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Need some 4speed help #2989650
11/27/21 05:55 PM
11/27/21 05:55 PM
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8urvette Offline OP
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I have a 69 A833 18 spline trans in my A body. It is a b body main case with a 68 a body tail shaft.

It has a hydraulic throw out bearing and wilwood master and a twin disc clutch.

Here is the problem. It shifts okay when driving around town, but my 1 / 2 shift is NON EXISTANT when the engine is over 5000 rpms.

It just wont go, it doenst grind it just wont go into 2nd. I can shift into 3rd or 4th, but not second. But under 5k it will go into 2nd no problem. I pulled the trans out and apart (also have to fix a leak) and the 1/2 stuff looks really good and shifts easily by hand. The 3/4 is a little beat up but that shifts fine.

HELP!!!!!

Ideas? Thoughts?

Re: Need some 4speed help [Re: 8urvette] #2989656
11/27/21 06:08 PM
11/27/21 06:08 PM
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lewtot184 Offline
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not sure if this will help but back in the day when i ran the transmissions a good high rpm shift was very dependent on proper clutch release. i adjusted for the most release i could get but still maintain reliable operation.

Re: Need some 4speed help [Re: lewtot184] #2989665
11/27/21 07:05 PM
11/27/21 07:05 PM
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lancer493 Offline
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Two things come to mind here, but a little clarification may help. You neglected to specify whether the trans fails to pull out of first gear on a high rpm shift or rather it only gets to a neutral position. The gears in a big mopar 4spd are bigger and heavier than a Muncie or Borg Warner T10 GM trans therefore as rpm increases it is a bigger job for the tapered cone brass synchro rings to slow down the next coming gear. GM transmissions shift like butter at high speed, but are much weaker than the big Mopar gear box. My guess would be a worn or cracked brass synchro ring on 2nd gear or grinding burrs on the 1st gear iron teeth that are integral to the gear itself. Those teeth can get to look like the starter ring gear teeth on a flywheel when they develope a burr on the edge of the teeth when the drive fails to engage properly, making a grinding sound.When that happens the starter drive gear can't pull out of the flywheel when the engine cranks or starts to run.This can happen to transmission gears in rare occassions. I would take a second look at ALL the syncro components in the 1-2 synchro assembly. I think you could get a good look just by pulling the side cover,but you may not be able to make a good check to see the actual engagement fit of the brass ring to the cone of the actual gear. The brass synchro ring should not totally butt up to the teeth on the actual gear. If that happens the ring has no ability to stop the gear effectively,especially at speed.This is why Mopar 4spds were slick shifted for drag racing, eliminating the synchronizing effect,but not at all street worthy, just power shifting. Bill

Re: Need some 4speed help [Re: lancer493] #2989681
11/27/21 08:00 PM
11/27/21 08:00 PM
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lewtot184 Offline
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my experience was the higher the rpm the more difficult it was to "move" the mass around inside. i didn't use soft clutch discs and eventually used a super shifter which did help. all the high horsepower drag cars back then were slick shifted. i just had to learn how to make them work and respected the limitations.

Re: Need some 4speed help [Re: lewtot184] #2989695
11/27/21 08:53 PM
11/27/21 08:53 PM
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Here is a pic of the 1/2 stuff. To me it looks fine, the 3/4 is worse but shifts better.

KIMG0246.JPGKIMG0247.JPG
Re: Need some 4speed help [Re: lancer493] #2989696
11/27/21 08:55 PM
11/27/21 08:55 PM
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Originally Posted by lancer493
Two things come to mind here, but a little clarification may help. You neglected to specify whether the trans fails to pull out of first gear on a high rpm shift or rather it only gets to a neutral position. The gears in a big mopar 4spd are bigger and heavier than a Muncie or Borg Warner T10 GM trans therefore as rpm increases it is a bigger job for the tapered cone brass synchro rings to slow down the next coming gear. GM transmissions shift like butter at high speed, but are much weaker than the big Mopar gear box. My guess would be a worn or cracked brass synchro ring on 2nd gear or grinding burrs on the 1st gear iron teeth that are integral to the gear itself. Those teeth can get to look like the starter ring gear teeth on a flywheel when they develope a burr on the edge of the teeth when the drive fails to engage properly, making a grinding sound.When that happens the starter drive gear can't pull out of the flywheel when the engine cranks or starts to run.This can happen to transmission gears in rare occassions. I would take a second look at ALL the syncro components in the 1-2 synchro assembly. I think you could get a good look just by pulling the side cover,but you may not be able to make a good check to see the actual engagement fit of the brass ring to the cone of the actual gear. The brass synchro ring should not totally butt up to the teeth on the actual gear. If that happens the ring has no ability to stop the gear effectively,especially at speed.This is why Mopar 4spds were slick shifted for drag racing, eliminating the synchronizing effect,but not at all street worthy, just power shifting. Bill


It comes out of gear fine, then only goes to neutral. Then can be fored into 3rd or 4th. but not second.

