Main clutch slipping

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bdtutton
Posts: 180
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* REQUIRED* Type and Year of Model Ts owned: 1914 Model T
Location: Southwest, MI

Main clutch slipping

Post by bdtutton » Sun Sep 12, 2021 11:04 pm

Over the weekend I was driving my 1914 Touring car and everything was running well. I was driving along at about 30mph and I started climbing a long shallow grade and all seemed well.....then I noticed the speed was dropping, but the engine RPM was staying the same. At this point the grade became steeper so I dropped to low pedal to get over the top. As I topped the hill I returned to high gear and things seemed OK until the next hill where it started slipping again. I pulled into a parking lot to make sure the brake lever was able to go fully forward and I even loosened the adjustments a bit to make sure the high gear clutch could fully engage. I headed for home and it was still slipping.
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I opened the transmission and checked the clutch measurement and it was at 13/16", but seemed kind of loose so I carefully pulled the cotter pins (yes, I used string to make sure I did not drop anything into the transmission) and I tightened the fingers on the clutch. It still slipped so I took it apart again and tightened everything up some more....and it still slips. I don't think any additional tightening will fix the problem.
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At this point either the clutch is ruined from slipping or there is some other issue going on. I am thinking that if it was just a clutch wear issue it would improve when I tighten the clutch...so I am wondering if it could be something else. I opened up the transmission and pushed the brake lever all the way forward to engage the clutch. I then worked the clutch pedal from high to low and noticed the transmission brake drum and other parts of the transmission moving forward and back when I moved the clutch. I don't know if this is normal...and I don't know if this is related to my slipping problem. I took a video on my phone, but am having a problem posting.
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Is this a straight clutch wear problem or could it be something else?
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Alan Long
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Re: Main clutch slipping

Post by Alan Long » Mon Sep 13, 2021 2:05 am

Maybe a worn or cracked Spring ? 2” at the Spring is the same as 13/16” Gap at the collar. Looks like a engine out job if all other settings are correct and the clutch fork is loose in high gear.
Alan in Western Australia


Joe Bell
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Re: Main clutch slipping

Post by Joe Bell » Mon Sep 13, 2021 7:15 am

This past year I replaced six sets of modern clutches people had installed on there rebuild jobs sounds as this is what is going on with yours. If you look back into the driven plate, the three holes, the ring should be about an 1/8 inside the clutch drum, if you see it is 1/4 then you have found the problem! The paper from the modern disc goes all through the engine, little redish brown particles. The sad part is the engine needs to come out to replace them.


Alan Long
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Re: Main clutch slipping

Post by Alan Long » Mon Sep 13, 2021 8:20 am

Joe could be on the money here but your 3 adjusting screws on the fingers will be screwed right down to achieve the 13/16 or
2” setting. Modern (Fibre) Turbo 400 / Jack Rabbit Plates won’t last long if subjected to slippage by the way the vehicle is driven from first to top. Additionally, any water or condensation in the oil will cause the friction material to peel off
the steel section of the plate. Factory steel on steel are much more forgiving. Alan in Western Australia


TXGOAT2
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Re: Main clutch slipping

Post by TXGOAT2 » Mon Sep 13, 2021 9:22 am

I think the forward and back movement is controlled by the engine's rear main bearing. Some movement is normal, but it should be slight. If your clutch began slipping over a short period of time, it could be the spring has broken. It looks like it isn't an adjustment issue, since you've addressed that.


Topic author
bdtutton
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Re: Main clutch slipping

Post by bdtutton » Mon Sep 13, 2021 11:41 am

Thank you everyone for the feedback....in response, here is a little more information.....
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I had just changed the oil so one of the first things I did was to drain the oil to see if there was any contamination in the oil from the slippage. The oil was clean and clear and looked like I would expect after only being in the car a few days.
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This transmission had very few hours on it since it was rebuilt by the previous owner. Prior to this incident the shifts into high gear had always been smooth with a solid engagement...this came on suddenly.
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Two issues stand out on this problem....The problem happened suddenly and no matter how much I tighten the clutch it does not seem to make much of an improvement. As several of you have pointed out it is sounding like a broken clutch spring.
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I am still kind of new to Model T's....is this an engine out issue or since the spring is on the back of the transmission, can it be accomplished by just pulling the rear axle/drive shaft and going into the back of the transmission?
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Thanks...


Joe Bell
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Re: Main clutch slipping

Post by Joe Bell » Mon Sep 13, 2021 12:15 pm

If you pull the rear axle just to replace the spring, then you find out it is the clutch disc instead now you have to pull the engine any ways? I have done this the hard way as you just mention and then had to pull the engine to fix the original problem.


