throttle cable vs mechanical linkage

[JJK]

This may be asking a question with various opinions, but wanted to hear some feedback from folks who have experienced both. I am putting together the Wilwood pedal box and have read a lot about the questionable quality of the supplied throttle cable. Seems like a lot of folks recommend switching to the Lokar cable with appropriate cable mounting kit to the throttle or a mechanical throttle linkage like Forte sells. The mechanical linkage is about 2x the price of the Lokar and mounting kit, is the mechanical worth the extra $100ish?
Also, other than aesthetics, is there any functional benefit to the RT or Breeze accelerator pedal compared to the one from the kit? Thanks

[rich grsc]

Had both, the mechanical is by far the best. No idea why it's so expensive. I'm a "I can do that myself" kinda guy, so I sourced everything from McMaster Carr. It cost about half of Forte's

[Papa]

I haven't used a mechanical linkage so I can't compare. What I can offer is that if you go with a cable, get a high-quality one like a Lokar. There is a huge difference in a cheap vs. good cable.

[Sdonnel]

I did the mechanical upgrade on my first car and incorporated into the build of my second car. It is so much smoother than a cable. I went with the Forte offering, as he has everything you need in one box. Sure it's more money, but the convenience of knowing you have everything is why I chose him again.

Scott

[RJD]

Also, other than aesthetics, is there any functional benefit to the RT or Breeze accelerator pedal compared to the one from the kit? Thanks

The RT throttle pedal clamps to the 3/4” frame tube using a set screw for easy adjustment fore and aft. No drilling needed.

[J R Jones]

Part quality is important and rewarding especially when safety is an issue.
A link-rod linkage is subject to actuating with engine movement on the mounts. A failed engine mount can cause the linkage to pull the throttle open.
A cable throttle assembly moves with the engine and does not inadvertently open the throttle with engine movement.

The geometry difference is a somewhat less significant issue.
A link rod throttle action is not linear. The throttle opens faster at idle and WOT than in the middle. Swing arc of a lever.
A cable throttle wraps around the sector wheel on the throttle shaft and the opening rate is consistent throughout the travel.
jim

[Jim1855]

My take. FYI, I've driven a Mk3 (little 5.0) with a very poorly installed cable and a Mk4 (big 351/462w) with a properly installed Forte's kit. The Mk4 was tractable, easily controlled and great to drive, the Mk3 was simply horrible, but it was a very poor installation that needed major repairs. My Mk4 isn't even close to needing throttle linkage but I will be doing a mechanical system and have had mechanical linkage in previous cars.

In another thread CraigS mentioned the adjustable leverage of the mechanical system. This is perhaps one of the greatest benefits of the system. By adjusting the position (up/down) on the two arms you can change how fast the carb comes on from a given throttle pedal push. This provides much greater control on how fast you get to full throttle. In the motorcycle world this was called "quick turn", great fun for an accomplished rider, not so much for normal folks.

Control comes from being able to incrementally apply the throttle, moderation perhaps, too fast and your response is jerky and with a very narrow range, too slow and you may not get full throttle. I believe that it's best to have the throttle a little slow acting, as you can push your foot down faster than you really need to.

I haven't seen an adjustable leverage arm linkage for the cable systems, might be available but I haven't heard about it. The Lokar or upgraded cable makes things smoother, a significant benefit but it still doesn't change the ratios.

Jim

[Bill_VA]

Been there, done both. First 10 years with cables (notice the plural form of cable). They were a major pain and I even used the more expensive stainless steel covered Lokar cables, but they always ended up binding. Tried graphite lube which worked for a while, but eventually had to replace the cable again. There was always a feeling of slop in the pedal with the cable.

Then I upgraded to Forte's mechanical setup. NIGHT AND DAY!!! Oh, how wonderful it feels. Feels like your foot is directly attached to the throttle plate of the carb (or throttle body).

