MG-Cars.info
MG MGB Technical Rear Leaf Spring Question BBS discussion at MG-Cars.info
MG-Cars.info
Welcome to our Site for MG, Triumph and Austin-Healey Car Information.
Recommendations
Parts
MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.
MG MGB Technical - Rear Leaf Spring Question
| Gents I have chrome bumper leaf springs and think they are not flexing as much as they should. They are over 2 years old but have only done about 2000 miles. If I take a straight line from each end of the springs (the front mounting point on the chassis and the lower part of the rear drop shackle I hit the axle just at the top. The bow of the springs is quite noticeable. This is of course normally loaded with the wheels on the ground. Can any one tell me if this bow is correct please? as I hear many owners quoting that their springs are almost flat when loaded. Regards Dave |
| D M Tetlow |
| dave not sure if its right or wrong but at the moment there is a very big shortage of rear springs in britain at the moment due to british springs going bust early 2007 i will only put gt springs on mine due to the springs sagging very quickly but gt ones keep the car level for many years with not too much probs with the hardness of them ste |
| STE |
| In my experience (five sets of various types on two cars) they *should* be nearly flat in normal loading, even RB V8s which are the hardest of the lot. As a guide the axle should be about mid-way between hitting the bump-rubber stop and taking up all the slack in the rebound strap, with a bit more distance to the bump rubber than the strap. The shackle should be pointing down and back slightly. (http://www.mgb-stuff.org.uk/wn_suspensionframe.htm and click on 'Ride Height' and 'Rear Spring Replacement'). You also need the correct combination of car (i.e. bumper type), springs, bump rubber pedestal, rebound rubber and damper drop-link. I've bought three sets over the years from different suppliers and had correct ride height from all of them, although tales of them being too arched and/or too stiff are legion (more so in the US but some here), sometimes so much so that you can't get the shackles or rebound rubbers attached without loading-up the back. You should be able to do this easily just from a fully built car and no extra loading. When buying the last set a few months ago my usual supplier said they hadn't had any for a long time, as the manufacturer had moved from Bridgnorth/Telford to Sheffield without checking first how many staff wanted to move as well, not enough did, and they hadn't been able to resume producution since! |
| Paul Hunt 2 |
| Paul My shell is rubber bumper with chrome bumper springs. Will this cause the ride height to be too high? I would have thought that the chrome springs would have given me a lower than normal position. Regards Dave |
| D M Tetlow |
| DAVE you have opened a new kettle of fish here as its a conversion not standard so you will need lowered chrome bumper of there may be a diff set for the conversion to chrome bumper ones ste |
| STE |
| A rubber bumper shell has lowered mountings for both ends of the rear spring. If you remove the rubber bumpers and their extra weight standard CB springs in an RB shell might even end up with a *higher* ride height, certainly no lower. So as STE says you will need flattened chrome bumper springs to get the same height as a CB, and that has knock-ons for all the other parts I mentioned. At the front the height is partially governed by the raised cross-member and partly by the spring spec. I've recently bought front springs for both the roadster and V8 GT, and although I've had good results from the rears both these seem too high to me, nearly 1/2" more free height for the V8. In fact when I bought them the roadster pair had one spring 1/4" higher than the other when standing on the counter. I politely requested a matching pair, he said it wouldn't make any difference but he did comply. On-car the V8 now has more disparity between the sides than it did before. |
| Paul Hunt 2 |
| Would anyone know where I can get my springs flattened here in the UK? Cheers Dave |
| D M Tetlow |
| dave moss do 2 1/2 inch uprated lowered rear springs which would be ok others will prob do them as well ifyou can find any ste |
| Ste Brown |
| Hi, I've finished building a V8 on a rubber bumper shell. To lower the back end I used "reverse eye" springs From the B Hive. They're brilliant and they don't seem to wind up either!!! |
| Allan |
| I've heard of turning over one of the leaves, a case of 'turning over an old leaf' being better than buying a new one for the same dismantling :o) |
| Paul Hunt 2 |
