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Old 17th July 2009, 09:35   #1
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Unhappy Engine races only when downshifting from 5th gear

I'm having a 2001 Alto LX which has cloaked about 75,000 KMS with stock clutch & no engine mods. The car is only used by me & my brother.

The problem is that when I down-shifts from 5th to 4th gear at speeds of 40 KM/H or below the engine RPM suddenly rises as if I made an early down-shift without rev-matching. And, this downshifting problem is not happening in any other gears say if I downshift to 2nd from 5th, then the engine is perfect. Sometimes if I wait till 30 KM/H & downshifts then sometimes the engine RPM is normal, but now always.

Because of this I'm forced to slot the gear into 3rd gear with clutch fully depressed before downshifting into 4th gear. Due to this I'm losing my advantage when overtaking/climbing up-hill etc...

The curious thing is that this problem happens only when I'm driving & not when my brother is driving ! I was riding this car for long and never faced this problem before. I've checked the vehicle with a MASS and their opinion is that there is still 20,000 KMS left for the clutch system.

Is the problem lies with the Alto or with me ?

OR

Do I need to unlearn my 5th gear downshifting technique ?

If the problem lies with me, please teach me a better 5th gear downshifting technique...I'm always ready to learn.
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Old 17th July 2009, 10:14   #2
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Quote:
Originally Posted by mithun View Post
The problem is that when I down-shifts from 5th to 4th gear at speeds of 40 KM/H or below the engine RPM suddenly rises as if I made an early down-shift without rev-matching.
mithun,

Does the rise in rpm happen with the clutch depressed and you are in 4'th gear or after you have released the clutch fully and you car sort of jerks forward due to variations in rpm?

Cheers,
gpa
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Old 17th July 2009, 10:17   #3
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mithun,

Does the rise in rpm happen with the clutch depressed and you are in 4'th gear or after you have released the clutch fully and you car sort of jerks forward due to variations in rpm?

Cheers,
gpa
RPM rises when I've fully released the clutch & when I'm in the 4th gear.

Also, jerks are happening.
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Old 17th July 2009, 10:31   #4
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From what you have mentioned, it sounds like the clutch is on its last legs. 75,000 kms is a long run on the original clutch and it does seem to be packing up. But that still doesn't explain why it doesn't happen when your brother drives the car.
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Old 17th July 2009, 11:33   #5
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Have you recently serviced your car, especially the throttle body and air filter?
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Old 17th July 2009, 11:34   #6
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My downshifting style from 5th->4th is :

1. Pull the lever down so that it'll come to the neutral position(which is b/w 3rd & 4th).
2. Then pull the lever down once again so that it slots to 4th gear.

Am I right ? Any other 5th gear downshifting technique ?

Quote:
Originally Posted by Jaggu
Have you recently serviced your car, especially the throttle body and air filter?
Done the full service 1000 KMS ago. Don't know whether they've done anything to throttle body. Does it have any effect on shifting gears ?

Last edited by mithun : 17th July 2009 at 11:36.
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Old 17th July 2009, 11:43   #7
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Quote:
Originally Posted by mithun View Post
Am I right? Any other 5th gear downshifting technique?
I don't think there is anything wrong with your technique so long as you do it in one fluid, seamless motion.
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Old 17th July 2009, 11:45   #8
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Throttle body might be slightly sticky and it might be getting stuck, and in 5th gear the issue is becoming pronounced. Just a guess, also check the idle speed actuators and the idle speed set.
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Old 17th July 2009, 12:33   #9
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Quote:
My downshifting style from 5th->4th is :

1. Pull the lever down so that it'll come to the neutral position(which is b/w 3rd & 4th).
2. Then pull the lever down once again so that it slots to 4th gear.
Maybe you're not doing it fast enough (you could be using too much time in the neutral position or releasing the clutch a bit too late), this lets the engine drop to idle rpm and when you slot into 4th and release the clutch, the engine is forced to revv upto the required rpm for that gear, at that vehicle speed. Which also explains the jerk (which is most common when downshifting without revv matching).

Shan2nu
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Old 17th July 2009, 12:53   #10
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75000 kms for stock clutch is well above its service life.
however i thing the following must be happening:
1. When you shift from 5th to 4th you say that you slot in neutral for few seconds. during this the idling must be dropping suddenly and when you again slot in the 4th gear due to the rolling speed the engine again springs back to high rpm.
try slotting the gear seamlessly i.e directly pull the lever from 5th to 4th gear and yet at speeds of 40. its but obvious that when you downshift from 5th to 4th gear the rpm will rise due to the gear ratios.

2. if your idling is irradicate i suggest you to clean the throttle body.


oops, while i was tying Shantanu posted the same thing which i wanted to say

Last edited by amit_mechengg : 17th July 2009 at 12:55.
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Old 17th July 2009, 14:47   #11
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5th to 4th - are you not below idle in 5th. If so then this may be the reason.
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Old 27th July 2009, 12:53   #12
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Update :

It was only my folly. When I was downshifting, I was giving too much pressure to the left side so that the gear was getting slotted into the 2nd gear. That was the reason for sudden RPM rise.

Anyway, I'll get the car checked for any gear/clutch troubles.
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Old 27th July 2009, 13:37   #13
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then you might not only be facing a rpm surge but also a jor ka zatka. not only you but your car too.
i remember my friend used to do the same when he was in a learning phase.
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Old 27th July 2009, 16:28   #14
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Quote:
Originally Posted by mithun View Post
It was only my folly. When I was downshifting, I was giving too much pressure to the left side so that the gear was getting slotted into the 2nd gear.
I never expected this to happen. The gears of the Alto are smooth and if you are missing the slot into 4'th gear when you downshift from 5'th, its best you get the gear linkages/bushes checked.
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Old 27th July 2009, 16:42   #15
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I think there is technique issue I do face the same issue when especially go down on gears from 3rd to second or 4th to 3rd , I get the jerk maybe because we leave the gear in neutral for few secs . Someone correct me if Im wrong here . Im also quite new to driving so learning through this forum

Also by doing this part like what Mithun expressed will the Gear Box get worn out ?
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