Shameless plug for FFmetal.com: The thicker firewalls, both as a direct replacement for the FFR unit or the option to extend the firewall another 1.5" to give more room for heaters and such, is perfect for attaching the mechanical linkage mount points. These firewalls are over twice the thickness at .090.

[Fman]

+1 Forte, you pay more than sourcing yourself but time is worth something and everything he sends you works. I was told the only con to mechanical linkage vs. cable is if a motor mount ever broke it could possibly cause your throttle to stick open. Probably slim to none chance of it ever happening. So far I have really been happy with Mike's set up, no regrets at this point. It also work very well with the Russ Thompson adjustable throttle pedal.

http://www.norcal-cobras.com/store/russ_garage/mk3/mk3ftp.html

[Nigel Allen]

Maybe I'm not qualified to comment, as I have a 'drive by wire' throttle, but I thought it worthwhile as a safety point.

A few years ago at a national cobra meet, a cobra replica suffered a wide open throttle during an autocross type of event. The driver was unable to react in time and the car went through a fence. It was bad. Despite the driver wearing a helmet, he lost some teeth amongst other injuries. The car suffered just as badly and was likely a write off.
Inspection revealed that the throttle lever had jammed against the underside of the air cleaner. This hadn't been a problem earlier. However, at some stage the air cleaner had been off for maintenance and when replaced, had been tightened further. This resulted in the underside of the air cleaner sitting lower than previous. The gun was loaded. Once the throttle was pressed fully the lever made contact with the air cleaner and could not self return.

Take away
- Always double check your design / work.
- like a plane, check your controls for operation, before start up.
- For most of us, our reaction times aren't what they used to be.

Stay safe

[jrcuz]

I built my mechanical linkage from parts Edward B put together on one of his earlier roadster builds. I can't remember which build. Maybe he will see this and jump in with the info. I also used the ffmetal firewall forward piece since it is much stronger than the F5 firewall. I also used the Russ Thompson (forum vendor) throttle pedal, I highly recommend it.
JR

[Scott L]

After several cables I switched to mechanical. Nice throttle feel and control. I would not go back.

[nucjd19]

Another Forte mechanical user. I installed mine through the 2" frame placing it lower in the setup helping with clearance and stiffness. I had to source longer bolts but thanks to the site it was no biggie.
https://thefactoryfiveforum.com/attachment.php?attachmentid=149563&d=1623884160

[J R Jones]

Maybe I'm not qualified to comment, as I have a 'drive by wire' throttle, but I thought it worthwhile as a safety point.

A few years ago at a national cobra meet, a cobra replica suffered a wide open throttle during an autocross type of event. The driver was unable to react in time and the car went through a fence. It was bad. Despite the driver wearing a helmet, he lost some teeth amongst other injuries. The car suffered just as badly and was likely a write off.
Inspection revealed that the throttle lever had jammed against the underside of the air cleaner. This hadn't been a problem earlier. However, at some stage the air cleaner had been off for maintenance and when replaced, had been tightened further. This resulted in the underside of the air cleaner sitting lower than previous. The gun was loaded. Once the throttle was pressed fully the lever made contact with the air cleaner and could not self return.

Take away
- Always double check your design / work.
- like a plane, check your controls for operation, before start up.
- For most of us, our reaction times aren't what they used to be.

Stay safe

As you mentioned drive by wire is a whole different ball game. I have Lexus power in my SSK street rod and it is a hybrid throttle. Cable actuated but over-ridden with electronic control.
I have never had a cable problem but my Toyota MR2 throttle cable is fraying. Feeding a new wire from back to front will be a challenge. In all cases routing is critical and bends lead to problems.
In the case of motorcycles, for several years cables have been push-pull for issues like your replica incident. One cable pulls the throttle open and one cable pulls it closed.
jim

[GFX2043mtu]

1000% Forte mechanical linkage bolted to a RT gas pedal assembly. It's as good as it comes, 100% bullet proof and simply can not fail or stick. Only down fall is it's a bit expensive.

