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MG MGB GT V8 Factory Originals Technical - Rear suspension

This is such a great idea I'm giving it it's own address for finding it again in the archives.

Nice kit, but is it not over two grand to buy? I keep thinking it could be done for about one grand.


If it is the Costello item then that price is about right but converting it to local pecos it is not cheap. Costello is a well know name and they have an excellent reputation for quality goods.

Another Pete, just to make a hat trick.

Peter Thomas

Damn, the Costello link won't work for me :-(



Try copying the link and pasting it in the address window (or type it out by hand) and it should work. I could not get there directly either.


Expensive yes, but I think I could make a variation up for my self much much cheaper. Can't see why the top link has to have a kink in it, or why the axle clamp needs be so elaborate. It's the link for the shock mount ot the hanger that really makes this such a smart idea.

Thought of a varient for rubber bumper cars. Place two pairs of trailing arms one directly above the other, BELOW the axle. A bit like two pairs of antitramp bars. Infact this could easily work for chrome bumper cars fitted with antitramp mounts.
The advantages of this is that it is cheap, bolt in, reversible, no brackets need welding to the car so simple easy and speedy construction and installation.
There is room on the rubber bumper spring hanger to place two trailing arms, infact when I lowered the car to chrome bumper height I redrilled the front spring hanger so I now have two sets of holes, one pair 45mm above the other. The axle on the MBG sites fairly high above the bottom of the spring and higher than the hanger. I also have blocks so the thickness of the spring plus one inch blocks within the u- bolts under the axle adds up to 4 inches.
Remove the springs from the axle, attach a four inch piece of channel steel with U bolts to the axle instead. Drill two sets of holes in the channel then simply bolt in the trailing arms. Put a coil spring above the axle that locates into the orrigional MGB prototype coil spring location, the bump stop. make the RHS piece of channel steel a little longer so you can attach a panhard rod to the back of it.
You can see the only construction required is cutting of a chuck of channel steel and drilling some holes in it. Also the arms of course, but I think that it is likly that these could be got off a wreck. Toyota Corrola trailng arms look about the right lenght (19inch). Their bushes look a little large though, about 2 inches diameter. Actually the toyota Terago panhard rod is just about three feet long, perfect for MGBs!

Can any one help me with data on the coil springs? What information do you need to specify them correctly?, to get the ride height right.
I've read in Rogers book that 250lbs is about the right rating (however I'm not entirely sure what that means!)and I'd guess that about three inches diameter would fit up into the bump stop mounts but I need to know more that that, maybe free standing height of the spring?
Also any suggestions on more suitable suspension trailing arms (smaller diameter bushes ie <1.75 inch) would be greatfully recieved.

A reasonably simple way of creating a 5 link rear end would be to buy the ready made anti tramp bars and panhard rod kit, modify the bottom clamp plates to take the coil spring damper units, the top of the coil overs could probably be bolted to the usual telescopic damper brakets, this would then only need two top links fabricated with brackets on the axle and rear bulkhead. I did some sketches of a possible set up before the Frontline costello kit came onto the market.
Costwise you are talking about approx £200 for the anti tramps, £200 for the Panhard rod say £150 for the coil overs plus what it costs to make the upper links. probably in region of £750 all up if you did all the work yourself. I'm sure it would work, but the question is how well will it work, will it handle well? will the spring rates and shock valving be correct? Will it be safe and reliable? I would dearly love to throw those awfull leaf springs away, they are especially bad on low mileage cars because of interleaf corrosion which cause them to virtually seize unless you regularly drive down very bumpy roads, which helps to grind down the rust and free them off a bit, a regular soaking in old oil does no harm either, (see thread in MGA section).I appreciate that the Frontline kit looks a bit pricey, but when you take into account the research and development and testing of a relatively low volume product it doesn't look so bad. I think I'll save my pennys and go for a proven product.
No connection with Frontline, just my personal opinion for what its worth.

Kevin Jackson.
K.R Jackson

(1st point) Kevin's comment about rust between spring leafs is interesting. It's been well over 15 years since I replaced springs on my GT, but I remember noticing something interesting at that time: those sagging old springs had plastic liners between leaves and the replacement springs didn't. (I think the replacements were from Moss, but they might've been from Victoria British.) One of the frustrations of owning an old car is the unpredictable, often lousy quality of replacement parts! If we could get "NOS" replacement shocks, springs, and bushings that were actually as good as the factory fitted, we might not be SO hungry for a new design.

