924Board.org

[gml]

Hey all, yesterday I had a fun time with the sleeve that couples the driveshaft to the transmission shaft. I ran into that issue where the notches in the shafts didn't line up with the bolt holes in the sleeve but was able to solve it by inserting (and hand tightening) the front (driveshaft) bolt and pushing the coupler back towards the transmission just a few mm using a prybar.

I cannot find a torque spec for these two bolts on this coupler sleeve.
For the 944 it seems well established 80 Nm (58 ft-lb), which I've seen on clarks-garage, and various Youtube guides like irina25661 who is a Porsche mechanic (enable english captions), spencerdog944, Ryan Anthony Deutsch who has a 924S.

For the 924 I cannot find a Haynes manual or workshop manual torque spec for these bolts. The Haynes manual doesn't even seem to reference these bolts (Chapter 7 Section 2). The most logical match I found in the Haynes manual is "Drive shaft clamping bolt" at 22 ft-lb (pg 150) but that's just so far off I don't think it's right.

I tried 58 ft-lb, assuming that this coupling sleeve and bolts have a very similar design to the 944 (esp. since I have a late 924), but with 58 ft-lb I got very worried about overtightening the bolts. Part of the problem is that I have to use a universal joint to reach the rear bolt and it doesn't feel great to try turning that with high force. I turned it down to 40 ft-lb and got it, even though that felt very tight.

Anyone have the right spec? Is 40 ft-lb too high or too low for these bolts?
_________________
George

1982 924 NA 5-speed

[Rasta Monsta]

80 Nm (58 ft-lb.)
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Toofah King Bad

• WeiBe (1987 924S 2.5t) - 931 S3

[gml]

Thanks Rasta
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George

1982 924 NA 5-speed

[gml]

One of the bolts broke... nightmare. I guess I have to take the transmission out again? After the replacement bolt arrives? Any tips for how I will be able to get the broken end out?

I am thinking its an awful idea to drive it around with just the one bolt torqued in... right?




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George

1982 924 NA 5-speed

[gml]

I should say my transmission drain plugs are rusted and stripped to hell as well, so if there's a tool I can get to help me extract this broken bolt as well as the drain plugs, that would be great.
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George

1982 924 NA 5-speed

[dubrict]

[quote="gml"]One of the bolts broke... nightmare. I guess I have to take the transmission out again? After the replacement bolt arrives? Any tips for how I will be able to get the broken end out?

Good lord, I can only imagine the variety of swear words that came out when that happened... Every church in a 50 mile radius would have burst into flames if that happened to me.

Anyway if your 82 is anything like my snailshell, you'll have to remove the tranny. As for getting the end out one of those extractor bits should be straightforward if you can get the coupler out on a bench.

And yes, driving around that way is an awful idea, you'll just end up with a chunk of the end of the coupler breaking off and you'll stop moving.

https://www.lowes.com/pd/CRAFTSMAN-5-Pack-Steel-5-in-Screw-Extractor-Set/1000594887?cm_mmc=shp-_-c-_-prd-_-tol-_-google-_-lia-_-218-_-mechanicstools-_-1000594887-_-0&placeholder=null&ds_rl=1286981&gclid=Cj0KCQjw--GFBhDeARIsACH_kdatdoQpRPj44LrpwEMlt1-qnGK5NSGtC5IcU-GtDEiyGqENlAqnK34aAjnzEALw_wcB&gclsrc=aw.ds
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1979 924 NA
2009 Chevy Impala
2005 Dodge Dakota

[gml]

Thanks dubrict! I certainly let a few swears fly when it happened but really I just had to laugh. I'm new to this game and when I took out the tranny and replaced the fuel tank I ran into no major issues, so I was just waiting for disaster to inevitably strike. It finally happened, and honestly it could have been a lot worse.

I was super relieved to see that the broken bolt was not locking the coupler sleeve in place on the shaft, so I was able to pry it back and remove the transmission as per standard procedure. Thank the gods! I was having nightmares thinking about using a screw extractor lying on my back facing up through the maintenance hole of the bellhousing. I didn't even drop the trans all the way out and managed to slide the sleeve off and out, so I can proceed on the bench and I am feeling okay about this job now.

