Transmission Studder Problem

[GaMBiTx]

Hello Nico Friends,

'89 240sx hatchback. Ka24e (SOHC)Recently converted from automatic to manual conversion.Parts were Fidanza lightweight flywheel, Exedy OEM clutch kit, and when I take off, the whole car is jerking/ studdering/bogging on light-medium acceleration from around 1,000 to 2,600 rpm range on gears 1,2,3 is most noticeable. If i gas it up to WOT, it isn't as noticeable, but can still feel that the studder is there.Anyone have any idea what could be wrong or a list of things to check first before I have to drop the whole transmission.

Thank you for your responses in advance

[wagzilla260rs]

is that clutch new or used if it is new did your replace everything.? do you have a pic of it before you put it in....

[GaMBiTx]

Clutch kit and flywheel was new.........Don't have pics.Only changed the front piece part connecting to transmission of driveshaft...does that need to be aligned to the 2nd part of the driveshaft that connects to the differential? I Know that if you take off the the driveshaft piece that goes to the differential u have to align it back

[greencar]

Check and see if the u-joints are phased together.

-Dan

[locoluna825]

The drive shaft and input shaft on the back of the transmission have to be aligned, (i dont think the differential to the drive shaft matters) but i do know for the transmission and drive shaft do. I read it in the a manual, they are supposed to connect a certain way. when i did mine i just took a marker and marked so i knew where to put it back at. if i didnt i dont know what i would have done. as for finding out where to insert it i cant help you there. but yes if you don't align that right you will notice vibration. BTW nice clutch setup you go there ;D

[locoluna825]

oh and cahck the mount for the transmission too

[GaMBiTx]

Yeah, i'll have to check the transmission mount..I did read that when they take the first part the shaft to mark it, but i was changing from a automatic 1/2 piece to a manual transmission half piece, so i wouldn't know where to mark... in the fsm i saw a bump that looks like it should line up, but i have yet to go under the car yet...this weekend probably...maybe buy one of those runout things to check runout on it....

Do you know if i can just unbolt the 4 bolts on the shaft without dropping the transmission and rotate it and bolt back? If i remember, i might be able to...but i'm not sure... Anyone can confirm this?Thanks everyone for the constructive feedbak

[locoluna825]

there are 4 bolts on the diff you can un-bold and just drop the shaft "walla" make sure to take off the carrier bearing too.

make sure your rear end is off the ground so you can spin the tires so you can get to the other 2 bolts

[GaMBiTx]

there are 4 bolts on the diff you can un-bold and just drop the shaft "walla" make sure to take off the carrier bearing too.

make sure your rear end is off the ground so you can spin the tires so you can get to the other 2 bolts

Which one has to align...?

TRANSMISSION -- FIRST PART OF DRIVESHAFT -X- SECOND PART OF DRIVESHAFT -X- DIFFERENTIAL...

i think the -X- part is where alignment DOES matter for the driveshaft....When we did the swap we didnt' unbolt the 2nd part of driveshaft from the differential so that part should be aligned correctly unless it was taken off by previous owner...What i'm concerned about is the connection between the first part of driveshaft to the 2nd part of driveshaft...and if i can jsut unbolt the 4 bolts that connect them to each other and rotate it in place and bolt it back to align it...the manual shows "bumps" on the driveshafts itself to align them...but i don't know if mine has it...reading a 89 fsm for a 89 hatchback

[del82]

Check and see if the u-joints are phased together.

-Dan

Um...what??

I'm gonna say something you may not like here (= you may need to learn how to drive a stickshift. Sounds like you're not using the clutch properly, since the problem is centered around the low rev range. As for still feeling the stutter at higher RPMs, you may want to put it on a chassis dyno (not a power testing dyno, mind you, this version is for driveability issues) and while it's rolling, check your driveshaft and center support for any play, it may be out of balance, or the support may be worn out. The mounts mentioned earlier can cause a bit of a stutter, since the engine is hopping around in the bay instead of delivering power.

Or the engine could be worn out. I had an old beater Tracer some years back that did that same thing. I had to re-learn how to drive the thing because the motor didn't have enough power to push the car around properly, so it'd keep winding up the clutch and running out of push, causing the jerking sensation.

[GaMBiTx]

Well, this is my first manual... however i have driven 3 of my friend's 5 speed cars b4 and none of them did that when i drove it...it happens more or less throughout the range at lower speeds...it can still be felt slightly at higher speeds (kinda like a chug chug chug) when i maintain (cruise) at the same speed with respect to the throttle.I had 4 ppl drive my car to see if it was me and it all did what I described...

What is winding up?

[locoluna825]

i think a drive shaft is balanced as a whole so if you go taken it apart from the middle of it and puttin it back together upside down or sumthin im pretty sure that will unbalance it. not every drive shaft is the same there all individually balanced... did you say you used half of the auto drive shaft or sumthin? you can take it apart form the middle but i would still go ahead and mark both halfs so you can line them back up like they were. and hes when they come apart they have funny lobes on the inside of them where your X's are marked.

[locoluna825]

[QUOTE=del82]

Um...what??

I'm gonna say something you may not like here (= you may need to learn how to drive a stickshift. Sounds like you're not using the clutch properly, since the problem is centered around the low rev range. As for still feeling the stutter at higher RPMs, you may want to put it on a chassis dyno (not a power testing dyno, mind you, this version is for driveability issues) and while it's rolling, check your driveshaft and center support for any play, it may be out of balance, or the support may be worn out. The mounts mentioned earlier can cause a bit of a stutter, since the engine is hopping around in the bay instead of delivering power.

Or the engine could be worn out. I had an old beater Tracer some years back that did that same thing. I had to re-learn how to drive the thing because the motor didn't have enough power to push the car around properly, so it'd keep winding up the clutch and running out of push, causing the jerking sensation.

[/QUOTE

the 4runenr i used to drive was the same way

[GaMBiTx]

Auto to manual conversion was done.

The manual front piece of driveshaft was used instead of the auto one...so i wouldn't know how to align it back...did u look at the fsm, it seems there is bumps....i'll check this weekend

[del82]

"Winding up" is what happens when the engine puts power through a sprung hub clutch. Instead of immediately turning the trans, the springs helps to soften the clutch application, and its why clutches have sprung hubs in factory stock condition on most MT cars. Once a car with a small engine gets a lot of miles, the motor tends to not have enough power at the low rpm range to smoothly push the car forward at part throttle, thus it compresses the clutch springs, but doesn't have the power to continue pushing the car so you get an initial jerk followed by the clutch essentially 'pushing back' against the engine and bogging it down. This is easy to reproduce, just let up on the clutch a bit too fast while shifting, or don't deliver the power properly. Other issues like broken motor mounts and worn out carrier bearings tend to severely accent this problem, and these are problems most old cars have as well.

In that case, it's not necessarily a driver error, but can usually be solved with finesse rather than fixing the parts if you don't have the cash on hand

[EDIT: misread a previous post, thinking a driveshaft was a cam, heh heh. i wear glasses for a reason i guess?]