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Old 01-14-2009, 04:32 PM   #1
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Default HELP...RPMs very low

Hey guys, I'm new to this forum and theres great help here and thanks for it.

I have an issue that hopefully someone can help me.
Car
HPI RS4 evo3+

Problem
Upon accelerating down the straight, the car revs up quite nicely but then doesn't feel like its moving anywhere. First I thought it might be the too rich because I put the needles back to factory settings, so I started slowly leaning the car out after a few minutes but nothing changed....still the same. Then I inspected the gears and they looked fine (not stripped or loose), and then I inspected the transmission and I figured, there would be no problem if i tightend the grub screw down all the way as it will engage 2nd gear later. I then thought lets try and engage 2nd gear ealier so I did 1 x 1/4 turn back, nothing worked, and another 1 x 1/4 turn back and nothing again, the revs still stay the same.

After inspecting the tranny again, the grub screw, spring, ball bearing popped out and I lost it after probably loosen its 2 x 1/4 turns anti-clockwise or probably vibration

My question basically is, whats causing the RPM to not increase?

What happens if you don't put in the ball bearing,spring and grubscrew, what will the symptoms be?

Do you have any other ideas what it may be?

Mind you when i was revving the car on a stand before taking my car out to test out 2nd gear, i remmeber reaching very high rpm, and heard a click, and some burning sensation....not sure if thats related...maybe maybe not...

Is it engine related problem you guys think?
or
Diffs?

I hope enough of this information helps.


Thanks.
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Old 01-14-2009, 07:16 PM   #2
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The engine revs on the stand and when you put it down, it runs but not hard.....?????

Check the flywheel nut on the shaft. If it's loose the flywheel will spin on the shaft when under a load. No tuneing or 2 speed adjustment will correct that problem. To correct that problem you have to take the motor out and tighten the flywheel clutch nut. Don't forget to locktite the clutch nut to the shaft. (blue locktite)
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Old 01-14-2009, 08:22 PM   #3
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First buy a grub screw, spring and ball other wise it will always be in second gear. I wouldnt hurt to check out the engine clutch, maybe its fryed. When is the last time you heard the trans shift gears?
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Old 01-14-2009, 08:47 PM   #4
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Quote:
Originally Posted by GHETTOTEACHER View Post
The engine revs on the stand and when you put it down, it runs but not hard.....?????

Check the flywheel nut on the shaft. If it's loose the flywheel will spin on the shaft when under a load. No tuneing or 2 speed adjustment will correct that problem. To correct that problem you have to take the motor out and tighten the flywheel clutch nut. Don't forget to locktite the clutch nut to the shaft. (blue locktite)

spot on! engine revs nicely on the stand, but when put down, it runs but not hard. Just to make it clear, incase your thinking of something else, lets say for e.g The car accelerates off the line not too fast, and then reaches 40km/h and stays and 40km/h. thats the type of issue im getting. And as you said, it does not go hard after that.

I will check the flywheel nut on the shaft...I assume I would have to remove the engine, take out the pinion gears, clutch bell, clutch and then tighten the flywheel nut?

thanks!

Last edited by beers4evo; 01-14-2009 at 08:58 PM. Reason: added something else
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Old 01-14-2009, 08:48 PM   #5
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Quote:
Originally Posted by wizby View Post
First buy a grub screw, spring and ball other wise it will always be in second gear. I wouldnt hurt to check out the engine clutch, maybe its fryed. When is the last time you heard the trans shift gears?
I actually ordered a new 2 speed tranny as it comes with a set, I wasn't sure if I could just use any ball and spring...grubscrew i ca get.
Engine clutch? never heard of that, will need to ask my friend...
You see the car goes very hard, that I have never heard it shift from first to second....for e.g the sound the serpent 720's change gear, thats sweet
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Old 01-14-2009, 09:36 PM   #6
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The engine clutch is the bell thats connected to your crankshaft.The shoes are on the flywheel.Its what turns your 2 speed.