Re: Need some 4speed help [Re: 8urvette] #2989709
11/27/21 09:56 PM
11/27/21 09:56 PM
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What we are able to see in these pictures, you're right, looks fine. What we can't see is whether or not the brass blocker ring is cracked and if the tapered inner portion of that blocker ring is worn excessively and not enabling the blocker ring and the integral tapered portion of the second gear to lock together and allow the slide to engage over the gears integral sychro teeth. If that blocker ring is cracked or excessively worn it won't stop and hold 2nd gear. It's job is very similar to that of the kickdown(2nd gear) band in a Torqueflite trans, stop and hold. The brass synchro rings are controlled by three fingers w/2 support rings. They are under the slide controlled by the shift fork. This is not visible here. My 66 B body was 383 4spd. Had a very similar problem to yours. Ended up being a cracked synchro brass blocker ring, cracked in one of the 3 notches that are machined to work with the 3 sliding actuator fingers. That is the weakest area of a blocker ring. You've got to go a little deeper or pull REALLY HARD for second. Bill

Re: Need some 4speed help [Re: 8urvette] #2989712
11/27/21 10:10 PM
11/27/21 10:10 PM
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fourgearsavoy Offline
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The syncro teeth rarely look bad but they do wear out on the cone. The ring has to grab the cone on the the gear to slow it down. You need to look at new brass and de-glaze or scuff up the cone on the gear so it has a new surface for the ring to grab onto. Also double check your shift linkage adjustment because if you are shifting at higher RPM you are probably pulling the lever faster and it has to be perfect .
I was just re-reading your original post and I see you are using a dual disc clutch. I tried a Mcleod Street-Twin in my Savoy and it would not get a clean release for any kind of power shifting. My Richmond box when it was stock it wouldn't power shift worth a crap with that clutch in it. Switched over to a single metallic disc and it shifted like butter. The 2 discs don't slow down enough at high RPM's for a clean 1-2 shift twocents

Gus beer

Last edited by fourgearsavoy; 11/27/21 10:20 PM.

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Re: Need some 4speed help [Re: fourgearsavoy] #2989736
11/27/21 11:27 PM
11/27/21 11:27 PM
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Okay, thanks guys. Ill dig a bit deeper tomorrow morning. Pull the 1/2 apart and see how they look.

Re: Need some 4speed help [Re: 8urvette] #2989744
11/27/21 11:45 PM
11/27/21 11:45 PM
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Clutch adjustments can cause that by not having enough clearance between the clutch disc and flywheel when the motor is revved up and you're shifting it with the clutch pedal twocents scope
There is waffle spring between the two halves of the clutch plates on street and strip disc that is not used on the race disc.
Look at yours and if it has that waffle spring in it try a race disc next scope twocents
Good luck, let us know what you find wrench

Last edited by Cab_Burge; 11/28/21 07:23 PM.

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Re: Need some 4speed help [Re: 8urvette] #2989755
11/28/21 01:45 AM
11/28/21 01:45 AM
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When you get it apart run your finger over the fine teeth (grooves) on the inside of the brass, perpendicular to the grooves. They should catch your skin as if you was running them over the sharp edge of razor blades. If they don't catch the skin, or they feel smooth, reflect light off the flattened lands (plateau) then they are garbage.

The brass synchronizer ring works like a cluth to slow, stop and match the speeds of the following componenets (clutch disc(s), input shaft, counter gear, and all three speed gears. That's a lot of mass. It must match the speed of then output shaft, hubs and sliders being driven by the momentum of the remaining driveline.

The clutching teeth pictured do nothing to slow and match the speed of the rotating masses, they simply line-up the teech for the slider.

Try fine steel whool to polish the cone surface of the speed gears. It should polish like glass. Too course and it will shorten the life of the new brass.

The smaller, lighter the clutch disc the easier it will be to shift fast, which has already been stated.

Re: Need some 4speed help [Re: Moparteacher] #2989783
11/28/21 10:12 AM
11/28/21 10:12 AM
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lewtot184 Offline
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i would think that two disc's, soft or not, would require more travel for the fork to fully release and at what point does this mean going over center on the diaphragm pressure plate?

