My swap to a 45mm SC throttle body continues to annoy me. This is not really an injection issue as even some HIF carbs need some special treatment for throttle cabling.
I have made a number of other changes along the way just to complicate things, but it all did work previously. I was trying to fix things that were marginally "broken."
This issue really has nothing to do with the throttle body as far as I can tell. It is an accelerator cable issue, maybe a cable alignment issue.
SC originally suggested using the MPi cable as they thought because I was using an MPi engine I must have an MPi. It is totally inappropriate and I abandoned it before we went to Oregon two years ago, too long, hits the bonnet and both ends of the cable are terminated.
I am using one of their cables which is supplied by the people who make their throttle bodies, AT Power(https://www.atpower.com/ (https://www.atpower.com/)). It worked fine for the 50 MM TB.
I have to be making a simple mistake. I never liked having the adjustable ferrule on the pedal end of the cable, but that is what they supply. I added a couple of Venhill(thanks for the tip) cable ends to make the curves as smooth as possible. I trimmed the cable as short as possible, making sure not to hit the bonnet and still have a smooth radius. I have tried several cable lengths. I added some shrink tubing to the cut cable ends to make sure they centered properly in the metal cable ends.
In this movie you can see that the mechanism sticks, yet the cable is not sticky and falls from the weight of the pedal when free. With no cable, the throttle returns to 0 all the time.
https://www.youtube.com/playlist?list=PLNWUxao2Iq7HsRWOL_yeIzjEL5G-26Bpo (https://www.youtube.com/playlist?list=PLNWUxao2Iq7HsRWOL_yeIzjEL5G-26Bpo)
The problem seems to be worse on the road. In the driveway, it will not stick all the time. On a drive, it will stick at the first stop sign. Give it a rev and it returns to 0 most of the time. Sometimes one or two strong revs are required to get it back to 0. I thought it was heat related, but I cannot confirm that.
A friend suggested I shorten the threaded portion of the Venhill cable end on the TB bracket to give the cable a longer untethered run to the throttle quadrant., which I have done. It seems to have improved things a bit.
But any other ideas are welcome.
It seems the slight dimensional changes of the inlet manifold and the throttle body have had some consequences I did not foresee...
Is there a throttle position sensor that is sticking?
I thought that might be the case. I swapped sensors with no change and this is a new throttle body with a new TPS and the issue remains.
Add an additional throttle return spring? Not heavy, but just enough to overcome whatever is causing the hangup? Could it be simple friction inside that radius tube?
I am looking at an extra spring. The later cars had one on the pedal. I am looking to see if the MK I pedal box will make this easy.
The cable slips easily when loose from the quadrant and falls from the weight of the pedal. I think I tweaked the cable bracket on the 50 mm TB to make a smoother transition, but with the position of the fuel rail and the revised filter location, there is no room to change anything.
I guess a spring pulling back on the acc pedal where the cable attaches could work - easy enough to try it
It looks to me like the turn radius of the throttle quadrant puts the cable at an angle going into the sleeve - causing possible rubbing.
My first inclination was to also suggest a mild return spring, but attached to the throttle quadrant to pull it back to zero.
If the cable angle into the sleeve at the TB is the issue, having the return spring on the pedal will leave the slack at the pedal and the cable may slip out of the slot in the pedal instead of fully returning the throttle to zero.
The other possibility would be stronger spring tension for the throttle quadrant itself is needed or the quadrant too tight on its shaft - not able to rotate freely enough for its spring to overcome the additional drag of the cable?
I adjusted the cable end at the bracket and it had helped.
There is a threaded hole in the quadrant that could be used for a spring, if it is at the right angle
The end of the outer cable needs to be all the way into hole on the firewall. You should be able to see the end of the cable looking from inside the cabin. The throttle pedal pulls the cable down as well as out, so it helps to have a chamfer on the hole in the outer cable.
Looking at your last picture, you can see the bare cable makes a slight bend toward the air filter between the end of the sleeve and the top of the throttle quadrant. As the cable pulls up, that bend will increase slightly and is likely the cause of the binding.
Having the end of the sleeve angle towards the air filter just a tiny bit would likely fix the problem; however, looking at some of the other pictures for how the cable has to route in there and is essentially touching the hard fuel connections, I don't think you have room to adjust the end of the bracket holding the end of the cable sleeve. A small return spring is likely best at this point.
