951 bellhousing same as 944?
#1
Rennlist Member
Thread Starter
951 bellhousing same as 944?
I don't think so and here's why. In order to get at the clutch in my 944 i had to destroy the bellhousing. Its a long story but you do what you have to do. I picked up a bellhousing at salvage and its for a 951, the owner thought they were interchangeable. All the bolt holes line up and there's no interference. The problem is the starter. It bolts in OK again without binding or interference. However when I try starting I get an ungodly racket, metal grinding noise and not a chance its going to start. I pulled the starter, ran power to it and it works OK. I'm guessing that the 951 clutch has different diameter starter ring and hence the starter location in the bellhousing would also be different so in my case the starter gear is not hitting the sweet spot on the flywheel starter ring. Does that make sense.
#4
Addic
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the flywheels, ring gears, and clutch's all have different numbers too
but the starters dont they are interchangeable, so i think the clutch housing is the issue, not the starter or flywheel ring gear.
the diameter on the ring may be kind of true, but i think its more the location of the starter hole
but the starters dont they are interchangeable, so i think the clutch housing is the issue, not the starter or flywheel ring gear.
the diameter on the ring may be kind of true, but i think its more the location of the starter hole
#5
Rennlist Member
Thread Starter
I decided to pull it all apart again anyway. Four hours to pull the bellhousing off. No sign of interference so its got to be how the starter is engaging the ring. More tomorrow.
#6
Addict
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The 951 flywheel is larger in diameter, the bellhousing is designed to locate the starter farther from the clutch hub to compensate for this. I do not think you can make it work... maybe somehow milling down the starter mount or something to move the starter gear closer would work but the right part would be a smarter choice.
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#8
Addict
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#10
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Thread Starter
UPDATE:
I spoke with my supplier and he was great and said to come up get what you need. He called back a half hour later and said the numbers are all the same. He also spoke with a shop that only works on 944s and was told they're all interchangeable. I took my old demolished housing and on a bench compared it to the replacement. First I traced a line around one and compared it. Same outline, even the location of the starter. The last 2 numbers of the castings were different and the only thing I could see was at the location of the speed sensors, one at the inner was a hole, to other was a slot. That was pretty well it. For fun I'll remove the PP and do a side to side with the old rubber centred unit to see if there's is a difference in height. I know the diameter is right because i'm using the same ring gear.
I spoke with my supplier and he was great and said to come up get what you need. He called back a half hour later and said the numbers are all the same. He also spoke with a shop that only works on 944s and was told they're all interchangeable. I took my old demolished housing and on a bench compared it to the replacement. First I traced a line around one and compared it. Same outline, even the location of the starter. The last 2 numbers of the castings were different and the only thing I could see was at the location of the speed sensors, one at the inner was a hole, to other was a slot. That was pretty well it. For fun I'll remove the PP and do a side to side with the old rubber centred unit to see if there's is a difference in height. I know the diameter is right because i'm using the same ring gear.
#12
Hey Man
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UPDATE:
I spoke with my supplier and he was great and said to come up get what you need. He called back a half hour later and said the numbers are all the same. He also spoke with a shop that only works on 944s and was told they're all interchangeable. I took my old demolished housing and on a bench compared it to the replacement. First I traced a line around one and compared it. Same outline, even the location of the starter. The last 2 numbers of the castings were different and the only thing I could see was at the location of the speed sensors, one at the inner was a hole, to other was a slot. That was pretty well it. For fun I'll remove the PP and do a side to side with the old rubber centred unit to see if there's is a difference in height. I know the diameter is right because i'm using the same ring gear.
I spoke with my supplier and he was great and said to come up get what you need. He called back a half hour later and said the numbers are all the same. He also spoke with a shop that only works on 944s and was told they're all interchangeable. I took my old demolished housing and on a bench compared it to the replacement. First I traced a line around one and compared it. Same outline, even the location of the starter. The last 2 numbers of the castings were different and the only thing I could see was at the location of the speed sensors, one at the inner was a hole, to other was a slot. That was pretty well it. For fun I'll remove the PP and do a side to side with the old rubber centred unit to see if there's is a difference in height. I know the diameter is right because i'm using the same ring gear.
#13
Addict
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The actual bellhousings are the same, but the starter is located 1mm further away, if you take a 944 NA bell housing and compare it to a 951 bell housing and look at the starter area, you'll slap your head and say "Oh yea, it's obvious!". The factory took the 944NA bell housing and milled it to accommodate the larger flywheel of the turbo. They moved the starter 1mm farther away, and clearanced the bell housing to make sure it would fit.
They are different part numbers, and the differences are obvious if you take the time to look at them closely side by side.
No, you can't use a 951 bell housing on a 944 NA.
Dal.
They are different part numbers, and the differences are obvious if you take the time to look at them closely side by side.
No, you can't use a 951 bell housing on a 944 NA.
Dal.
#14
Rennlist Member
Thread Starter
Thanks, this is outstanding. I have to say though its not obvious and that just might be my advanced age. However i have both bellhousings side by side on the kitchen table I found possibly the 1 mm shaved of the housing from the 951. The best I coud tell it was on the big end of the housing. I couldn't see any difference on the starter mount surface. On the inside I could see evidence of milling on the side of the housing close to the starter location evidently to all for a larger diameter spinning mass. Other than that nothing.
#15
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Thread Starter
OH YEA, it is so obvious. Once one discovers that one was looking but not seeing. I spent the better part of an hour with both the wrecked housing and 951 on my workbench and using vernier calipers measuring all kinds of common reference points when I looked at the starting mounting bolts and the bottom edge of the casting. Wait a minute the 951 wall on the housing is noticably thinner. Its 1 mm thinner and guess what, the bolt holes are also a mm further out. I shared my new found knowledge with my supplier, got a 944 housing and all is good. RENNLIST AND YOU FOKS ROCK.
944, 951, bell, bellhousing, bellhousings, difference, differences, gear, housing, na, number, part, porsche, ring, turbo