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MG MGB GT V8 Factory Originals Technical - Lowering rubber bumper suspension
|Has anybody any practical experience of lowering their rubber bumper V8?|
If so, what route did you go, what kit or parts did you use and was it worth the effort?
I want to lower my V8 but don't want to get all technical and spend hundreds of pounds unnecessarily.
All advice gratefully received.
|I bought some lowering springs from Victoria British. They were uprated springs (550lb) It lowered the front end approximately 2". First problem was that the suspension went into negative camber. So much that it started wearing out the inner edge of my tire. I believe that Moss sells springs that only lowers it about 1". Second problem was bump steer. You would either have to move the steering rack, or modify the arm that mounts to the tie rod joint. Third the uprated springs in combination with, Spax on the rear, and a bigger front sway bar made the ride very rough. Nice for the track, but I would get cramps when driving on the interstate due to the expansion joints in the pavement. You can see some pictures of my car after when it was lowered at: http://mhartwig.tripod.com/myB/|
There is about 3 fingers width of clearance between the top of the tire and the fender. As you can see from the pictures, I have the ST air dam installed. Lowering the car only gave me about 4-5" of clearance under the air dam. You have to be really careful about speed bumps and driveways.
You will not be able to lower the car with lowering springs enough to get down to CB height. People do it all the time and end up with the wishbone arms at huge angles-lack of suspension travel and bump steer. The B suspesion is designed to run with the lower wishbones approximately parallel to the ground. In the RB car the whole X member is packed away from the body and unless you change to a CB X member something diffent is req.
My friend Bob Pulleyblank has obtained from sombody in the US a set of kinpin/subaxle assemblies which have been modified so that the lowering takes place within the kinpin axis-these semm quit promising as they do not change alla the suspension angles.
|I have a friend that lowered his car. He had the front springs "cut" which lowered the car 1". Then he had the problem of the car being twitchy due to steering rack angle, so he had the control arms reamed out (I believe) and and rotated the rack arms to attach from above the control arms. I hope that makes sense...|
He seems to be very happy with the results.
|The factory V8 was always higher than the 4-cyl, even in CB guise. MG World did an article a while ago on a conversion of a 4-cyl.|
I've got the same problem on my factory V8. At the moment I've got the MGOC "Rubber bumper lowering kit" front springs on. These are standard stiffness but shorter which lowers the car without ride quality suffering. I've also got the lowered bump stops from Moss, which gives brings the suspension travel back to a reasonable level. This does come with problems though, namely the problem that the lower suspension A-arms are no longer parallel with the steering rack links arms. This is what gives bump steer. I like Larry's idea of fitting the track rod ends to the top of the stub axle steering arms to get the links back parallel again. I had thought of this but thought that there would'nt be room inside the rim, I'll go and stare under the car again this evening. Anyway the steering arms are handed, wouldn't I only have to swap them left for right to be able to install the track rod ends upside down? My only concern is that this would put more strain on the track rod ends.
At the back you'll need lowering blocks. This I havent done yet because I want to put on the anti tramp bars that the MGRV8 used at the same time. to deal with the extra torque the lowering blocks will put on the leaf springs
Anyway I'd say do it, it makes the car much easier to drive and it isn't too expensive.
Easier = more fun + less tiring = Safer
I'll let you know if you can swap the steering arms tomorrow.
|I build 1" lowering kingpin stubs,for MGB racing.Please E-mail me,cost is $280 for the pair of stubs. If you take your leaf spring,and turn the end eyelits down,you can lower the rear a lot.|
DICK(Head B Keeper)THE KILLER BEEZ
|Unless you fit Dicks special stub axless and retain standard height - if uprated springs, you will find that the lower wishbone pair will not be parallel to the ground in static condition.|
I bought mine from Dick 18 months or so ago and have been too busy with my Magnette and V8 Roadster to fit them. They are very well made but you will need to have them reamed to match the kingpin itself. When I do, they will be used in conjunction with a Ron Hopkinson front double wishbone set.