I would see about mounting a small 'L' bracket on the bulkhead cross-member straight below that hole in the throttle quadrant and hook a small return spring between the two. As the quadrant rotates from the throttle cable pulling up, it will also pull up the return spring. Releasing the throttle, the spring will pull the quadrant back down.
Was looking on their website and they offer a 45 and 50mm throttle body. One for small bore and other for large bore?
For the 50 mm you would need a well worked head and matching exhaust, maybe 1380. The 50 mm has been on the car for about three years, seemed to overfuel no matter what adjustments I made. Hence the reason to try the 45 mm.
I did email SC to see if they had runinto this before.
Hmm. Well I'm curious to know how that works. I have a hot 1310.
Can you compare the profiles of the throttle quadrants?
If the quadrant from the 50mm TB is a tighter radius, it would be more in line with the end of the cable sleeve. If the quadrants could be swapped, that might also fix the problem.
I gave S.C. the specs of my setup at the start of this and they suggested the 50. I do not have a hot engine, mildly tuned head etc.
The original Rover setup is 48 mm, but that apples to oranges
Here is a little history on the evolution of the S.C. throttle body.
Silver version is early, a lot of hand machines parts
Cast grey version is about five years old
Black version is current
No parts except for injectors and TPS are interchangeable
Something else to check would be the alignment of the pedal and cable through the firewall hole, it is a bit fiddly but the pedal assembly has some wiggle room to get them aligned 100%, after removing the cable i check the alignment with a straight piece of wire or an appropriate drill bit.
Also years ago I changed a throttle cable on a Mini that was miss aligned and had worn a groove where it passes through the firewall which made the new throttle cable stick just like yours, I ended up drilling it out the next size and had no more sticking throttle cable issues.
If you add a return spring I would add it to the pedal rather than the throttle shaft. You could use a P clip on the pedal and drill a small hole in the pedal box to mount it.
There are a lot of suggestions above, but I'm curious about the interesting setup you've got at the throttle pedal and why you haven't gone for a known mini cable such as the C-AHT85 with a suitable casting which nestles within the recess of the pedal, and utilizes a NAM6983 retaining clip to hold the cable within the pedal's slotted nest. I made a very nice HIF cable from a new C-AHT85 by cutting it slightly shorter and fitting an HIF bracket-end to the shortened '85 sheath.
As you know, cable sheaths can be carefully trimmed shorter and cables can be cut and soldered to prevent fraying. I suspect that your current setup is fouling on the slotted pedal shaft.
Unfortunately that is the way the S.C. setup is designed. The throttle body quadrant is not machined to take an adjustable ferrule at that end. I have thought of modifying it, but the existing setup has worked fine for about 5000 miles, just not with this throttle body and the the other accommodations that have been made.
I never liked the way they did that, but I guess most modern cables are terminated at both ends with fittings.
I took the car for a drive around the neighborhood and it seems much better. It did not really stick, but was slow to return to idle at a couple of spots. It seems the longer throw from the quadrant to the Venhill curved/radiused cable end has helped.
The quadrant does have a 5 mm threaded hole which I may be able to use for an aux spring.
As I am stuck with the ferrule at the pedal end I would really like to find a ferrule with the shape in the photo. The narrow end would fit into the pedal bar and the larger section would be used to clamp onto the cable. The firewall passage is clear as the car was stripped when we had it painted a few years ago.
Is it possible to use a longer cable and get rid of the 90 degree bend at the firewall, maybe over the rocker cover similar to a regular Mini set up.
I started long and kept going shorter.
The cable bracket location means the cable points up at the bonnet. I had issues with the bonnet closing changing the shape of the cable loop and causing an idle change.
It was a real problem with the MPi throttle cable as it is much thicker and does not like to bend.
Something like the right hand drive throttle cable support on the valve cover bolt would probably help with a longer cable.
Simple lathe projects are fun. Could not find 3/8 brass rod so used aluminum. I can mail it to you if you want to try it.
I would love to try it!!!!
I sent a personal message, but i cannot tell if it went through.
tmsmith510@gmail
I got it. Will get mailed Monday.
