View Poll Results: Have you had problems with your N/A tranny?
Yes
16
32.00%
No
33
66.00%
I installed a 944 S2 tranny
1
2.00%
Voters: 50. You may not vote on this poll
have you had problems with your N/A tranny?
12-15-2009, 10:14 AM
#1
Race Director
Thread Starter
have you had problems with your N/A tranny?
Talked to a knowledgeable person yesterday who said I should look at the S2 tranny because the output shaft and internals are beefier than the N/A tranny. Have you had issues with your N/A tranny?
12-15-2009, 10:34 AM
#2
Race Director
It's not a matter of the "output shaft and internals".
The Ring and Pinion gears are what fail on an N/A trans, due to many reasons. You will find that cars that have higher mileage, have been abused, and/or have been driven for a length of time with a failing clutch center are candidates for transaxle failure.
Tolerance levels increase with wear as well. Ideally you would have the transaxle cracked open at specific intervals to have the lash adjusted for the r&p so that they fit together properly. Otherwise the increased tolerance will cause failure, especially in a high shock instance (like dropping the clutch at high rpms or speed shifting). However there is no mention of regular lash adjustment intervals in the FSM.
The S2 transaxle (and 951) have a different r&p ratio (among other differences of course) that make for a more robust r&p.
Keep in mind that if you swap to a S2 trans that it is geared differently than your 944 N/A trans, you may not like it.
The Ring and Pinion gears are what fail on an N/A trans, due to many reasons. You will find that cars that have higher mileage, have been abused, and/or have been driven for a length of time with a failing clutch center are candidates for transaxle failure.
Tolerance levels increase with wear as well. Ideally you would have the transaxle cracked open at specific intervals to have the lash adjusted for the r&p so that they fit together properly. Otherwise the increased tolerance will cause failure, especially in a high shock instance (like dropping the clutch at high rpms or speed shifting). However there is no mention of regular lash adjustment intervals in the FSM.
The S2 transaxle (and 951) have a different r&p ratio (among other differences of course) that make for a more robust r&p.
Keep in mind that if you swap to a S2 trans that it is geared differently than your 944 N/A trans, you may not like it.
12-15-2009, 11:29 AM
#3
Race Car
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Relatedly, I've always wondered about the LSD vs non-LSD debate, and still suspect non-LSDs are more prone to failure.
BTW, this survey might get more people reading who have had a tranny problem than people who haven't (hence biasing the results). Also, conditional on having had a problem, some clown did a very nice survey of which years tend to fail -- https://rennlist.com/forums/924-931-...re-survey.html and some 48 people at the time reported failure.
BTW, this survey might get more people reading who have had a tranny problem than people who haven't (hence biasing the results). Also, conditional on having had a problem, some clown did a very nice survey of which years tend to fail -- https://rennlist.com/forums/924-931-...re-survey.html and some 48 people at the time reported failure.
12-15-2009, 12:04 PM
#5
It's not a matter of the "output shaft and internals".
The Ring and Pinion gears are what fail on an N/A trans, due to many reasons. You will find that cars that have higher mileage, have been abused, and/or have been driven for a length of time with a failing clutch center are candidates for transaxle failure.
Tolerance levels increase with wear as well. Ideally you would have the transaxle cracked open at specific intervals to have the lash adjusted for the r&p so that they fit together properly. Otherwise the increased tolerance will cause failure, especially in a high shock instance (like dropping the clutch at high rpms or speed shifting). However there is no mention of regular lash adjustment intervals in the FSM.
The S2 transaxle (and 951) have a different r&p ratio (among other differences of course) that make for a more robust r&p.
Keep in mind that if you swap to a S2 trans that it is geared differently than your 944 N/A trans, you may not like it.
The Ring and Pinion gears are what fail on an N/A trans, due to many reasons. You will find that cars that have higher mileage, have been abused, and/or have been driven for a length of time with a failing clutch center are candidates for transaxle failure.
Tolerance levels increase with wear as well. Ideally you would have the transaxle cracked open at specific intervals to have the lash adjusted for the r&p so that they fit together properly. Otherwise the increased tolerance will cause failure, especially in a high shock instance (like dropping the clutch at high rpms or speed shifting). However there is no mention of regular lash adjustment intervals in the FSM.
The S2 transaxle (and 951) have a different r&p ratio (among other differences of course) that make for a more robust r&p.
Keep in mind that if you swap to a S2 trans that it is geared differently than your 944 N/A trans, you may not like it.
