Folded Carb Coupling

[Gordo]

I'm getting some lag in my rear carb due to the folded coupling is getting weak. I can see that the front is moving before the rear.

I happened to see on Brosky's Rat-Co pics, (beautiful car)that there appears to be a solid coupling between the carbs.

Two questions:

1. Are those couplings part of either the Ratco kit or the tri-carb set up?

2. Has anyone updated/replaced the folded coupling with a solid coupling? If so, from where?

Maybe that was 4 questions.

Thanks, Gordo

 

[Tinster]

Gordo-

I think Paul and Jeff co-designed that solid coupling.
Paul will chime in after he gets out of bed. He sleeps
late on Mondays from too much golf on the weekends.

d

 

[Brosky]

Good morning BCF!!!!!

Contrary to what my friend in PR says, I have been up and at it since 5:30AM.

Contact Jeff Palya at PalTech Micropolishing regarding the solid couplers. There are several items to take into consideration, such as throttle shaft length and Jeff can tell you what needs to be done, if anything to over come that.

I have very tight clearance between each of my carb shafts, and the couplers fit these well, but may not be long enough to cover stock carbs. Jeff will know the answers.

https://paltech1.com/index.html

Proper alignment is critical to these working as well as preventing premature wear on the throttle shafts and carbs.

 

[Brosky]

I cannot take any credit for the design, only for the opportunity to test them on my car, in place of the folded couplers, thanks to Jeff at Paltech. His design and his machining. Quality part, with out a doubt. Maybe too good for the design of the carb setup though.

I'm not ready to pass judgment just yet, so give me a few more days to try a few more tweaks.

 

[dklawson]

My GT6 doesn't have the folded metal couplers, nor does it have the type shown above. My car has cylindrical nylon couplers with what are best described as slots in the end. The brass rods rest in the middle of these slots and they are pinned to the nylon with a roll-type spring pins. Basically this creates a u-joint out of each nylon cylinder. Like the folded metal couplers they aren't sensitive to alignment. Like the metal couplers shown above, they don't flex. I haven't seen these on other Triumphs but surely they must be from the factory. I had to make one cylinder to replace one that cracked shortly after we started restoring the car. I never found them in the parts catalogs I have access to.

 

[rotoflex]

My GT6 doesn't have the folded metal couplers, nor does it have the type shown above. My car has cylindrical nylon couplers with what are best described as slots in the end. The brass rods rest in the middle of these slots and they are pinned to the nylon with a roll-type spring pins. Basically this creates a u-joint out of each nylon cylinder. Like the folded metal couplers they aren't sensitive to alignment. Like the metal couplers shown above, they don't flex. I haven't seen these on other Triumphs but surely they must be from the factory. I had to make one cylinder to replace one that cracked shortly after we started restoring the car. I never found them in the parts catalogs I have access to.

Those are correct for the GT6 (Mk1). You can see them in most repair manuals, if you can't find them in parts catalogs. The folded steel couplings really work best, as rotationally they're very rigid but flexible for varying alignments of the carbs & are very simple with almost nothing to wear or break besides stripping the easily replaced little bolts.

I've never seen any fatigued folded steel couplings; they're brittle blued spring steel. I wonder if someone may have replaced one with brass or something. If the front one is moving before the rear, I would suspect that they are not clamping well. Check &/or replace the tiny bolts & nuts if they're stripped. Remove them from the throttle shafts to see if the shafts have worn somehow to keep the couplings from clamping down enough. If it's just a bad score, you can slide the coupling a bit to either side of the score.

Carburettor linkages over time & owners tend to get altered from original: it seems like there should be tiny washers fitted to the bolts. Check the parts manual if you've got one handy.

 

[Guest]

Unfortunately, the little folding spring couplers were not really designed to work with the triple carb setup and the throttle shafts being so close together. Basically, the throttle shafts are almost touching each other. I had gotten some really heavy-duty spring clips from Joe Curto, thinking these would be better than the blue-steel lighter duty stock spring clips. Essentially zero flex, so I pulled them and went back to the factory clips. One of the inherent defects in Richard Good's manifold is the fact that it is not a one-piece unit that can be precision-drilled to perfectly align the carbs. Hence, the shafts will never perfectly align and there is always gonna be some bad torque on the shafts. I just did the best I could, wallowed out the mounting holes on the back of the carbs, installed my spring clips with the old Eye-Ball method, then tightened down the carbs. Someone will come up with a better way. The problem with the brass sleeve connectors, as I see it, is there is absolutely no room for misalignment. This may have ramifications.

 

[Gordo]

I went to the McMaster-Carr website and looked up various shaft couplers. I tried to copy it but didn't have much luck. I found a coupler that I think I'm going to try. This aluminum coupler allows for .010 parallel, 4 degrees on angular and .005 axial misalignment. Once I get and install them I'll post with my findings.

Gordo

 

[Brosky]

So Bill, would you recommend cutting the shaft between the carbs to allow about 3/8 to 1/2" between then, before putting the flexible couplers back on?

I just cannot get mine to work properly with the solid couplers and as much as I hate to tear everything apart, it looks like I will have to.

I looked at my old twin carb setup and there is between 3/8 to 1/2" between the center section and the two carbs. That center section with the bellcrank is about 1/8" off the centerline (actually behind) of the carb shafts and they never had a binding problem.

I can easily put a cutter blade in my Dremel and fire it up while the front and rear carbs are off of the car.

I was going to install the flex linkage as is, with the very close gap as shown in the earlier picture, but I'll wait for your opinion or anyone else's who weighs in on this.

 

[LastDeadLast]

Paul,

I missed something.... Are the solid couplers not working for you?

