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MG Midget and Sprite Technical - Rear Spring Pads

After fitting 165-13-70 Yokohamas and installing lowering blocks on my square wheel arch Sprite, I'm getting a bit of rubbing on the wheel arches, despite rolling the lips and the judicious application of a bottle jack to the inner wings.

I've decided that new springs to replace tired 50 year old springs might help to reduce the axle movement but at Loton Park this weekend I got talking to a guy from Peter May who told me about their aluminium rear spring pads:

http://www.petermayengineering.com/product/alloy-spring-pad-set/

He assured me that this would reduce axle movement and improve the handling further over the poly pads that I have currently.

Does anyone have any experience of these pads as they sound like they might be just what I need.


As for the springs - does anyone know if parabolic springs are available for Spridgets?

If I go for normal leaf springs, I'm torn between going for standard and keeping the lowering blocks to allow me to return it to normal easily, or ditching the blocks and going for lowered and up-rated springs.

I understand that 1500 springs are stiffer - will they fit a 1275 shell or do they raise the ride height to meet the rubber bumper regulations?

I'd welcome any comments.

Colin
C Mee

My Sprite's wheels aren't really that big - it should say 165-70-13!
C Mee

Hi Colin, I will get the ball rolling with one of the easy ones.

Yes the 1500 springs are stiffer and yes they will raise the ride height a little as they have a bit more curve to them too than the 1275 springs.
Malcolm Le Chevalier

Hi Colin,
I want to start with going o/t, what model of Yokos?

As you know I know nothing of racing and engineering but surely metal instead of rubber type bushes/pads would be harsher/harder, less dampening of vibrations, perhaps good on a track but not so pleasant on the public roads.

IIRC Jan recently fitted 1500 rear springs to his 1275, it's in a recent(ish) thread, and the ones he got didn't raise the rear very much and he put they improve the rear handling. (IIRC Jan's also has lowering blocks).

If the other racers aren't using parabolic then they're probably not available and not of much use to racing.

This class your car's in seems to allow a fair bit of deviation from standard.
Nigel Atkins

Jans thread is called 1500 rear springs on a 1275 - YES!, started 14 July this year.

I put below in one of my posts, do bear in mind these figures were for original equipment, how much within tolerance or not modern made springs are I wouldnt know -

As per Terry Horler's book 1275 rear springs were "uprated to 80 sq/in with a free camber of 4.72" (119.9mm)".

Whereas the 1500 rear springs - "To increase ride height and support the extra weight, stronger six-leaf rear springs rated at 86 lb/sq in were fitted to all 1500 midgets.The spring free camber was increased from 4.72in (119.9mm) to 5.58in (141.7mm)".
Nigel Atkins

Thanks both. That's pretty much what I thought regarding 1500 springs but I thought it worth asking the question.

Nigel, the tyres are Yokohama Blue Earth AEO1s - the replacement for your much loved A Drives. They are light years ahead of the best-forgotten Toyo 350s! Much more grip, especially in the wet. They are much softer and generate a surprising amount of heat on a spirited run!

You are also right, the 'Roadgoing Production' class does allow a fair bit of deviation from standard, with emphasis on fair! A Panhard rod or Watts linkage would solve my problem but, as it was never a factory option, I can't put one on.

Basically, you can up-rate for safety and performance but not drop in completely alien engines or gearboxes. I can have a light weight bonnet or boot lid but that's it as far as lightening goes, so I'm stuck with chrome bumpers - but I like the look of them, so that's OK. :)
C Mee

I never understood why there's a rubber pad there. There's a bush in the front of the spring, and a set of bushes in the back. Next time I've got mine apart I will pop some aluminium ones in.

Are you allowed extra spring clamps?
Rob Armstrong

Yeah
On my old racer I had a centrebolt with an oversized head to suit the hole in the axle housing and had it fitted up direct to the springs -no spacer or anything and a steel plate at the bottom with the shocky mount in it---solid as a rock, no movement at all
willy

please excuse the grotty temporary handbrake cable


William Revit

My square arch sprite is fitted with 175/70 tyres and lowering blocks, like you I have eased out the arches with a bottle jack but didn't attempt to roll the lip of the arch - its not actually the lip that rubs - its the area above the lip where the fit is tightest if that makes sense.
What wheels do you have - I have 4 spoke revolutions and the offset is about 10mm less, providing extra clearance compared to a steel wheel.
Have you got polybushes in the rear shackles, combine this with poly spring pads instead of the rubber and your axle should be (relatively)well located. My tyres don't rub, but I had to tighten the u bolts to the point where I thought they may actually be stretching
What about nylatron pads - how do they compare to aluminium?
With rubber pads you can just keep tightening the u bolts until all the rubber has "squished" out anyway to the point where as said above - you may as well not have them.
Taking out the pads all together will raise the ride height slightly - by the thickness of one pad I think
Alternatively keep the side walls well lubed with tyre shine................







