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MG Midget and Sprite Technical - 1500 best ride height ?

A quick question to those who have gone before as it were...

I am mod'ing my 1500 midget just for road use.

I intend to junk the heavy bumpers and also reduce the ride height..

Any experience on what is the best height for a road car? I have seen lowering kits - are these the best choice for height reduction?


Lastly after lowering how does it look with std 1500 wings?

Any advise gratefully received !
John Barber

Hi
the 1500 was raised up 1", but the front spring length was not changed, so, unfortunately, fitting a "1275" spring from '73 or '74 will still give you the same thing. The 1500 was raised by moving the front suspension mounting points, and as you noted, the fenders were "lengthened" to fill in the gap above the tire, so lowering the car is limited to a few options (aside from major surgery):

- fit spacers between the spring pan and the a arm (1/2" spacers = 1" overall ride height reduction, approximately).

- fit shorter springs with a higher spring rate (to prevent crashing due to reduced travel). The 1500 engine and transmission weigh 45lbs more than the 1275 (not counting the ~95# bumpers, which you are removing), so using the 1/4" shorter springs from a '64 ~ '72, or the 0.45" lower springs from a 948, might result in a lot of time spent on the bump stops.

After lowering the front, you might want to also swap for earlier fenders to avoid the tires looking like they are too far "inside' (or avoid rubbing issues).

Luckily, the rear end is more straightforward, the rear springs were curved more, and added a 6th leaf when the 1500 was launched, so fitting rear springs from a '63 ~ '74 ought to bring that down about an inch.
1100 & 1275 free camber = 4.437", 5 leaves
1500 free camber = 5.58". 6 leaves

You can also lower the rear by fitting spacer blocks between the axle and the spring, but that can increase axle tramp due to the increased lever arm they create.

* Interestingly, the spring rate was never changed in the front, from 948 ~ 1500, at 271 lbs inch.


Hope that this helps!
Norm
Norm Kerr

Norm, I put 1275 springs on my 1500 and that lowered it?!?

Steve
Steve H K-ser

I know the B had a redesign of the front suspention to make it ruber bumper height.
But i though the midget's just had higher springs fitted!
Onno Könemann

I based all of that on what is in the Bentley manual, but I am ready to be corrected!

In fact, I should apologize, because I did all of that research last night and i should have prefaced my reply with, "this is all based on just what I can glean from studying the data in the front of the Bentley manual, and is limited by that". ":o)

I, too, had long assumed that the ride height was raised by taller springs, and was surprised to see the spring dimensions listed in the Bentley showed them to be the same.

Though, the Bentley sure has a lousy description of the rear brake shoe /spring installation, they could certainly have mistakes elsewhere!


Norm "suspenseful" Kerr
Norm Kerr

Steve, do you know what year your 1275 springs came from? The pre-'73 springs ought to lower the ride height about 1/2".

Another thought: there is a bit of variation between stock springs, even in modern cars. The two on my Midget are 4 and 6mm longer than the 250mm that the book says they should be. Something like +/-10mm is probably "normal" tolerance (sorry for switching all of a sudden to metric - I got this tolerance from a Toyota suspension spring drawing).

10mm, 0.40" tolerance, is a lot, when that is doubled at the ride height, by the suspension geometry, to 0.8".

Norm
Norm Kerr

STOP PRESS

Horler has set me straight!

the 1500 front springs WHERE increased to 10.2"

This, along with the raised front crossmember, both of them provided the raised ride height.

To sum up: simply changing the springs to a 9.85" (late 1275), or 9.59" (early 1275) won't completely lower a 1500, because the suspension mounting points were also modified.

But changing the springs ought to provide some lowering (at the expense of the suspension sitting a little bit off from its ideal angles).

Also, Horler pointed out that my rear spring free curve data for the late 1275 was wrong:

1275 5 leaves was 4.72 (not 4.437, as I had seen in the Bentley for the early cars, but must have been increased at some point during production and I missed it).
The 1500 6 leaves is still the 5.58" free curve I said (whew).

Norm "gotta update my dang notes!" Kerr
Norm Kerr

There you go John, with 1275 springs and the lower 1500 wings it should look just so!

On the rear, I used lowering blocks

Steve
Steve H K-ser

What a shame another person sees fit not to look at active and archived threads on this subject in the millions ....

You can get the springs you need from Kim Dear at Magic Midget - google it - and that will answer your question.
rachmacb

Thanks to all for the advise ...


I will try search next time Rach ... to avoid repeats...
Steve - do you have any pics of your 1500 lowered?
John Barber

Bearing in mind that the archive searching on this site leaves a LOT to be desired. I have searched for threads based on printouts of the thread and not found them. Besides, we all like the human interaction of asking. I, for one, find it more pleasant to see the questions over and over again rather than the dead silence prevalent on some of the other forums.
David "anyone else ever search for the 'car rocks when engine stopped' thread?" Lieb
David Lieb

This was with standard springs, spacers at the front and lowering blocks at the back


J M Dilkes

Looks pretty good to me - thanks
John Barber

Looks ace JM, how think were the front spring spacers?
I think I will try the same as soon as I work out why my suspension is wonky (2.5cm lower on the drivers side).

-- Josh
J Levine

This is my de-rubber bumpered 1500.

Front and rear wings and rear springs are standard 1500 items.

Front springs are CHA 129 from a 1964-74 Midget.

No other modifications.

Sorry the picture is a bit dark, cheap camera and useless photographer...


JB Anderson

Another one.


