67 replies to this topic

[jschwarz]

If you watch my Runoffs video, you can get an audible sense of the "delay" when shifting 3rd to 4th.  http://youtu.be/iXma17Eihjk

 

About your observations that the problem only started 3/4 thru your race, but then went away for the beginning of the next day's race...same thing happened to me at Watkins Glen.  I had the problem in the video above after about 10 laps (maybe less), and then pulled it in.  We took the car back to the paddock, had lunch, looked at a few things, and went back out.  The first couple of laps weren't that bad, but it just got progressively worse again.  I'm guessing heat has something to do with the seal's efficiency.  We then noticed some oil dripping as it went up into the trailer. 

 

I will post what I find.

 

Please do! I plan to tear mine down this winter too so I can also compare notes with what I find.

[SaulSpeedwell]

Saul, thanks so much.  My plan is to get the transmission out today, and "see what's going on".  I've gone back and looked at video throughout the year, and realize that this problem was going on for a long time, but to a much lesser extent.  I would even notice/realize it while driving, but just figured it was "normal".

 

And Saul, what's your preference for type of disc/pressure plate?

 

Drago and I are in agreement here, as we are on most things - 3 puck unsprung disc from ClutchNet, stock pressure plate.  If you are "abusive" and having gear stripping or spline twisting issues, consider a sprung-hub version. 

 

Good luck!!!

[SaulSpeedwell]

This is great!

 

I just was asking about this exact thing on mine on 3-4 shifts at RA (up hill). This was in August so it was warm and it only started 3/4 of the way through the race. The next day all was well again until about again 3/4 through the race it started slipping on 3-4 shifts again up hill. I assumed the clutch was getting too hot but was still thinking it might be worth it to replace the disk if it was glazed or something.

 

My thought is if it was oil it would do this right away right? Should be able to see how oily things are on tear down too?

 

The oil will be obvious, but sometimes the clutch doesn't get "broken in" very well on our cars precisely because we are not slipping them some as a street car might.  The other problem is resrufaced flywheels that aren't flat.

 

So - look for a glazing or burning pattern, or some other sign the disc is only contacting on, say, the outer 1/2" instead of the whole swept area of the pucks.

 

The bottom line is we have only 125HP, these puck clutches can handle double that.  If they are slipping, something fairly serious is wrong - copious amounts of oil, or something very wrong with the engagement/"break in".

[DrDomm]

Picture of the pressure plate...not sure how greasy it should be...

 

[DrDomm]

Here's a look at the bell housing.  If you look at where I removed the boot from the linkage, you can see some golden-colored oil.

 

[DrDomm]

This is the flywheel...yesterday my father-in-law and I were commenting on how it had more wear around the outer edge. 

 

[DrDomm]

[DrDomm]

Now I gotta figure out how to change that rear main seal (and the transmission seal).  At first, we were thinking the oil was from the transimission, but the oil I drained from it wasn't golden, now that I think about it.  The engine oil is.

[Ron Alan]

Doc,

 

You may have grabbed the wrong picture but the first one is your pressure plate...no clutch picture. When you buy a new rear main seal it will be obvious what you need to do! Looks like your old one is bad or the flywheel bolts were not locktited. Break clean everything really well including bolts before you reassemble. Install main seal first then flywheel(resurface if youre concerned and new pilot bearing)and put locktite on the bolts. New clutch disc and your cleaned PP!  

[davew]

That is an ACT pressure plate and it looks reusable.

 

The flywheel looks to have been resurfaced at some point in its life by the "swirl marks on the inner radius of the flywheel and corresponding marks on the  flywheel towers. My only concern is the bolt holes on the flywheel. The look a little roughed up, but that may be the picture.

 

The rear main seal can be popped out with a screwdriver. I have found the seal installer available from Flyin Miata to be well worth the $30 they charge for it. Even if you only use it once.

 

Use blue locktite on the flywheel bolt threads.

 

If there is any roughness in either the pilot or release bearings, change them.

 

You don't show a pic of the clutch disc. I assume since you have a ACT plate, you also have a ACT disc. I use the ACT unsprung unless you are tough on gears, then the sprung disc helps. The ACT 4 puck clutch is actually lighter than the 3 puck clutches many are using. But I have never compared to the unit Jim and Saul are using.

 

Replace both the front trans seal and gasket while in there.

 

And get everything clean.

 

Dave

[DrDomm]

Doc,

 

You may have grabbed the wrong picture but the first one is your pressure plate...no clutch picture. When you buy a new rear main seal it will be obvious what you need to do! Looks like your old one is bad or the flywheel bolts were not locktited. Break clean everything really well including bolts before you reassemble. Install main seal first then flywheel(resurface if youre concerned and new pilot bearing)and put locktite on the bolts. New clutch disc and your cleaned PP!  

 

Thanks.  Yeah, my automotive anatomy isn't as good as my human anatomy.  I've edited my posts above.

 

FWIW, flywheel bolts came out pretty easily.  Pilot bearing just fell out.

 

Thanks again.

[DrDomm]

Dave, clutch disc is ACT unsprung 4 hub.  I'm going to replace with Jim/Saul's suggestion.

 

I thought those flywheel holes looked a bit rough too.  Gonna put a new flywheel in.

 

Thanks for recommendations.

[AW33COM]

It's impossible to verify your flywheel by looking at online pictures. At minimum I would resurface it or buy a new one.  Otherwise chances are you will be ripping it out again.  There must be a lot of oil for it to drip on the plates in order to have a problem every time you up shift.  Seems strange, but possible, since I don't like the amount of grease/oil I see in those pics.

 

One more thing, always put (do not over do it) locktite inside the threads and not on the bolts when installing the flywheel.  Once you're done, just clean the flywheel and everything there.

[Stix37867]

Dave, clutch disc is ACT unsprung 4 hub.  I'm going to replace with Jim/Saul's suggestion.
 
I thought those flywheel holes looked a bit rough too.  Gonna put a new flywheel in.
 
Thanks for recommendations.

Can you post the difference in weight of the two discs once you get the new one?

[davew]

IIRC the brand I weighed was a "SPEC" clutch, 3 puck, unsprung and it weighed a few ounces more that the ACT 4 puck unsprung.

 

Not enough to be an advantage, but interesting that the 4 puck was lighter than the 3 puck.

 

Dave

[Bench Racer]

This is the flywheel...yesterday my father-in-law and I were commenting on how it had more wear around the outer edge. 

 

With reference to more wear on the outter edge of the flywheel. put a straight edge across the flywheel and across the pressure plate and check if the surfaces are flat with feeler gauges between the straight edge and the surface. Also before installing the flywheel bolts you might clean the crank internal threads with some carb cleaner and a piece of rag twisted into and out of the thread holes.

 

If in fact your flywheel has been resurfaced as it looks like it has, the material removed may be more in terms of weight than changing from a 3 pad to a 4 pad clutch disc.

[DrDomm]

Can you post the difference in weight of the two discs once you get the new one?

 

Of course.  Just ordered it.

[AW33COM]

IIRC the brand I weighed was a "SPEC" clutch, 3 puck, unsprung and it weighed a few ounces more that the ACT 4 puck unsprung.

 

 

How many ounces? lol

[DrDomm]

Just curious, why does a spec class allow clutch options?

[chris haldeman]

Just curious, why does a spec class allow clutch options?

Simple answer too that question. The factory clutch will not perform under racing conditions and for the good of the class they allowed a clutch kit that will out last the car