This is great, thank you so much
Quote from: Willie_B on May 02, 2020, 01:52:20 PM
Simple lathe projects are fun. Could not find 3/8 brass rod so used aluminum. I can mail it to you if you want to try it.
Not trying to interfere or criticize - I like the concept - but if it were a tad longer a cotter pin on the backside could help hold it in place.
The same spring tension that holds the throttle closed should hold the tab in the slot on the pedal linkage....
But.....the OEM cable has a ball of sorts on the end which allows the pedal to pivot without binding up the cable, not sure it matters in such a limited amount of travel, but there it is......
That's sorta what I was thinking, along with reducing the likelihood of any eventual slack in the cable from causing it to jam or jump from the slot.
Quote from: John Gervais on May 02, 2020, 05:26:00 PM
Quote from: Willie_B on May 02, 2020, 01:52:20 PM
Simple lathe projects are fun. Could not find 3/8 brass rod so used aluminum. I can mail it to you if you want to try it.
Not trying to interfere or criticize - I like the concept - but if it were a tad longer a cotter pin on the backside could help hold it in place.
There is a bottom to the hole in the pedal. A ferrule cannot go all the way thru the arm for a clip on the rear side. But a good idea anyway.
Oh - :-[
And the use of this clip helps keep things in place.
(https://s3-us-west-1.amazonaws.com/sevenentimages/product_images/DCP7342-www.7ent.com.jpg)
Although I have not been using it with this setup up to this point.
And it may not work as it will need to be reversed.
Waiting for a spring to try, I ordered a short one from the twin setup.
I am wondering if I need to bend the plate towards the quadrant to get a better spring angle?
A Dremel and bench grinder do OK to make a spring attachment point. I order a used HIF abutment plate that I thought of using To attach the spring, but this might work.
I see what you mean about the angle, ideally you'd want a dead straight pull.
I don't know if there will be room when you put the fuel rails back on, but if you could very slightly straighten one of these two bends to get a straighter pull of the cable into its sleeve you may not need the return spring.
Quote from: MiniDave on May 06, 2020, 01:19:46 PM
I see what you mean about the angle, ideally you'd want a dead straight pull.
Agreed - I'd be tempted to try to either oval the hole and walk the cable over, or insert a shim (bronze washer) behind the throttle quadrant and use a longer screw to hold it all together.
If I go back to the cable end the TB is supplied with, then I might be able to bend the bracket. With t he Venhill there is no room.
The spring works, but as you approach WOT, it touches the pivot point.
Bending the spring attachment might help the angle as well
Does the arm have a torsional return spring? It may not be strong enough if it does. You may try to tweak it to increase the torsion or get a stronger one. From your video it won't take much increase to work.
There is a torsional spring. On the 50 mm TB there are six coils and strong return. I can't tell how many coils on this one as it is covered by the quadrant.
Quote from: tmsmini on May 06, 2020, 05:07:12 PM
There is a torsional spring. On the 50 mm TB there are six coils and strong return. I can't tell how many coils on this one as it is covered by the quadrant.
Is the 50 mm spring stronger than this one and will it fit on this one? The one you tried seems way too strong just to pull it back a few mm's. IMO.
The design of the quadrants is different on the versions I have.
I agree the spring is too strong and may cause issues either the throttle shaft eventually.
Still reviewing options
Bent the plate to get a better angle and reduced tension, still not convinced this is the way to go.
I will wait for the custom ferrule to arrive and try some other alternatives. The problem is that the sticking doesn't show up trying in the driveway all the time , I need to take it for a drive
Is it possible to elongate the hole in order to slide the cable further to the right?
In this photo, are you suggesting moving it to the right? Or down?
Only because there is a threaded hole in the quadrant at that point.
I am not sure I want to drill a hole in the quadrant yet.
It may only be the angle of the photo and video, but is the cable lined up with the cam or is it biased to the side?
Any chance of rotating the quadrant 180 deg. and coming up from the bottom with the cable? Would eliminate the loop fouling the bonnet.
Nicholas Upton looked into that on the original install with the 50 mm TB and because of the way the spring locating holes are machined, it was not possible. I have not taken the 45 mm apart to see if it is the same.
