Weak manual transmission, how to strengthen?

Transmission to Rear-end

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SupStk
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Re: Weak manual transmission, how to strengthen?

Post by SupStk » Sun Aug 26, 2018 2:06 pm

Speaking in general, if stock transmission pieces aren't surviving and if aftermarket stuff is nonexistent or prohibitively expensive. Things I'd consider with OEM parts, is drawing the gears back in hardness, cryogenic treatment and surface finishing. I'm not convinced cryo-treatment makes a big difference on castings but on steel parts the difference is very noticeable.
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Re: Weak manual transmission, how to strengthen?

Post by Kenova » Sun Aug 26, 2018 2:18 pm

ptuomov wrote:
Sat Aug 25, 2018 6:23 pm
PackardV8 wrote:
Sat Aug 25, 2018 6:18 pm
Describe the failure modes and that will point toward what might be possible.
Gears come out the drain plug hole in small pieces.
That is priceless. Thanks for the laugh. :lol:

Would this be adaptable to your use? https://www.gforcetransmissions.com/tran_honda%20b.asp

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Re: Weak manual transmission, how to strengthen?

Post by ptuomov » Sun Aug 26, 2018 2:21 pm

SupStk wrote:
Sun Aug 26, 2018 2:06 pm
Speaking in general, if stock transmission pieces aren't surviving and if aftermarket stuff is nonexistent or prohibitively expensive. Things I'd consider with OEM parts, is drawing the gears back in hardness, cryogenic treatment and surface finishing. I'm not convinced cryo-treatment makes a big difference on castings but on steel parts the difference is very noticeable.
We're going to magnetically check them for cracks, cryo treat them, then bake out hydrogen, then REM ISF process them. I don't want to reduce hardness as the gears also pit.

Anything that is commonly done to the case, bearing housings, bearing outer races, etc.?
Paradigms often shift without the clutch -- https://www.youtube.com/watch?v=cxn-LxwsrnU

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Re: Weak manual transmission, how to strengthen?

Post by ptuomov » Sun Aug 26, 2018 2:22 pm

Kenova wrote:
Sun Aug 26, 2018 2:18 pm
ptuomov wrote:
Sat Aug 25, 2018 6:23 pm
PackardV8 wrote:
Sat Aug 25, 2018 6:18 pm
Describe the failure modes and that will point toward what might be possible.
Gears come out the drain plug hole in small pieces.
That is priceless. Thanks for the laugh. :lol:

Would this be adaptable to your use? https://www.gforcetransmissions.com/tran_honda%20b.asp

Ken
Street transmission, must have synchros. And it's a transaxle anyway.

Some people swap in a Corvette transaxle, but I don't want to swap in a Corvette transaxle if it can be avoided.
Paradigms often shift without the clutch -- https://www.youtube.com/watch?v=cxn-LxwsrnU

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Re: Weak manual transmission, how to strengthen?

Post by Roundybout » Sun Aug 26, 2018 2:30 pm

Is it possible to adapt another transaxle that is more robust or at least a better starting point to upgrade? I feel you'll never be able to get the stock stuff reliable enough for that output. At 4 grand I'd imagine custom gears could be made with cryo polishing to boot. Not sure if that'd help anyway as usually stuff like this happens from deflection and things moving that shouldn't be.

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Re: Weak manual transmission, how to strengthen?

Post by ChevyEFI » Sun Aug 26, 2018 2:58 pm

Keeping it short.

Teeth breaking off leads to probable poor structural case strength, or spreading of shafts.

Overfascinating with fluid leads to singing Kumbay Yah over on that oil forum with out an actual solution.

A lack of lubrication will tend to show up as temperature surface degradation on the gear teeth surfaces, before outright breakage.

Not knowing bearing, case, and or other structure of the box in question, start by verifying case saddle bores are uniform and not elongated / ovaled from age, wear, and vibration. Bearing preload and condition too.

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Re: Weak manual transmission, how to strengthen?

Post by user-23911 » Sun Aug 26, 2018 5:36 pm

ChevyEFI wrote:
Sun Aug 26, 2018 2:58 pm


Teeth breaking off leads to probable poor structural case strength, or spreading of shafts.

You mean leads FROM.


Like I said........the tapered roller bearings need re shimming
Otherwise this WILL happen.
Because when the bearings wear, the shafts spread.

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Re: Weak manual transmission, how to strengthen?

Post by Keith Morganstein » Sun Aug 26, 2018 8:42 pm

If the “shafts are spreading”. Clearance increasing between the gears, there will be evidence. The tip of the driving gear, will be making contact in the face of the driven gear. Look for unusual contact in the face of the gear teeth.
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Re: Weak manual transmission, how to strengthen?