JB Anderson

Hi again,
here is the whole spring history, I put this list together from the data found Terry Horler's book, I hope that this posts ok, and the spacing doesn't get mucked up. Unfortunately, we can not attach .pdf files here, so I have to do it as text like this instead. Anyway, I was surprised by two things after researching this. The front springs were not changed with the engine in '64, or in '75, but as much as two years later. I wonder if those height changes were made later due to issues with ground clearance from the market. As a result, funnily enough, the '75 front spring is the same as the '73 ~ '74, according to Horler's research. Mid-year in '76 it was raised. Same thing happened in '66, two years after the heavier doors and folding top were adopted.

The other thing is that the front spring retained the same spring rate from '58 ~ '79, and the only change was in free height (and the front cross member shape change at '75).

Springs History:

reference, Front Spring Rear Spring
engines
free length free camber spring rate
948 9.4" (qtr elliptic) 97.8 lb/in
('58~'63) ('58~'66) 14 leaves


1098~1275 note: fr spring not 4.437" 75 lb/in
('64~'72) changed until 1/'66 ('64 ~ 66) 5 leaves
9.59" (wkg load 375#)
('66~'72)
4.72" 80 lb/in
1275 ('67 ~ '74) 5 leaves
('72~'74) 9.85"
('73~'75)

1500 note: fr spring not 5.58" 86 lb/in
('75~'79) changed until 1/'76 ('75~ '79) 6 leaves
10.2"
('76~'79)

271 lb/in
wire dia 0.5"
coil dia 3.625"
fitted length 7.08" *
effective coils 7
* fitted length at 750lb working load


Front geometry:
Camber +1 deg
Caster 3 deg
Kingpin inclination 6.5 deg

2:1 ratio (1/2" spring length = approx 1" ride height)
Example of uprated road springs for the front: 360 lb in, 8.5" free length (~1.5 lower ride height)
Norm Kerr

oh sh*t, that didn't work at all.

Look, I'll post it on another website and then post a link to it here!

Norm "crap" Kerr

Norm Kerr

here is a link to the information the way it was meant to be seen:

http://www.mgexperience.net/phorum/read.php?3,1732562,1732562#msg-1732562



Norm "making amends" Kerr
Norm Kerr

I managed to lighten the previous posted pictures a little.


JB Anderson

And the other one...


JB Anderson

JM, what size tyres are you running on your car?
The ride hight looks spot on, think I will try and replicate that on mine (when it is again roadworthy!).

Thanks,
-- Josh
J Levine

Just a note - if you have the car sitting too low or ride too hard then some of the fun (and speed) can be lost on some back roads that a Spridget would normally be well suited for

Bit of a slight extreme example - I had a standard MX-5 and going up to Tan Hill behind me was a lowered, hard set Mx-5 that was part of our group that wanted to go faster and as there was no where to pull over I dropped a gear and made haste - he soon dropped back unable to keep up or his spoilers in one piece - softer suspension and better clearances are a good overall compromise, hard and low are fine for tracks and trunk roads
Nigel Atkins

Nigel, I couldn't agree more.
A supple suspension will usually out-drive a harsh and "overdone" one, out in the real world.


Here is that spring history in .jpg format.


Norm


Norm Kerr

Josh
Spacers on the front were probably about 1/2in, tyres were 155/80
It's actually about 25 years ago that I had the car. The back of the car gradually lowered itself over the 100000 miles I drove it (in addition to the 1" from the lowering blocks) because by the time I sold it the rear springs had lost most of the camber and were virtually flat!
It also had negative camber front trunnions and an 11/16 roll bar (tried solid mounts but became a bit noisy so went back to rubber - don't think poly bushes were only just starting to become more available then)
JM
jules d

Your 1500 can never be too low!

8.5" fronts and near flat rears


Andrew Dunn

Hello all, I am overwhelmed by the flood of useful comments and detailed technical info.. Thanks to all..

I am really after just correcting the heightto somewhere near the level the earlier cars had - once i have removed the big heavy rubber bumpers.

I am just going to be driving on std roads ( no specific plans for any track driving on a regukar basis at this point!) so I would have in mind not to go too low ..

I already had made an upgrade to the thicker anti roll bar many years ago. Can 't even recall what difference it made it was so long ago ( car has been off road for 'N' years now) I am too embarassed to say what 'N' is.. Hazzard a guess if you wish.

Last thought I do recall last time I drove it - having a power down tail out moment ( damp road ?)
and I let off the throttle and was fairly violently taken back into line - hit my hip on the ashtray in the process..

The question I was getting too in all thie reminicing ( check spelling) is it worth doing something about axle location on a std road car?

I am not a lunatic - but just want to be able to drive in a spirited fashion without it getting out of shape...?

Any further comments about experiences on this would be helpful..



John Barber

IMO probably not, for a standard road car. I'm on the standard rear end with slanty spax dampers and although have hummed and haa-ed at more axle location I've not done it yet as I've seen no need. Handling is predictable and it does 'snap' back into line if you let off sharply mid slide. I'm running 175 tyres and a 1.4K series...

have the tyres been on the car for N years as well?

check spring U bolt tightness as well, it's the number one cause of odd handling IME.
Rob Armstrong

Nope - it's not necessary, and, probably would result in a worse ride anyway ...!

As for the height - you CAN go lower than a standard 1275 car, but, it's not worth going too low and having to buy new fuel tanks/exhausts every few months. Not to mention all those ruddy traffic calming devices that some councils have seen fit to put three astride so you can't just go up the centre (grrrrrrr)
rachmacb

as Rob

but were the tyres at the time less than 6 years old regarless of tyre tread left, of good quality, right pressures(?)

rest of suspension (including bushes) in good condition(?)

in other words a standard set up (relevant to the car as now) in good condtion will be fine for spirited driving on the road - subject to driving within the prevailing conditions

start with standard in good condition, live with it for a good while and then decide if you need to move on

ETA: I posted same time as rach
Nigel Atkins

This thread was discussed between 19/04/2011 and 05/05/2011

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