Trever the rever]

Ive successfully fitted all 3 bushes this morning. The centre one using the Waldi method. Just a point ref setting the butterflies, Im almost there, interesting observation as 5&6 were lagging behind, I increase the load there, revs pick up slightly and engine runs smoother at about 1000 rpm. If I use the air bleed valve to slow up the idle, the revs hunt up and down, Ive the new moss supplied linkage, and use a basic air flow meter. Even so its such a fine adjustment, even tightening the lock nuts subtlety changes the air flow. Interested on thoughts ref the hunting phenomena. Regards Trevor.

Edited July 13, 2018 by Trever the rever

[YankeeTR5]

On the PI cars, owners don't have to deal with the accelerator shaft bushings since our throttles are driven by cable. That said, the bushings do appear to be the same part as the throttle spindle bushings on the PI cars. They wear and are near impossible to retrofit without mangling the bushing as it goes thru sheetmetal - in fact any ideas of how the factory did the install would make the person a hero. A solution has come along using a brass sleeve in two pieces...super easy to fit and works the part. When I get to my TR5 in the coming year I'm going to try this solution for the PI spindles. I only post as the accelerator shaft on the carb cars is the same diameter as the PI. Easy enough to replicate without buying but wanted to share.

 

https://www.bpnorthwest.com/triumph/tr250-tr6/accelerator-shaft-bushing-kit-heavy-duty-tr250-tr6.html

[Waldi]

On the PI cars, owners don't have to deal with the accelerator shaft bushings since our throttles are driven by cable. That said, the bushings do appear to be the same part as the throttle spindle bushings on the PI cars. They wear and are near impossible to retrofit without mangling the bushing as it goes thru sheetmetal - in fact any ideas of how the factory did the install would make the person a hero. A solution has come along using a brass sleeve in two pieces...super easy to fit and works the part. When I get to my TR5 in the coming year I'm going to try this solution for the PI spindles. I only post as the accelerator shaft on the carb cars is the same diameter as the PI. Easy enough to replicate without buying but wanted to share.

 

https://www.bpnorthwest.com/triumph/tr250-tr6/accelerator-shaft-bushing-kit-heavy-duty-tr250-tr6.html

That is a smart idea. They look like modified pipe couplings, bit given the price probably not that easy.

Another option:

Since the bushes on rhe PI linkage and pedal shaft are the same, I used the PU bushes for the pedal shaft as well.

Thats what I did.

 

Regards,

Waldi

[YankeeTR5]

Yes, pricey, considering the pieces themselves can be sourced for about $7! Them who solves a problem reap the rewards I believe.

[Kevo_6]

Sorry Double Post

Edited July 16, 2018 by Kevo_6

[Kevo_6]

Hi all,

Currently have the car stripped down and in for a respray. This has given me time to look at the state of the various ancillaries that i had to take off the car. So usual suspects have been rebuilt e.g. Heater, instruments.... Now I'm looking at the throttle linkage.. its the underslung one as the car is a CP. Had previously replaced the linkages that link the crossbar to the throttle bodies with the ball jointed ones from Moss. But looking at the cross shaft itself the nylon? Bushes it runs in look shocking. The DPO has obviously replaced them but to do this he has cut them to make them easier to fit..

Anyhow don't know that I like the nylon as a solution. I have seen some people have replaced them with needle bearings but this looks pretty involved. So I have bought some oilite flanged bronze bushes. Amazingly they fit not only the cross shaft (which they should!) but the outside diameter makes them a good fit in the brackets that support the cross shaft (and they only cost 4 quid!). I still need to work how to secure them to the cross brackets (but i have some ideas!).

My question is, to replace the centre bearing I would have to remove one of the cams on the shaft. This means grinding off a weld which should be easy. I could then replaced the bush but I would have to re-weld the cam back in place. I am guessing that this would have to be done with the cam perfectly placed with respect to the other cams to ensure that the throttles act in synchrony.

So my question is... has anyone done this? And did you use some form of jig to ensure that everything went back OK..

Cheers

Tim

PS if I can get this to work i'll write it up and put it on the blog!

Hi Tim,

Ive recently replaced all 3 bushes with oilite and I did have to grind off the weld but if you make a mark on each piece its fine when welding back together. I also bought one of these https://www.bearingboys.co.uk/Double-Split-/CADB16Z--16mm-Shaft-Collar-Double-Split-40378-p and welded to the centre bracket with some adaptation of the collar. (originally my idea was to split 2 bushes and clamp on with the collar so I did not have to grind off the weld but changed my mind) I then fitted 2 oilite bushes inside the collar. I was worried that a single bush without the collar may not stay in the right position or foul something. Hope this all makes some sense.

 

For others who wish to do this, these are the bushes I used https://www.bearingboys.co.uk/Imperial-Flanged-Oilite-Bearings/AJ061006-Flanged-Oilite-Bearing-Bush-38-x-58-x-38-42863-p

The 2 end bushes are held in place by the mounting plates.

