Need a little help

DeathBus · Post by **DeathBus** » Fri Jul 23, 2004 9:58 am

Put my AJ Simms rebuilt Dual Kads on my rebuilt engine. 2 litre Type 4. Each cylinder runs 120 psi on compression check. Drive the vehicle, when I reach 4K on the tach I can get no more power out of the vehicle and the tach will start moving faster up to 5k, 6k, even 7k! Some people have said my clutch is slipping, so I replaced the clutch, flywheel and pressure plate with ones I had been saving for another project, took it for a spin and whamo, same thing. With the progressive I just junked off this motor i was always able to keep going way past 4k and stay in the power band. Are the Kads letting me get so much more torque that they are causing the clutch to slip? Will a BRAND NEW pressure plate and clutch disc save me?

THANKS!

Guest · Post by **Guest** » Fri Jul 23, 2004 11:10 am

Yea, I hd the same thing happen on the Bradley GT when I
put the dual progs on it. First slipping clutch I ever had!

It is prolly the pressure plate, but while you have it out......
always go new everything, even tranny and engine rear seal!

Don

MASSIVE TYPE IV · Post by **MASSIVE TYPE IV** » Fri Jul 23, 2004 11:24 am

A bus shouldn't rev to 7K! Can you hear the engine revving higher and higher?? If not sounds like an electrical tach problem.

DeathBus · Post by **DeathBus** » Fri Jul 23, 2004 11:54 am

I checked the tach, it checks ok. Yes you can hear the engine rev higher and higher and when the carbs cant give any more they spit.

dstar · Post by **dstar** » Fri Jul 23, 2004 1:27 pm

DeathBus wrote:I checked the tach, it checks ok. Yes you can hear the engine rev higher and higher and when the carbs cant give any more they spit.

"they spit"

BUWAHAHAHAHAHAHAHHAAHAAHA!

That is valve float!

IF you ever had an autotranny go bad(See my "tranny going bad?" post)
a slipping clutch is the same, engine REVS all of a sudden,
but you ain't going any FASTER!

Don

DeathBus · Post by **DeathBus** » Fri Jul 23, 2004 3:01 pm

"engine REVS all of a sudden,
but you ain't going any FASTER!"

THATS exactly what it does! Now with this other clutch and pressure plate I can barely get up a hill

MASSIVE TYPE IV · Post by **MASSIVE TYPE IV** » Fri Jul 23, 2004 4:14 pm

yep, yer valves are a floatin!!

DudeAndHisBus · Post by **DudeAndHisBus** » Fri Jul 23, 2004 4:20 pm

MASSIVE TYPE IV wrote:yep, yer valves are a floatin!!

Maybe, but that still doesn't answer his question about what's going on with the clutch/tranny, now does it Jake?

DeathBus · Post by **DeathBus** » Fri Jul 23, 2004 4:35 pm

It just doesnt make sense, with a progressive and a valve that was about to drop a seat I was able to do burn outs, now I cant rev past 4k without dieing?

MASSIVE TYPE IV · Post by **MASSIVE TYPE IV** » Fri Jul 23, 2004 4:48 pm

Its a type 4...

Anyway, sounds like the clutch disc is contaminated with oil, or the pressure plate is wasted..

Every time it slips like that, you are frying the flywheel. Inspect it for heat cracks thoroughly on disassembly.

DudeAndHisBus · Post by **DudeAndHisBus** » Fri Jul 23, 2004 5:13 pm

MASSIVE TYPE IV wrote:Its a type 4...

Anyway, sounds like the clutch disc is contaminated with oil, or the pressure plate is wasted..

Every time it slips like that, you are frying the flywheel. Inspect it for heat cracks thoroughly on disassembly.

In other words, get to working, bitch!

You've got to be ready to drive it tomorrow!

DeathBus · Post by **DeathBus** » Fri Jul 23, 2004 6:22 pm

DudeAndHisBus wrote:
MASSIVE TYPE IV wrote:Its a type 4...

Anyway, sounds like the clutch disc is contaminated with oil, or the pressure plate is wasted..

Every time it slips like that, you are frying the flywheel. Inspect it for heat cracks thoroughly on disassembly.
In other words, get to working, witch! You've got to be ready to drive it tomorrow!

Dont have a new clutch disc or pressure plate, will have one next week,

Have fun at Dyno day without me!

