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MG Midget and Sprite Technical - Suspension Set-Up
|Looking to go into Sprints this year, has anyone got ideas on suspension set-up?|
Currently car is Polybushed all round, 1.5 degree top trunnions, 9/16"ARB, Standard height 360lb front springs, standard shocks, rear springs 5 leaf.
Other parts I have are 8.5" 360lb front springs,11/16"
ARB, rear lowering blocks.I also have somewhere a pair of 25% S/Abs valves.
Any ideas would be appreciated.
I'm no expert but a very amateurish (and clumsy) amateur, but here are a few thoughts:
How far you modify will depend on the rules that apply. Section S in the Motorsport UK (formerly MSA) 'Blue Book' is your guide for any event running to MSUK rules. http://www.motorsportuk.org/assets/bluebook2019revisedversion.pdf
Other sprint series are run by the likes of Javelin but I have no knowledge of their class structure or what their rules allow.
I hillclimb my Sprite in the 'Roadgoing Production'class - a hillclimb is a sprint where the finish is a bit higher than the start and the same rules apply.
Polybushes and 1.5 degree trunnions improved the turn in no end and almost eliminated understeer.
I have 400lb front springs lowered 1/2". These reduced dive under braking and almost eliminated rear-end lock-ups.
I think the thicker anti-roll bar would help as my Sprite still rolls a lot with a 9/16" ARB. Make sure you investigate beefing up the mountings as stiffer bars can lead to the mountings failing.
I have 1 1/2" lowering blocks on the rear. Think carefully about this one as square rear wheel arches will restrict the tyres you can fit, I don't think it's a problem for round wheel arch cars. Before fitting the blocks my car had a distinct 'rake' and the elevated rear end helped go give it severe 'roll-over steer' on tight corners (i.e. embarrassing tank slappers or spins!). The lowering blocks have removed the roll over steer - I just find other ways of generating embarrassing spins, like putting one wheel on the grass when braking hard in front of the main spectator area on my last outing.
The shock absorber valves sound like a good idea. I'd be interested to hear how you get on with them. I have adjustable telescopics on the rear and setting them too stiff just caused handling issues!
If you're in Clwyd you're only just up the road from the Loton Park hillclimb track where I hang out. This weekend's meeting has just finished but the next one is the weekend of May 18/19 and the Austin Healey and MG clubs will be there the weekend of August 24 and 25 so why not pop over and have a chat with folk and check out the mods folk have on their cars.
Good luck and keep us posted on how you get on.
|Hi Colin, If you send me your email I'll send you some photos of the car.If you go to Loton you'll know Adrian Longstaff. Regards Peter|
I couldn't claim to know Adrian Longstaff but he has scrutinised the car a few times. Pleased to say he's given it his mark of approval each time!
My car is definitely better viewed from a distance but I'd be interested to see a few photos of your car. meecclspa at aol dot com should reach me.
|450 lb springs with a 5/8" bar on the front might go better, depending on your driving style. Leave the back soft - if you stiffen it then it'll be nasty in the wet. Don't forget tyres and pressures are an important part of setup - what are you running on?|
Best setup I ended up with was-
1 deg neg camber
550 lb springs
Bilstein gas telescopics set on stiff/stiff
Re-arched flatter std rear springs with an extra second leaf in the front half only
Removed the spring mounting towers from the body and extended them as far as possible about 40mm from memory to lift the front of the spring up into the body-This was to eliminate turn in understeer
as Colin mentioned don't go too stiff with the rear shocks and just a normal 50/50 shock setup--if the rebound setting is too heavy it tends to gradually suck the car down while you're going and ends up a horrible skippy little mess
If you have 25% up valves for the rear that's about as much as you want / need
As far as tyres I don't know yet I did run on A032R but not on the list now. have some Uniroyal rainmaster3s just to run around but other than that on tyres not sure yet-any suggestions as I think I'll have to run on list 1A and try Road going class but need to weight car as I think it's a bit heavy.
I can't go mad on spec incase I want to do some more HRCR rallies.
Any experience with front shock mods?
|I've always raced with Peter May 30% uprated front levers and found them satisfactory. Frontline kits and teles are all a bit OTT for me, and the organisers I race with prefer things to look 'period'.|
|David,Quite agree keeping in period means you don't have to prove it with certain classes.I take it that Peter May's lever have the uprated valves fitted, what oil?|
This thread was discussed between 21/04/2019 and 22/04/2019
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