S G Macfarlane

Hi Colin, if you are competing be aware that the Yoko BluEarths aren't on the MSA approved list 1A as of next year (not that they ever check). I have them on the rear so need to consider a change. I have found them to be a good tyre for the Spridget too.

Also, I am pretty sure there is a rule about bushes must be rubber/poly. Solid bushes/rose joints are not allowed.

Malc.
Malcolm Le Chevalier

Section S 11.7.6 "For Road-going Series Production Cars bushes may be changed for similar polymer materials but not to spherical or similar metal joints."
Malcolm Le Chevalier

Hi

Thanks S - that's extremely helpful. I pondered long and hard as to whether I should go for Minilite clones of Revolutions, which are about 1kg lighter I think. Had I known about the off-set difference, that would probably have swung it but I went for 5" minilites.

In my case, the rubbing has been a bit of both and the clearances are different on each side. I even managed to destroy one tyre in less than 200m when I first put them on due to a nib of weld that a PO had left on the lip that I hadn't spotted!

The rear shackles are polybushed and its a poly spring pad. I'll try squishing them up a bit tighter to see if that helps - it's the cheapest option after all.

Malcolm
Thanks for the warning about the Blue Earth's coming off the list, I hadn't spotted that and it's a real bummer as I think they only went on last year. The asterisk in the blue book shows they MAY be deleted next year, so I'll keep my fingers crossed. Uniroyal Rain Sport 3 and Rain Expert 3 were asterisked last year but are on the list this year without an asterisk, though the Rain Expert 3s are red for some reason. There are so few good tyres on the list that come in Spridget sizes.

After I finished my last post Section S 11.7.6 sprang to mind - so I did a bit of googling to see if I could find a definition of a bush and, sadly, some interpretations could include these pads. I'll have a word with a friendly scrutineer at the next event. Otherwise I guess I'll just have to rely on extra tight U bolts.

If I do have to get new tyres, maybe 165/65s or 165/60s would reduce the problem. That, combined with my new lower ratio diff that is waiting to go in, should at least improve the acceleration a bit!
C Mee

Colin there are lots of different grades of 'poly' used for bushes, do you know for sure what you have?
Then of course the hardest of all would be Nylatron. Moss do both materials....
David Smith

Colin,
as you know I don't know racing, I also don't know the Loton track, your suspension set up or driving technique/style - do you really need 165 tyres, would 155 be OK. When I've helped out at Curborough with our club road cars it seems on that tight track that sometimes the cars with the greater grip seem to lose on the flow of their runs so swings and roundabouts - or perhaps a change of technique is needed.
Nigel Atkins

This is Loton

http://www.flickr.com/photos/34910348@N08/36712848331/in/album-72157639738071493/

more tyres is probably better.

I also struggled with decent sticky road legal tyres in Midget sizes, I'm on 14s though.

Good plan asking the Scrutineers. And in the meantime the cheapest thing is to get those U bolts done up to almost the point of stripping...
Rob Armstrong

Nigel
I think the 165s are about right for my car in its current state of tune. It's on the tyres' limit on a number of bends and will slide if pushed too hard. 175s or sticky list 1b tyres might be too much and probably would scrub speed off, plus giving greater rolling resistance, which I can ill afford. I think 155s would see me having to ease off where I can currently push hard. Whereas the 'big boys' can more-or less point and squirt, I have to maintain as much speed as I can through corners to sustain the momentum.

Rob
I think, in your case, with that great-sounding K series, you're right about more tyres being better.

Thanks for the video link – That’s a very respectable time - you certainly learnt the track quickly!

Here's my best run from the weekend just gone when I managed a new PB at 73.35: http://youtu.be/eJ-6B8E2yL8

I’ll be studying your Harewood video carefully as I’ve got an entry for Saturday 15th September, I hope to see you there.
C Mee

Colin
You mention-
"175s or sticky list 1b tyres might be too much and probably would scrub speed off,"

nah.-sticky will always be faster
I ran 205/60 Advans on 8" rims on mine and would have liked more

willy
William Revit

I'll be at Harewood on the 15th, see you there Colin!

