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MG MGA - Calling Gaylord, Hester & Spohn
Gents, I hope no one minds me singling these guys out. Since the three have competition experience with A's I wanted their direct input. Of course if anyone else has thoughts about this, please share. I was looking at a thread from 12/05 on mgbexperience regarding the lowering of ride height on an MGB rear end. There was comment, some by Bill, about removing some of the individual leaves, restacking them on top of the main leaf, and in some cases turn one upside down to de-arch the leaf spring. I can invision how this is done and the physical effect on the ride height of the car. My question is what does it do to the spring rate? I read an article a while back by Boyd Mace in Victory Lane about lowering the rear of an A for competition. He had his springs de-arched and the mounting points rolled under. He also states that the rear should be a bit softer anyway so I think he removed a leaf. In the Denver area I cannot find anyone that has a furnace large enough to do this process anymore & I'm pretty sure it would cost a few hundred bucks to go this route if I could find someone willing. I prefer the idea of manipulating the individual leaves. BTW, anyone going to Hallett for the all MG event in a few weeks? I'll be in the yellow #730 Mk2. Hope to see you there! Thanks! |
JohnB |
Denver Spring 3510 N Brighton Blvd (303) 295-7638 can help you. They rework old springs to order and can make springs from scratch any size you want. Most of their work is for semi's. They have a big enough oven. I use them regularly. Randy |
R J Brown |
John, not one of the experts you listed, but I believe that restacking the spring as described would lower the compression rate and raise the extension rate. Probably not the best for competition as I would think you would want just the opposite rate for maximum suspension compliance to keep the tires on the track surface. Glad Randy had the answer, I also have used truck spring shops for different projects. I've even made my own rear anti-sway bar and had it tempered at such a shop. Usually great work at reasonable pricing. I'll also be at Hallett next month. Just a spectator, but will stop by and say hi. Red midget with a V6 and #73. |
Bill Young |
Guys, I don't profess to be an expert on this, all I can do is just share my experiences. What you need to do first is tell us how much BHP ish you have. If loads then your problems in this area multiply 1) Reverse leaf, this is to reduce tramp, so the wheels can spin and not tramp(bounce)plus not wind up the 1/2 shafts and break them when the tire rebounds onto the road again. Easy to do. if you go for a reverse leaf, it is a custom made thing, not just take one of your existing leaves and turn it upside down. In fact it only needs to run in one direction from the centre. towards the front I seem to remember. If you think of tramp as trying to make the spring into an 'S' shape, the reverse leaf try's to keep the leaf straight. 2) rear sway bars... I hate the things... and with a LSD it made my MGB racer very lively to say the least, but I guess I hate understeer and love oversteer... drifting... Having said that, maybe start with a thin one 5/8 maybe... we have 7/8 on the front of our MGA racer and nothing on the rear ... at the moment. 3) spring rates: yes standard is OK and you will increase the spring rate if you add another leaf. This is where my knowledge gets thin. You need a little more on the rear, but not too much. The biggest benefit here is to get rid of the leaver arms and go for telescopic... but they need to be mounted as vertically as you can get them. Most kits don't achieve this correctly enough. There is a S/T book somewhere that lists MGB rear spring rates. 4) De-Arcing the springs. Yes we have lowered springs on our racer about 2 inches I think. However we are using MGB springs, as the front has a bigger eye, which helps reduce the need for a pannard rod (ever so slightly). You can just fit lowering blocks which I have done before, but that makes tramp worse, as your moving the leverage point away from the spring base. 5) Nylon interleaves. you need this, so the spring rebounds faster. later MGB's have it, but it's hard to find in the imperial size, so you usually end up with metric. makes little odds though. If you have some old MGB springs you can play about yourself. I guess you have heard of the old sand bag trick. If you remove the leaves one my one, you can apply force to each leaf and thus when you re-assemble the leaf... hey presto it's lower...although cold bending is not really to be advised. Phew... worn out the keyboard... Back to work !!! <MARK> |
Mark Hester |
Oh, For MGB spring rates, see page 34-35 here: http://www.1978mgmidget.com/Special_Tuning_for_the_MGB.pdf Hope this helps. |
Mark Hester |
I don't believe reversing one leaf will have any effect on rate as the leaf has one rate, not one for bending one way and another for bending the other way. Correct me if you think that is wrong. Flipping a leaf is just a quick and dirty way of lowering - you can do the same by having a set made with a different camber. I agree with Mark that soft at the rear is the ticket (and bloody hard at the front!) for springing, and I'm not absolutely sure that any increase on stock rate on rears is an improvement - experiment and see what you like. I disagree (mildly) about tube shocks. I've run all sorts of cars with and without tubes. If I was running a current SCCA MGB with 7" rubber, I'd probably opt for tubes, but frankly, the original Armstrongs, brand new, fitted with suitable valving, are pretty damned good and I doubt any vintage racer would tell any difference. I still use them on the MGA race car, and remember that my other car was a TVR with all independent suspension, and 6 tube shocks (4 on the rear), so I do have a basis for comparison. |
Bill Spohn |
Bill, We did not flip a leaf, it was a whole new leaf made of thicker material, specifically to help stop tramp and really had nothing to do with lowering. Can't remember off hand if it made any difference to the ride height. I do agree that leaver arms are ok. Adjustable tube shocks offer a small advantage and tube shocks if mounted correctly may help a little with sideways location (pannard rod), although the manufacturers will defiantly say you should not try to make the shock to this. Bill right on the front springs, we have 480 Lbs and I think harder would be even better, especially as we have wilwood 4 pot brakes on the front and they really bite hard. She's in a sad state at the mo. http://freespace.virgin.net/marka.hester/MKII_April2005.jpg Have a good weekend. <MARK> |
Mark Hester |
"Bill right on the front springs, we have 480 Lbs and I think harder would be even better, especially as we have wilwood 4 pot brakes on the front and they really bite hard." I've never bothered with 'fancy' new brakes as the original Twincam Dunlops stop the car as well as any peirod car and the pads I use will just not fade, even at tracks much harder on brakes than most. They were good in the old days when I was using DS11, and are even better, in that I don't have to warm them up and have brakes on the first lap, using carbon/kevlar. Besides, using newer calipers isn't legal in my form of vintage (and wasn't legal when I was doing SCCA style years ago, either). I see you are in a rebuild period on the car - periodic refurbishment, or making it faster, or both? BTW, I use 900 lb+ fronts - try it, you might like it! I use 550 pound springs on the street cars and that seems adequate. |
Bill Spohn |
Since I was solicited, I'll respond. I have no personal experience with lowering the ride height, but god forbid you should ever make it higher. |
Barney Gaylord |
Thanks to all of you who have responded to this post! After reading these suggestions and further research, I have decided to manipulate my existing springs, experimenting with various combinations of leaves, etc. I also plan on going to heavier coils up front as I'm using 550's now and will give the 660's or more a try. Thanks again! John |
JohnB |
This thread was discussed between 11/05/2006 and 16/05/2006
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