I am going to try a number of the ideas mentioned to see if I can sort this out. The custom ferrule should come today.
Didn't read through the whole post but watching that vid you could probably use a 2nd spring at the end of the arm going nearly straight down to that plate to snap it back without the less than stellar pivot point you have. Maybe two lighter tension springs vs 1 stiff....dunno, just spit balling.
Quote from: tmsmini on May 06, 2020, 05:07:12 PM
There is a torsional spring. On the 50 mm TB there are six coils and strong return. I can't tell how many coils on this one as it is covered by the quadrant.
I keep coming bck to the torsional spring. Is it possible to strengthen it by permanently by winding/unwinding it maybe 1/4 turn? make a new one with thicker wire? IMO the return spring would be the simplest solution.
None of this should be required as this is a system sold as a complete replacement. On the other hand I have made additional modifications and I am using a different intake manifold to make it fit better in a MK I engine bay.
I am going to start at the basics and replace my "replacements/modifications" where I can. If I can remove the adjustment to the air filter location and the filter still fits that will give me room to adjust the bracket that holds the cable end.
It is about 85 degrees and expected to hit and with the car in the driveway, it may wait until tomorrow to try somethings. Mail has not come yet.
I really appreciate all the suggestions and especially Willie for the ferrule!
Quote from: tmsmini on May 07, 2020, 05:20:31 PM
In this photo, are you suggesting moving it to the right? Or down?
Just my thoughts.
I do not know the specifics if the throttle shaft is bushed (I would assume and hope so) or is just turning in the body itself on your FI set up and it is the reason I suggested putting a small return spring on the accelerator pedal, this was the solution that Rover came up with on the MPI's the SPI's did not have this set up.
The problem I have run into several times over the years working on SU's is when owners had idle problems and decided to use a bigger spring to solve it on the Carb end, this resulted in increased wear mainly noticeable on HS2 and HS4 set ups.
Volvo had a mechanical linkage on their twin carbed 4 cylinders with way overrated return springs that would wear a set of carbs out in less than 30k.
The "bird cage" spring you are using is the same as BMC used in a set of 3 on Mini Coopers and S's and is not a powerful spring but will wear out a set of HS2's.
I am not saying it will wear out your throttle shaft like I said I don't know the specifics but I myself would rather risk a cheap throttle pedal assembly than that expensive FI set up.
The only other thing I would look into is getting the cable to run straight from the bulkhead instead of the 90 degree turn it currently has.
Great build btw and Good luck I hope you get it sorted.
I was planning to start back at the beginning. I got side lined by a MPI sedan heater valve that need replacing.
I got around to removing the TB and installed one of the cable ends.
It does not line up very well.
That is definitely a "Houston, we have a problem ..." type arrangement.
I imagine it is not any better when trying to use the 90* adapter you had on previously.
Actually it is better, as the bend starts early enough to clear the fuel rail.
I will remove one of the spacers I added for the air filter. Then I will see if that allows me to bend or tweak the bracket to clear the fuel rail and get a straighter shot at the quadrant.
The things I have done to fix things that may have made things worse
- Modified plate for air filter to offset it away from the firewall
- added spacers to move filter away from fire wall
- used AN fittings on hoses which increased the diameter of the fitting
- added fixed radius cable ends
Is there enough space under the bonnet to 'extend and/or invert the bracket' such that the bent cable end can be situated above the fuel rail instead of under it?
It might be possible, but it seems one change requires another.
With some bending and reorientation, I now have what the picture shows. Just a question of weather it will fit back in. It seems the quadrant is not circular.
The more I adjusted things to get the best angle at part throttle to closed throttle, the greater the angle became at WOT.
A bicycle item that might work. Instead of the curved metal pipe.
https://www.ebay.com/itm/caramba-cable-guide-v-brake-derailleur-roller-noodle-rollamajig-vintage-retro/312871363509?hash=item48d89623b5:m:m5JzfOVswOBdyiZrg4AGD5Q
I think I will just install one of these. Canepa offers rebuild service.