| Dave, I also fitted the reverse spring eye rear springs to my rubber bumper GT. The springs are rated at 110lb and lower the car approx 2". I can only second what Alan said above. I got mine from Moss after a recommendation from Doug at MG Motorsort and they totally transform the car which handles, grips and drives much better. They are certainly worth every penny of the £146.00 Part no. Moss MGS40721 They do also seem to resist wind up and tramp, if you a rear anti-roll bar I recommend you remove it asap the car will much better without it. Kevin. |
| Kevin Jackson |
| Hi Ken I was wondering about my rear anti roll bar. It is home made (not by me!!!) but I assumed it would be an advantage. (pic) You mention the springs, I nearly ordered some last night but are the Moss ones reverse spring eye ones. They look the same style as I have at the moment. Dave 
|
| D M Tetlow |
| Oops Sorry Kev, Typo!! |
| D M Tetlow |
| Dave, I fitted a set of 'lowering' springs from MGBhive to my '78 BGT. They made the car very low - I hurt a sleeping policeman and he displaced my exhaust! I followed this up with some 'parabolic' springs from the MGOC. Much better ride but you need telescopic dampers. Hope this helps. Peter |
| Peter Hills |
| Peter I have the highest ride height of any B I know. Ages ago I sent in my info to add to a ride table (I think it was Paul H's). I believe I was top or there abouts. Were your springs from the B Hive reverse eye ? Dave |
| D M Tetlow |
| Dave, From your pic as I cant see the ends of the spring, it looks like you have the normal type uprated one's whats the number on them? The Moss No. is MGS40721 and the main difference is that that are specially made with the spring eyes below the leafs, rather than above as on normal leaf springs. Moss state they are made to a much higher standard than the normal springs and that the spring rates are correct and as stated which is not the case with the majority of cheap Indian made ones. I would not recommend Parabolics as you can't use them without an anti tramp bar kit with a V8 and you can't be certain of the ride height, a friend of mine bought a pair and his chrome bumper car now rides at rubber bumper height and I have heard this also from other people. The anti-roll bar you have is the same as the one I had on mine and is part of the Moss/Hopkinson handling kit, my advice is to remove it immediately as it makes the rear of the car far too stiff and induces sudden oversteer, especially if you get the ride height down to chrome bumper spec. The other part of the kit was a 7/8" front anti-roll bar which I find fine and the car is now well balanced front to rear. I spent an age deliberating on which springs to buy having listened to all the horror stories from people who were unhappy with the springs they had bought, and often returned several sets, I am very happy that I took Doug Smiths at MG Motorsports advice to buy the one I did. Kevin. |
| Kevin Jackson |
| Kevin, I must have the same complete kit. The rear bar is a pain as it hits the support brackets so I will remove it. I have a Quaife LSD so that should help too. The part number on the springs I have at the moment is AHH79080. These are Chrome Bumper std ones. Thanks for your help. Regards Dave 
|
| D M Tetlow |
| Typo - AHH7080, and yes you are top by 3/8" :o) |
| Paul Hunt 2 |
| Thanks Paul When I have finished I will add to your chart. Dave |
| D M Tetlow |
| Dave, If you cars a roadster they do a specific spring which is rated at 93lb which should be fine, unless you intend carrying a lot of weight in the car touring the USA! There was a comment above re the exhaust grounding with the lowered springs, which is not surprising if you still have the rubber bumper exhaust rear section which has to be that low to clear the underside of the axle with the original rubber bumper springs. Either have the pipe rebent to raise the front part of the silencer or just replace the rear section with a chrome bumper one. Kevin. |
| Kevin Jackson |
| Some thing I forgot to mention, because the springs sit virtually flat in their laden state, there is very little leverage being applied to the standard spring mounting bushes when cornering, and the added benefit is the axle is better located and does not seem to move side ways even when cornering quite hard! I am running 6" x 15" KN Minilites with 195/65 x 15" tyre and now the car is lower there is not a lot of clearance but I have not had a rubbing on arches with these springs but I did have the inner lips of the arches removed when the car was painted. Kevin. Pic of my car before new springs fitted now 2" lower. 