You'ld be better off with reprofiled springs at the back than lowering blocks. Opinions vary, Roger Parker has one of the fibre glass units from British Automotive. John uses an RV8 spring. British Automotive have some nice looking torque arms which look in the picture as though they are being used with the fibre spring. I have standard V8 leaves with poly bushes and spring pads. Sometime , hopefully before Xmas we'll finish fitting the Panhard rod!
|In the rear a crescent has been welded onto the frame to lower the bump stop. You can cut that crescent add on off and re locate the bump stop to give original axle travel. Note, you will have to change the bump strap to the early short strap if you lower the rear. If you lower the rear with lowering blocks the shock lever mount will stay in the original position. If you lower via changed mounts or a decambered or flatter spring you will need to use the shorter shock rods from the cb car. The later front coils are longer coils that are precompressed (apparently softer per inch of compression but longer to maintain or increase ride height). The earlier coils apparently are stiffer and will not ride as nicely as the late coils. Stiffer springs give better transient response and less roll. i.e. better handling. Stiff sway/roll bars can compensate for soft springs. You pay your money and take your choice. I installed a cb crossmember and then adapted the late steering rack. I would seriously consider the modified king pins as an easier and still technically correct way to lower the front end. As several have noted above any time the lower A arms aren't parallel with the ground, the steering starts exhibiting bump steer and the car will dart right or left unpredicatbly as you drive down the road.|
|Barry is correct...lowering rear end is real simple...just get rid of the bump that was spot welded to rear body.....see my web site for photos of process....<http://www.theautoist.com> & go to garage page......front end is even simplier...replace rubber beam w/complete chrome beam...tilt steering assembly just a bit (.004") using shims so the shaft doesn't bind on body....voila!!! real rubber bumper suspension with no problems...one good long weekend!!!|
|Excellent website Tony,|
I finally got round to looking under my car last night, and found that the track rod arms ARE installed into the top of the steering arms. I guess they could be shimmed upwards to reduce bump steer but to be honest the arms don't look out of parallel enough to create a huge amount of bump steer. What using lower springs does do is to lower the front end roll centre which is bad news. So I agree with Tony, a chrome bumber cross member is the best way to go on the front. How are you doing with your front suspension mods Tony? Can you really just bolt up a chrome bumber cross member and shim the rack so it doen't foul? From peering under my car it looks like the rack would then miss the hole in the engine mounting point.
|The cb crossmember combo with the rb steering rack will interfere with the motormount on the steering side. In my car I built new mounts for a 300zx engine, however it looks like the existing mount could be modified to clear the steering shaft in its new higher position. I don't know how the rb steering rack could be mounted on the cb xmember without substantial modification. I put 5/8" box tubing on top of the cb steering rack mounts which allowed the rack to be mounted farther forward to accomadate the longer steering shaft. The mounts slope downward so that just extending the mounts forward also lowers the position of the steering rack in relation to the suspension. The 5/8" tube while extending the mounts forward also raises the mount back up to original cb height so the tie rods are parallel to to the A arms.|
|Phillip/Barry.....I bolted the chrome beam under the car & then mounted a rubber rack...it was binding against the top of the motor mount where the pinion shaft went through & was too high for the opening in the firewall...I loosened the rack & started tilting it until I found the center of the hole in the firewall (where it aligned w/column..oh, I'm using a '67 column in my '77 body so have modified hole in firewall to take mounting points for '67 column)....stuck some temporary shims under rack & checked clearance inside motor mount..no problem there either....measured the angle of offset & took rack to machine shop to have them machine back side of mounting points to fit that angle...suppose I could have used the shims indefinitely but machine shop (they're having fun w/my car...right now, they're trying to figure out how to mount TF hub caps on Nissan 200SX wheels!!) isn't that expensive & it is more permanent.|
This thread was discussed between 02/09/2000 and 08/09/2000
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