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MG Midget and Sprite Technical - Throttle return springs

Mk2 Sprite, 948cc , 1 1/4" SU's
Are the throttle return springs the same as later 1098 and 1275 models.
Thanks

Les
Les Robinson

Les. No one has answered, and I do not know myself. Why not check the Moss catalog, either in printed form or on line, and see if the same part number is used for the throttle return spring on the various engines? That should provide you with an answer.

Les, too
Les Bengtson

Les
Thanks. Moss only list them for 1098 engine, however I'm guessing they will be the same.
The reason for my question is that my current springs, the two off, appear over stretched making the throttle pedal quite hard to move. Its been this way for years, just thought I'd finally get it sorted.

The English Les
Les Robinson

English Les. The US Moss catalog only lists a single part number for the throttle return spring. It does not differentiate between engine sizes.

As to the problem you are trying to correct, I doubt it is spring related, if you currently have the correct springs. If they have stretched, it will make the pedal more easily moved, not more hard to move. Disconnect the springs and the throttle cable and see if the throttle plates may be moved easily by hand.

If not, the linkage may be too tight, causing a bind. Loosen slightly and try again.

If the throttle plates can be moved easily by hand, attach the springs and try again.

If the throttle plates are hard to move, the most common cause is that someone has replaced the springs with some "generic" spring and the reason that yours have stretched because they were too short for proper application.

If the throttle plates move easily, attach the throttle cable and check the feel of the throttle pedal. If the system is now stiff to operate, you have a problem in the throttle cable or in the pedal itself.

A small amount of a good quality grease on the item the throttle cable connects to and which is connected to the carb linkage is not a bad idea, under most circumstances. When one lives in a dry, dusty area, such as I do, the grit mixes with the grease to make an abrasive paste, rapidly wearing the contact surfaces. In most climates, however, a very light coating of a good (Teflon, if available) grease is a good idea.

Les
Les Bengtson

Hi Les,

I've just put new springs on my carbs on my 64 car. I ordered them from moss, there are 2 part numbers, the 2 shorter springs for the choke return and a longer one for the accelerator.

I always thought all 3 were the same!

I've put a photo of how I have fitted them, hopefully its right!

John


John Collins

John. You are perfectly correct. The throttle return springs are a different part number from the choke return springs.

It has been a long time since I owned my Mark II Sprite (948), but I seem to remember two throttle return springs.

How do you find the operation of the throttle? Remember, Les R. posted about a problem with a hard to move throttle pedal. I do not remember this from my Sprite, nor the others I drove back then. Nor, has it been a problem with any of my MGBs. Do you feel, with the new springs, that the accelerator pedal is hard to operate? If not, that may back up the idea that the problem is not in the springs, but elsewhere.

Les
Les Bengtson

John
Very interesting. Your outer springs act as choke return but on mine they are fitted to the other side of the spindle and act as throttle return, at which position they are pulled quite tight. Looks like your installation is correct and mine wrong. Will investigate further tomorrow.
Thanks Les
Les Robinson

Blimey John your heat shield is shiney, shiney!

Is that one of Ashley's special jobs?

(hum Beatles Music... Gotta admit it's getting better, getting better all the time)

Have you heard from Bob today or do you need me to forward his email to you ref: Shugborough on Sunday?
Bill

Les - USA - thanks for the comments, as for the pedal pressures, I cant comment as I've not connected up the throttle linkage (if you look closely at top of pic, you will see the bolt/clasp for the cable that hasn't been fitted yet) I've not driven the car in 20 years, but amhoping that it wont be a heavy pedal - my 1970 midget was awful, it felt like I was stepping in concrete when I pressed the lod pedal - one reason for changing to a hif44!

Les UK - I'm only going on moss catalogue pics with my reassembly work - hopefully its ok?

Bill, you are dead right, its an ashley heat shield! nice & shiney in stainless. I've got quite a few of his products on my car. I finished the master cylinder tonight so hopefully will have stop and go at the weekend!

As for Bobs email, I've not received anything, so I'd be grateful if you could forward it to me.

John


John Collins

I think Les (UK) is correct in the spring placement. Two throttle return springs and one choke. I quite often run three throttle returns, one on each buterfly and one in the centre. Never suffered from a heavey pedal with this set up.

Mark.
Mark Boldry

Mark
My current setup is in effect three throttle return springs. The two on the butterflies seem as if their free length is too short and look over stretched when fitted, will look at length of new springs to compare.
If there is a spring on the butterfly spindles then why is there one needed at the centre?
As an aside, I removed the cable and have noticed that the hole in the ferrule at the pedal end is worn eliptical as if the inner cable is being pulled downwards which in turn will cause drag, there is also a slight kink in the inner cable at this point. Its possible that the cable mounting on the body is not at the correct angle to the pedal, something else to look at.