Jason
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Old 01-15-2009, 09:25 AM   #7
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To check the security of your flywheel nut, is simple. Remove the motor from the car, remove the clutch bell (leave the pinions alone), remember the order your spacers,bearing and clutch shoes come out. With a 7mm socket, and a set of channel locks with something on the ends not to mar the flywheel, tighten the nut on the shaft. If it is loose, remove the nut, apply locktite (blue) on the shaft and tighten. Reassemble the clutch/pinion assembly then reinstall in the car.
Not hard to do. Sometimes when you have a torquey motor, the flywheel does spin free from the shaft. Normally the shaft cone slips causing the flywheel to spin then the nut comes loose. Check it out and give us the findings! Good luck!
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Old 01-15-2009, 10:46 AM   #8
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When you get the new trans in and running. Make only small adjustments to the grub screw in the trans. When its set right it will shift like a 720. But they way your makeing adjustments is causeing you alot of headaches. 2 1/4 and 1 1/4 turns are way to much. 1/4 of a turn is the way to adjust shift points. Have the engine up to normal temp and the mixture tuned good before you make trans adjustments.
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Old 01-15-2009, 03:23 PM   #9
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Quote:
Originally Posted by GHETTOTEACHER View Post
To check the security of your flywheel nut, is simple. Remove the motor from the car, remove the clutch bell (leave the pinions alone), remember the order your spacers,bearing and clutch shoes come out. With a 7mm socket, and a set of channel locks with something on the ends not to mar the flywheel, tighten the nut on the shaft. If it is loose, remove the nut, apply locktite (blue) on the shaft and tighten. Reassemble the clutch/pinion assembly then reinstall in the car.
Not hard to do. Sometimes when you have a torquey motor, the flywheel does spin free from the shaft. Normally the shaft cone slips causing the flywheel to spin then the nut comes loose. Check it out and give us the findings! Good luck!
I have taken the car to the workshop today, im just so pee'd off at the fact that I tighten the screw to the engine when i tried to unscrew one of them I warped it. my issues never end...but anyways hope the technician can fix that up.
Any how I have seen the flywheel nut before, but if you move the flywheel and it feels a bit hard to turn which is moving the piston up and down, would the flywheel nut be tighten still? or you would be able to tell unless I remove the engine, clutch bell etc?
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Old 01-15-2009, 03:26 PM   #10
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Quote:
Originally Posted by wizby View Post
When you get the new trans in and running. Make only small adjustments to the grub screw in the trans. When its set right it will shift like a 720. But they way your makeing adjustments is causeing you alot of headaches. 2 1/4 and 1 1/4 turns are way to much. 1/4 of a turn is the way to adjust shift points. Have the engine up to normal temp and the mixture tuned good before you make trans adjustments.

I did make small adjustments to the grubscrew. I think the shift noise does not change like a serpent 720. I did mentioned in the post i did a 1/4 turn...you might have mistaken it as 1 1/4 turn...which it shows as n x 1/4 turn where n is the amount of 1/4 turns.
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Old 01-15-2009, 03:30 PM   #11
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Is it possible that the clutch spring snapped causing the symptoms on my car? (I can't take off my engine, I warped the screw and the car in the workshop)
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Old 01-15-2009, 06:57 PM   #12
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If a spring on the engine clutch was broken the car would not stand still while the engine idled. Is that one of your cars symptoms?
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Old 01-15-2009, 07:14 PM   #13
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Quote:
Originally Posted by wizby View Post
If a spring on the engine clutch was broken the car would not stand still while the engine idled. Is that one of your cars symptoms?
hey,

what do you mean the car would not stand STILL ?
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Old 01-15-2009, 07:18 PM   #14
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Will the car remain static while the engine idles?
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Old 01-15-2009, 07:22 PM   #15
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Quote:
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Will the car remain static while the engine idles?
well if i put the car on the ground while the engine idles, it slowly wants to get going, my idle screw is set for a bit of movement.
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