Engine Throttle Question

[Skykingrob]

I have a 91 Prevost LeMirage XL over the road coach. It had a lower drivers floor and I raised it to make a level floor with the rest of the coach. In order to make the throttle linkage long enough, I welded a 9" piece of 1/4" rod onto the original throttle linkage (the part from the foot pedal to the throttle cable), which is the same amount I raised the drivers floor. Problem is, when I push the throttle pedal all the way to the stop, the engine revs but just enough to make the coach creep along maybe 1-2 mph on level ground. I don't have a tach I so can't tell you what the max rpm is. If the coach needs to go up a hill, forget it, it just won't move even with the throttle all the way to the stop. I called Prevost thinking maybe they could tell me the length of the throttle linkage for the motorhome version, which is a 9" raised driver floor, like I converted mine to from the over the road that I had. He searched and said both versions are the same length in the factory manual. Apparently, the way Prevost solved the raised driver floor to keep the linkage the same length for both versions was to move the pivot point for the throttle cable to a higher spot. Unfortunately, I can't do that. So the question is, is there an adjustment on the cable to compensate or do I just have to trial and error the length I need to weld in place until I get it right. If there is an adjustment, how do I do it? If I don't have a tach, is there something else to use to set max rpms with throttle cable at the stop. I have a mechanical 8V92 TA, with a mechanical throttle cable.

Rob
91 Prevost LeMirage XL
Missouri

[robertglines1]

I have a 89 with 8v92....will look in the manual tomorrow ,a little late tonight and see what it says.You said you have a manual throttle cable??? was that original??

[luvrbus]

Rob,the 2 people I know that raised the floor  on a XL and Eagles used a air throttle that could be a choice for you, don't worry about the rpms open the throttle to full postion and the governor will control that part.Make sure your cable is pushing and not pulling


good luck

[Utahclaimjumper]

Also hydraulic throttles work very well.>>>Dan

[bevans6]

Have you checked to see if the engine will rev up  if you work the throttle lever on the engine itself?  Have you observed full movement of the engine lever when you depress the throttle pedal at the front?  You need to decide if you have an engine end problem or a front end problem. 

Brian

[robertglines1]

Rob ..Checked the prevost book and all they had was the info on the electronic foot pedal adjustment and nothing else...sorry the other guys prob.have more insight than me...as far as length disconnect the rod pull the pedal to idle position.start engine and make sure it is at idle then measure the length the rod should be at a idle.     

[Skykingrob]

 Hi Guys
Yes, I have moved the throttle arm on top of the engine and it does rev up, considerably more than with the foot feet which makes me suspicious that the cable is to long and with the addition of 9" of 1/4 rod, makes me think I added to much. That is why I was hoping I could "adjust" out the difference rather than rewelding the rod. Mechanics is not my forte, so doing an air throttle, will require a mechanic unless someone is willing to "walk" me through it as I can follow directions pretty well.
No, I have not observed full movement of the throttle lever from depressing the foot pedal as I am the only here. I will have to ask a neighbor to help.

Rob
91 LeMirage XL
Missouri

[bevans6]

Engine off, brick on throttle, measure before and after!  No need for no stinking neighbour!  Although they do help a lot...

your cable is probably still right, since from what you've described you didn't move the throttle pivot and the cable would be running back from that pivot point.  Can you see the pivot, or is it now obscured?  maybe disconnect the pedal from the linkage and see if by moving your extension rod by itself you can see any slack.

Good luck!

[luvrbus]

Rob, if you are asking if you can move the throttle arm on the governor housing for adjustment yes you can if it is splines and not keyed

good luck

[zubzub]

seems like standard "scratch your head and work it out" stuff.  Since you had the ability to raise the floor you have the ability to adjust the linkage extension to spec.  I usually work on my bus alone so yeah the brick on the pedal thing is part of the deal.  Look for total throw of the cable and measure front and back, you'll work it out.

[muddog16]

Rob, I raised that floor also.......but I'm installing a air throttle,  after looking at the route taken under the drivers floor....i think there was probably enough cable to just move the "L" bracket and pivot triangle up under the floor giving you plenty cable without adding to you're cable.   I'm not sure how much difference there is between our model years.....

[muddog16]

I keep changing my mind..........I do have an idea.........the link coming from the pivot triangle to the bottom of the throttle pedal.......you might be able to make you're adjustments there.......but you would have to cut the cable and put it back to the orginal length, then making adjustments all at the drivers end...!   Good luck!!!

[bevans6]

btw, when you are checking things I would make sure the top of that triangle pivot piece is in line with the cable exactly the way it's shown in the picture.  that will make the leverages correct to get correct throttle lever movement.  Those angles are important when your are designing a throttle linkage, and I've done enough of them wrong on race cars to know! 

Brian

[Skykingrob]

Hi Pat and All
In Pat's picture, which is exactly what I have in my 91, I welded in 9" (same as the 9" of driver platform raise) of 1/4" rod where Pat has marked "make adjustment here". The triangle pivot is undisturbed from the factory design and the throttle cable is original as well, I did not add to the cable, it is factory length. So in essence, I did make the adjustment where Pat said to make it but it seems like 9" is to much.
The triangle pivot is visible from the spare tire wheel well behind the front bumper. I just can't see all the push rod from the top backside of the footfeet to where it attaches to the traingle pivot except for both ends.
Bevan, I had not thought of the brick, good idea. But not sure I get what you mean by "measure before and after the brick. Can you be more specific in your instructions, please.

Rob
91 Prevost LeMirage XL
Missouri

[Adarian]

Does the pedal have the same angle of incline as before?
Or is the pedal bottoming out before the cable goes through full movement?
Just a thought