Engine/Transmission (1994 - 1998) South Bend OFE chatter

[JGheen]

Just wondering from you more personally experienced SBC clutch runners how much chatter is normal and how long does it last?

I have been running my first SBC OFE for about 1000 or so miles and I have chatter pretty much all the time. It isn't so bad when it warms up after driving for a while, and it shifts fine going to 3rd gear and beyond. But starting out from second, it seems like it is never going to go away. I know some of you have told me that chatter is normal, but does it last the entire life of the clutch? I know I have no oil leaks and the clutch is clean, so that rules out any dirty disk chatter reasons. It holds up to my 320hp and 750ft/lbs. just fine, so is this just a characteristic of a 13" SBC? I plan on stepping up to 370s and a B1 soon, so will the extra power and torque load the clutch better and rid me of the chatter?



TIA for the help!



Joe

 

[Forrest Nearing]

I never notice enough to be concerned about... but I've never driven w/ a stock clutch

 

[Joseph Donnelly]

Did you resurface the flywheel? Are you sure it was doe correctly, concentric and not deeper on one side? [You can check by using a micrometer different places around the perimeter before installing it].

My con-FE is almost as smooth as stock but you have to accept some compromise. The stocker is a compromise on cost and torque capacity. All other clutches entail compromises too.

 

[Got Smoke?]

Did you resurface the flywheel? Are you sure it was doe correctly, concentric and not deeper on one side? [You can check by using a micrometer different places around the perimeter before installing it].

My con-FE is almost as smooth as stock but you have to accept some compromise. The stocker is a compromise on cost and torque capacity. All other clutches entail compromises too.

Joe... . 13" Clutches for 5spd's come with redrilled flywheels from Southbend

 

[JGheen]

Joe... . 13" Clutches for 5spd's come with redrilled flywheels from Southbend

Yeah, I got an all new flywheel with the new drilled holes to accept the 13" clutch, so everything was new, flywheel, pilot bearing, disk, pressure plate, throw out bearing.

Don't get me wrong it is a very smooth clutch, but it is just from a dead stop letting it out in second that it seems to chatter a little excessive to me, but that I why I am asking the SBC experienced cuz this is my first SBC.

Like I said once it warms up it goes away somewhat and even when I give it just the right amount of "throttle" while letting it out nice, slow and easy it doesn't seem to chatter as bad, but I just hope all this is normal and it eventually goes away.

 

[SMorneau]

I noticed some chatter when mine was first installed and I don't notice any now. I don't think the change is in the clutch as much as my change in driving habits. I drive the truck pretty aggressively getting the clutch engaged quickly so it doesn't have time to chatter.

 

[Got Smoke?]

Joe after reading your last post here's my conclusion.



I have have used several different clutches since entering the world of CTD's almost 5 years ago.



1st aftermarket was a TST Button clutch... don't get me started... . it was IN or OUT and I'll leave it at that. Even bringing the RPM's up didn't help to detur a 2nd gear shudder start.



2nd was a SBC 13" FE (rated @ 500RWHP & I was only pushing 430RWHP) I had this also in my previous 97. It was a great clutch, little grabby backing up and taking off in 2nd. However, a little light/moderate throttle (i. e. bringing the RPM's to just over 1K) really helped with 2nd gear take offs.



3rd is my current SBC Dual Disk. It engages much smoother than my FE did for sure I would have to say, however if I do let of out of the clutch with the RPM's under 1K I still get some shudder on a 2nd gear take off. If I bring the RPM's to 1K or just above it takes off as smooth as a stock clutch.



The only other clutches I have used besides these 3 have been the OEM stockers that came in both trucks, and one OEM "hold me over" that Briar Hopper (Tom Meers) gave me when I burnt up the TST. Its been so long since I've driven a stock clutch truck that I would say it would probably take off without the shudder but I'm not sure.



However, even if it does you have to compare the materials used in the two. The stock clutch is designed for just stock power, where the aftermarket's necessitate a slightly more aggressive (Con O/OFE) or really aggressive (Con FE) material to hold the power.