(But I'd still want my Panhard rod!)

(2nd point) Kevin wrote: "the top of the coil-overs could probably be bolted to the usual telescopic damper brackets..." I hope no one tries that! Mounting either end of the coil-over in single-shear would be substantially inferior in performance and safety. Costello appears to recognize this issue and IMHO his solution is one of the better aspects of the design.

You are of course correct re top mounting, I was thinking it was a plate with two brackets for a bolt to locate the top of the coil damper unit. Never thought the single shear solution for the damper on its own was all that good.

K.R Jackson

Made a call to a local hot rod shop about having the trailing arms custom made. $110 Australian dollars for each one ie $550. Apparently most of the cost is in the joints/ends which are expensive and requesite for an engineers approval. These 'ends' are 33mm diameter and will bolt right onto the spring hanger.
I was going to stick with the hydrolic shocks because
-there is much controversy about if the spax style are infact better
-They are already there, work just fine and I like the flexibility of using different grades of oil.
-I like the thought of using the orrigional spring locations.

Also the main point to this is to do it easily & cheaply, and if it doesn't work (can't see why not however..) can be undone very easily. Also the pan hard rod and one of the sets of antitramp bars would be kept whatever the outcome. I'm out the cost of one set of 'antitramp' bars/trailing arms (which could likely be sold to some one else) and coil springs. Also some bolts and steel.

Still looking for spring details, anyone? Some where there must be some pioneering type who's worked it all out and has the details (other than frontline of course!)
Was able to find that they are $110 a pair, so total cost is looking to be $660, or $330 more than the tried and true panhard rod plus pair of antitramp bars.


Not sure what year car you have. On my 1980 I thought I might be able to use the position of anti roll bar mount for the upper arm mounts. I bet this would need to be reinforced but looked like a good posibility. Then its just a matter of using the front spring mount for the lower arm. Anyone looked into this before?


I suspect some people have, more for having the top trailing arm axle mounts in place, it would be tempting. Also you're right there would have to be some heavy reinforcement and some fancy brackets around the heel board to distribute the load because the top trailing arm is going to push very hard on a flat panel. Because of the backward slope of the heel board (not sure if that should be 'heal')there would have to be problems with getting the upper arms the same lenght as the bottom, a fair amount of back offset on the top axle arm mount, which sort of obviates the point of having them there in the begining. If you just went with it and used them as is then the different arm lengths, top and bottom, would have to cause some axle roll steer in corners, which is one of the things I'm trying to get away from. If you hit a bump in a turn the MGB light weight back end would dance about horribly I suspect. It's bad enough with the leaf springs!
All do-able, using roll bar mount, but alot more hard work. Anyway for me all this is moot as my car is a '75 and never did have the rear roll bar!
A pair of horrizontal bars each side under the axle has got to be better. Certainly easier to do, or undo. Also you might want to have a rear anti-roll bar at some stage!

Any way still looking for coil spring info'. Searched through the archives and came across one unsuported report of the orrigional coil springs being 8 inches free standing and 2.5 inches in diameter. The rating is 250 lbs so that gets me most of the way. I'm guessing I'm going to need to know the weight of the rear end and how that effects the 'compressability' and hence ride height.
Its frustrating because I can distincly recall seeing photos of a trailing arm set up, and can't relocate them. I might post this as a new thread, the coil spring experts may have gotten board with it a while back.

There is a link below:
which has a detailed description of a coil over rear suspension set up for a CB MGB GT V8.
I found this whilst looking for something else and I post it here since it may be of use to somemone.

Cheers , Pete
Peter Thomas

Thanks Pete,
This must have been the site I saw and lost. I had though he had used coil springs in the orrigional bump stop spot, I must have been mistaken. When I'm next back home I give an engineer I know a ring re: legality and start getting serious about this. Its just to attractive to let go.
Note the trouble he had with the movement in the bushes because of the distance the arms are apart!
Close together is better I think, Less rotation/lateral movement required, tighter/harder bushes can be used and less sloppy movement overall.

Glad to help out.
I must say I was somewhat puzzled by this particular conversion.

The builder seemed to me to select coil overs which are far longer then necessary and then , as a result , ends up doing more work than needed.

The locating of the upper arms seems to have involved a lot of extra work as well in relocating the battery box side panel and fabricating an inverted channel for the necessay clearance for the upper arm.

That said this is not my car and I am not doing the work so if the builder IS happy to go about it that way then so be it.