Re: Need some 4speed help [Re: 8urvette] #2989805
11/28/21 11:01 AM
11/28/21 11:01 AM
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jwb123 Offline
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many years ago I raced a A833 behind a 340 first in a Dart and then in an Anglia, not to brag but I was pretty good shifting it. Then 35 years I raced automatics. Then to regain my youth I guess I built a 340 cuda 4 speed for the street. When I built the A833 it got all new syncro's. And it just shifts hard under power, I can get all the gears, but it is just not as smooth as I remember my old dart. I wonder if it is the quality of the aftermarket syncro's? When I get a chance I am going to pull mine out and use some good used ones that I have saved. The proper way to check the brass syncro's is to hold the gear with the cone side up and lightly press down and turn it should lock on the cone with little effort, polishing the cone is necessary sometimes as it gets a residue coating from old gear lube and heat. There is also a feeler gauge measurement between the brass ring and the syncro teeth on the gear. Let us know if you fix your issue.

Re: Need some 4speed help [Re: jwb123] #2989835
11/28/21 01:20 PM
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well the synchros look to be in good condition, and i cannot see any issues with any of the other parts,

grefrrtrKIMG0250 copy.jpgnewKIMG0249 copy.jpg
Re: Need some 4speed help [Re: 8urvette] #2989844
11/28/21 02:09 PM
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Yep, those are garbage.

Inspect the speed gear closely. The clutching teeth should have a sharp edge all the way down to the tip. If it's rounded, and it will be, replace the speed gear. Inspect the teeth on the slider, again if the teeth are rounded at the tip or crown then replace the slider.

I suspect you will need a synchro assembly that includes the hub, keys, springs, slider, and brass for 1st and 2nd. Additionally you will need a 2nd gear speed gear, minimum.

Another option is to install a slick shift conversion kit from Passon Performance, and then modify either a new 2nd gear speed gear or the old gear by removing every other tooth to work with the modified slider.
https://www.passonperformance.com/categories/transmission-parts/product/278-slick-shift-kit

Typically only 2nd, 3rd, and 4th are modified.

Liberty gears can make those changes for you or set you up with what they call a "Pro Shift Modification" to the speed gears and sliders. Or go straight to a Face Plate.
https://libertysgears.com/services/face-platepro-shift-gear-modifications/

Regardless, you're spending money to fix it correctly.

Re: Need some 4speed help [Re: 8urvette] #2989846
11/28/21 02:16 PM
11/28/21 02:16 PM
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Looking at the second picture of the brass ring posted it appears to show wear marks on the outer surface of the ring. I am referring to the surface that actually faces the gear. At this point I would check ,as jwb123 pointed out, how the rings actually fit and grab the gears. If they go on too far and bottom out against the integral synchro teeth on the gear, its not good. The bottom picture has those scuff marks that give the impression of that surface coming in contact with another at some point. It never should. I also realize it is a photo and that may just be a glare that I am seeing at my point of view. If they are in fact grind marks (radial) you would need to establish how they got there. It suggests interference of some kind. I do not have any personal experience with dual disc clutches,but it would seem that those discs may act as 2 big flywheels wanting to stay in motion ,when the clutch is trying to release, but keeping that input shaft in rotation. I hope you find a solution to this issue. Bill

Re: Need some 4speed help [Re: lancer493] #2989885
11/28/21 04:12 PM
11/28/21 04:12 PM
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i know nothing about 4 speeds.
with that said, the second picture [as mentioned above] sure seems to show an odd wear pattern and score marks [to me, anyway] that shouldn't be there.
beer

Re: Need some 4speed help [Re: moparx] #2989924
11/28/21 06:02 PM
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Okay, if i need to replace parts... WOuld i be able to save the cost of replacing the gears by going with a faceplated gear from liberty? Do they just remove the synchro teeth and weld on their part? What about the sliders? Is theirs a custom made one or is it machined from a stock unit?

Re: Need some 4speed help [Re: lancer493] #2989944
11/28/21 07:11 PM
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I don't even need to put that on the cone to see its junk. Scuff the cones and get some good brass in there from Passon or Brewers and don't buy some of the crap you see on Ebay or other retail sites, buy only from the guys who install what they sell because they wouldn't sell it if they didn't work.

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Re: Need some 4speed help [Re: 8urvette] #2989946
11/28/21 07:14 PM
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Street/strip, or radical street is all tall order as crash box or slick shifted gearboxes are tough or near impossible to drive in a light foot manner. I think you should figure out what you really expect from this combo before you go any further. It can get very expensive to reliably get this trans to shift at high RPM. As others have pointed out earlier in this thread, the total clutch situation needs to be up to the job also. If you can get all these issues co-ordinated you will have a really FUN ride,but your bank account is gonna be a bit lighter. I have spoken with (member screen name:Jeremiah) on several issues over the past few years. I was hoping he would come in on this thread. You should PM him. I'm sure he would have some good help for you.He is very big on stick shift Mopars, as I believe he is working on several cars right now, one being a 68 Dart 4spd budget nitrous car. Bill

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