MG-Cars.net

Welcome to our resource for MG Car Information.

Recommendations

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG Midget and Sprite Technical - a mind of its own above 52 mph

Hello to all, first of all I am a total newby when it comes to the midget. I have read through countless articles regarding performance tuning and upgrades etc. I have a 1979 Midget with the Triumph engine. Why would anyone ever need more power out of these. On my first drive in town traffic and low speed everything was just fine. It has all the power I will ever need. Onto the open road... a different matter!! I very nearly crashed. Once the car got to 51mph (I did notice a slight wheel vibration at 50) the car felt like it was dancing on ice. The front end went very light and started to drift all over the place. 49 mph and all was well. It is fitted with 145 13's. I have driven B's for many years and understand the suspension system well. Can someone throw some light onto this for me. It also seems to be suffering from slight oversteer. I'm thinking shocks and bushes. The car has just passed a UK MOT and I realise that 90% of the kiddies employed MOT centres would not have the first idea about the setup of these cars. What should I change first?
N Sayle

I had that problem with my TR6 when I first got it. Tried everything I could think of and finally realized it was the old redline tires that looked great but were coming apart. Replaced the tires and it drove great.

One of the redlines still looked pretty good so I thought I would keep it for a spare. I wanted to take it out of the wheel well one day so I could clean the car and it was stuck. It had actually expanded to the point that it was tight and I had to let out the air before I could get it out.
tomshobby

Its possible that the tyres have gone oval. Tends to chuck the car all over the place alarmingly. Jack each corner up and spin wheel with a solid datum point like the end of an axle stand by the periphery of the tyre and see if the gap gets smaller and bigger as one spins.

Roly
Roly Alcock

The suspension on the medget is one of the week spots because maintance is over looked by previous owners...the midgets LOVE atten.

Id look at shocks are properly filled with oil and not leaking, the bushings are in good shape...If not then use red poly bush instead of rubber...if the rack is pre 71 make sure it has gear oil, not grease, give the wheels a good shake both vertcally and horizontially to check bearings and Ball joints...if its ball joints, just take the rack apart and re-tighten the ball joint inside the gator boots...these rarly need replacing...its an old design, so pay no atten. to the wheel alingment guy when he says it needs new inner ball joints...check outer outer tie rod ends....Make sure you got the front sway bar hooked up and give the U-bolt nuts on the rear springs to axle a good twist, these like to work loose every 2-3000 miles

Prop
Prop

N Sayle

Welcome to the Spridget World!

Yep, the same thing happened with me when I first purchased my '78 1500...ended up my tires were 20+ years old with no balance weights on any of them.

Had modern 155/13's installed & balanced properly & all was right again.

Also, check tire pressures...alot of folks will overfill them & this can cause the dancing you're talking about...these little cars are super light & very sensitive to tire pressures...I run 26psi front 28psi rear & that's perfect for my car & driving style.

And yes, alot of folks put down the 1500, but I love mine...is pretty torquey...I love that torque!

Once again welcome,
Dave(from the Land of Torquey V8s)Rhine
Dave Rhine ('78 1500)

Check the rear springs are tight, clamps work loose and you get rear end steering!

Andy
Andy Borris

The car in standard condition should be stable up to around 100 mph so it sounds as if something is wrong with the set-up. The easy things to check are tyre conditions and particularly tyre pressure. I use 24 psi Front and 27 Rear. Get the tracking set accurately as well as if this is wrong it will certainly make the car very wayward! I would also check that the U bolts on the rear axle are really tight.

Beyond that, if it still isn't right, then it would suggest that there is wear or breakage in the suspension somewhere. Dampers, king pins, wheel bearings, track rod ends, steering arms, broken spring, worn bushes .....


Guy
Guy Weller

First off, the car is supposed to have a bit of oversteer.