Sticky almost always quicker. I'm on sticky 1b tyres, took 4.5 seconds out of my last harewood time (though I added 200ccs and 20bhp too)

here it is: http://www.flickr.com/photos/34910348@N08/42561206190/in/album-72157639738071493/
Rob Armstrong

Colin. If the clearances are different on each side you can jiggle the axle a bit after loosening the u bolts to even things up and make the most of the clearances.
S G Macfarlane

Nigel
You'r right.... well, apart from this: (IIRC Jan's also has lowering blocks)
No I haven't any lowering blocks, but I'm vey satisfied with the 1500 springs which did not raise the rear more than maybe 5mm.
C Mee
I can only recommend the 1500, I bought them at Sussex Classics, I'm very happy with them.
I too have the rubbing issue, but only on the right hand arch, but the 1500 springs has made the rubbing more rare, it only occurs when driving aggressivily in small bumpy bends. I will solve it during the winter with a jack, as suggested, or something like that.....
Jan Kruber

Jan,
sorry, is it just the front that has lowering blocks (to resolve the front on yours sitting higher than you wanted with the springs I recommended from Kim), I don't always mentally retain the correct information.
Nigel Atkins

Nigel
You'r right once again, Sir. Yes Kim delivered my new 340lbs springs. When placing the order, I didn't dare to order the lowered front springs. But it turned out, that I could have done that, since I had to, as you mention, lower the front by approx 1" with 1/2" spacers, since I considered it was high at the front end.
CMee
Here is attached a photo of the car with the 340lbs front springs lowered 1" and with the four layer 1500 springs rear, NOT lowered at all.


Jan Kruber

I wish I could get my meanings right in my posts!

I still find the fact that you needed 1" lower at the front a bit of a head scrather but that's how things go on these cars.


Nigel Atkins

Jan, just out of curiosity what size are the tyres in that photo?
Nigel Atkins

Thanks Jan

You've got me thinking now about which springs to go for!

I've got Peter May 1/2" shorter 400lb springs on the front. This gave quite a pronounced rake from front to rear and made it prone to roll oversteer (only on the track, I never push it that hard on the road!) Putting 1 1/2" lowering blocks on the back means it sits just about level and has much better balance with only very mild oversteer when cornering hard.

S G, Thanks for the suggestion, I'll check the clearance between the wheels and the chassis but I think the axle's pretty well centered, it's the wings that are asymmetric!
C Mee

Nigel
The tyres are Avon ZT5 165/70 R13 79T
Jan Kruber

Colin
Excactly the same issue here with the rubbing on the RH wing. I thought that maybe the rear axle/wheels were situated to far right, but they are not. It is the wing. I can see in the in old invoices, that came with the car, that it had an injury sometime in past. I can not see it on the car where the damage was, but it could happen, that it was on the right wing - who knows.
I will try to sort it out during the winter break
Jan Kruber

Cheers Jan.

In that case, subject to the road being level across and along the axles, I still think your car sits lower than factory which is fine as you're happy with it but does make the rear sitting lower without spacers a little curious.
Nigel Atkins

An aside, Hi again Jan. I just installed the 360 lb, 9.5" (standard height) springs from Magic Midget. I ended up retaining my front lowering spacers too. Seems we are running the same set up although you look a little lower at the rear. My tyre size is smaller though, 155/70s.

It drives superbly now.

Did you get sorted on dampers?

Cheers,
Malc.


Malcolm Le Chevalier

Willy, it looks like you have Bilstein Dampers fitted on your car , which Bilsteins are they, do you have the part number ?

Ian
Ian Webb 1973 GAN5

Malcolm, sorry, I didn't notice your question until now:
I filled the rear dampers with w30 oil as a test, that was better, but I have ordered four new dampers at Peter Caldwell. It will take a while before I receive them, since he is short of cores right now.
Another thing, I discovered recently, that the car leans towards the left side. All the springs are new or firly new, and during winter I will have to swap them right / left to check if I can get the car to lean to the RH side by doing that.
I suspect the spring are not alike allthough new.
Jan


Jan Kruber

This thread was discussed between 28/08/2018 and 12/09/2018

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