I picked up a screw extractor similar to what you shared there, as per usual the selection of parts in Canada is subpar. I found this set — it looks like the actual extractor bits are the same as this set which has a positive review from a self-claimed mechanic, but the 10pc set was on clearance at a nearby store and even cheaper. Hope it's actually the same extractor set and decently durable, but I don't think that small chunk of bolt will give me too much trouble... will it? I'll share pics of my journey here.
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George

1982 924 NA 5-speed

[gml]

Bolt extraction was successful. https://imgur.com/a/KIrHhgA

Second time's a charm when my replacement bolts arrive next week. Torquing down to 58 ft-lb.
_________________
George

1982 924 NA 5-speed

[MikeJinCO]

I have a 5 speed with coupler sitting on the garage floor waiting for installation. The 8mm coupling bolts are Gr 12.9 which is 8740 steel with a tensile strength of about 175K-180K. I don't normally disagree with Rasta, but I would clean up the threads with a tap and then use blue Locktite and torque it to 35ft- lbs which is what the Technical Specifications call for the central shaft to transmission shaft 8x35mm bolt for the 016/8 and 016/9 transmissions. Engineering recommended torque for 8mm 12.9 bolts is 40 ft-lbs dry. ARP recommends 24 ft-lbs using their lube and straight oil would be even lower

On my track car since the transmission needs to be easily removed (fuel cell so fuel tank not an issue and exhaust above axle) I have taken to drilling a about 1-1/2-2" hole in the transmission housing with a hole saw to make that bolt easier to get to. Then just cover the hole with a bolt on cover plate. The aluminum bell housing is less than 1/4" thick. I think the whole car is built with lock nuts or Locktite and it still shakes apart.
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Mike


'67 MG Midget Dp
'71 Ocelot Dsr Kawasaki 1000(under rebuild)

[Rasta Monsta]

My sincere apologies if that spec was wrong. Was a cut and paste from Clark's Garage.
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Toofah King Bad

• WeiBe (1987 924S 2.5t) - 931 S3

[gml]

Rasta, no worries. I saw that spec on Clark's Garage and could only assume it was the truth as well. It's a good learning experience.

MikeJinCO thanks so much for the info. I will use my blue medium-strength threadlocker and torque to 35 ft-lb.

It makes sense to compute the torque based on the bolt grade + size but you also brought up the Technical Specifications, where are these? I looked in the workshop manual, the Haynes manual and found nothing. Just checked the Workshop Manual and nothing matches for 35 ft-lb. I also looked all over online for a spec and only saw 58 ft-lbs based on the 944 (i.e. Clark's Garage).

I will clean the threads with a tap if that's strongly recommended, if you think I could get away without it I would appreciate that. How does one find the right tap, what are the thread specifications?
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George

1982 924 NA 5-speed

[Rasta Monsta]

[MikeJinCO]

I looked at it this morning, it is a standard 8mm thread 8x1.25. I'll try to scan the tech specs to a .pdf then I could email it to you. It is about 6-8 pages and covers the whole line. Harbor Freight has a large set of taps and dies that isn't expensive. They are great for cleaning threads, I wouldn't trust them for cutting threads in steel.
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Mike


'67 MG Midget Dp
'71 Ocelot Dsr Kawasaki 1000(under rebuild)

[Rasta Monsta]

FSM says 22 for the 4 speed (p 30-04) and 25 for the 016 (p 30-06a & 30-06c).


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Toofah King Bad

• WeiBe (1987 924S 2.5t) - 931 S3

[gml]

Thanks guys. Again Rasta no worries, it took me 30 mins to drop the trans again and remove the coupling sleeve.

We don't have Harbor Freight here so I'm gonna pick up this set: https://www.canadiantire.ca/en/pdp/maximum-tap-set-20-pc-0587213p.0587213.html Its cheap so I bet it's better suited to cleaning than re-threading. It looks to have the 8X1.25 tap.

So FSM states 25 ft-lb for the new bolt? I think 35 ft-lb sounded more reasonable. This chart suggests an M8 grade 12.9 bolt gets 35.6 ft-lb.
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George

1982 924 NA 5-speed