Clutches are different on early and late engines

C

coyoteboy

New member
I was recently checking prices for a new clutch for my 185. Its getting a 205 box so while i was looking down the price lists of TCB in the UK I spotted two clutches listed. Aisin (original suppliers of the GT4 gearbox and clutch) have two clutch/gearbox spline sizes listed - 28.8 and 29.8mm. The 29.8 is the 165 and early 185. 28.8 is the late 185 and 205.

I checked against all other aftermarket clutch people and found everyone else just has the 29.8 specification. So i measured the 205 spline diam and get 28.3mm (28.8 less a little for easy fitting I presume). But throwing in a clutch designed to fit a 29.8 is a fairly large difference and cant be good IMO. This could be the cause of many early failures, noises and rapid wear rates. I'm trying to contact Aisin for 100% confirmation.

Does anyone have a 185 box out, of known year, that can measure the input shaft spline diameter accurately? I'm trying to build up a mini database of sizes to see if its true.

Cheers all!
 
S

SuperWhite92

New member
coyoteboy":shyrqpsp said:
I was recently checking prices for a new clutch for my 185. Its getting a 205 box so while i was looking down the price lists of TCB in the UK I spotted two clutches listed. Aisin (original suppliers of the GT4 gearbox and clutch) have two clutch/gearbox spline sizes listed - 28.8 and 29.8mm. The 29.8 is the 165 and early 185. 28.8 is the late 185 and 205.

I checked against all other aftermarket clutch people and found everyone else just has the 29.8 specification. So i measured the 205 spline diam and get 28.3mm (28.8 less a little for easy fitting I presume). But throwing in a clutch designed to fit a 29.8 is a fairly large difference and cant be good IMO. This could be the cause of many early failures, noises and rapid wear rates. I'm trying to contact Aisin for 100% confirmation.

Does anyone have a 185 box out, of known year, that can measure the input shaft spline diameter accurately? I'm trying to build up a mini database of sizes to see if its true.

Cheers all!
Click to expand...

Both my 1990 JDM tranny and 1992 USM tranny are 28.somethings
 
G

gearhead313

New member
I just went into the garage to measure an st165 trans i have out and i swear it measures 27.78mm with my vernier caliper. ???
 
C

coyoteboy

New member
lol im not sure what youre offering now :wink:

I was expecting values of 28.5>30mm but 27.X seems very small considering the clutches hole diameter is designed for 29.8!
 
A

all-trac's plus

New member
When I first read this thread, I got a little excited because I was informed by several on our site that all of the All-Trac transaxles were interchangeable with no or few changes. The shaft diameter was never mentioned.

Now that I've had a minute or two to study the situation, I can comment. 29.9mm or 28.8mm is only critical when installing the transaxle. Obviously, the one with a diameter of 28.8mm is easier to install. The difference of 0.0394" on the diameter is next to nothing. It has very little if any effect on the load rating of the splined assembly.

Hope this helps.



Tony
 
G

gearhead313

New member
Though the difference is small, its imperative to the setup. Your asking for big problems if one is the wrong size, like having a large clutch hub on the smaller input shaft.

I measured mine again and the total outside diameter is definitly 27.78mm. I have no idea what that means and I dont have any other trannys out to measure them.
 
A

all-trac's plus

New member
gearhead313":278krbok said:
Though the difference is small, its imperative to the setup. Your asking for big problems if one is the wrong size, like having a large clutch hub on the smaller input shaft.

I measured mine again and the total outside diameter is definitly 27.78mm. I have no idea what that means and I don't have any other trannys out to measure them.
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You missed the point. The size & location of this shaft is so unimportant that it doesn't even have a pilot bearing on the front-end and the up & down movement of the shaft is greater than the difference in the diameters of the two sizes. The newer shafts are made smaller by 1mm to make assembly easier. No doubt in my mind. Can you think of another reason why they would make the effort to make the shaft smaller?
 
C

Conan

New member
ourall-trac":25plf0m8 said:
29.9mm or 28.8mm is only critical when installing the transaxle.
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Are you talking about the transfer carrier (case)? I've checked the EPC, at least Euro and JDM cases have the same part number for all years.
 
A

all-trac's plus

New member
Conan":1hy69i2f said:
ourall-trac":1hy69i2f said:
29.9mm or 28.8mm is only critical when installing the transaxle.
Click to expand...
Are you talking about the transfer carrier (case)? I've checked the EPC, at least Euro and JDM cases have the same part number for all years.
Click to expand...