Cheers , Pete.
Peter Thomas

If you are interested I could send pictures, and other info, on the rear coil over setup in my 1977 B. I also have a 8.8 ford rear axle installed. Yes, the swaybar mount does need to be reinforced if used for the upper A arm as Mike suspected.

We will soon have a 4 link coil over suspension for the B. One for the stock rear end and the other for the Ford GM differential, the latter will have weld upper brackets.
The kit for the stock rear end is a 100% bolt on, Production kits may change a bit.
It's mot that simple to fabricate a multi link rear suspension, geometry has to be right in order to work on all conditions. you have anti dive etc. to consider. Simplicity of installation and more.

Yes James, you will get the first one!!!
Bill Guzman

Would be very interested Rick, but unfortunatly I'm working up in the Moomba gas field in Central Australia at the moment and won't be back Home down south in Melbourne for a week or two yet.
Do you have any figures you can give on the coil springs?
What are you going to charge? Costello's is nice but way way over priced. You'd think he'd go for volume, the production costs can't be that high.

Following on from the above postings I am wondering if anyone has looked at using the Moss coil over front spring assembly for the rear suspension of the B?

Lindsay Porters book : The mgb restoration Manual (2nd. Edition) by Haynes shows the item on pages 173 to 176 under the heading :Front Suspension Conversion.

This would mean fabricating a lower trailing arm to locate at the original leaf spring location point ahead of the rear wheel and at a point on the axle center line below the rear axle housing. Ground clearance considerations mean this would be about 125 to 150 mm at the lowest point directly under the rear axle.
Vertically this would be in line with the chassis leg so all vertical loads are fed into this member
The coil spring assembly would then fit into the space between this arm and the chassis leg with little or no modification apart from the necessary locating brackets to mount the eye / eye damper fittings. The upper end would be about the position of the original bump stop rubber mounts. This also would locate the trailing arm and spring / damper assembly as close to the wheel as possible to give the widest spring base , given the limitations of the axle type. Finally the unit would be mounted vertically or fairly close to the vertical to allow maximum effectiveness over the operating range.

The installed length is around ten inches and given the minimal differences in weigh distribution it appears this may be a viable option.

It would still be necessary to have an upper trailing arm and a Panhard Rod for reasonable location for the live axle.

One point which will need further investigation is the actual location since the unit will be mounted some distance inboard of the wheel center line so the lever arm effect needs to be accounted for.
I have not measured it but it appears the unit , when mounted at the front , is about two thirds of the way toward the outer end of the front lower arm so a similar mounting location at the rear should be a good starting point.

Peter Thomas

Rick, Is it possible to include me on that as well. I am also very interested and exploring ideas at the moment.

Cheers , Pete.
Peter Thomas

Much less than other kits. Final price depends on the fabricator and how many I order. I completed the protype and have been doing some minor adjustments.
Kit will have upper arm adjustment for different set ups.
Bill Guzman

Peter and Peter,
I orderedr a coil over kit from Summit (HAL-1500k). Turns out I ordered the wrong kit the coils would collapse all the way. The progressive springs are rated 100-200 lbs in that kit. The other kit (HAL-2000k) is the same except the spring rating is 130-250. I'd try the 2000k kit. For my problem after I talked to the cusomer sevice folks at QA1 (maker of the shocks) I ended up buying straight 200 lb springs. They actually have more available travel because there are fewer coils/length.
Other items needed
4 rods (links) with adjustable rod ends
4 pairs of brackets welded to the axle for the 4 links
appropriate bolts for the 4 links
2 mounting plates for the upper shock end (a little tricky)
panhard rod recommended
I think these are all the pieces for my setup.
If youíre interested in having pieces custom made using my car (1977 MGB) as a template e-mail me and Iíll give you the contact information.
My lower links are mounted in the forward leaf spring position.
My upper links are mounted to the swaybar positions The brackets need to be reinforced.
The top end of the shocks extend into the original shock location and attach to a plate fabricated for this application. Iíd try to explain it but picture is much better.
Peter Moomba contact me for the pictures when you can. Peter Thomas, Iíll e-mail some pictures.
Hope this helps.

Hi Rick, Thanks for the prompt email with the photos of your car. They are greatly appreciated.
Cheers , Pete.
Peter Thomas

Hi Rick,
could you send me some pic's as well please
Tony Bates

This thread was discussed between 10/07/2005 and 05/08/2005

MG MGB GT V8 Factory Originals Technical index

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