As mentioned above, the erratic driving could be toe-in (0 to 1/8" by the book); shocks low on fluid; tyres out of balance, old, etc; bad ARB mount or link. Heck, it could be a bad leaf spring in the back for that matter ;-)

If you take the tyres in to check the balance, be sure to watch them do it. The original wheels are a bit of a challenge to centre properly on modern balancing equipment, so it is essential to watch the edge of the rim (generally visible at the bottom) for runout when they spin it up. If there is visible runout, the tyre will not be in balance on the car. The RO-Style rims are not "hub-centric"; the hole in the middle is not necessarily concentric to the rim. Instead, the lugnuts centre the rim.
David "top off the front shocks, check the toe-in and try it again" Lieb
David Lieb

Yes do all the basic checks as described above

If I were a betting man I would be
Rear tyre pressures very low
Tracking set at 3 or 4 degrees toeing OUT
Rear springs loose ETC, ETC.
Robert (Bob) Midget Turbo

I have had my suspicions about the tyres as the problem was far more during night time driving than it was today in warmer conditions, although they look to be in good condition I do not know anything about them apart from the tread depth. The fronts to my horror I have just noticed to be of different manufacture and tread pattern. Even in Spain where I spend half the year that is an ITV (MOT) failure. Tomorrow I will buy a new set of rubber. Perhaps 155's. I would really like opinions on 155's on J4's. Being that it is a 79 car I will have issues with anything larger. Would I be better off with a 155 70 or 80 and what implications will this have on the speedo. The power acceleration and gearing could easily take a bigger diameter. sorry about all the questions but these are such different animals to the B. Apart from it tryng to throw me into a hedge row every few hundred yards, its a great little car
N Sayle

I know i already mentioned this as well as everyone else except for tomshobby...Im not sure why he didnt mention it ( LOL) Come on tom what gives?


But check the springs at the rear axle and make sure the hardware is tight...it does work loose. I just wanted to make sure that ponit wasnt glazed over, in case you didnt get it the 1st 6 times...LOL

Im sorry i couldnt resist the parady of it...LOL

Prop...It could be a loose rear spring
Prop

N,
155s will fit. 165s will generally fit as well. The wider you go, the more options you have and the sportier the options. Are you on wires or RO-Styles? The RO-Styles are 4.5" and work fine with 175s (but they are a bit wide for an SWA car like yours).
David "I autocross my RWA on 185s" Lieb
David Lieb

I am very lucky to be alive!! Thanks to the suggestion regarding the U bolts on the rear I checked all 3! of them. These have been replaced as they are shiny and new looking. All 3 of them!!!! The missing one in passengers side (UK Car) inner (closet to the diff) Car off the road! Have ordered a complete new set as the stresses on the others could have done anything to them. The car has has a serious amount of rework, including, new floors sills wings doors, But think it has been rushed in the mechanical assembly. With all the B work I have done over the years this car is unlikely to cause any spannering problems for me, it just about getting used to a new beast with its different tempers. Due to the percentage of happy tyre size fiddlers I am going to go for 155's. Perhaps with a 155's I might need 3rd gear one day! 1500cc triumphs have the grunt of a hog
N Sayle

I run 155 80's - that is quite near original gearing but with the slightly wider rubber + no issues with square wheel arches etc.

R.
richard boobier

I run 165/70 13" tires on Rostyles. No rubbing, and total circumference same as 145/R13. Keeps your speedometer reading correct and does not raise the height of the car. Hard to find here in the Land Of SUV'S but they are out there.

Richard
R J Reeves

Good work, glad you found the u bolt problem.

I run 155/80 x 13 on Minator wheels, no problems at all.

Used a tire size calculator to figure out the speedo may be off around 2 mph, not enough for me to worry about.

Dave


Dave Rhine ('78 1500)

Did you order new mounting rubbers for the U-bolt assemblies? Might not hurt.

I agree with all the above. Tire pressures make a world of difference on Midgets. Likewise the condition of the front dampers; if the lever arm bushes are worn, you get a lot of slop and "bump steer" over any kind of uneven pavement. Been there... I'd suggest other things as well, but all my suggestions would have been caught by a good MoT man, such as perished suspension bushes, track rod ends, etc.

Best of luck with your car! I've had my '78 for nearly 15 years, and when properly set up they're a joy on the road. The car should be very stable at speed and should corner as if it's on rails.

Cheers,

-:G:-
Gryf Ketcherside

I had a similar problem about 25 years ago. It was a late RWA Midget with only 48k on the clock, but over 30MPH it wandered all over the road. No wonder the PO let it go cheap!