12-15-2009, 12:32 PM
#6
Burning Brakes
I would think that if you were going to swap a trans out of an N/A you would want to put in the 1988 or later N/A Trans. This is because it has a lower ratio gear box and will give you better preformance.
The only reason i can think of to go with the S2 or 951 Trans would be if you are going to beef up the HP of the car with something like a supercharger.
The only reason i can think of to go with the S2 or 951 Trans would be if you are going to beef up the HP of the car with something like a supercharger.
12-15-2009, 01:15 PM
#7
Rainman
Rennlist Member
Rennlist Member
i put in a 951 gearbox because my NA box nuked its r/p while coasting on the highway for 60 miles.
dont want that to happen again.
you dont really notice any change in speed or acceleration, it is a little harder to get off the line but i think it makes up for it a bit because you only make one shift all the way up to just over 70.
dont want that to happen again.
you dont really notice any change in speed or acceleration, it is a little harder to get off the line but i think it makes up for it a bit because you only make one shift all the way up to just over 70.
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12-15-2009, 03:11 PM
#8
Drifting
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I would think that if you were going to swap a trans out of an N/A you would want to put in the 1988 or later N/A Trans. This is because it has a lower ratio gear box and will give you better preformance.
The only reason i can think of to go with the S2 or 951 Trans would be if you are going to beef up the HP of the car with something like a supercharger.
The only reason i can think of to go with the S2 or 951 Trans would be if you are going to beef up the HP of the car with something like a supercharger.
PS: I answered "No" to the polls. I have had my clutch replaced, but I don't consider that to be my transmission.
12-15-2009, 05:35 PM
#9
Three Wheelin'
Yes, I have seen many 944s with broken R/Ps in my shop, and I have grenaded a few myself.
Upgrading to a 951 box doesnt make you invincible, Ive seen those shear teeth off the ring.
Upgrading to a 951 box doesnt make you invincible, Ive seen those shear teeth off the ring.
12-15-2009, 05:48 PM
#11
Burning Brakes
Potomac-greg: Thank you fro clarifying the diference in the trannies. I knew one had lower gearing but that is interesting to find out it is only in 5th.
12-15-2009, 05:51 PM
#12
Racer
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Used na trannys are relatively inexpensive and can be bought anywhere from $100-$300 with an open diff. I have experience with a few of these. I own several 944's from early 1983' NA, 1988, 1987 944S and 1991 944S2. My S2 tranny needed a rebuild after 195K miles as the bearings and races were bad. Wanted to swap out my LSD tranny from the 944S but people told me that the S2 had a slightly harder R&P so I didn't swap this out.
When my 88' 944 Spec race car needed a new clutch, I decided to take apart the tranny and also the tranny from my 1987 944S with LSD and did an internal swap. Now my 88' feels great on the track with the LSD. The 944S, I decided to buy a used late tranny from a 1986 na for $200 and put that into the S. I did this because the first 4 gears are shorter than the stock 944S tranny so this improves on the acceleration while the 5th gear is taller so that will give me better gas mileage on the 944S.
The stock 944S feels very slow until you reach about 4,500 rpm, then the car comes alive. Now it comes alive around 3K rpm. So if you are asking about swapping your NA tranny with a turbo or S2, I would so NO! You will really be disappointed in the acceleration of your car.
When my 88' 944 Spec race car needed a new clutch, I decided to take apart the tranny and also the tranny from my 1987 944S with LSD and did an internal swap. Now my 88' feels great on the track with the LSD. The 944S, I decided to buy a used late tranny from a 1986 na for $200 and put that into the S. I did this because the first 4 gears are shorter than the stock 944S tranny so this improves on the acceleration while the 5th gear is taller so that will give me better gas mileage on the 944S.
The stock 944S feels very slow until you reach about 4,500 rpm, then the car comes alive. Now it comes alive around 3K rpm. So if you are asking about swapping your NA tranny with a turbo or S2, I would so NO! You will really be disappointed in the acceleration of your car.
12-15-2009, 05:55 PM
#13
Race Director
LOL.
Me thinks your "butt-dyno" needs some serious re-calibration. Swapping a 951 transaxle into a 944 N/A will seriously add (seconds) to your 0-60 time.
12-15-2009, 07:22 PM
#15
My (original) 85 transaxle lunched the R&P at around 175,000 miles. That was with around 15 to 20 driver's ed track hours. I never did clutch drops but bought the car used with 40,000 miles so who knows?