(https://scontent-sjc3-1.xx.fbcdn.net/v/t1.0-9/97274753_2969291343106903_1152948240778264576_o.jpg?_nc_cat=1&_nc_sid=9e2e56&_nc_ohc=4aEaKFa_B_0AX9KI4Bb&_nc_ht=scontent-sjc3-1.xx&oh=5afb53dafa3b4ee08ca7aa07859ee014&oe=5EE0EEE1)
https://www.facebook.com/canepamotorsport/ (https://www.facebook.com/canepamotorsport/)
Wonder how much one of those weighs?
Surprised to see plastic fuel injection lines instead of metal.....
Looks like things are working, at least in the drive way. The cable offset in the cable end is more towards WOT, but the spring pressure is greater at that point.
And the air filter goes on and off easily.
I need to do a drive to really test it.
Wiille's ferrule worked great. I used the clip on the firewall side.
So this picture is for really for Willie.
He gets his pick of any of these spare parts.
Bunch of stuff, valve cover, instrument pods, distributors A+, fans, HS2 elbows, sintered rockers, oil filter housing and pipe, etc.
Thanks Willie!!!!
Quote
Just my thoughts.
I do not know the specifics if the throttle shaft is bushed (I would assume and hope so) or is just turning in the body itself on your FI set up and it is the reason I suggested putting a small return spring on the accelerator pedal, this was the solution that Rover came up with on the MPI's the SPI's did not have this set up.
The problem I have run into several times over the years working on SU's is when owners had idle problems and decided to use a bigger spring to solve it on the Carb end, this resulted in increased wear mainly noticeable on HS2 and HS4 set ups.
Volvo had a mechanical linkage on their twin carbed 4 cylinders with way overrated return springs that would wear a set of carbs out in less than 30k.
The "bird cage" spring you are using is the same as BMC used in a set of 3 on Mini Coopers and S's and is not a powerful spring but will wear out a set of HS2's.
I am not saying it will wear out your throttle shaft like I said I don't know the specifics but I myself would rather risk a cheap throttle pedal assembly than that expensive FI set up.
The only other thing I would look into is getting the cable to run straight from the bulkhead instead of the 90 degree turn it currently has.
Great build btw and Good luck I hope you get it sorted.
Solution is not in hand, but I wanted to respond to this.
This version of the TB has a unique design, "shaftless."
(http://www.tmsmini.com/cooper/images/IMG_3200.jpg)
I am sure the side loading of the extra spring would eventually cause an issue.
I had a "half of Volvo HIF 44" on another engine and someone had engineered an extra spring solution. I had it rebuilt by Joe Curto and he said it was more trouble than it was worth to replace the existing linkage with Mini style linkage. All it needed was a proper spring replacement.
With the latest attempt I am running the cable with out the curved end at the firewall. This is a left hand drive car, so the cable can come close to the exhaust which is why I tried the curved cable end.
So with some confidence that yesterday's changes seemed to work, I had my wife drive while I attempted to update the fuel MAP on the fly.
It was working pretty good, but it is hard to hold a station while driving. Other cars get in the way, etc.
But after 15 minutes or so the throttle was sticking again.
So for today attempt I took a 30 inch standard cable and cut one end off. This way I could use the brass end with the standard ferule on the firewall side.
(http://www.tmsmini.com/cooper/images/IMG_3193.jpg)
I did have to remove a half inch or so of the sheath as it would not fit in the adjustable cable end.
(http://www.tmsmini.com/cooper/images/IMG_3195.jpg)
With the extra length and to try to keep the cable away from the exhaust manifold(LHD car), I looped it through the master cylinder plate. Actually this is the way I originally had it with the 50 mm TB.
(http://www.tmsmini.com/cooper/images/IMG_3196.jpg)
Bad picture but you can see the cable comes straight out of the firewall and clears the manifold to makes its turn towards the master cylinder plate.
(http://www.tmsmini.com/cooper/images/IMG_3197.jpg)
(http://www.tmsmini.com/cooper/images/IMG_3198.jpg)
The cable barely sits below the bonnet.
(http://www.tmsmini.com/cooper/images/IMG_3199.jpg)
I was thinking of trying a valve cover bracket to hold it in place, like RHD cars with the longer cable. It appears the master cylinder plate holds things in a large radius loop.
With Willie's custom ferrule, it makes changing the cable petty easy.
But you still have to adjust the cable, reset the TPS, adjust idle, adjust lambda...