 

[Brosky]

No Shannon, they are not. After many, many hours spent adjusting and aligning the carbs and manifolds, both cold and then when warmed up, I am going to throw in the towel.

The solid couplers are excellent quality, probably too good for the amount of movement and expansion that can take place in three separate manifolds and carb setups. I have the carbs lined up within thousandths of an inch, but when they heat up and expand or cool down and contract, the previous hot or cold setting is not acceptable to the solid joints. Look at the picture above and you'll see what I mean.

I looked at my old twin setup and the center section with the bellcrank sits back about 1/8" from the centerline of the carb shafts and they never had a binding issue with the old style flex couplers, so I'm going to pull the solids and try the new (old style) flexible couplers that Jeff sent to me.

 

[LastDeadLast]

Paul,

Interesting. I'm in the middle of "re-aligning" my carbs/manifolds myself (along with getting the headers Jet Hotted) and I was thinking about using Palya's new solid couplers as well.

The biggest problem that I'm having is the manifold mounting holes don't have enough play to align...with or without the headers installed. I slightly enlarged the holes with a drill bit and it looks like things will line up... won't know for sure until the headers get back next week.

 

[Brosky]

More to follow after I install the folded couplers in the next few days to see if the problems go away. My carb shaft alignment is as good as it's ever gonna get, so this should fix the issues.

 

[Gordo]

Paul,

I'm guessing here but I'm assuming they worked correctly when cold and tend to bind up when hot? It would be helpful to me to know before I order some couplers. I can substitute couplers to account for the expansion/contraction factor.

Gordon

 

[Brosky]

Gordo,

I've been playing with this for over two weeks now, as my time allows. I am as meticulous and patient as any mechanic can be, given my experience and fact that I'm in no hurry to get any particular job done. With that being said, I'm going back to the flex couplers because a sticking throttle is not only dangerous, but causes wear on all of the shafts.

You just cannot compensate enough for the heating and cooling expansion and contraction of the metal(s), when using solid machined parts, made of an entirely different material. Perhaps a solid/flexible u-joint affair would work. I'll wait for the "films at 11".

The thermal expansion rates of a cast iron head, having three separate aluminum manifolds bolted to it, along with the heat coming up from the headers to the carbs and shafts all play a role in making this a poor candidate for solid couplers.

For what it's worth, I can make them work perfectly when either hot or cold, but the car does not remain in either condition permanently, so there is the problem.

 

[Brosky]

Well, the folded couplers are now in. Tomorrow will tell the tale. I still have a very slight sticking problem, but probably have to go back through and realign all of the carbs again, since I had the center unit off.

I can't say that I'll be unhappy when this annoying little project is finally put to bed and I can move on to the next endeavor.

I bought these neat little clamps to block off the fuel lines without damaging or crimping the lines and they work great. Made by Lisle Tool and sold at PepBoys. They are plastic with a rounded edge that mates against a round steel pin that is pushed down to shut of the fuel without damaging the rubber. I slid the lines back from the carbs and lowered them out of the way. Not a drop of fuel spilled anywhere.

Center carb is off and couplers are being swapped. I have to re-polish the shafts to remove the scratches when this is done.

These are the new couplers like TR6 Bill has on his. These are very stiff also, but not as bad as the solids.

Back together and just about show time.

One last tweak with the Synchrometer before locking down clamps. Tomorrow is another day and I may have to realign all of the carbs again. The front carb is now slightly sticking in the linkage, but I want to see what everything is like cold before moving anything around.

 

[Guest]

Paul, I see you straightened out your band clamp on your crossover hose. Man, that was bothering me. Hehehe.

 

[Guest]

Now I can see where some of those extra vacuum hoses are routed to. On my carbs, those are all either non-existent (2) or non-functional (1). That said, my three carbs are off of who-knows-what kind of car. When I bought this particular TR6 it had a set of DGV Webers on it, which I promptly sold. When I had carbs built for this triple setup, I contacted Gary Martin (at the suggestion of Richard Good) who just reached in his grab bag of ZS carbs and came up with my mis-matched set. This bothered me for a while (you would have to look close to see that one is different from the others) but Gary swore this wouldn't make a difference. He was right. Anyway, their ain't no thru-n-thru holes on my carbs where you have vacuum hoses.

 

[Brosky]

<div class="ubbcode-block"><div class="ubbcode-header">Quote:] This bothered me for a while (you would have to look close to see that one is different from the others) but Gary swore this wouldn't make a difference. He was right. Anyway, their ain't no thru-n-thru holes on my carbs where you have vacuum hoses.[/QUOTE]

Which begs the question; Could I eliminate all but one of these and get rid of the plumbing affair?

Yes, Bill, the alignment of the clamps was eating at me as well. After doing this little swap I also neatened up the vacuum hoses and used some nylon tie straps to get them all together going back to the canister. Thus my question about the elimination of two.

I'm going to try to realign the front carb at lunch, while everything is cold and run it after to see the results. Then I'll let it cool overnight and check everything again in the AM.

Do you have any additional throttle return springs added to yours, and if so, where and how? Now that this seems to be minimized and after I tweak the alignment once more to protect from any shaft wear, that would solve my problem if any slight bind was left.

But it seems a bit tricky as to where to connect it.

 

[Guest]

Paul, when I was using the OE-style throttle mechanism, indeed I did put a double spring on the throttle cross shaft arm. But now that I (we) have the cable mechanism, any additional spring would serve no purpose as obviously the cable is, well, flexible. I find that the three (one on each) throttle return springs are adequate for my throttle to return to idle. Now, maybe the jinx is on me, but lately I find that my choke is wanting to stick open. Have to play with it to get it at a reasonable level. Might need some graphite.