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Hammering in 1st and 2nd


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I don't know if anyone has posted anything like this but I've got a 71 240z with a 5 speed from a 78 280z an R200 from the same 78 with the 3.54 ratio. I just put a new stage 1 centerforce clutch in and used an alignment tool, I put new seals in the tranny and a new rear main seal on the motor. The input shaft on the tranny has a little bit of play but I don't think its too much. My U joints on the drive line seem to be ok and I put a new tranny mount bushing in.

 

Now my problem is in 1st and 2nd gear if i give it a lot of power or if I'm on a steep incline it hammers really loud. Also I can sit at a light and have it it gear with my foot on the break and let out the clutch just a bit and it will shutter and the whole car vibrates. I thought replacing the clutch and the tranny mount bushing would fix those issues but it didn't and I'm kind of out of ideas!

 

Does anybody know what it could be?

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flywheel machined and pressure plate tightened to specs ?

Input shaft bushing good ?

 

If the input shaft is really loose .. plan on another tranny unless repaired fairly promptly ( solely my opinion )

 

By "hammering" are you reffering to a sound or a feel ?

 

Typically 240z drivelines and halfshaft's bolts come loose and go "pop" really bad ...

12mm wrench for driveline and (2) 14mm wrenches for halfshafts

I put a touch of blue thread-locker on them (light).

 

Half-shaft u-joints go bad.

Check your differential strap as well.

A long shot , but make sure your balancer is good.

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Yeah I had the flywheel resurfaced and put in a new pilot bushing. I did tighten the pressure plate bolts to spec. Oh and I did put a new throw out bearing in as well.

 

By "hammering" I do mean a feel and sound. It doesn't last for more than a second or two. It sounds like an impact drill.

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You said " let out the clutch just a bit and it will shutter and the whole car vibrates".

 

You should be able to let the clutch out 1-2" before anything happens?

If you are too tight on the push tube to the clutch cylnder you might have the clutch slipping and perhaps already cooked it a little?

 

I know my 240mm clutch likes lots of clearance,

Tom.

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Oh... and take it easy on the new clutch for a while until everything is seated. They are much like brake pads and need time to conform to the flywheel and burn off any machining oil. Just go gentle for a while seemed to work for me. By "gentle" I mean drop the clutch instantly like a drunk chimp, or just super easy.

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  • 5 months later...

You might need to check your differential mounts and limit strap, unless you're running the RT mount in which case I'd suspect a worn transmission and a grippy clutch. Mine does this exact same thing....but the transmission is where all my driveline slop is.

 

The splines and keyways in my transmission are very worn and allow a LOT of movement in it...which is why I’m rebuilding a different trans to go in it. Also, check the fit of your slip yoke to the tailshaft...if it's worn much it can cause this too.

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  • 2 weeks later...

Sounds like your stage 1clutch might have a havier pressure plate, meaning higher rating. The higher the rating on the pressure plate the harder the release which also creates clutch chatter when engaging slowly. Depending on clutch company they have different rated clutch pressure plates. My car has a 20% over stock, and they have 10%, 30%, and 40% available. When I had a 30% over stock I reacted like yours is. Chatter and heavy engagement to the sound of gear slapping.

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Sounds like your stage 1clutch might have a havier pressure plate, meaning higher rating. The higher the rating on the pressure plate the harder the release which also creates clutch chatter when engaging slowly. Depending on clutch company they have different rated clutch pressure plates. My car has a 20% over stock, and they have 10%, 30%, and 40% available. When I had a 30% over stock I reacted like yours is. Chatter and heavy engagement to the sound of gear slapping.

Yep, good advice.

 

The other thing is your clutch plate in all probability has what is called a "higher coefficient of friction" than a standard clutch plate.

 

What this means basically is it will grab much better thana standard clutch,but you won't be able to do what we call "riding, or slipping the clutch".

 

These clutches, when coupled with a heavier duty pressure plate like to be either engaged, or disengaged (clutch pedal pushed right in).

 

Trying to drive it like a stock clutch will possibly result in the symptoms you are experiencing.

 

Trick with these setups is you need to use slightly higher engine revs and drop the clutch when taking off (without spinning the wheels).

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 My U joints on the drive line seem to be ok and I put a new tranny mount bushing in.

 

Now my problem is in 1st and 2nd gear if i give it a lot of power or if I'm on a steep incline it hammers really loud. Also I can sit at a light and have it it gear with my foot on the break and let out the clutch just a bit and it will shutter and the whole car vibrates.

 

The first sentence seems to me to mean with clutch engaged and driving, if you give it the heat there is shuddering. This, to me, does not indicate the clutch as it's engaged. Now the second line could indicate an engagement problem but there is another that satisfies both.

 

As the transmission was recently removed for a clutch change it's possible that the engine to trans mounting bolts were not tightened properly and are loose or came loose/missing. The rear transmission mount could also be loose or has come loose (or being new has failed or was the wrong one) The driveshaft was also removed so look at the rear yoke to differential bolts too. (better take a look at those U joints too.

 

 

Any time there is a sudden load you will get shuddering.

 

 

One other thing that could be banging noise is the exhaust pipe hitting something. Grab it and shake it. See if it hits anything.

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Centerforce clutches suck, or at least they used to. I assume the clutch disc has a sprung hub? 

 

 

Its possible you could have a chipped tooth somewhere in the trans that only shows up under heavy loading(maximum force of the input/counter shaft pushing away from each other) 
With the car running in neutral, depress the clutch and see if there is any major noise change in the transmission. also put your hand on the shifter and push downward so that you are in neutral still, but can feel any vibrations coming through the shifter handle from the transmission. Also a mechanics stethoscope against the case of the transmission is a good diagnosis tool(helps if you have a loud exhaust and cant hear any transmission noises)

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  • 2 weeks later...

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