[CDXXVII]

Mechanical linkage made a big difference in throttle response. With the cable the throttle felt like an on/off switch. With the high performance clutch it make the roadster hard to drive.

With the mechanical linkage everything is adjustable. You can increase the travel ratio and also how the throttle comes on depending on how you set up the linkage.

I can't say that I saved any money building it myself but I enjoyed the process and I love the look. The pedal started out as a Russ Thompson setup but I ended up just keeping the mount and pivot.


https://thefactoryfiveforum.com/attachment.php?attachmentid=176699&d=1586715668

https://thefactoryfiveforum.com/attachment.php?attachmentid=176700&d=1544244801

https://thefactoryfiveforum.com/attachment.php?attachmentid=176701&d=1588277903

[Badfish]

When I went carb’d, I did the fab’d linkage based on guidance from the forums. Couldn’t be happier with the look and the feel.

https://i.imgur.com/aaqGat9.jpg

[edwardb]

Since it was mentioned earlier in this thread, this is the post I did over eight years ago (could it really be that long??) with a homebrew mechanical throttle linkage. This was before Forte was offering one. I haven't checked current prices or availability. But suspect it's a cheaper and maybe easier option. Note also with a RT accelerator pedal and a thicker firewall that I fabricated myself. https://thefactoryfiveforum.com/showthread.php?8296-Mk4-7750-Build-Progress-Update&p=137426&viewfull=1#post137426. It worked perfectly for the several years I had the car. Haven't heard from the new owner for some time. But no reason to think it's still not going strong. Properly installed and checked no reason for this to fail or get hung up on anything. Everything is free and clear.

[CraigS]

I had cables for years and finally decided to bite the bullet and go mechanical. I had my throttle return spring on the carb lever so it stayed the same cable to linkage. My first test drive I got 2 blocks away and had to go back to the garage. The effort needed to move the pedal was so low that every little bump changed my throttle position. I couldn't keep a steady speed no matter how hard I tried. The quick fix was doubling the throttle spring w/ a second one. I will never ever have a cable throttle again. I also love the RT pedal. Once you start driving you will find that it is really nice to be able to customize you driving position. The RT pedal allows that almost infinitely.

[ggunter]

FFR cable, OK. Lokar cable, better. Forte mechanical, BEST. I originally had the Holley Sniper, and with the FFR cable, and no progressive linkage on the sniper, it was very difficult to modulate the throttle. Seemed like all or nothing. Very sticky. Lokar was smoother and better but still difficult to modulate the Sniper. With the mechanical Forte linkage, there is almost infinite adjustment for leverage, and it is smooth as silk.

[Theshandman]

I went with a Lokar cable. Added a bracket to the Sniper throttle assy with three linkage attachment points. Currently its in the "most responsive" position.
176707

[Papa]

I went with a Lokar cable. Added a bracket to the Sniper throttle assy with three linkage attachment points. Currently its in the "most responsive" position.
176707

This is really the trick to get the Sniper to work well in terms of throttle feel. The typical linkage geometries have the cable pulling at a nearly horizontal angle, which is what makes it feel hard initially and then snap to open very quickly. By creating more of an angle at the cable to linkage connection, it eases the initial force required to get the linkage to move and smooths that transition. It's amazing what just a few degrees of angle does to change the feel.

[boat737]

I built my mechanical linkage from parts Edward B put together on one of his earlier roadster builds. I can't remember which build. Maybe he will see this and jump in with the info. I also used the ffmetal firewall forward piece since it is much stronger than the F5 firewall. I also used the Russ Thompson (forum vendor) throttle pedal, I highly recommend it.
JR


Since it was mentioned earlier in this thread, this is the post I did over eight years ago (could it really be that long??) with a homebrew mechanical throttle linkage. This was before Forte was offering one. I haven't checked current prices or availability. But suspect it's a cheaper and maybe easier option. Note also with a RT accelerator pedal and a thicker firewall that I fabricated myself. https://thefactoryfiveforum.com/showthread.php?8296-Mk4-7750-Build-Progress-Update&p=137426&viewfull=1#post137426. It worked perfectly for the several years I had the car. Haven't heard from the new owner for some time. But no reason to think it's still not going strong. Properly installed and checked no reason for this to fail or get hung up on anything. Everything is free and clear.