No, the discussion is about the main shaft on the transmission that goes through the clutch plate. The transaxle is the overall assembly including the transmission, the front differential and the transfer case (all inclusive). I use the term transaxle (correct) because if you ask to purchase a transmission, that might be all that you get (surprise!). I just like to use the correct terms.
 
C

Conan

New member
ourall-trac":fopbao5c said:
I use the term transaxle (correct) because if you ask to purchase a transmission, that might be all that you get (surprise!). I just like to use the correct terms.
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That's much clearer now, so many people using different terms gets really confusing.
 
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gearhead313

New member
ourall-trac":257gzqc0 said:
gearhead313":257gzqc0 said:
Though the difference is small, its imperative to the setup. Your asking for big problems if one is the wrong size, like having a large clutch hub on the smaller input shaft.

I measured mine again and the total outside diameter is definitly 27.78mm. I have no idea what that means and I don't have any other trannys out to measure them.
Click to expand...

You missed the point. The size & location of this shaft is so unimportant that it doesn't even have a pilot bearing on the front-end and the up & down movement of the shaft is greater than the difference in the diameters of the two sizes. The newer shafts are made smaller by 1mm to make assembly easier. No doubt in my mind. Can you think of another reason why they would make the effort to make the shaft smaller?
Click to expand...

ahhhhh, im going to have to go ahead and... disagree with you on that one...

The shaft is not made smaller to make installation easier. the input shaft and clutch disc mesh has to be within thousandths of an inch to maintain a precision fit. Why the setups are different, you can try calling toyota on that one. I see small changes like that over year changes all the time.
 
A

all-trac's plus

New member
gearhead313":i0gtdcgd said:
ourall-trac":i0gtdcgd said:
gearhead313":i0gtdcgd said:
Though the difference is small, its imperative to the setup. Your asking for big problems if one is the wrong size, like having a large clutch hub on the smaller input shaft.

I measured mine again and the total outside diameter is definitly 27.78mm. I have no idea what that means and I don't have any other trannys out to measure them.
Click to expand...

You missed the point. The size & location of this shaft is so unimportant that it doesn't even have a pilot bearing on the front-end and the up & down movement of the shaft is greater than the difference in the diameters of the two sizes. The newer shafts are made smaller by 1mm to make assembly easier. No doubt in my mind. Can you think of another reason why they would make the effort to make the shaft smaller?
Click to expand...

ahhhhh, im going to have to go ahead and... disagree with you on that one...

The shaft is not made smaller to make installation easier. the input shaft and clutch disc mesh has to be within thousandths of an inch to maintain a precision fit. Why the setups are different, you can try calling toyota on that one. I see small changes like that over year changes all the time.
Click to expand...

No disrespect, but so much learning to do. I'm a Mechanical Engineer with my Machinery Design Handbook at my side at all times. Here's the spoof. The O.D. of the shaft and/or the I.D. of the spline in the clutch have nothing to do with the driving forces of either. 100% of the driving forces are handled by the angled surfaces of the spline. This is the same as with any gear type. Trust me on this, the O.D. of the shaft was reduced to make life easier and the tooth formation is the same, just slightly shorter.

At today's prices, the handbook must be about $150. However, it's really helpful and covers everything under the sun when it comes to mechanical stuff.

Hope this helps!
 
C

coyoteboy

New member
No disrespect, but so much learning to do. I'm a Mechanical Engineer with my Machinery Design Handbook at my side at all times. Here's the spoof. The O.D. of the shaft and/or the I.D. of the spline in the clutch have nothing to do with the driving forces of either. 100% of the driving forces are handled by the angled surfaces of the spline. This is the same as with any gear type. Trust me on this, the O.D. of the shaft was reduced to make life easier and the tooth formation is the same, just slightly shorter.
Click to expand...

Actually you're sort of right and sort of wrong (also a mechanical eng, although now working in robotics). Yes the loads are taken ON the angled faces of the teeth. However they are *carried* in a shear plane through the tooth at the point where the female teeth tips reach the male teeth sides (approximately, its not quite that simple). If you allow the loading to occur too far up the tooth (your driven plate is too large a diameter so the teeth do not fully mesh as OEM) you will be carrying your load through a narrower tooth section (the teeth are triangular) and so has less plane to shear - therefore the more likely to fail. Add to that that on a larger diameter shaft the teeth are, overall, thicker for the same tooth-count and that gives you even less material on the shaft teeth to carry the load.