TXGOAT2
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Re: Main clutch slipping

Post by TXGOAT2 » Mon Sep 13, 2021 1:42 pm

The Ford manual describes the procedure to change the clutch spring. They classify it as a two man, 1 1/2 hour job. Mention is made of a clutch spring compressor tool. The rear axle has to be removed and the ball cap disassembled. Before doing anything else, I'd try to get a look at the clutch spring and check how far the pressure ring goes into the drum when the clutch is engaged as mentioned above.


Dan Haynes
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Re: Main clutch slipping

Post by Dan Haynes » Mon Sep 13, 2021 1:55 pm

Check to make sure your handbrake lever is staying all the way forward. Sometimes brake rods are adjusted so they will push the levers that normally pull them, making the controller shaft roll backwards and the lever come back toward you a little, causing the throw-out cam to sort of wedge under the throw-out lever adjustment bolt, easing the pressure on the clutch discs. It doesn't take much to make a clutch slip
"The further a society drifts from truth, the more it will hate those who speak it." -George Orwell


Topic author
bdtutton
Posts: 180
Joined: Thu Feb 18, 2021 10:19 pm
First Name: Bryan
Last Name: Tutton
* REQUIRED* Type and Year of Model Ts owned: 1914 Model T
Location: Southwest, MI

Re: Main clutch slipping

Post by bdtutton » Mon Sep 13, 2021 5:55 pm

I plan to do some additional checking, but I may have to pull the engine/transmission and replace the clutch. I have access to an engine puller and an engine stand that can hold a model T engine, but I don't know all the other tools I may need. I guess I better buy a transmission book and start reading up on what I need to do. Does anyone have any good tips on tools I need to start looking for? I know that having the right tools to do a job can make all the difference in the world when you are doing a job like this.


John Illinois
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Re: Main clutch slipping

Post by John Illinois » Tue Sep 14, 2021 5:41 pm

I would suggest Mike Benders videos on transmissions.

https://www.youtube.com/channel/UCz9Cs_ ... d6e-WMvuRQ

John


speedytinc
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Re: Main clutch slipping

Post by speedytinc » Wed Sep 15, 2021 9:37 am

Alan Long wrote:
Mon Sep 13, 2021 8:20 am
Joe could be on the money here but your 3 adjusting screws on the fingers will be screwed right down to achieve the 13/16 or
2” setting. Modern (Fibre) Turbo 400 / Jack Rabbit Plates won’t last long if subjected to slippage by the way the vehicle is driven from first to top. Additionally, any water or condensation in the oil will cause the friction material to peel off
the steel section of the plate. Factory steel on steel are much more forgiving. Alan in Western Australia
This does sound like a 400 clutch wear/set up problem. You can typically see enough of the disk on the clutch hub to confirm a 400 disk.
The 13/16 dimension is ok with a perfect or new spring. If the spring is weak, you may not have enough lock up force. (either clutch disks) Any slipping with the 400 disks cause quick wear out. The are ment to lock up & stay locked. When I install 400's, I add extra tension on a new higher pressure spring for a safety margin. They MUST be set up correctly. Never had a problem with the dozens I have done. Yes they are less forgiving than stock disks, But I find the effort worthwhile.
As long as you have enough of the 3 plate pins out from the output plate, increase the spring tension untill you loose the slip +. You may have caught it in time.
Service manual covers the adjustment to change the pressure to attain the proper "controlled" slip. Its not the dimension, its the result you are looking for. The dimension is a starting point for a stock clutch & to readjust from controlled slip wear as necessary.


speedytinc
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Re: Main clutch slipping

Post by speedytinc » Fri Sep 17, 2021 1:26 pm

Your post came up @ our thursday night T party.
Is the clutch/brake drum the original early style that requires a special thick first disk?
If so, & you dont have that special first disk, as REQUIRED, the thin disk can slip past the drum tabs & jam stuff up.
If you are using the later, narrow drum, this is not applicable.


Jerry VanOoteghem
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Re: Main clutch slipping

Post by Jerry VanOoteghem » Fri Sep 17, 2021 3:56 pm

It's not an adjustment issue, as you've confirmed, and words won't fix it. It's got to come out for a "look see".


speedytinc
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Re: Main clutch slipping

Post by speedytinc » Fri Sep 17, 2021 4:15 pm

Jerry VanOoteghem wrote:
Fri Sep 17, 2021 3:56 pm
It's not an adjustment issue, as you've confirmed, and words won't fix it. It's got to come out for a "look see".
Agreed. This could be some thing to be aware of. The thick plate issue/need is not well known.


Altair
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Re: Main clutch slipping

Post by Altair » Sat Sep 18, 2021 11:30 pm

You say that you turned the clutch forks in I think that is the not correct they should be turned out so that they clear the pressure plate, you should be able to wiggle the forks when in top gear.

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