I did order a pedal spring as a back though.
All of this should not be necessary with a kit design to be used in MK I cars, unless I am missing something.
If you could twist the notched end of the cable bracket, perhaps the cable could sit under the fuel rail (on the side closest to the bonnet rather than the firewall side). As it sits now, I suspect that the cable will develop a kink smack-dab above the adjuster.
Thanks for the reply.
It seems like you have tried just about every way to cure this issue.
As it is now sticking after the car has been driven for a while maybe it is a heat issue which i would assume would be affecting the throttle body area of the cable.
Maybe a heat shield or remove the tb and heat it up to see if the linkage in the body itself is sticking.
Like I said before you need to chamfer the hole in the ferrule in the firewall. The pedal pulls down on the cable as well as out and the drag of the cable on a sharp edge causes the restriction.
I used a hand reamer to do this on all the cable ends I have tried to far.
I need to go for the longer drive to test it. I have repositioned the cable within the master cylinder bracket, so the cable does not interfere with the bonnet. It almost touches the block as it comes out of the firewall before turning.
It looks like it has stopped raining, so I may go for a drive.
I'm envisioning something like this, as it would give the cable arc enough to 'flow' under the bonnet without snaking (baggy) and too close to the engine, though in my modified image I cannot rotate the cable adjuster (copied & pasted) counter-clockwise to line up to the exposed cable or black cable sheath. Imagine it to be rotated 25° - 30° (+/-) counter clockwise to clear the fuel rail.
I took a few drives and the issue was still present intermittently.
I do think I need to look at the throttle body itself, as I can touch the cable when it is stuck and it is loose. I think this means even a pedal spring wont help.
I could try bending the bracket at some other angles , but a problem is getting parts from S.C. I am afraid if I bend things too much I won't be able to get a replacement.
This is such a simple issue, but I seem incapable of resolving it.
I also need to get it fully mapped as there are some settings that "street" mapping can't help with.
Car also needs alignment, but I don't want to take it in with a sticking throttle.
After thinking about it I don't think a spring on the pedal is the right answer, as it pulls the wrong direction. My bad....
If the problem was with the cable, it is possible that the pedal spring would help.
This is how the pedal on the MPi uses a spring, I am guessing SPi are similar.
My box from Sommerford should come today and it has a pedal spring. I will give that a try.
I did hear back from SC and they are asking if it sticks with no cable. I cannot seem to get it to do that, but if heat affect it, by the time I open the hood and get a camera setup, take the cable off, it does not stick.
[youtube width=600]https://youtu.be/kuB-ya38Dmc[/youtube]
[youtube width=600]https://youtu.be/emxc-QWXmAI[/youtube]
I added the pedal spring, but my back is not happy.
I will have to wait a few days to test as we are headed to my daughter's.
Unless I recover enough after dinner.
While it seems like that would help if the weight of the pedal was holding it open, in the video you posted that really didn't seem to be the case.... but if it works then.......Yay!
Yes, I certainly don't understand the dynamics of what is happening.
I went for a 15 minute drive and no sticking at all. I need to a longer test, but it seems good.
A little more pedal pressure required that could be bothersome on a long trip, but I can adjust it a to a certain extent. I don't remember the MPI requiring as much pressure.
Now on to other things needing to be done before MMW!
Good news, after a 50 minute drive on surface streets with lots of stops and a few places to get up to 60 MPH, I had no sticking of the TB.
It also seems the seat of the pants "street" mapping worked pretty well, as in closed loop, most of the closed loop offsets were only 1 or 2 percentage points.
There are some flat spots and other issues at oddball fringe areas of the map.
I would like to adjust the idle up a little bit. It is idling well at 900 RPM which the 50 MM TB never did. I am concerned that in the Fall, there could be issues on cold mornings.
But that means recalibrating after making the adjustment.
You have to recalibrate just for changing the idle?
Doesn't it have a simple point and click setting in the software?
No, it is an iterative process.
The TPS needs to know where zero is and you just changed it.
The fuel map is based on TPS and RPM, you just changed it.
You may also have moved the target AFR.
It is pretty straightforward, just a little back and forth.
Once you get it set, it is nice to not have to change it.
But if you try to fix things that are not necessarily broken, but just a little off...
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