Clutch slipping?

[CAROLINA CUMMINS]

How hard is it to differentiate(sp) between the clutch slipping and spinning the tires, neither of which have I had experience with my truck until this week. Like coming home, I merged onto the bypass and stomped it in 2nd, it revved quickly from 15-20 then I shifted to 3rd, got on it hard and it revved the same 30-35, real quick. I'm for the tires spinning this time because it was wet. How much power have you guys put to it before you had trouble with the clutch??









Thanks Steve

 

[KBalzuweit]

My guess would be clutch is slipping. On my old 92 I had the same thing happen. Start out from a stop slow no problem. Hit it hard and the rpm's went up and no go. After a couple more days it got worse and that was it for the clutch. Also the longer you go with the slip the more you tear up your flywheel. Hope this helps.

 

[JFitzgerald]

Steve,



I'd be inclined to believe it was more likely spinning tires because of the wet road and the substantial torque you're making with 33# boost. One way to check the clutch would be to put a heavy load in the bed or a heavy trailer with a good amount of tongue weight to hold those tires to the road, then pour on the torque and see what happens.



The stock first gen clutch is quite good and I believe I read that it can hold 600 lb. ft. Can someone confirm or correct me? I'm at that torque level, and mine shows no apparent slip.



P. S. The first CTD truck I drove was a bone stock, tired old 5 spd. farm truck with tons of miles. The road was wet, and I could hardly keep from spinning the nearly bald tires. I was amazed by the torque - sold me on the Cummins.

 

[CAROLINA CUMMINS]

If it was the clutch, wouldn't the speedometer stop, or slow down? the needle jumped from 20-25 and 30-35 very fast.

Which gears would be the most likely to slip, my cousin has a 98 24 valve 3500 and with 300 hp inj and a edge comp his slips in 4-5th gears.







Thanks, Steve

 

[KBalzuweit]

My mistake I miss read, I thought when you said 15-20 that you were talking rpm (1500-2000). If speedo is jumping like that I would like to change my opinion to tire spin. If you have tach and it jumps and speedo does not then its the clutch.

 

[CAROLINA CUMMINS]

Sorry if I didn't clarify, I really do need a tach.







Thanks, Steve

 

[JLEONARD]

I would guess spinning tires as well. As you see mine is pretty stock and I have good tires and they still spin easily on wet roads.

 

[JFitzgerald]

Originally posted by CAROLINA CUMMINS

If it was the clutch, wouldn't the speedometer stop, or slow down? the needle jumped from 20-25 and 30-35 very fast.

Which gears would be the most likely to slip, my cousin has a 98 24 valve 3500 and with 300 hp inj and a edge comp his slips in 4-5th gears.







Thanks, Steve

Yes, if the speedo jumped, you were spinning the tires. As far as gears, it'd be easier to spin the tires in the lower gears, but easier to slip the clutch in the higher gears - more load on the engine/clutch and more boost.

 

[CAROLINA CUMMINS]

Yeah I see what you mean, I only get about 15# max boost in 2nd and about 25 or so in 3rd, but watch out 4th and 5th 33#!!





Thanks, Steve

 

[JFitzgerald]

Steve, I'm curious what you've done to get to 33# of boost, since I don't see injectors mentioned in your sig. C'mon, what's your secret (if you don't mind)??

 

[dusthomps]

A little off topic

I'm curious to see what someone has to say as well. With my 91, (non-intercooled) I can keep the boost gauge buried at WOT down the interstate. Gauge is an ultra-light and goes to 35#. I always thought it was a bit high, but never bothered to mention anything until it was just brought up.

 

[JLEONARD]

I can get 27 psi boost max on a "bonsai run" or if I nail it at about 60 or so on my non-intercooled 91.

My pump is not turned up from stock, and I haven't touched the timing, I just rotated the fuel pin to max.

 

[CAROLINA CUMMINS]

No secret guys,





Besides the obvious in my sig, I have got the pump cranked, quite a bit actually,



1. fuel diaphragm pin is set at max



2. Starwheel +2-3 turns



3. Smoke screw +2 turns



4. full load fuel pin +2 turns ?? (not sure actually, I lost count of the turns I backed it out to get the collar off)



5. Swiss cheesed airbox.



6. My exhaust (what of it there is) is very short, which may help some.



What suprises me is my EGT is not really that high, I tried to bury it but could only get it to 1300-1350 deg empty.



Besides the boost, the coolest thing is how much this sucker smokes!



:--)



And for some reason my mileage isn't all that bad, with those settings being on for half a tank I got almost 18 MPG, may be that big rig nozzle.



Steve

 

[CAROLINA CUMMINS]

Oh, and add to that one HEAVY size 13 right foot

 

[JFitzgerald]

OK, there's something going on with these 91's. Is it the better flowing injectors the non-intercooled trucks had, or just big feet?:-laf Steve, dusthomps, JLEONARD, have you guys had your trucks on the dyno? Just curious what those boost numbers relate to on the 91's.

 

[CAROLINA CUMMINS]

Sorry, I haven't been on the dyno yet. I'd like to though.



I was thinking about POD's, but I might not need them, if I did get them it would be for a little better mileage and to reduce stress on the pump. Should I save my money for something else?

I'm saving the dough for Thunder in Muncie, Looking at maybe a Mag-hytec, Fast coolers, Tach, Air bags for the rear, And maybe next year, new paintOo.







Steve

 

[JLEONARD]

I've had mine on the dyno, but before I played with the fuel delivery pin.

I was at 25 psi max then and I dynoed at 165 rwhp and 371 ft-lb torque with a K&N filter, opened up airbox, 16 cm housing, stock exhaust with muffler, and no pump adjustments.



Now after playing with the fuel pin and starwheel (1/2 turn) I get a couple more psi boost, and the truck pulls much harder than before.

AND I still can get 24 mpg with a light foot, and 22 with a heavy foot.

I really want to get on a dyno again and see where I'm at.

Jay

 

[dusthomps]

I haven't gotten my truck on the dyno yet either. I heard there is one in La Crosse, WI about 3 hours from my town. Maybe one of these days I'll have to try and find it. I had another TDR member stop at my place who owns a 93 1 ton and asked him to go for a quick run with me. He said he hasn't seen any older CTD pull as hard as mine. He was impressed. Maybe I'll see if I can't find that dyno this week.



Dustin

 

[JFitzgerald]

Come down to Thunder in Muncie, Dustin. You could dyno there.

 

[CAROLINA CUMMINS]

Yeah, thats what stinks, I'll be at TIM 03 but my truck won't. It's about too far, I wouldn't have as much money left after 2-300 bucks in fuel.







Steve