Urgent Clutch Swap Gone Wrong

[7.3IDIDSL]

Well guys i swapped out the original DMF for a Southbend SMF this weekend. And after hearing horror stories of severe cases of gear rattle i was prepared for the worst the whole time i was installing the clutch.

Well good thing i was preparing for the worst because the worst happened. I started the truck and went to let the clutch out and i heard the worst sound in the world. Its a very loud vibration noise that goes almost completely away when i push the clutch back in. As long as im sitting with my foot on the clutch the truck doesnt sound all that bad...but as soon as i let the clutch out in gear or neutral i get that loud vibration sound back.

I got a mechanic friend of mine to listen to the sound and he says he doesnt think it has anyting to do with the clutch and he got me to go under the truck and listen and feel for the sound while he let the clutch out in neutral and the sound is definately coming from the tranny and if i put my hands on the side of the tranny i can feel a vibration. He says it sounds like gear rattle but he has done 5 of these swaps on these trucks and has never once heard a sound like that.

Also if im driving the truck and let the rpms drop down to about 1200 rpm the sound comes back. At this point im completely lost and have no idea what to do. My buddy suggested i call southbend and tell them whats going on as well as take my truck to a local tranny shop and see what they say about the sound. He also says it might be worth it to go out and buy some gear oil and drain the atf in the tranny and refill with gear oil and see what happens. I really need some help here i dont know what to do haha i would feel better if i knew forsure that it was gear rattle and not my brand new clutch dieing.

 

[david85]

I did a SMF conversion on a 1995 powerstroke, and while there was a difference, it wasn't really all that bad. It was most noticable while idling along at low speed and RPMs below 1500. I somehow doubt that the truck I worked on idled any smoother than yours.

The only thing that might have been different is that I used a Valair clutch kit.

Heard of others switching to a heavy weight gear oil and over filling the tranny to drop the gear clatter.

 

[7.3IDIDSL]

Yeah im hoping some others will give me some advice. But either way i think im going to go get some heavy weight gear oil in the morning and see if that helps with the sound at all. My buddy said i should try some 75W90 gear oil and see what happens with the noise.

 

[Diesel JD]

Are you sure you want to do the gear oil thing? I wonder if it might make your situation worse by killing the ZF5.

 

[Dieselguy123]

That sounds like standard gear rollover caused by the SMF swap. Guy at a local tranny shop told me to run a mix of 80-90 and 15-40 syn, Told me it would queit it down but wouldnt completly go away.

 

[RLDSL]

I know a lot of folks have done the motor oil thing to quiet them down, but there are a few things in motor oil that aren't real friendly with the inards of a zf5.
I did a bit of poking on this while matching up a fluid for my spicer box a while back and I wanted one I could use in the zf as well.
The factory fill ATF is 20 wt atf.
I found a 30 wt synthetic atf that was compatible with manual boxes and met the spec for the spicer boxes so I could use it in both. that same tranny fluid is available in 50 wt as well and both these wts keep you in a tranny fluid so there's not the compatibility problems of using a motor oil.

I'm not sure what the wt of the old standard mineral oil is that they used to ( and still do in many cases ) use in a lot of the commercial boxes, but that might be another option

 

[Cheaper Jeeper]

What you are describing sounds like it may be just the typical gear rattle issue with a ZF5 SMF conversion. Maybe a little worse than normal - or maybe just worse than you expected. Mine sounded like a washing machine full of marbles or like a bearing was on its last legs.

Everything I have read on this subject says DO NOT use gear oil. The ZF is built to really tight tolerances and gear oil is too thick to get into the some of the gaps and crevices, and you can end up with metal to metal contact between some of the internal parts.

Either way, here is what I did to quiet mine way, WAY down...

You do want to use heavier oil to dampen the vibrations that are rattling the gears. Most ATF is around 15W to 30W, so I chose 15W50 Mobil1. Here is my logic behind that choice. First it is a synthetic - which is closest to what they recommend for the ZF (synthetic ATF). Second, at cold temps it will be as thin a straight 15W so you shouldn't have any galling issues due to it being too thick to get into the fine tolerance parts. Third, at hot temps it will be as thick as 40W so it should provide better wear protection.