DeathBus · Post by **DeathBus** » Thu Jul 29, 2004 2:10 pm

Well here is an update, replaced the clutch, pressure plate and throw out bearing. It takes higher rpms a little better, but still when I am running 3200 rpm or so with steady gas pressure I still get a fluctuation in my TACH of 2 to 300 rpm WITH NO NOTICABLE DIFFERENCE IN THE WAY THE VAN IS RUNNING. Should I start looking at the ignition system? I am running a stock vacuum advance dist with pertronix and some MexiBosch plug wires along with mexiBosch plugs. At about 4500RPM in 1st 2nd and 3rd my rpms still run real fast past 4k in 4th I can run close to what I was doing with a progressive.

flybayb · Post by **flybayb** » Thu Jul 29, 2004 5:53 pm

my 2 cents:

check yr tach. Y mentioned y use an 'ignitor' which is an HEI ignition. Is yr tach HEI-proof?

I recently installed a new electronic tach from Equus. Had some 'flickering' when my engine was running. I double-checked with my timing light in reference to my rpm.
Here are my findings:

1. Is yr tach HEI capable?
2. Where does yr 'positive' come from? I unfortunately used the '+' from the injector resistor. To keep my gauge bus 'clean' I wired a seperate '+'-bus into the compartment.
3. Is yr '-' (mass, negative) loose?

Y also mentioned that those 'runaways' happen when y've driven yr bus for a while. Did y connect yr '+' or '-' to a source which is in relation w/ a heat indicator/gauge/sensor?

I try to keep my electrical bus for the gauges as 'clean' as possible. I don't connect '+' or '-' to any 'dirty' source (=used by any other consumer)

well, just my 2 cents..

Happy Westy

PS: Some tachs can be configured for different cyl-#. Did y check yrs?

raygreenwood · Post by **raygreenwood** » Thu Jul 29, 2004 9:05 pm

Ok....question. So you can physically hear the engine revving up..right? You just changed to a new disc and its better but not right..right? Did you change the pressure plate at this time? If not...here is what can happen. If for whatever reason, when the clutch last started slipping...you greatly over-revved the engine with a slipping clutch, you can wear just a hair bit of metal from the flywheel face and the PP face. So no...you have a good bit less clamping pressure. This is indicative that you were borderline in clamping pressure in the first place. This comes from the several sources (a) there are nominal variations in clutch disc thickness and sping tension of the shims between each friction disc face. It can be more or less compressable. (b) there are differences in total face thickness dimensions of the Pressure plates (c) The shop that machined the flywheel most probably did not get the machining of the step...the same distance as what they took off the flywheel face. This is in fact the most common problem. They ususally start machining the flywheel face...and take it down until its clean. They rarely exactly check the set distance bewteen the PP step and the flywheel friction face to see if it was in spec in the first place.....AND most basic flywheel/clutch shops do not know what that gap should be anyway.
Bear in mind...that the flywheel face wears down...but the step does not. So if the flywheel face is already .010" out of spec....and they just take it down .010"...and the step down .010"....you have lost signifcant clamping pressure, because you have .010" less metal than the clutc was designed to have. The gap changes. All they did was smooth it off...not correct it.

Take your flywheel in...and have then take the face down .005". Then have them take the step for the PP down .015-.020 total. That is a safe bet.
Now....install the PP on the flywheel.....with no disc. Measure the gap between PP and flywheel faces. Now...compress both sides of the clutch disc in a vice. It should change the thickness by about .010" as the spring shim compresses. Compare the disc measurement with the flywheel/PP gap of an installed clutch cover. It the flywheel/PP gap should be about .020" thinner at least ,to make sure you have clamping. This is what causes the clutch fingers to rise up as you tighten the bolts on the PP while installing it. It is this preload, that supplies clamping force to the disc. Its a good idea to make sure that the fingers rise up to the same height when installing a new disc or PP...or you may have a good deal less clamping force than you had previously. I had these same problems on my 412. I aleviated it by milling the step a further .010".

Why did it just start now? Because you put new carbs on...and got more torque. You have probably always been borderline in your clamping pressure set up. A good indicator of variation....is if I you either change the PP or the flywheel...but not both...and the clutch cable adjustment changes significantly. That tells you the fingers on the PP have more or less pre-load than they did before. Sorry for the length. Ray