I got a stack of bills with it for work which had been done...shocks, wishbones, rear springs, etc., etc. Had the tracking checked and it was spot-on.

The only thing that didn't seem to have been changed was the steering rack. I bought a used one off a friend, but it made no difference at all.

One day while idly looking around the car, I noticed that the tyres were steel-braced radials on the front and textile on the rear (or vice-versa, I can't quite remember). I swapped them from front to rear and it was totally transformed.
Dave O'Neill 2

Dave,

The rule used to be if you have to mix them textile front + steel rears - gosh that takes me back ! 40 years I think !!

R.
richard boobier

Ok, here is what happened today. I went to my local village garage ( its one of those old school one where they fix things rather than replace ) where I asked if I could have a look under the car on the ramp. I first replaced the U bolts on the rear axle. No change but I am now happier knowing that these are al good. Then I checked the front and rear shocks for oil, They were low at the front so I removed them flushed them out and put new correct grade oil in. No change but the front is much tighter. I had a good look around all the bushes and gave everything a proper wiggle. Checked and reset the front bearings, still no change. I then went to my local tyre fitter and put on a set of 155 80 13's on. Had the the wheels balanced on the hubs ( great advantage with Rostyles ) and I now have a new car!! Took the car to max revs in top without requiring the spare underpants kept in the tool box. Bloody hell its wonderful!! The tyres that were removed showed no sign of tread wear or rubber degradation. I took one of the tyres home as I had to find out what was happening. I used a jigsaw and cut the tyre into sections. about 1/3 of the steel belting was rusty and feeling the inside, lump could be found. It is my opinion that these tyres had been on the rims for a very long time without the car turning a wheel and caused flat spots. It now goes like pooh of a stick and feels like a go cart to drive. one happy bunny with very oily hands today!!
N Sayle

I get a preachy about tyres and change them if they are old (often they are 20yrs old on little used classics) look for the date codes.

http://www.carbibles.com/tyre_bible.html

The biggest improvements on my 1275 were tyres (like yours jumping around at speed) and putting oil in the gearbox and axel.

Do the simple stuff 1st
R Fowler

Yep, tires transformed mine too.

It originally had 3 different brands & tread patterns!

20+ years old.

Very scary handling above 60 mph.

Glad you found the problem & the other work needed to be done anyway, so that's a plus.

Enjoy your ride, these are fun little cars!

Dave
Dave Rhine ('78 1500)

@ Dave -

>>> It originally had 3 different brands & tread patterns! <<<

Yours too, then? ;-) I remember how pleased I was when I replaced my Midget's tire collection with four that actually matched. Drove better, too! Gotta love POs.

-:G:-
Gryf Ketcherside

N,
The best part is that none of that effort was wasted. It was all (and more) to do sooner or later anyway.
David "waste not, want not" Lieb
David Lieb

Gryf

Yep, 3 different ones!

Put the 2 treads that matched on the front just to get by (PO had the 2 that matched on one side...go figure), until I got a new set of 4!

Dave
Dave Rhine ('78 1500)

Righto, Dave... sounds like our Midgets are where old tires go to die.

;-)

-:G:-
Gryf Ketcherside

Glad you sorted everything out. When I got my 72 Midget, the tyres were in what looked like new condition. After asking lots of questions here, I replaced springs, bushes (to poly) and got refurb dampers. The car was a lot better on the highway, but still felt like it floated and if I hit a bump, things were a little hairy. I took David's advise and got Sumitomo HTR200's
It made a great deal of difference. The car sits on the highway and felt comfortable even at 75-80 during passing. I know the car sat for a long time and even though the tyres still had the nipple rubber on them, they were over 20 years old. The previous owner had only done 18000 miles in the 30 years he had owned it and even though he kept them clean, they were distorted in someway.
Not only do I feel more comfortable driving it, but its a pleasure on the highway.
Allan
Allan Jacks

Perhaps I'm just old fashioned but I notice N Sayle told us two days ago that he was lucky to be alive. Today he goes out with a new full set of boots and goes flat out! Asking to die in my opinion. Although todays tyres are not as bad as crossplies I for one would not run any car on new rubber flat out until they were scrubbed in.

Trev
T Mason

This thread was discussed between 16/03/2010 and 18/03/2010

MG Midget and Sprite Technical index

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