What you said would be almost right if the teeth were square-section and perfectly meshed, though youre still ignoring bending in the tooth. Also, should your teeth be improperly meshed allowing play, as soon as you disengage the clutch your friction plate is free to rattle about on the input shaft as it is not centralised by the natural equal interface of the teeth. This will off-centrally load the spline teeth further with some being fully meshed and some being little-meshed. This will lead to damage to the little-meshed teeth faces which will then be even less capable of transferring the load evenly to the already lacking shear plane. Remember we arent talking light loads here, or working at the lower limit of their strength - we are talking about cars that are capable of shearing the teeth right off hte input shaft (know of one that has done this) and ripping the transfer case in two, know one that has done this also, so its not a nice simple textbook tooth loading scenario.

Bad drawing ability i know but im on linux and dont have any decent CAD packages on this machine or I'd have scaled them all accurately for you.
 

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A

all-trac's plus

New member
coyoteboy":35u1tswr said:
No disrespect, but so much learning to do. I'm a Mechanical Engineer with my Machinery Design Handbook at my side at all times. Here's the spoof. The O.D. of the shaft and/or the I.D. of the spline in the clutch have nothing to do with the driving forces of either. 100% of the driving forces are handled by the angled surfaces of the spline. This is the same as with any gear type. Trust me on this, the O.D. of the shaft was reduced to make life easier and the tooth formation is the same, just slightly shorter.
Click to expand...

Actually you're sort of right and sort of wrong (also a mechanical eng, although now working in robotics). Yes the loads are taken ON the angled faces of the teeth. However they are *carried* in a shear plane through the tooth at the point where the female teeth tips reach the male teeth sides (approximately, its not quite that simple). If you allow the loading to occur too far up the tooth (your driven plate is too large a diameter so the teeth do not fully mesh as OEM) you will be carrying your load through a narrower tooth section (the teeth are triangular) and so has less plane to shear - therefore the more likely to fail. Add to that that on a larger diameter shaft the teeth are, overall, thicker for the same tooth-count and that gives you even less material on the shaft teeth to carry the load.

What you said would be almost right if the teeth were square-section and perfectly meshed, though youre still ignoring bending in the tooth. Also, should your teeth be improperly meshed allowing play, as soon as you disengage the clutch your friction plate is free to rattle about on the input shaft as it is not centralised by the natural equal interface of the teeth. This will off-centrally load the spline teeth further with some being fully meshed and some being little-meshed. This will lead to damage to the little-meshed teeth faces which will then be even less capable of transferring the load evenly to the already lacking shear plane. Remember we arent talking light loads here, or working at the lower limit of their strength - we are talking about cars that are capable of shearing the teeth right off hte input shaft (know of one that has done this) and ripping the transfer case in two, know one that has done this also, so its not a nice simple textbook tooth loading scenario.

Bad drawing ability i know but im on linux and dont have any decent CAD packages on this machine or I'd have scaled them all accurately for you.
Click to expand...

What you point out is nice, but the reality is that these are not precision gears, but very simple splines. If you take a supposedly matched set (clutch plate & shaft) you will realize a very large clearance as this is something less than a slip fit. And remember, we're talking 1mm on the overall diameter. This is nothing on this type of set-up.

Regarding the supposed shearing experience. This is simple overload as the load exceeded the torque rating of the spline members. This is why large HP engines have much (not 1mm)larger spine assemblies. Enough said & last time.
 
C

coyoteboy

New member
LOL I hope i dont use products made by whoever you work for. Reminds me of working for a big engine-transfer-line manufacturing company a few years back. Ohh just extend that, it'll be fine - if it fails we'll redesign it when we have more time. Has anyone calculated the FOS on that? Nahh its always worked before, it'll cope. Precisely the reason I left them.
 
G

gearhead313

New member
I dont know, for some reason, I just can't see toyota engineers saying,

"Hey Jim, I've been hearing its a bitch putting those transmissions on the motors."

"Ya Bob, your right. Lets sacrifice some meshing material between the input and clutch hub by loosing strength of the input through making it smaller. I want more than anything for those guys to have an easier time putting those engine and transmissions together."
 
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