 

 

Well worth doing as the shaft feels so much firmer and balancing the butterflies seemed to be easier and quicker to do, I also have the ball jointed linkages from Moss.

Edited July 16, 2018 by Kevo_6

[Richard Baines]

Hi Kev,

old thread I know but hopefully you might remember. Did you have any issues with the countershaft binding in the bearings?

I've had a go at this using the above bearingboys.co.uk oilite bearings for the 2 outers, and a cut polyurethane bush in the middle location. It works very smoothly until I tighten down the 2 outer bush brackets, at which point the countershaft binds and sticks leaving the throttles open - even with everything well oiled and the weight of the throttle spindle and throttle cable springs trying to stop it doing that. It even binds a bit with just one bronze bush and an old nylon one on the other outer.

Obviously the shaft isn't in the same plane as the bushings, but I wouldn't even know how to start ensuring that it is. I'm inclined to just revert to poly bushes as it's a safety issue if it sticks, but grateful if anyone can add any advice that might help.

kind regards, Richard

[JohnC]

Is it possible the countershaft is bent? When I tighten up the brackets (CP car, original underslung linkage) there’s enough adjustment to make sure the bushes are aligned with the shaft. I have bronze bushes at each end and PU in the middle. If your shaft is bent then it could bind as it rotates, regardless of how carefully you align it at rest.

Kohn

[JochemsTR]

 

Hello Richard,

adding two bearings at each end may sound great, but the system is not able to compensate any play, bend or tolerances. I installed the TR5, TR6 Throttle Countershaft Bearing Upgrade from Martin https://fredmillturnparts.com/parts-list-and-ordering/

The difference is, that the bearings are self aligning and can compensate for such this. The middle bushing is ignored. No need for Poly or anything else.

In my opinion the best solution currently available. Cutting the shaft in half and putting couplings or other connections, I would never do such thing.

You can also contact Martin in case you really need a new shaft.

Jochem

Edited December 13, 2020 by JochemsTR

[Richard Baines]

Thanks both, the shaft is definitely not bent. It's actually a new one from Martin @JochemsTR!

The manifolds are aligned well, and the brackets are new, but the binding occurs with either the new brackets or the original ones. The new parts are all very well made and I've checked the tolerances.

I am starting to wonder if the oilite bushes work better for others due a combination of slightly undersize countershafts due to wear (instead of a new one) and a bit of luck in the alignment of all the parts in totality.

I could play about with fitment and alignment for ages, I guess that might fix things, or go for the bearings as you mention Jochems, but now that I've tweaked things I can get it working extremely well with a bronze bush on the rear manifold and a polybush on the other two. So think I'll stick with that for now, it's easy to change later. Once it's all running and tuned well I'll do a writeup, as I've been taking photos as I go.

[TriumphV8]

It is the question how precise it must be. If you are on PI you are often on the rich side with AFR setting, so metering a bit not precise will not do any harm.

With our EFI we want to go lean close to the limit and can not tolerate any difference in airflow to each cylinder. That ist why modern throttle bodies for bikes and sports cars are made with watch precision.

If the linkage does not move when nuts are fixed something ist not in line. Make a precision shaft and try to fix outer holders and bearings without linkage. Try than to move the shaft through the outer bearing to meet the inner bearing.

 

If it does not slide in than bent the outer holder until it does and so the same procedure at other side.

 

I used the needle bearings because they do not stick that easy.

 

I cut the shaft for the middle bearing because I found precision not that precise with only two bearings. Must have been the same conclusion like Triumph had in the past. Simply make a precise tube over separated shaft, outer side welded, inner bolted with a screw.

Edited December 14, 2020 by TriumphV8
mistakes a lot

[JohnC]

Another thought: Could the centre PU bush be the problem? If it's pushing the countershaft out of alignment (i.e., bending it), that could easily cause binding at either end, or even in that bush itself. Does the binding happen if the centre bracket isn't bolted down?

[Kevo_6]

On 12/12/2020 at 5:28 PM, Richard Baines said:

Hi Kev,

old thread I know but hopefully you might remember. Did you have any issues with the countershaft binding in the bearings?

I've had a go at this using the above bearingboys.co.uk oilite bearings for the 2 outers, and a cut polyurethane bush in the middle location. It works very smoothly until I tighten down the 2 outer bush brackets, at which point the countershaft binds and sticks leaving the throttles open - even with everything well oiled and the weight of the throttle spindle and throttle cable springs trying to stop it doing that. It even binds a bit with just one bronze bush and an old nylon one on the other outer.

Obviously the shaft isn't in the same plane as the bushings, but I wouldn't even know how to start ensuring that it is. I'm inclined to just revert to poly bushes as it's a safety issue if it sticks, but grateful if anyone can add any advice that might help.

kind regards, Richard

Hi Richard

I had no problem with alignment or stiffness, the only thing I did was polish the shafts before assembly. Sorry I can’t help you anymore than the great suggestions above.