Alfa Romeo Forums banner

1 - 11 of 11 Posts

·
Registered
Joined
·
229 Posts
Discussion Starter #1
Is the attached list of torques that I copied from the 2600 Technical Specifications manual the correct one for me to use when I start to piece my engine back together?

Are there any not on the list that I should know about?

I'm grateful for any info.

Thanks.
 

Attachments

·
Registered
Joined
·
229 Posts
Discussion Starter #2
Not in the manual but does 30 lb inch sound about right for the torque of the bolts holding the clutch pressure plate? Plus a drop of Loctite blue I guess.

Thanks.
 

·
Registered
Joined
·
9,409 Posts
Yes, general tightening torque specifications for various components are given in both mkgs and ft-lbs (and in English) on page 8 of Pub. 912 "Technical Characteristics and Principal Inspection Specifications." More information about the clutch (but not torque specs) can be found in the shop manual for "Engine - Clutch - Gearbox" that is also included on the CarDisc DVD.

These factory specs from the Austin Healey 3000 BJ8, which uses a similar clutch mechanism, mention as clutch-to-flywheel torque of 300 in-lbs (25 ft-lbs or 3.45 mkgs).
 

·
Registered
Joined
·
1,303 Posts
Bolt torques

Having succesfully stripped threads on the main flywheel bolts and the clutch cover bolts , I can certainly advise that close attention to the low torques specified is the best approach - maybe with some loctite
 

·
Registered
Joined
·
229 Posts
Discussion Starter #5
Thanks Ruedi - I'll go for 25 lbft then.

Ian, you must be lucky - I'm sure if I'd over-tightened these I would have stripped the female thread not the bolts. I decided not to re-skim the flywheel in the end as the engineering shop are closed until early Jan and I must get on with re-assembling this engine. Hopefully I won't regret that!
 

·
Registered
Joined
·
93 Posts
Clutch mounting bolt length

I have a question about the bolts connecting the clutch to the flywheel. The parts manual shows bolts of two different lengths, 10.5mm and 19.5mm. Can't figure out the reason for this or where the shorter bolts should go since the holes in the flywheel all appear to be of the same depth.
 

·
Registered
Joined
·
9,409 Posts
I have a question about the bolts connecting the clutch to the flywheel. The parts manual shows bolts of two different lengths, 10.5mm and 19.5mm. Can't figure out the reason for this or where the shorter bolts should go since the holes in the flywheel all appear to be of the same depth.
This is a bit of a mystery, for me, too, but I have some conjectures. Let's first look at the information in the parts catalogs:

102 parts catalog (Pub. 685, Tav. 31) and single-volume 106 parts catalog (Pub. 992, Tav. 32):
  • 2100.00235 --> 8 x 1.25 x 16
  • 102.00.12.300.00 --> 8 x 1.25 x 15.5
2-volume 106 parts catalog (Pub. 1147, Tav. 38):
  • 106.00.12.315.00 --> con filetto lungo mm. 19.5
  • 106.00.12.300.00 --> con filetto lungo mm. 10.5
Amendment 001/1147 dated April, 1967:
  • 105.00.12.315.00 [sic - yes, the amendment has a typo in the first number] --> VITE fissaggio frizione con filetto lungo mm. 19.5 -- Annulato e sostituito dal normale 2100.20213. (19.5 mm screw replaced by 2100.20213)
  • 2100.20213 --> VITE da 8 x 1.25 x 19.5 fissaggio frizione
From the information above, we can derive that (a) the 102 and early 106 clutch assemblies used the same bolts, (b) that the bolts were changed for later versions (Series 2 cars), and (c) that the longer bolt was changed from a "special" bolt to a generic or "normal" bolt.

All versions of the parts manuals seem to list 3 pairs of 2 different bolts, it seems plausible that there are 3 pairs that correspond to the pressure plate assembly's arrangement of 3 saddle brackets (each pair consisting of one long, "special" bolt and one short, "normal" bolt).

The fact that the 102 and early 106 parts catalog list bolts that are almost the same length may be an indicator that the "special" bolt may have had a different tensile strength than the "normal" bolt -- which was first increased in length until later it was found that a regular, longer bolt was sufficient.

From what I can tell, there's no mentioning anywhere (in parts catalogs or shop manuals) where the shorter or longer bolts should go. However, since the arrangement of the hole on the clutch cover is such that the two saddle holes are closer together than what the saddles are apart, I would guess that direction of rotation matters, and that, in terms of rotation, the first of the two holes in each saddle would have to absorb higher forces than the second one and therefore have more tensile strength and/or a longer thread.

If my conjectures are correct, this would mean that, since the engine turns clockwise when viewed from the front, the longer and/or stronger bolt would be in the counter-clockwise position of each saddle when looking at the flywheel.

And, just after posting the above, I found this (note that the female thread for the shorter bolt shown on the right side of the drawing on p. 2 seems to have a recess cut into the thread -- which may indicated that the holes in the clutch cover may have different diameters ?!?):
 

Attachments

·
Registered
Joined
·
93 Posts
Thanks for solving the mystery

Thanks for the help. Learned two things from this exercise. First, I looked all over to try to find an answer but didn't look in the service bulletins. Will also look there next time. Since my Spider, 192686, was produced in March of 1964 it appears that the modifications described in the bulletin were made on production models earlier than date of the bulletin - not surprising. So the answer is to go back with two long bolts. Thanks for the help.
 

·
Registered
Joined
·
229 Posts
Discussion Starter #10
The fact that the 102 and early 106 parts catalog list bolts that are almost the same length may be an indicator that the "special" bolt may have had a different tensile strength than the "normal" bolt -- which was first increased in length until later it was found that a regular, longer bolt was sufficient.
The small difference of 0.5mm in the thickness of the early bolts may have perhaps been due to a variance of the designed thickness of the pressure plate housing - the technical drawing seems to indicate that although I accept the bulletin is of a later vintage.
 
1 - 11 of 11 Posts
Top