The other thing to do is overfill it - a lot - like double the normal amount of oil. I put a full two gallons in mine. Filling it to the fill plug on the side will only allow you to get a gallon in it, but if you remove the shift lever and pour it in the top you can easily get twice as much in it. That way all of the shafts and gears are mostly submerged in oil - which also dampens the vibrations a lot.

Increase your idle to about 750-800 RPMs. The rattle only happens at lower RPMS where the torque spikes of the high compression cylinders firing are far enough apart to be "seen" as separate events by the internals of the tranny. If there is less time between the spikes the gears don't have enough time to fully rock back and forth from one end play position to the other, and end up just kind of floating somewhere in between the two extremes of their end play.

Lastly, just get used to the fact that it is going to be noisier. It isn't hurting anything and if you do the 3 things listed above it will only be loud when creeping along below 1000 or 1200 RPMs.

That is what worked for me. Between these 3 steps mine has quieted down to where you can hardly hear it over the engine noise when idling in neutral with your foot off the clutch. It is still a bit noisy when idling along in gear, but that's the only time the noise is really noticeable.

As far as statements about motor oil not being compatible with a tranny, I'd like more info on that. I've always understood that the only difference between ATF and thin motor oil is that the ATF has a lot more detergent addatives - which an automatic tranny needs, but a manual doesn't.

Good luck with it...

 

[Agnem]

Cheaper Jeeper is telling it to you streight. You have NORMAL gear roll over noise as the result of your conversion to a SMF. This noise is a hell of a racket, and can be VERY loud. I put 2 gallons of non-detergent 30 wt. motor oil in mine, and it helps some. I also turned the idle up to 750. On hot days, you may actually find that it goes away completely for a little while. By and large though, your going to have to learn to live with it. This is why we all love cast iron transmissions like the T-19. If only they had given it an overdrive, it would have been perfect.

 

[7.3IDIDSL]

What you are describing sounds like it may be just the typical gear rattle issue with a ZF5 SMF conversion. Maybe a little worse than normal - or maybe just worse than you expected. Mine sounded like a washing machine full of marbles or like a bearing was on its last legs.

Everything I have read on this subject says DO NOT use gear oil. The ZF is built to really tight tolerances and gear oil is too thick to get into the some of the gaps and crevices, and you can end up with metal to metal contact between some of the internal parts.

Either way, here is what I did to quiet mine way, WAY down...

You do want to use heavier oil to dampen the vibrations that are rattling the gears. Most ATF is around 15W to 30W, so I chose 15W50 Mobil1. Here is my logic behind that choice. First it is a synthetic - which is closest to what they recommend for the ZF (synthetic ATF). Second, at cold temps it will be as thin a straight 15W so you shouldn't have any galling issues due to it being too thick to get into the fine tolerance parts. Third, at hot temps it will be as thick as 40W so it should provide better wear protection.

The other thing to do is overfill it - a lot - like double the normal amount of oil. I put a full two gallons in mine. Filling it to the fill plug on the side will only allow you to get a gallon in it, but if you remove the shift lever and pour it in the top you can easily get twice as much in it. That way all of the shafts and gears are mostly submerged in oil - which also dampens the vibrations a lot.

Increase your idle to about 750-800 RPMs. The rattle only happens at lower RPMS where the torque spikes of the high compression cylinders firing are far enough apart to be "seen" as separate events by the internals of the tranny. If there is less time between the spikes the gears don't have enough time to fully rock back and forth from one end play position to the other, and end up just kind of floating somewhere in between the two extremes of their end play.

Lastly, just get used to the fact that it is going to be noisier. It isn't hurting anything and if you do the 3 things listed above it will only be loud when creeping along below 1000 or 1200 RPMs.

That is what worked for me. Between these 3 steps mine has quieted down to where you can hardly hear it over the engine noise when idling in neutral with your foot off the clutch. It is still a bit noisy when idling along in gear, but that's the only time the noise is really noticeable.