I also shamelessly copied eduardb's design and materials list. (Sorry Paul.) It works perfectly. It's instantaneous and precise. No binding, surging, or unexpected responses. I mounted it in the 2x2 on the lower edge of the firewall.

[JJK]

Thank you all. As usual, a ton of great information.

[Dave Tabor]

any greater chance of the mechanical linkage binding up- either to full or no throttle vs. a cable setup?

Dave
Gen III Coupe #17
16,000+ miles

[skidd]

Everytime I start to plan a swap to a mechanical linkage, I always talk myself out of it. My cable setup just works quite well. No binding, smooth and not heavy.

Now, I attribute this to 3 things.
3. Enormous effort spent to align the cable so the pedal pulls it straight back, and not rubbing on an angle.
2. Custom pedal with a pillow-block bearing for smooth operation.
#1. My carb is reversed and the linkage pulles on the passenger side. My throttle cable makes a nice easy single 180 degree bend from the foot box, over to the passenger side.

My 02c

[CraigS]

skidd, all of that definitely helps. It is also a good idea to insulate the cable from the header heat.

[Theshandman]

...the throttle lever had jammed against the underside of the air cleaner.
The instructors at the build school cautioned us about a rare potential for the kit-supplied throttle pedal arm to get jammed on a frame member at WOT position and demonstrated how that could happen. They suggested we might want to look at the Russ Thompson pedal (http://www.norcal-cobras.com/store/russ_garage/mk3/mk3ftp.html) to circumvent that might-could-happen situation. I got one and its a good solution. However, to alleviate the bit of lateral slop at the pedal pivot as supplied, I bored the pivot, installed a bushing (brass) and a properly sized SS shank bolt and nylon spacers to get it right. Maybe some overkill there but now its solid laterally with no wiggle; it just feels better under my foot.

[Papa]

The instructors at the build school cautioned us about a rare potential for the kit-supplied throttle pedal arm to get jammed on a frame member at WOT position and demonstrated how that could happen. They suggested we might want to look at the Russ Thompson pedal to circumvent that might-could-happen situation. I got one and its a good solution. However, to alleviate the bit of lateral slop at the pedal pivot as supplied, I bored the pivot, installed a bushing (brass) and a properly sized SS shank bolt and nylon spacers to get it right. Maybe some overkill there but now its solid laterally with no wiggle; it just feels better under my foot.

When I was redoing my EFI this last summer, I replaced the FFR throttle pedal with the Russ Thompson pedal (purchased through Breeze). It is a very nice upgrade!

https://thefactoryfiveforum.com/attachment.php?attachmentid=167934&d=1654871624

You can get it with the pad that matches the Wilwood pedal pads or with the rubber gromets if you prefer.

[J R Jones]

I went with a Lokar cable. Added a bracket to the Sniper throttle assy with three linkage attachment points. Currently its in the "most responsive" position.
176707

I have worked exclusively with OEM throttle cables in motorcycle, marine and automotive applications. I have never seen a cable pulling a lever before this photo of the Lokar parts. This is engineering for convenience not function.
As I mentioned previously, OEM cable systems actuate the throttle with a sector wheel and the cable pulls from idle to WOT at a constant radius and turn rate. Having not had to add this technology to an induction system, I do not have an aftermarket part to suggest; OEM salvage?
The picture is my 1929 Mercedes SSK with Lexus power.
jim

176765

[Papa]

I have worked exclusively with OEM throttle cables in motorcycle, marine and automotive applications. I have never seen a cable pulling a lever before this photo of the Lokar parts. This is engineering for convenience not function.
As I mentioned previously, OEM cable systems actuate the throttle with a sector wheel and the cable pulls from idle to WOT at a constant radius and turn rate. Having not had to add this technology to an induction system, I do not have an aftermarket part to suggest; OEM salvage?
The picture is my 1929 Mercedes SSK with Lexus power.
jim

