Welcome to our resource for MG Car Information.
MG Midget and Sprite Technical - Clutch inoperative!
I have rebuilt my Frogeye during lock down. Its almost ready for testing but I cant get the clutch to work. I run a Toyota 5 speed box utilising a Hillman Hunter 7.5" pressure plate and a Celica friction plate. I last ran this set up 20 years ago when the car was Turbo charged. This clutch set worked then other than it couldn't take the 175hp from the turbo,so I went to a Formula 3 sintered clutch.This work well but is over kill for a normally aspirated engine.
I have 12mm of movement at the outer end of the clutch arm and I have made a new pushrod so that most of that movement is acting upon the clutch, but the clutch will not disengage.
Any body any ideas how much travel at the outer end of the clutch arm should be need to actuate the clutch, or any other ideas.
Thanks, and stay safe.
|Whilst you wait for someone who knows what they're talking about and to get the subject to the top (of some listings) - there'll be stuff in the Archive here, B section and a live thread in the MGA section, as well as the MGA Archives.|
Your clutch set up whilst not standard will still have the basic remedies to try, anything unusual about your hydraulics?
How long ago were the clutch components fitted and how new/old are they.
|is this 'spinner' Page by any chance?|
|How long has it been assembled? If it has been undisturbed for 20 years the plates may simply be stuck together.
If so there are a number of possible remedies ranging from the passive to the frankly violent. Initially you could try pumping the clutch for a while, until you get tired of it, then jamming the pedal down with a bit of timber scrap overnight.
Personally I've never got that to work but I know others have been successful. At least it's a fairly benign first step and you never know...
You say you've rebuilt it, but what have you done?
Have the engine and 'box been split, so you know the clutch plate isn't stuck?
If you've had it apart, is it possible that the friction plate is the wrong way round?
When you press the pedal, does it feel like it's acting on the pressure plate?
Could it be over-throwing?
|Dave O'Neill 2|
I am not sure of the Toyota set up. If it uses a midget belhousing and clutch arm, it has been known that the Midget arm can bend backwards due to the extra pressure of the F3 clutch .Check the arm and if it is bending change it for another arm of correct profile,if you are going to use the F3 clutch have a strengthening rib welded to the back of it.Hopefully that should do it.If you are using a 7.5 inch another arm will suffice. By the way I assume that you are the Simon page that took part in the Motoring news test day at Brandshatch in 1984 with Mark Hales driving a selection of race Sprdgets.
|Hi. Yes Bob it is Spinner.
The whole car was taken apart 20 years ago and been repainted and reassembled. The clutch parts were disassembled and put on a shelf. It does use standard sprite arm and I must have been lucky because my Sebring still uses a Formula 3 clutch and I haven't bent an arm.
The latest theory is even with an 0.875"clutch master I am not getting quite enough travel. I will try a bigger master today and if necessary a smaller slave to get the travel I need.
I will let you know what I find.
|My standard 1275 diaphragm clutch uses a concentric slave, which has a travel of 11mm. Not sure if this helps except that by measuring the clutch lever arm either side of its pivot point you could calculate the ratio and therefore the travel my 11mm would correspond to at the outer end.|
Is this the same black frogeye you raced in the AHC series in the 80's? If so it looks most impressive. I lost track of my frogeye after I sold it to Nigel Bance
It is one of the Frogeyes I raced in the 80s. I sold my first to fund my 3rd the Sebring.
|Hi. A 15/16ths master cyclinder seems to solved a lot of the issues.|
This thread was discussed between 20/06/2020 and 21/06/2020
This thread is from the archive. The Live MG Midget and Sprite Technical BBS is active now.