Les
Les Robinson

Mark and Les:
quote from Horler (p 61) talking about the HS2 type on the Sprite Mk2 & Midget Mk1:
"...an external spring was connected to each carburettor throttle lever, the lower end of the spring being anchored to the bottom of the revised heat shield. A further spring placed between these acted directly upon the throttle cable lever."
So three springs (AEA602) all installed in a row and in the same plane. The 1500 UK market also had 3 springs but different part numbers and 2 of one type and 1 of another...



David Smith(davidDOTsmithATstonesDOTcom

David,
Thats how mine is set up.

3 springs all on throttle 1275 rwa.
The outer two close the butterflies and are definately needed when you tune the carbs as the centre bar is released to allow individual adjustment of air volume.

The chokes on HS2's have 2 coil type springs each around the spindle assembly.

Richard.
richard boobier

David. Many thanks. That is how I remember it being--a spring on each carb. I also seem to remember that, unlike later linkages, the linkage only opened the throttle, but did not close it. I seem to remember, twice, having a throttle spring break and the effected carb sticking full open. But, all that was 40 years ago and I may not be remembering correctly, even if I am remembering vividly.

Les
Les Bengtson

I know this an old thread but I want to share my recent experience with my 1275 Midget. I have had the head off and the carbs. The carbs dismantled themselves on the bench as I separated them from the heat shield which I want to repair. So when I reassembled it I was referring to catalogues but mainly the web. I put the two outer return springs on the throttle return and the odd spring in the bell crank which is wher the throttle cable attaches. The car did not run properly and I started suspecting timing, advance and retard and SUs out of balance. I redid all these but no improvement. Today I place the centre spring on the choke return and the Midget is back to its old self again.
W Clough

Didn't spot the date and was amazed to see I had posted on the thread - thought the grey matter had finally given up if I couldn't remember that - now see it was 4 years ago !!

Feel better now so off for a celebration pint !

R.
richard boobier

WC - something has worked for you - but it's certainly not right! The centre spring is for the throttle cable quadrant.
David Smith

The chokes do not have external long springs - there are coil springs mounted around the shafts that should close them if working correctly.

R.
richard boobier

On my present and previous set of carbs the long neck centre spring wasn't and isn’t needed so isn’t fitted on mine now or before – which would be this spring -Return Spring, centre (long) AEA602 or Spring- Accelerator return AEA602

the two side springs are the short neck type as in the photo below of a spare set, these are – Return Sring, side (short) AEC2075 or Spring- Carburettor return AEC2075



Nigel Atkins

Nigel, AEA602 is the part number for the 3 springs used on standard SU HS2 installations.
AEC2075 was listed by the factory under the ST section, used with the Weber 45DCOE and the twin HS6 kits.
David Smith

David,
thanks for info, very interesting

I know you can’t always trust the parts suppliers catalogues so I’ve checked the reprint of the factory Parts Catalogue AKM 0036 - on page 121 under ‘CARBURETTER FITTINGS-HEAT SHIELD-AIR CLEANER-EXCEPT 1500’ and it has AEA 602 being shown as a long neck throttle return spring

and confirming you on page 311, item 56 is listed as AEC 2075 spring (1) competition part (but not shown in the illustration) under ‘SPECIAL TUNING-CARBURETTER-WEBER TYPE’

I based what I put on the two springs photo’d being supplied to me by MGOC as carb return springs AEC2075 and at another time AEA602 as the throttle return spring which I gave away as it was too long for my fittings see this page - http://www.mgocspares.co.uk/acatalog/MGOC_SPARES_CONTROLS__MIDGET__163.html

and shown same here but for ?1967- mid 1968? http://www.moss-europe.co.uk/Shop/ViewProducts.aspx?PlateIndexID=15730

and listed here - http://www.rimmerbros.co.uk/Item--i-GRID012628

after taking the photo I picked the stained microfibre cloth up and have lost one of the springs it must be in the room somewhere but where, when I find it if anyone needs the springs they can have them, they fit Bs too
Nigel Atkins

Nigel I would never trust to a dodgy reprint, I am using an original 1977 1st edition as my source and it states 'Spring - throttle return' so I really don't know where the 'long neck ' comes from, I treat that as entirely spurious. Having owned and run Midgets since 1975 I also have some NOS AEA602 purchased in 1991 and am happy to share dimensions and/or pictures if that would help.
AEC2075 appears on pages Q16 (Weber) and Q22 (HS6). It is not a competition part, if it were it would be C-AEC2075.
David Smith

