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Triumph Repair/1976 TR7 clutch slave cylinder bolts



  Thanks again for all the info on starting up a car after sitting for years - I'm getting close to firing the TR7 up again !  My problem now is I lost the bolts for the clutch slave cylinder, they screw directly into blind holes in the clutch housing.  I bought a kit with master & slave and hose and it has 2 bolts that are 8mm.  There were no nuts so I assume they are for the slave.  They only go in about 1 revolution, but if I try a 5/16 bolt, it goes in about 6 revolutions.  So I guess the right bolts are 5/16, the manual is confusing - it reports 3 types of bolts for the slave - slave cylinder to boss - 5/16, slave cylinder to clutch housing - 8mm and slave cylinder attachment - 5/16 !  There are only 2 holes - surely they are both the same or is one standard and one metric ?!  Just thought I'd ask before I strip any threads !
Thanks again,


ANSWER: Hi Steve,

I think they are mixed up. There should only be two bolts to hold the slave cylinder in place. I don't remember what threads they were but if you can rotate a bolt 6 full revolutions, then it is the correct one, because you can't get 6 turns if the threads are wrong. The two ears (mounting flange) are a cast part of the slave cylinder correct?

Put the slave up in place and put lock washers on the two bolts that turn in 6 turns and see that they tighten up on the flange ok.

I did read in one of the manuals about a pinch bolt and different flange mounting of a mountiing flange and the slave slid into that and a long pinch bolt located the slave but that was on a Triumph Spitfire. I don't remember seeing any "7" with that type of mount.

The only metrics I seen on the TR-7 was the bottom edge of the bell housing had two short metric bolts straight up from the bottom to hold the back pan skid plate to the bell housing.


---------- FOLLOW-UP ----------


   My concern is stripping threads since the bell housing is alloy.  The holes are quite deep so I thought I should be able to get more than 6 turns in.  The slave has 2 ears with holes and the bolts pass through the engine plate to get to the bell housing threads.  My spitfire had the single pinch bolt you mentioned.  I think 6 threads should be enough - about 1/4 inch of the bolt.  I did find one mention on the web that said the bolts were 8mm so yes it is confusing !   Standard bolts usually are coarse or fine, I think metric have 2 thread pitches also ?  Maybe I have the wrong version.  Anyway, I'll let you know how it works out.

Thanks again,


ANSWER: The 8mm bolts have three different thread pitches. The 8mm is close to a 5/16" American bolt and you are correct that in aluminum you should see course threads usually.

If you strip one out, there is enough meat there to tape the bell housing out to 3/8" NC thread and just drill the flange of the salve cylinder out to 3/8". I have had to do that on other kinds of cars and a few have the bolts so close the the cylinder you can't put a large head in so all I did there was use a Allen cap screw.

Most of the time a 5/16" strips out in aluminum you can just tape the hole to 3/8" NC thread because the tap drill for 3/8" is 5/16" anyway.

let me know,


---------- FOLLOW-UP ----------


  I bought a variety of metric and 5/16 bolts, coarse and fine and from different manufacturers.  Oddly enough, an old 5/16 bolt that held the rear engine plate on fit the best but is too short so I managed to get 2 new 1 1/4 inch 5/16 fine to thread all the way in.  I'm pretty sure I cleaned the bolt holes before I put the transmission back and I cleaned them again on the weekend so maybe all this fuss was due to dirt or dust in the holes.  I put the starter back in and have a question - the manual talks of a heat shield for the starter wires but my car didn't have any.  Instead it had a partially melted plastic corrugated tube holding the wires.  Do you know what the heat shield looked like or have another suggestion like a metal tube ?



Hi Steve,

Check to see if the rear engine plate it threaded. If it is, that would explain the fine threads.
They don't usually use fine thread in aluminum. But if the backing plate is threaded it is ok because it is steel.

I still have some TR-7 engines so I will look later and let you know. But I think the plate is threaded.

I never seen any heat shield for the wires but there was a clip-on heat sheald on the solenoid and that stuck out over the end enough to shield the first part of the wires. Some of the CATs had their own heat shield also.

I have to make heat shields often as I make many modifications that need them. That was a large project on my conversion to a V-8 and I made 8 individual exhaust pipes for it so you can just picture all the heat shields I had to make.

All you need to do is mount sheets of aluminum and keep in mind air flow. Just don't let it contact the wires nor the pipes and have it open at the front and back as there is a lot of air movement under the car and aroung the starter.

I looked in several parts suppliers and couldn't find that clip on heat shield listed for the solenoid.


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Howard M. Fitzcharles III


Triumph TR-4 up & Spitfire, and Engine theory


Dealership line mechanic on MG, Triumph, Jaguar for 15 years, Instructor in commercial mechanics school 2 yr. Product information manager for piston and valve manufacture, Instructor & hotline answer man for import car parts importer 15 yrs.

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