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MG MGB Technical - Lowering blocks

1973 CB
I want to lower my rear suspension and the lowering blocks look simple enough to make. Can anyone help with dimensions and a sketch.
J White

dont bother with lowering blocks,change the springs .the ride is awfull
daren

The difficult bit is the U bolts.
The blocks are very simple. They have a small recess drilled in the bottom for the head off the spring centre bolt to locate into, and a raised bit on the top to locate tightly into the hole in the spring perch on the axle (that the spring centre bolt normally locates into). On mine (which are on the car and I can't get at) the raised bit is just a cut off piece of metal tubing pushed into a hole. The important dimention is the hole in the perch, which you can measure for yourself by undoing the U bolts. Obviously the blocks need to fit between the Ubolts, which you can measure for yourself easily, before you undo anything.
If you want to save money, I suggest that you adapt a set from auto shop made for ford or holden etc.
I saw some that were quite cheap compared to MGB ones.
The problem with the U bolts is that you can't buy any off the shelf ones long enough, that have the same diameter as the MG bolt holes. I think you could get around this by redrilling the bottom plate and carefully squeezing a "slightly larger curvature" set of bolts in a vice to get them down to MG size.
You will need to shorten you bump stops a little to allow enought supension travel. This is not just a comfort issue. If you do not have enough suspension travel there is every chance you bumpstop will contact in a corner and cause lots of sudden oversteer. I found this to be the case when I lowered my '75. This was quickly and easily cured by simply cutting one inch off the rubber bumpstop with a hand saw. Clearance for shock absorber arm link travel should not be a problem because by fitting blocks you are moving the bottom attachment point down. If you use flatter springs instead of blocks then you do need to shorten those links. I still have about half an inch at full travel. Even so, you should check.

By fitting blocks I have found only an improvement in ride and handleing, perhaps Daz might need to shorten his bump stops.
My car was a rubber bumper so started off pretty high anyway and I still have plenty of road clearance. This may become an issue with a chrome bumper car. In Australia we have speed humps on inner suburan roads.

Do not fit heavier rated springs to the rear. This will cause oversteer. Put uprated springs and antisway bar into the front. The idea is that the rear suspension is free to follow the raod and keep as much rubber on contact as possible. Keeping the car flat is controlled by the front suspension.
Some people are even taking leaves out of their springs.
Peter

I fitted lowering blocks to My 64 MGB as the rear ride height was too high using newish standard springs
and I could not be guaranteed a lower ride height if I renewed the springs.
The extended "U" blots can be bought separatly form the MGOC.
Rob
R J Collier

Thanks for the comments everyone, but heres some more information and the reason I am interested in lowering blocks.
The car was sagging about 1 1/4" down on the drivers side, so I renewed the rear leaf springs, the front coil springs, all shock absorbers and all of the suspension bushes. This improved the sag but did not even the car up perfectly as I am still left with the driver's side down about a 1/2". I tried swapping the leaf springs but this had no effect. I checked the chassis alignment as best as you can with a tape measure and plumb-line and nothing seemed that far out.
Having looked on the net for some kind of solution, found that this seems to be a very common problem and can be caused by 40 years of predominantly driver only use. So I reckoned the only thing left to do was either to raise the low side by using a 1" longer shackle or by lowering the high side by using a single 1/2" lowering block. Lowering the high side seemed easy enough as there is more than 1/2" spare length in the U-bolts. The distance between the centers of the rear wheels to the underside of the chrome body strip is 15" on the kerb side and 14 1/2" on the drivers side.
John White

John,

if the difference comes with the front springs, there are leveling dishes for Mercedes W201, the old 190 series, that should fit at front, helping to egalize the leveling. I did not try this myself but a fellow MGB driver reported upon this item on the German MG Drivers Club board and made use of this.

hope this helps

Ralph
Ralph

You could also put a spacer between the front cross member and the body on one side. You would need to realign the steering rack , and check clearances but that is not hard and shimms can be bought. I added a quater inch to my front drivers side. This was to get enough clearance around the steering shaft in my case, and it also corrected a little "drivers sag", which did not hurt.
Peter

John

I had the same problem with my 64B as you have and I swapped the newish rear springs over, fitted new front springs etc exactly as you did.
It is still slightly lower at the rear on the drivers side but improved. I dont think the cause of the "lean" is long term driving with just the driver in as my car was Left hand drive until 10 years ago.

An idea I had instead of using lowering block(s) was to cut a couple of approx 5" sections from an old leaf spring and use these as packing. You will probably need a longer bolt to go bolt through the spring.

The same principle of packing pieces to equalise ride height is used if you fit parabolic rear springs so I dont see why it shouldnt work.

Robert
R J Collier

Peter / Robert

Thank you both for the info. I like the idea of the sections of old leaf spring as I could use the originals for this at no cost.

John
J White

This thread was discussed between 24/04/2007 and 01/05/2007

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