Secondary Spring Clearance/shift assist

Arctic Thunder · Jan 20, 2013

Couple questions/observations.

Using a 0648-774 Cat secondary spring.
Free lenght is 5.538"
Compressed is 1.461"
Secondary clutch spring clearnance is 1.521" this is with a shift assist and both of the .153" thick shims installed.

So I don't believe even at full shift this spring would coil bind. Would you agree?

Now the interesting question. When taking the secondary to full shift without a spring, it appears to me that the belt could fall all the way down to the straight cut in the secondary sheeves and even hit the helix if it wanted to. I didn't see any scuffs on the helix, I would assume it would slip like crazy if it ever shifted out that far.

Also I believe the instructions for a shift assist says to remove ONE of the two factory plastic shims (.153") when you put the shift assist in. Correct?

Anyway, tell me your ideas. I have had pretty good belt lift over all. But on a trail if I am messing around and doing some drag racing about 4-5 good pulls and BAM! their goes a belt.

Thinking the extra .153" shim was installed along with the shift assist was causing coil bind. not to sure now.

Thunder

fordpickupman · Jan 20, 2013

This is interesting. I just blew a belt racing down the road. It chewed all the cogs off and blew the outer layer off. I assumed it wasn't shifting enough to keep up with how much the primary was trying to close and snapped it. But shifting to the point of the belt hitting the helix makes more sense to me. Maybe the DD secondary isn't big enough to run 100 mph.

FORDpickupman

fordpickupman · Jan 20, 2013

DD

Thunder,

Great pic of the belt dropped in too far. It shows what the problem could be very well.

I am pretty sure you are correct. I ran just shy of a mile at around 100 mph (the SP Doo I left behind said he was running 92 mph, I didn't look at the speedo as I can't really see it at this point as I don't have a gauge lifter yet).

The fun part is going to be cleaning up the belt fuzz that distributed itself throughout the engine compartment.

My 05 still has the 10" clutch on it, I don't know that the 10.4 will help much to prevent the belt from riding on the helix. I am guessing that I will probably just "keep her under a hunerd" to prevent this from happening again. The opportunity rarely arises to race the road that fast anyhow.

m8magicandmystery · Jan 20, 2013

Arctic Thunder said:
Couple questions/observations.

Using a 0648-774 Cat secondary spring.
Free lenght is 5.538"
Compressed is 1.461"
Secondary clutch spring clearnance is 1.521" this is with a shift assist and both of the .153" thick shims installed.

Also I believe the instructions for a shift assist says to remove ONE of the two factory plastic shims (.153") when you put the shift assist in. Correct?

Anyway, tell me your ideas. I have had pretty good belt lift over all. But on a trail if I am messing around and doing some drag racing about 4-5 good pulls and BAM! their goes a belt.

Thinking the extra .153" shim was installed along with the shift assist was causing coil bind. not to sure now.

Thunder

yes one of the shims removed

yes i think you are correct in your assumption that you should never shift out far enough for that belt to be that low in the secondary given that the secondary spring and the D/D gearing is condusive to having the ratio working well...and like you said i would think some residue would be on the helix

i would have a heat sensor gun and after those hard pulls on the trail see what has the real heat...the primary or the secondary...maybe your concentrating on the wrong clutch..??

fordpickupman · Jan 20, 2013

clutch temps

My clutches were not hot at all, I could touch them with my hands. I have them vented really well. I would not think that heat was the problem.

m8magicandmystery · Jan 20, 2013

fordpickupman said:
My clutches were not hot at all, I could touch them with my hands. I have them vented really well. I would not think that heat was the problem.

i not saying heat is the necessary issue...but the hotter clutch may be an indicator of mismatched components..

diggerdown · Jan 21, 2013

I always assumed the plastic washer you removed was the one on the other end of the spring that was replaced with the thrust bearing. I see no reason to change the any other thing.

Arctic Thunder · Jan 21, 2013

diggerdown said:
I always assumed the plastic washer you removed was the one on the other end of the spring that was replaced with the thrust bearing. I see no reason to change the any other thing.

Agreed, but I think the guys selling the shift assist say to remove the spacer where the shift assist bearing goes AND one of the shims out on the end of the helix. I always assumed it was to gain some coil clearnace. Maybe they say to do it to back off on the spring tension just a bit because you now have a free moving bearing under the sping. Not a clearance issue at all.

Again I don't think I have any clearance issues with both shims installed. With only one installed I just have a bit less secondary spring tension.

Thunder

Desperado · Jan 21, 2013

secondary

I was told when I installed my SA to only remove the spacer where the SA will now ride. I left the 2 shims in at the other end of the helix. As for going 100mph never tried pushing it that far. We usually stop the race at about 70 or 75 or about 2 to 300 yrds. Guess where we like the bragging rights is on a hill drag or in a climb.

Arctic Thunder · Jan 26, 2013

Alright, did some more looking. I see no reason to remove the upper two spacers. Their is enough room for the clutch to shift out all the way without coil binding. (also looked back at my D&D instructions and it just says to replace the one spacer and put it back together, nothing about removing one)

So I would agree with digger, leave both of them in.

Now I know someone else said to check this. The ID of the shift assist is big enough that the clutch spacer will slip down inside of it. Thus you over shift by .125". So I am going to cut me a spacer to get the full shift back to where it should be.

My first pictures were taken with the spacer down inside the shift asist bearing, these ones are with the correct spacing. Notice the darn belt is where it should be!!

Thunder

fordpickupman · Jan 26, 2013

That looks way better.

I have an RKT torsion conversion on mine. It doesn't have any spacers in it. I am thinking about converting it to compression & putting the spacers and shift assist back in it. I am not convinced of the torsion setup's efficiency.

FORDpickupman

clutch · Jan 26, 2013

Arctic Thunder said:
Alright, did some more looking. I see no reason to remove the upper two spacers. Their is enough room for the clutch to shift out all the way without coil binding. (also looked back at my D&D instructions and it just says to replace the one spacer and put it back together, nothing about removing one)

So I would agree with digger, leave both of them in.

Now I know someone else said to check this. The ID of the shift assist is big enough that the clutch spacer will slip down inside of it. Thus you over shift by .125". So I am going to cut me a spacer to get the full shift back to where it should be.

My first pictures were taken with the spacer down inside the shift asist bearing, these ones are with the correct spacing. Notice the darn belt is where it should be!!

Thunder

I thought that might be your problem. If it shifts too far in the driven, it will definitely give you the problem you were having. I hope that is the cure for ya!:face-icon-small-coo

Desperado · Jan 27, 2013

SA

We must have different brands of SA bearings cause my white spacer sits on top of the SA bearing not inside of it. I always know the SA ID was smaller than the OD of the spacer... Kind of wondered if the SA ID should have been bigger to accommodate the spacer. Now I know the answer to that is no.

Ford, I also ran the RKT secondary until this season when I went back to the stock secondary with MDS weights in the primary. Although the RKT setup held RPM's ok I still saw a loss of track speed in climbs and clutches that were pretty hot. Once I switched back to a stock secondary with the MDS weights I saw consistent RPM's but more importantly track speed that didn't drop off as before. Might be something to consider.... On a side note the snow yesterday was very heavy and hard on clutching. That said without changing any weights in my primary I did loose a little bit of RPM but not very much in track speed at the end of a climb. The snow was simply harder to go though.

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Secondary Spring Clearance/shift assist

Arctic Thunder

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fordpickupman

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m8magicandmystery

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