David,
I was trying to do two things at once by conveying information to someone without the parts book at the same time as someone with the parts book - and done neither well

the long neck bit was just my description of it to help distinguish it more

again my writing was poor I have a (non-original) copy of the Parts Catalogue part No. AKM 0036, February 1977 1st Edition, British Leyland UK Ltd 1976 copyright

I saw AEC2075 on plate Q16 (page 311 of my print) but missed it on plate Q22 - my eyes (and brain) are not the best hence I looked across and dropped a line thus thinking it was a competion part, that was for the line below, I should have used a ruler (or is it rule) - my cock-up there again

the AEA602 that I got was, I remember it, like the middle spring in the first photo of this thread which is slighly different to as shown on plates D49 (page 121) and G1 (page 152)
Nigel Atkins

Nigel if you re-read the whole thread including the 2008 original part you will know that it's already been established that the first photo is a completely wrong installation. Read my post and pic dated 18th April 2008 - nothing has changed since then!
David Smith

David,
when I referred to the first photo it was to the type of middle spring only rather than fixing locations

all very confusing, as well as the ones I put before listing for 1275 GAN4/5 HS2 1¼” Sussex Classic MG Car Parts web site shows -
Spring Throttle Return - carburettor return spring, accelerator - 1098-1275 Midget, quantity required per car 1 – AEA602
Spring Carb Return - carburettor return spring, MGB + Midget, quanity required per car MGB x3 / Midget 1098/1275 x2 – AEC2075

I’ve not put what’s right or wrong just what is listed and shown and I did put >> you can’t always trust the parts suppliers catalogues<< and that my car works fine on just the two AEC2075 so I suppose it’s another case of more than one way to skin a cat

I’ve looked at my two (different year of publication) Haynes and the later one shows with a set of 3 AEC2075 but the earlier version shows on the ‘latest’ heat shield with stays at either ends with AEA602 in the middle and two AEC2075 but I’ve found Haynes to have errors before

I might should try two AEC2075 and see if it makes the accelerator pedal lighter

all this illustrates just how many changes are variations there are to the models over various years
Nigel Atkins

Nigel it does not illustrate changes over the years at all. It illustrates how if one person gets it wrong, them other people quote it incorrectly over and over again, for year after year, and perpetuate misinformation. It is neither helpful nor serves any useful purpose for anyone to keep quoting sources which are known to be wrong. There are no external choke springs only spindle-mounted ones. There are 3 throttle return springs, all the same length, and part number. Nobody expects the Spanish inquisition.

David Smith

W Clough
"The carbs dismantled themselves on the bench as I separated them from the heat shield which I want to repair" Ha ha. These are very clever carbs, where can you buy them? :)

Nigel, if you don't need the "long neck" as you call it, throttle return (centre spring), you're lucky. If the throttle cable sticks, or the pedal is tight, the carburettor springs often can't close the butterflies properly against the stiffness of the cable/pedal, making it harder to set tick-over and balance.

The picture below shows the same springs I had on my twin HS2’s (now sitting in loft), prior to swapping to the single HIF44.




BTW, the 1500 springs are different, and are :
145197 -- Carburettor return spring,
153959 -- Throttle return spring (so called long neck).



Lawrence Slater

David,
I quite agree if it's wrong then it needs sorting but I also think if it works then it's just an alternative to the original set up

just to defend myself I've not mentioned external choke spring and as for quoting from know sources that can on ocassion be wrong you quoted from Terry Horler's book

if I'm wrong I very happy to say so I don't have dogmatic expert reputation to protect

perhaps there a good engine shot in one of Dave o'Neil's brochure

Lawrence,
I don't think the car's ever had that long neck spring (can't remember with previous Spridget) and it's been through mg specialists and three tuning specialists - one that specialises in A-series engines and another that specialising in classics and MGs and I can't remember any commenting on the lack of the spring but I do remember one saying not to worry about ot as the two springs on were strong and they certainly feel that way
Nigel Atkins

I really never cease to be amazed; you repeatedly tell us how you've been ripped off by so-called specialists in the past yet still seem to believe everything they tell you... unbelievable.
David Smith

I didn't I believe them, in fact I put
>>I know you can’t always trust the parts suppliers catalogues<<

and often put that you need to crossreference all information you get

and I know Terry horler's book has mistakes

I also know that expert concours judges can be wrong :)
Nigel Atkins

ETA Imeant to put I didn't say I believed them all, darn keyboard
Nigel Atkins

This thread was discussed between 16/04/2008 and 30/03/2012

MG Midget and Sprite Technical index

This thread is from the archive. The Live MG Midget and Sprite Technical BBS is active now.