Just try bringing the throttle up just a bit (minmum of 1K RPM's or a little above) when taking off in 2nd and see if it doesn't cure your shudder. I think that is the only way to get around it with any type of aftermarket clutch, however I've only used 2 brands so I cannot speak for EVERY aftermarket clutch.



Sorry so long winded..... just my $2. 00 worth! :-laf

 

[Forrest Nearing]

I almost dump the clutch in 2nd to get moving because it makes a cool chugging sound out the exhaust when it lugs down against the governor at 500rpm



maybe that's why I never notice any chatter? :-laf

 

[Fred Swanson]

JGheen, since this is your first HP clutch with this truck, you may be feeling what most of see as normal characteristics. A certain amount is expected. Have you talked to Peter to describe what it is doing?

Does it do it at all starting in 1st, or using reverse?

 

[Bob4x4]

Joe, With your Tire size you may want to start out in first unless you are LAUNCHING .



Bob

 

[Fred Swanson]

Bob, didn't even notice the 37's. What gears? Hopefully 4. 11's. If not, by all means, 1st gear, or you'll have to feather it to start(Peter, don't shoot me for saying that!)



With the FE I had originally, it wasn't chattery per se, it just hit. A couple of good lauches helped that.

The DD I have now with the Toyo 37's(they look at least 1. 5 inches taller than the MTR 37's, though), 2nd gear is still possible. Some chatter on certian launches, but for the most part, no problem.



Greg Boardman has the same 13 conversion in his 03 5speed with 4. 10's and 37's, and his launches good, but has a little stiffness going between 1st/reverse.

 

[JGheen]

Thanks for the replies guys,



Bob, you do have a good point. I used to start out in first for a while with my old clutch and with this one it does not shudder/chatter/shake when I start out in 1st, only in second.

With my stock 3. 54 gears, it does tend to lug when I get the clutch fully engaged and have the revs above 1K.

I did some experiementing while at lunch break and didn't really notice it that much when I gave it a little more revs like letting it out at about 1500 rpms. Also, I tried starting out in first a couple times and no chatter.

I guess it is just cuz of the combination of the large tires, the high gear ratio and starting out in second gear. I really don't want to start out in 1st, but I guess if it rids me of the shaking I can deal with it. I'll give it a little more mile and maybe some road trips and see how it engages then. I guess it just takes quite a while for this HP material on the disk to seat in the flywheel and engage smoothly.

Haven't talked to Peter, but I will try and call him and see what he says about it for a final word.



Thanks again guys,



Joe

 

[Forrest Nearing]

FWIW, I couldn't tell any difference when I replaced a blown OFE with 50k miles on it with a brand spankin' new one... felt exactly the same.

 

[Joseph Donnelly]

Oh yeah! 37" tires, lots of inertia to get moving. Only 3. 54 gears. You have an engine spinning and tires that don't want to move = shudder. First gear starts will help a lot and prolong the life of the clutch.

 

[JGheen]

Oh yeah! 37" tires, lots of inertia to get moving. Only 3. 54 gears. You have an engine spinning and tires that don't want to move = shudder. First gear starts will help a lot and prolong the life of the clutch.

Thanks Joe,



I guess I could start using first gear and just live with the real slow starts.



BTW, how many miles does someone expect to get out of these clutches? I would think they would last as long as the stocker(80-100K) as long as you don't go over the max rated HP/torque or smoke the thing in a truck pull, correct?

I guess I really need to call and ask Peter these questions.



Joe

 

[Bob4x4]

The life span decreases in direct proportion to the size of the grin on take off :-laf Don't ask how I know



Bob

 

[TPCDrafting]

LaserBob told me 80 to 100k with my OFE. I find myself starting out in first more with the new clutch due to shudder/lugging. People sometimes look hearing me row through 3 gears just getting through the intersection. There is some breakin on the clutch and I think it got better with time/miles, but I also think I had to be broken in as well driving a somewhat different clutch.

 

[Forrest Nearing]

I've only got 265's so 2nd gear starts are no problem at all, but I sometimes row 1-2-3 from a stop because it sounds cool out the stacks :-laf