Standard 3 speed tranny question
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From: Saraland, AL
Standard 3 speed tranny question
While restoring the '52 F-1 truck with the flathead V8, we did our best on the standard 3 speed transmission. Some water had collected inside over the years so we had some pitted gears to replace.
I have been driving it for the past few months. As I increase engine rpm and shift from first to second, it is very smooth. While in second gear and increasing the engine rpm, I often get a gear clash going into third. It is not bad, but drives me crazy. If while in second, I do not allow the engine rpm to increase very much, then shifting into third is smooth.
I am about to pull it back into the shop and take the tranny back off for some more surgery. Before doing all that effort, I was wondering what results/experience others have had if they were also using the standard 3 speed....
Thanks for any input.
Fred
I have been driving it for the past few months. As I increase engine rpm and shift from first to second, it is very smooth. While in second gear and increasing the engine rpm, I often get a gear clash going into third. It is not bad, but drives me crazy. If while in second, I do not allow the engine rpm to increase very much, then shifting into third is smooth.
I am about to pull it back into the shop and take the tranny back off for some more surgery. Before doing all that effort, I was wondering what results/experience others have had if they were also using the standard 3 speed....
Thanks for any input.
Fred
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From: NM
When you had it apart, did you replace the needle bearings inside the input gear? Actually, I guess I'd want to know what all you replaced besides gears; synchro rings? input bearing? synchro struts?
I replaced all my brass blocker rings with new, and 2nd has never been smooth since. Never sure exactly why, it was smooth as silk before the rebuild.
I replaced all my brass blocker rings with new, and 2nd has never been smooth since. Never sure exactly why, it was smooth as silk before the rebuild.
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From: Saraland, AL
The main and most expensive replacement was the cluster gear. We did replace some of the roller bearings (seems like we bought a roller bearing set), one or two bushings, and the synchro hub. My memory is foggy, as it has been over three years as the tranny was one of our first items to rebuild. I bought the transmission rebuild manual from Mac Van Pelt as a guide but my Dad and I are not transmission experts to say the least!
Ross - when you shift from second to third, if your engine was at a fairly high rpm just prior to clutching, does it shift smoothly into third?
I can only shift into third with no gear clashing if I quickly go from second to third, not allowing the engine rpm to increase very much as speed is building. Going up or down into second is sweet.
Fred
Ross - when you shift from second to third, if your engine was at a fairly high rpm just prior to clutching, does it shift smoothly into third?
I can only shift into third with no gear clashing if I quickly go from second to third, not allowing the engine rpm to increase very much as speed is building. Going up or down into second is sweet.
Fred
Cargo Master
Joined: Jun 2001
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From: Oxford, Indiana
Your 3rd gear synchro blocking ring is worn out. The ring acts like a brake and matches the speed of the input shaft, countershaft cluster, and 3rd gear and to the speed of the output shaft - all in that split second that it takes to shift gears. When the ring accummulates enough wear, it can't match the speeds anymore and the gears clash. It sounds like you did a decent job rebuilding the rest of it. I'd pull it, break it down, and replace both 2nd and 3rd gear synchro rings. With the rest of the work you did, it should last for a long time.
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From: NM
I think BOR is right, although synch'ing 3rd gear is so easy that I'm suspicious that there is some angular misalignment due to bad needles in the inside of the input shaft. It's rare for 3rd to clash even on real old trannies. Check the end play too. Is this a column shifter? Make sure the linkage isn't so sloppy that it isn't pulling 3rd all the way in.
See highlighted needles below. Also make sure the ring highlighted is there; I believe it is shrunk onto the shaft, doesn't just slide off. The blocker rings are the 7107's
See highlighted needles below. Also make sure the ring highlighted is there; I believe it is shrunk onto the shaft, doesn't just slide off. The blocker rings are the 7107's
Cargo Master
Joined: Aug 2010
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From: Houston
I had a discussion with our local old transmission "expert" a couple years back. His opinion was that new synchro rings are softer than the originals. He tries to reuse good original synchro rings and claims good results. I don't know if he is correct or not, but it is food for thought.
Fleet Owner
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From: NM
Well, you can guess where they come from... they look OK but right out of the box mine snag unevenly.
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From: Saraland, AL
I wanted to provide an update on this one...
I pulled the tranny out last week. It was the brass synchronizer ring. The one for third gear was shot. The one on second gear looked great and because of what Ross said about his rebuild, I only ordered one new brass ring.
While doing assembly and doing a hand fit up, I noticed that when the new ring was slid in place on the main drive shaft, it had a 1/16" gap. My original ring on second gear mated right up against the second gear, so I wrote Mac Van Pelt (the vendor I used). He told me that the 1/16" gap is the correct gap and that my ring on second gear was worn... so another ring was mailed to me.
The end results was that with two new synchronizer rings, the transmission shifts great. No gear clashing into or out of second or third.
Thanks for all of the input. I can call this issue solved. One problem down, 5 more to go.
Now to find out why my cowl vent leaks ....!
Fred
I pulled the tranny out last week. It was the brass synchronizer ring. The one for third gear was shot. The one on second gear looked great and because of what Ross said about his rebuild, I only ordered one new brass ring.
While doing assembly and doing a hand fit up, I noticed that when the new ring was slid in place on the main drive shaft, it had a 1/16" gap. My original ring on second gear mated right up against the second gear, so I wrote Mac Van Pelt (the vendor I used). He told me that the 1/16" gap is the correct gap and that my ring on second gear was worn... so another ring was mailed to me.
The end results was that with two new synchronizer rings, the transmission shifts great. No gear clashing into or out of second or third.
Thanks for all of the input. I can call this issue solved. One problem down, 5 more to go.
Now to find out why my cowl vent leaks ....!
Fred
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Fleet Owner
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From: NM
That's great news! Mac was right, as the rings wear, they snug up to the bottom of the conical seat.
Glad to see you updated your avatar, too! Much more appropriate!
Cowl seal -- easy. Don't drive in the rain!
Glad to see you updated your avatar, too! Much more appropriate!
Cowl seal -- easy. Don't drive in the rain!
Fleet Owner
Joined: Jul 2004
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From: NM
Well, there's more to the story (usually is). When I had it apart, I found the case thrust surface (where the cluster gear bears on it) was torn up. The thrust washers (just barely in the picture above at extreme bottom right) are supposed to be locked from turning by a tab on them, but if they get worn enough they start to spin and tear up the case. I cleaned it up best I could and did some shadetree work to restore clearances. Van Pelt offers a service to restore the surface ($250 or so) but I'm probably going to just use a clean used case. So to answer your question, I intend to take it back apart this winter, but it is going to be much more than just a quick replacement of the bronze blocker ring.
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