Post by ptuomov » Mon Aug 27, 2018 7:26 am

ChevyEFI wrote:
Sun Aug 26, 2018 2:58 pm
Keeping it short.

Teeth breaking off leads to probable poor structural case strength, or spreading of shafts.

Overfascinating with fluid leads to singing Kumbay Yah over on that oil forum with out an actual solution.

A lack of lubrication will tend to show up as temperature surface degradation on the gear teeth surfaces, before outright breakage.

Not knowing bearing, case, and or other structure of the box in question, start by verifying case saddle bores are uniform and not elongated / ovaled from age, wear, and vibration. Bearing preload and condition too.
This is indeed an issue with these boxes. The bearing races are steel and the case is aluminum. The fit between the two doesn't have much interference even when cold, and then the when the box heats up the case expands more. Now, the bearings are quite loose in their saddles. Being loose, they can spread out and can pound the saddle to be out of round.

What to do about it?

I think cooling the whole box must help, and we'll improve that. But is there something to be done structurally to help with this?
Paradigms often shift without the clutch -- https://www.youtube.com/watch?v=cxn-LxwsrnU

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Re: Weak manual transmission, how to strengthen?

Post by ptuomov » Mon Aug 27, 2018 7:28 am

joe 90 wrote:
Sun Aug 26, 2018 5:36 pm
Like I said........the tapered roller bearings need re shimming
Otherwise this WILL happen.
Because when the bearings wear, the shafts spread.
The factory workshop manual has shimming instructions and tolerances for multiple areas. When maintaining these boxes, it of course makes sense to reshim them to the spec. However, it's my sense that this isn't the only issue with these boxes.
Paradigms often shift without the clutch -- https://www.youtube.com/watch?v=cxn-LxwsrnU

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Re: Weak manual transmission, how to strengthen?

Post by Keith Morganstein » Mon Aug 27, 2018 12:38 pm

I had to read a little about these boxes. They are prone to failure with stock engines. I doubt any "treatment" or cooling mod is going to be remotely effective. Eventually (if not already) you'll spend what it takes to put the Z06 trans in the car. Smarter money is the better trans.
Automotive Machining, cylinder head rebuilding, engine building. Old school shop, semi-retired moonlighter. Can't seem to quit #-o

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Re: Weak manual transmission, how to strengthen?

Post by ptuomov » Mon Aug 27, 2018 1:34 pm

Keith Morganstein wrote:
Mon Aug 27, 2018 12:38 pm
I had to read a little about these boxes. They are prone to failure with stock engines. I doubt any "treatment" or cooling mod is going to be remotely effective. Eventually (if not already) you'll spend what it takes to put the Z06 trans in the car. Smarter money is the better trans.
Because I know next to nothing about transmissions, I’ll just use this as a learning experience and hopefully make some useful discoveries along the way, whether or not they’ll ultimately be enough. It’s the journey. And the original transmission in the car lasted for 31 years, 8 of those with twin turbos (including 500 experiments on the dyno).
Paradigms often shift without the clutch -- https://www.youtube.com/watch?v=cxn-LxwsrnU

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Re: Weak manual transmission, how to strengthen?

Post by mekilljoydammit » Mon Aug 27, 2018 3:10 pm

Having come across this kind of thing with little Mazda and Subaru transmissions... in my experience, if you're breaking gears in something to the stock design, any solution that makes the stock design work is going to be vastly more expensive and a worse headache than any solution that goes to some other design that just works.

Speaking as an engineer, the temptation to design your way out of a problem is great, but stop and ask yourself if you want to be a transmission designer or if you want to drive the car. I have a friend who admitted to me that after a decade of figuring out how to solve transmission stuff, he could have bought some very nice gearboxes for the price he spent on stuff that didn't work.

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Re: Weak manual transmission, how to strengthen?

Post by ptuomov » Mon Aug 27, 2018 5:52 pm

Some visuals:
CA79D2CC-863C-48DD-9E9E-BE72154DB6E8.jpeg
F01FAA02-5FA3-4F3B-BFE8-DF5AD4C2D7CB.jpeg
6AB5A3E1-7BA6-44C1-8BCE-593F3B62A1C7.jpeg
Paradigms often shift without the clutch -- https://www.youtube.com/watch?v=cxn-LxwsrnU

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Re: Weak manual transmission, how to strengthen?

Post by ptuomov » Mon Aug 27, 2018 7:11 pm

Keith Morganstein wrote:
Sun Aug 26, 2018 8:42 pm
If the “shafts are spreading”. Clearance increasing between the gears, there will be evidence. The tip of the driving gear, will be making contact in the face of the driven gear. Look for unusual contact in the face of the gear teeth.
Do you have a photo of what this sort of damage looks like?
Paradigms often shift without the clutch -- https://www.youtube.com/watch?v=cxn-LxwsrnU

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