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MG Midget and Sprite Technical - Are there torque specs for the pressure plate?

Neither Haynes nor the Archives answer this question. I am installing a new clutch. I just wonder if I need to be concerned.
P Burke

http://gerardsgarage.com/Garage/Tech/torqueSpec.htm


At the bottom of all the Torque specs he has a chart for bolt to torque specification....

You are talking clutch basket bolts.....right?

Goodluck!
Steven Devine

Will the settings for a 1.3 Austin Rover Maestro do you?

Clutch 1.3 and 1.6

Flywheel to pressure plate

15 Nm 14 lbf/ft 1.5 kgf/m

Being BMC transverse they have slightly different clutch assemblies to most other cars but I checked with my manual for the old front engine rear axle Ford Escort and its clutch bolt torques are given as 13 to 15 lbf/ft

14 lbf/ft seems about the ball park and if Haynes and t'others don't want to get serious about it I wouldn't either
Bill sdgpM

My Autodata manual says 22 lb/ft for Clutch to Flywheel attachment.

Rob
Rob aka MG Moneypit

Mmm... rob I competely respect you and your mechanical abilities

But... if calling the referee for a video replay on this one...hahaha

22 ft lbs would be similar to.a lid on a jar of mustard... :-)

Id think they would be at leaste 40 to 50 ft lbs and id use grade 8 hardware with red locktite thread glue

The cly head is torqued to 50 ft lbs if that gives you any insight as to what level of toque is needed on the clutch pressure plate

Check with the manufature of your clutch kit, it could be on the box or there website

Prop
Prop and the Blackhole Midget

According to Moss, the part number for the set screw is SH605061, which is just a standard 5/16" UNF set screw.

No more than 25lb/ft, I should think.
Dave O'Neill 2

Because Haynes doesnt I have been searching for the averages of clutch cover bolts torque in my extensive collection of Manuals

Fords from Escort through Cortina, all, like our Spridgets rear wheel drive transmissions

12 to 15 lbs / ft

Nissan Micra

Front wheel drive (like Maestros maybe)

12 to 15 lbs /ft

Triumph Dolomite 1854 beastie

16 to 22 lbs/ft

Me?

Happy to stick with 14

I once had six Transit clutch bolt heads shear (on re-use, who doesnt?) with a six inch spanner tightening them

Trip to Ford's on Saturday afternoon for that :(

They really do not need to be welded on rock hard
Bill sdgpM

Interesting.
The following table gives suggested torque values from 17 to 25 lb/ft for unplated screws, depending on whether they're grade 5 or grade 8. (More likely to be helpful to American readers than to British).

5/16" is not a big section. I'm confident I could shear one fairly easily. It has a lot to do also with the contact face. A flat faced (AKA washer faced) hex head has more contact area than a double chamfered type, which would affect the grip it has on the contact surface.

On that basis I'd go for a relatively light setting, given the weight of opinion saying about 14 lb/ft, but I'm definitely with Prop on the use of Loctite threadlocker. (Partly because I get it for free).
I think I'd chance going to 20 lb/ft, but I'd be reluctant to go further.

You dont say if there are split washers or star washers being used and I can't find a drawing right now, but if it were me I'd for sure be using Loctite either way.

http://www.almabolt.com/pages/catalog/bolts/tighteningtorque.htm
RS Hughes

Factory specification for the MGB, from the factory workshop manual, is "25-30 lbft (3.4 to 4.1 kg/m) for clutch to flywheel". I have never had a clutch system come free of the flywheel when only tightening to factory specified torque settings. Red Loctite would be excessive and may make future removal of the pressure plate difficult. The blue Loctite (medium strength) would be more than adequate if one desires the use of any form of chemical bonding compound.

The Bentley Publishing Company reprints the factory workshop manuals for most British cars and includes the Driver's Handbook in the same manual. Use other manuals if you find them to be of some assistance. But, all are based on the more complete factory workshop manual which should be the basic reference work of anyone who is serious about maintaining their vehicle.

Les
Les Bengtson

Thanks Les for the lead on the Bentley books. I just had a look - very interesting.

Good point on the different grades of Loctite, but I'm not completely convinced it would be altogether necessary at all. Just as a "belt and braces" approach I'd use a drop of it. And I mean a drop - it doesn't take much.

After all - these screws are not subjected to very significant counter-torque forces to cause them to unscrew. Possibly the most significant deleterious force they encounter is vibration so a wee drop of the good stuff may be no bad thing.

Incidentally I sometimes use stuff called SWAK, which is a PTFE paste intended for tapered hydraulic fittings. It works very well isolating vibratory forces due to its "pasty" composition, but I'm not sure about using PTFE anywhere near a clutch haha!

Regards;
Rod.
RS Hughes

We just use new square section spring washer, flat plain washer and 24 lbs ft on a calibrated torque wrench.

Peter
Peter Burgess Tuning

Never used loctite on a clutch cover in over 40 years. I've always done mine to 20lbft on the standard clutch. But now I have a Sierra clutch, I go to 25, which is what the Ford spec is. But it's the same size screw, and it's the same flywheel. So I reckon 25 is ok for Spridget clutch too.

Nobody bothered to consult the midget/Sprite BMC w/s manual then? Page 40 btw.






Lawrence Slater

I had a quick look, but I didn't spot it.
Dave O'Neill 2

Thanks for all your responses!

I'm fitting a Datsun clutch plate, but I don't think that matters since the f'wheel and bolts are MG.

I'll go with the consensus, 14-15 lbs. with a drop of blue threadlock to be sure. I'm going for new Grade 5 bolts with a new split washer.

AFAIK, this is the last piece of the puzzle, and the lump should be ready to re-install by the weeks end. This is a good thing because I have a job interview today, and hope to be too busy working to play with the Midget very soon!!
P Burke

Good luck on both counts.
Dave O'Neill 2

Wow... I have been corrected,

I dont remember what I did mine at ... but im sure it was alot more then 15 ft lbs

Are you using geralds 5speed kit or the rivergate ?

Good luck with your knuckles, the 5 speed is worth there damage and scaring

And best wishes on the new job front...will you still be defending in court the innocence of wife beaters and child rapist ?

LOL.

Prop
Prop and the Blackhole Midget

"I'll go with the consensus, 14-15 lbs."

Why?

The official BMC book says, 18-22lbft.

Yup it's not exactly easy to find Dave. I think the BMC manuals are badly laid out.
Lawrence Slater

My Autodata manual (for the MG Midget and Austin Healey Sprite) has a table of all torque settings and says 22 lb/ft for Clutch to Flywheel attachment.

I might add that it doesn't say anything about the big nut on either end of the back axle in case that topic was bubbling under somewhere!!!!


Rob
Rob aka MG Moneypit

Doh! Someone just had to mention it . . . . .
Nick and Cherry Scoop

Clutch plate on!!

20Lbs. with a small drop of removable locktite.
New grade 8 1 /14 bolts with new split washers. These bolts just peek through the back of the flywheel but don't come close to interfering with anything.
I went with new and longer bolts because a couple of the original bolts had marginal thread, and evidence of wear.

Something may go wrong in the future, but it wont be the clutch plate loosening!!

Thanks for all the help/advice
Phil



































P Burke

Good job phil

How did the interview go

Prop
Prop and the Blackhole Midget

This thread was discussed between 24/06/2015 and 28/06/2015

MG Midget and Sprite Technical index

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