As far as statements about motor oil not being compatible with a tranny, I'd like more info on that. I've always understood that the only difference between ATF and thin motor oil is that the ATF has a lot more detergent addatives - which an automatic tranny needs, but a manual doesn't.

Good luck with it...

I dont know if ill be able to find a store that sells mobil up here...ive never seen it before. But i think if i can find some 15w50 syn in any brand it would be worth it to see if it quiets the noise down right?

When you are overfilling it front inside the cab do you go untill the fluid is right at the top of the trans and about to pour over. Or do you leave a bit of room?

Im going to try the fluid first and then ill figure out how to adjust my idle and see if that helps too. I understood that a SMF wasnt going to be as quiet as a DMF but this noise is unbearable. If it is gear rattle than its hard to beleive it isnt causing damage because it just sounds nasty. I took it for a short drive around the block yesterday and everybody i passed turned and looked.

Cheaper Jeeper is telling it to you streight. You have NORMAL gear roll over noise as the result of your conversion to a SMF. This noise is a hell of a racket, and can be VERY loud. I put 2 gallons of non-detergent 30 wt. motor oil in mine, and it helps some. I also turned the idle up to 750. On hot days, you may actually find that it goes away completely for a little while. By and large though, your going to have to learn to live with it. This is why we all love cast iron transmissions like the T-19. If only they had given it an overdrive, it would have been perfect.

So you are running SAE 30 wt. in your trans agnem? I havnt looked yet. But i think im going to have a hard time finding mobil up here. I do know one store that carrys a huge line of RP oils. But RP only has 0W40, 5W20, 5W30, 5W40, 10W30, 10W40, 15W40, 20W50, SAE 30, SAE 40 and SAE 50 weights.
Is there one thats close to the 15w50 that cheeper recommends or should i get 30wt.? This is really getting confussing. I dont want to spend all that money on oil and end up getting a wrong wt?

 

[Cheaper Jeeper]

I dont know if ill be able to find a store that sells mobil up here...ive never seen it before. But i think if i can find some 15w50 syn in any brand it would be worth it to see if it quiets the noise down right?

Sure. The benefit of the synthetic is that it has no sulfur in it like petroleum oils do. Sulfur is bad for the brass parts inside the tranny (syncros, etc.)

When you are overfilling it front inside the cab do you go untill the fluid is right at the top of the trans and about to pour over. Or do you leave a bit of room?

You don't want to fill it clear up to the top. If you do when the oil heats up and expands it is going to push a quart or more out of the breather tube - hopefully before it pushes out one of the seals. I just figured that if it held a gallon to get it full to the fill plug - which is a little below half way up the side of the case - it ought to hold two gallons without overflowing. So I put two in it and it seems that I guessed right, because it hasn't blown any out the breather.

Im going to try the fluid first and then ill figure out how to adjust my idle and see if that helps too. I understood that a SMF wasnt going to be as quiet as a DMF but this noise is unbearable. If it is gear rattle than its hard to beleive it isnt causing damage because it just sounds nasty. I took it for a short drive around the block yesterday and everybody i passed turned and looked.

I know what you mean. I took mine to get it emissions tested right after installing the SMF last year. The emissions inspector asked me what was wrong with it and if I "thought it was going to make it" - as in was it going make it back home!

Adjusting the idle is easy - IIRC there is a set screw with a lock nut on the passenger side front of the IP that acts as a travel-stop for the throttle linkage. Loosening the locknut and turning in the screw will increase your idle. Once you have is set where you want it, tighten the lock nut to hold it there.

So you are running SAE 30 wt. in your trans agnem? I havnt looked yet. But i think im going to have a hard time finding mobil up here. I do know one store that carrys a huge line of RP oils. But RP only has 0W40, 5W20, 5W30, 5W40, 10W30, 10W40, 15W40, 20W50, SAE 30, SAE 40 and SAE 50 weights.
Is there one thats close to the 15w50 that cheeper recommends or should i get 30wt.? This is really getting confussing. I dont want to spend all that money on oil and end up getting a wrong wt?