176754

Jim,

The Sniper is not OEM on any application I know of, so the geometry of the cable connection can be less than optimal depending on any number of variables. Holley makes a lever and recommends it to eliminate the condition described above. I can say from experience, that it works well.

https://www.amazon.com/Holley-Sniper-SNIPER-THROTTLE-EXTENSION/dp/B07WN2SPHN/ref=asc_df_B07WN2SPHN/?tag=hyprod-20&linkCode=df0&hvadid=434795592233&hvpos=&hvnetw=g&hvrand=2925345756104362578&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9028739&hvtargid=pla-911549092440&psc=1&tag=&ref=&adgrpid=101305226135&hvpone=&hvptwo=&hvadid=434795592233&hvpos=&hvnetw=g&hvrand=2925345756104362578&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9028739&hvtargid=pla-911549092440

Dave

[burchfieldb]

Since it was mentioned earlier in this thread, this is the post I did over eight years ago (could it really be that long??) with a homebrew mechanical throttle linkage. This was before Forte was offering one. I haven't checked current prices or availability. But suspect it's a cheaper and maybe easier option. Note also with a RT accelerator pedal and a thicker firewall that I fabricated myself. https://thefactoryfiveforum.com/showthread.php?8296-Mk4-7750-Build-Progress-Update&p=137426&viewfull=1#post137426. It worked perfectly for the several years I had the car. Haven't heard from the new owner for some time. But no reason to think it's still not going strong. Properly installed and checked no reason for this to fail or get hung up on anything. Everything is free and clear.

Looks like the current going rate for Paul's is about $300. Anyone know what the cost would be from Forte?

[65 Cobra Dude]

$194.00 https://fortesparts.com/product/mechanical-throttle-linkage-kit/

Henry

[J R Jones]

I have worked exclusively with OEM throttle cables in motorcycle, marine and automotive applications. I have never seen a cable pulling a lever before this photo of the Lokar parts. This is engineering for convenience not function.
As I mentioned previously, OEM cable systems actuate the throttle with a sector wheel and the cable pulls from idle to WOT at a constant radius and turn rate. Having not had to add this technology to an induction system, I do not have an aftermarket part to suggest; OEM salvage?
The picture is my 1929 Mercedes SSK with Lexus power.
jim

176765

FFR seems to have blocked my previous photo, maybe non FFR photos are verboten

I have a Studebaker Avanti body on a Corvette C4 chassis that is getting an LS engine. The original L98 TPI is also a sector equipped throttle body as (maybe) pictured.
jim

176766

[Papa]

I found this for reference:

https://thefactoryfiveforum.com/attachment.php?attachmentid=176769&d=1671057303

[Scott Zackowski]

Another vote for Mechanical Throttle and RT pedal!

At least in my carbed 408W it made all the difference in the world for throttle control and feel. Worth every penny. I originally tried the cable throttle and did not like the feel.
Throttle control is very important to the safety and driving experience in these cars.

[burchfieldb]

$194.00 https://fortesparts.com/product/mechanical-throttle-linkage-kit/

Henry

For anyone looking to purchase one, I talked with Mike yesterday and order one, he said the one for the coupe is $300, but this includes the throttle pedal. He said he could not see it working any other way.

[Namrups]

I recently installed Mikes linkage in my coupe. I love it. Simple installation and works like a dream.
https://thefactoryfiveforum.com/attachment.php?attachmentid=176733&d=1670966923
https://thefactoryfiveforum.com/attachment.php?attachmentid=176688&d=1670878281

[rponfick]

skidd, I did the same thing. Funny that the carb does not know it is on backwards. But, I forgot and kept dribbling fuel in after car sitting awhile into the front carb opening (secondaries), instead of the back opening (primary side). But, I am a little old.
Ralph