924Board.org

[PeterW]

I've been chasing vacuum leaks for awhile now. Took it into a shop and had them "smoke" it and found that the throttle body leaks around the shafts. (It's an S1, so oval body similar to na) Took apart another TB that I had laying around to see how difficult the 931 was going to be to rebuild and started looking around for parts. Can't seem to find the bearings, INA F96748. Found a source for something similar, but will require a small machine job to make it work. Not happy about that.. but parts are getting hard to find.

Has anyone ever rebuilt one of these before? If so, what did you use to rebuild/replace the bearings? I'm not sure that a repack will work; the precision of the machining may be the problem (wear on the casting) and I don't trust the grease to hold the pressure change from idle to boost. Any ideas?
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1980 931

[Rasta Monsta]

Time to toss the S1 manifold? You won't be sorry.
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Toofah King Bad

• WeiBe (1987 924S 2.5t) - 931 S3

[fiat22turbo]

Didn't Ideola say that the seals were still available? Or am I imagining things?

Also, wasn't there a similar TB from an Audi or VW that could be used (with perhaps less age and wear on the casting)

Seems like a little machining to replace the bushings isn't the worse thing in the world to keep the car on the road. Though switching to the S2 manifold isn't a bad idea if the parts are readily available to you.
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Stefan
1979 924 Carrera GTS (clone-ish)
1988 944 Turbo S (Silver Rose)

[PeterW]

Well, it was really the last place I would have thought to look for a vacuum leak, but clearly the smoke was coming out around the shafts. A little frustrated after all that time replacing rubber, but it was probably worth it to do anyway.

I will have to check with Dan WRT the seals. Thanks!
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1980 931

[ideola]

The NA/S1 ovoid TB use different seals than the S2 round TB. I sent an ovoid TB to my supplier, and he said he could not get correctly sized parts, and the way they were pressed in would make repair difficult, if not beyond the capabilities of most home mechanics, so I never bothered to pursue it further. So at present time, I only have kits for the S2 TB.

It doesn't surprise me at all that it's leaking, and it is quite remarkable the difference it makes when the seals let go. The seals recently failed on the 937 throttle body, and my idle went all wonky. Given that the ovoid TB does not appear to be easily rebuildable, now would be a good time to consider switching to an S2 setup as Rasta suggests. You will need the TB, the intake, the upper charge tube, the three large o-rings for sealing the TB/charge tube, and the correct TPS pigtail to adapt the WOT switch wiring from the S1 to the S2 TPS style switch. You will probably also need to transfer the throttle linkage from your S1 TB over to the S2 TB, as there are some subtle differences in how they attach.

This is not a hard conversion to do. Don't let the list above dissuade you...just trying to point out everything you will need to make it happen.
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erstwhile owner of just about every 924 variant ever made

[Rasta Monsta]

Updating the hard vacuum pipe that runs under the charge tube is also recommended. The S1 unit can be made to work, but the fit of the later one is better.
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Toofah King Bad

• WeiBe (1987 924S 2.5t) - 931 S3

[PeterW]

I'm sold on the conversion. Looking for parts...
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1980 931

[ideola]

I probably have everything you need except for the pig tail. PM if interested in a package deal.
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erstwhile owner of just about every 924 variant ever made