|
| Kevin Jackson |
| Kevin Very nice car. What colour is it? I have ordered a set of springs this afternoon. I have 5.5" x 15 wires, with 185x65's. My exhaust is a bespoke twin SS set up with a good ground clearance, so there should not be any problems there. Dave I hope to have a set of redundant chrome leaf springs, rear anti-roll bar and lowering kit on E-Bay soon!! |
| D M Tetlow |
| Dave, The colour is Jaguar Alpine Green Metallic, two pack paint in the darkest of three shades. Kevin. |
| Kevin Jackson |
| Guess what. Moss don't have any in stock, and have been waiting for 3 months!! MGBHive have no stock and no delivery date too. Any other suppliers? Dave |
| D M Tetlow |
| Dave, You could give Doug Smith at MG Motorsport a ring, he may have a pair. http://www.mgmotorsport.com/ Kevin. |
| Kevin Jackson |
| Cheers Kevin I will ring him tomorrow. Dave |
| D M Tetlow |
| DM Suggest that you research the archives for inputs on the rear roll bar. From what I remember the general consensus is to not install one unless you have greatly increased the size of the front roll bar. FWIW Larry 72BGT |
| Larry Hallanger |
| dave you will struggle everywhere as i said out of stock for over a year and now coming in from india the new chrome bumper spring have dmr printed on them not ahh so are from another supplier other than moss so maybe there springs are diff if not put a 2 inch lowering kit on until you can find new springs ste |
| Ste Brown |
| Kevin your a star. I am going over to Doug's this evening to pick up a pair. Thanks for the help. Regards Dave |
| D M Tetlow |
| Dave, Glad you found some, hope you like them as much as I do. Kevin. |
| Kevin Jackson |
| Forgot to mention that it is very important to shorten the bump stops,about 1 1/2" should do.The chrome bumper cars have them in a higher position. If you do not do this and the car is in a corner and you hit a bump, the axle will make contact with the bumpstop and cause very sudden oversteer as the suspension runs out of travel. Kevin. |
| Kevin Jackson |
| Picked up the springs, Superflex bush kit and -ve camber wishbone arms. Doug is a real help. We just dropped in to pick up the parts but ended up there for 2 hrs. He realy knows MG's. Well he must do as he has been racing them for 30 years!! I will up post an undate on the ride height when I the new springs are fitted. Many regards Dave |
| D M Tetlow |
| Hi Does anyone know how much a parabolic spring weighs? I am in the UK on biz and plan on buying a pair to take back to the US (in checked luggage). Regards Tony |
| Tony Bates |
| Tony Give Doug a ring on 01442 832019. He could give you the weight and supply them if needed. Regards Dave |
| D M Tetlow |
| Rather than shortening the bump rubbers you should fit the lower chrome bumper pedestals for the reason given. Then *either* method can cause the lever arm dampers to hit their end-stops before the bump-rubber contacts, so you must fit the shorter drop-arms as well. That then means the lever arms can hit their other end-stop i.e. on extension, so you should also fit the shorter rebound straps. |
| Paul Hunt 2 |
| Dave - Great idea,I'll call him Friday Paul - So what should I do for a CB roadster, leave them as is? Regards Tony |
| Tony Bates |
| Hi Dave, Forgot to ask, did you buy "reverse eye" or "parabolic" springs? Which doe Doug recommend? Tony |
| Tony Bates |
| Tony I bought the reverse eye ones. I have a ex-rubber bumper roadster. Ask Doug. He will tell you what he recommends. It depends on a lot of things. Most of them well above my head. Dave |
| D M Tetlow |
| Tony I forgot. Also ask about the Superflex bushes for the springs. :-) Dave |
| D M Tetlow |
| Tony - not sure what you are trying to achieve. If it is a lowered CB car then the same conditions apply i.e. you are going to hit the bump-rubber more often than with a standard ride-height. To get round that with the same compliance you would have to fit even shorter bump rubber/pedestals, drop-links and rebound straps, which would be quite a lot of non-standard work. Alternatively you could fit stiffer dampers and/or springs and simply not move the axle as much under the same conditions, at the expense of less compliance and a harder ride. |
| Paul Hunt |
| Paul, Yes I am trying to lower a CB and improve the rear end. One option is lowering blocks but as I need to replace the rear springs anyway (170,000 miles) I am wondering what my options are. FYI, it's a Rover 4.2L V8 roadster with a full sebring body kit, 16"x8" wheels with 245/45/16 and traction bars Regards Tony |
| Tony Bates |
| I think the same as above, then, i.e. modified CB springs either with a reverse eye, reversed leaf, or simply flatter. That will lower a CB below standard height just as it will lower an RB body to CB height. |
| Paul Hunt 2 |
This thread was discussed between 18/01/2008 and 26/01/2008
MG MGB Technical index
This thread is from the archives. Join the live MG MGB Technical BBS now