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MG Midget and Sprite Technical - Ride height after de-bumpering

Hi all ,

ive just de-bumpered my 1978 1500 midget . As the ride height has now altered could anyone tell me how to reduce the ride height ? Is it just the case of using front springs from an earlier midget ?

thanks in advance
D Stratton

Hi,

Has this also altered the REAR ride height? Has this also increased?
Lawrence Slater

Hi,

Front:
The 1500 has a different front cross member from the earlier cars that moved the suspension mounting points, and has fenders with reduced wheel openings to fill in the resulting gap, so fitting shorter front springs might (in worse case) lead to running out of travel and crash over large bumps.

So, it is probably best to fit higher rate front springs when you go lower (the spring rate was 271 lb/in from '58 ~ '79, only the length was changed). Going up in spring rate while taking an inch or so off, should help prevent crashing due to the reduced travel, and help tighten up the handling.

Rear:
On a solid rear axle, leaf spring car, you want the front springs to be firm and the rear springs to be as soft as possible, for the best handling, so what you'll, ideally, want to do is to fit the earlier, softer, and lower rear springs, as the 6th leaf added to the 1500s will make them way too stiff for your de-bumpered car.

Removing the bumpers should have taken off around 80+ lbs from your car.

(FYI: regarding the +140 lb difference from 1275 -> 1500, the engine/transmission account for about +45lbs, and the rest of is in the heavier rear springs and those big "horns" that held up the front bumper)

Hope this helps,
Norm
Norm Kerr

here is a list of the springs used over the years, as told by the Bentley manual:

Springs:

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
toe 1/16 +/-1/16"

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

crap, that didn't work at all

this website will only accept .jpg files, but I can't save in that format

sorry, too bad, email me and I can send the list, if you'd like.


Norm
Norm Kerr

Norm you posted it on british car net once in .BMP format, I converted to jpg using photoshop.

Here it is with your permission I hope. :)





Lawrence Slater

Thanks for all your replies guys
D Stratton

dat be da one!


thx,
Norm
Norm Kerr

I did this to my car last year. I got some new springs from Magic midget and lowered the front by 1inch. Great service from them too.
n Allen

This thread was discussed between 04/10/2011 and 05/10/2011

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