Mel seems to have had no problems with his and he's been running one a lot longer than I have. I certainly wouldn't go with anything heavier than 30W and would highly recommend synthetic for its low sulfur content. I just went with the 15W-50W because the temperature variable viscosity seemed like a good idea. I wanted something as thin as possible when cold and thick as possible when hot to get the benefits of increased wear protection and still get it into those tight tolerance spaces. But of course as an engineer I do have a tenddancy to over-analyze and over-think things sometimes (most times?).

 

[7.3IDIDSL]

Sure. The benefit of the synthetic is that it has no sulfur in it like petroleum oils do. Sulfur is bad for the brass parts inside the tranny (syncros, etc.)



You don't want to fill it clear up to the top. If you do when the oil heats up and expands it is going to push a quart or more out of the breather tube - hopefully before it pushes out one of the seals. I just figured that if it held a gallon to get it full to the fill plug - which is a little below half way up the side of the case - it ought to hold two gallons without overflowing. So I put two in it and it seems that I guessed right, because it hasn't blown any out the breather.



I know what you mean. I took mine to get it emissions tested right after installing the SMF last year. The emissions inspector asked me what was wrong with it and if I "thought it was goine to make it" - as in was it going make it back home!

Adjusting the idle is easy - IIRC there is a set screw with a lock nut on the passenger side front of the IP that acts as a travel-stop for the throttle linkage. Loosening the locknut and turning in the screw will increase your idle. Once you have is set where you want it, tighten the lock nut to hold it there.



Mel seems to have had no problems with his and he's been running one a lot longer than I have. I certainly wouldn't go with anything heavier than 30W and would highly recommend synthetic for its low sulfur content. I just went with the 15W-50W because the temperature variable viscosity seemed like a good idea. I wanted something as thin as possible when cold and thick as possible when hot to get the benefits of increased wear protection and still get it into those tight tolerance spaces. But of course as an engineer I do have a tenddancy to over-analyze and over-think things sometimes (most times?).

yeah the variable viscosity sounds like a good idea. But where i live it doesnt usually get that cold even in the winter. If i cant find 15w50 im just going to get whatever i can find thats close to it. RP sells 15w40 and 20w50 so i could get something like that but i have got to be able to find some 15w50 somewhere. Alright im heading to the store now. Ill let you guys know what happens.

 

[Cheaper Jeeper]

yeah the variable viscosity sounds like a good idea. But where i live it doesnt usually get that cold even in the winter. If i cant find 15w50 im just going to get whatever i can find thats close to it. RP sells 15w40 and 20w50 so i could get something like that but i have got to be able to find some 15w50 somewhere. Alright im heading to the store now. Ill let you guys know what happens.

Heck, order a case of Mobil1 from the Schucks/Checker/Kragen website if you can't find it anywhere else. Their site is www.partsamerica.com

 

[kpj]

I got the same annoying noise when i did the smf conversion. At first i thought also that there has to be something wrong, but i have driven about 8000 miles after it and had no problems, hopefully there isn't coming either.

I also lifted the idle speed like Cheaper Jeeper and it really helped. I turned the screw about 3/4 tighter, don't know how much the rpm is at the moment. I use Kendall dexron synthetic automatic transmission oil and the next time when i change the oil i will overfill the transmission and test does it work.

After driving a while you'll get use to that noise driving at slow speed, but still sometimes i miss that quietness of dmf...

 

[Agnem]

I went with the streight 30 weight based on the recommendation of my friend and Ford diesel tech Bob at Stoner-Wade. He said it was a common practice for SMF conversions, and dispite the noise, has never seen a ZF ruined by a SMF.

 

[wwwabbit]

Ditto on the noise with the SMF. I laugh when I pull up to a light, let the clutch out in neutral and watch the cars around me roll up the windows. I should try a little heavier weight oil too and see how it does. Mine is mostly a hauling/firewood truck so I don't mind, but I found a old sheet around the shifter boot quited things down some what too.