Let me start off by saying there won't be a detailed set of pictures to go with this post.
There are some excellent Hoyw-Tos on the net, so check those out to see how do do the job first!
I knew the job would be challenging but it turned out to be Muy Challenging. Hence-No Pics!
Well, OK there may be a few!

Lowering the suspension on an MGF is/should be a very simple affair. All it involves is replacing the
stock pins of your suspension knuckles with pins which are 10mm shorter. Easy-Peasy!
To change the pins you simply drain the Hydragas suspension, remove the shocks and Hydragas displacers,
pop out the suspension knuckles. Swap the pins for the shorter ones and, of course, "Reassembly is the opposite
of disassembly"
As usual, that's all very simple until you add in the "UK Corrosion Factor" You guys with Japanese market cars
won't have this problem so go ahead and lower your cars-It should take one sunny day and half a dozen beers.

So what's the challenge? Other than the usual rusty bolts and other bits, and the fact that many of the fasteners are all
but inaccessable, the big problem is the plastic housing for the suspension knuckles. In their wisdom MG/Rover made these out of plastic to prevent them rusting together with the steel upper suspension arms. Of course 15 years later the arms have rusted with the result that the plastic knuckles are nicely siezed into the arms.
The simple "Pry the knuckle out with a screwdriver" becomes a major exercise in using naughty words. Of my 4 knuckles, one came out easily, two with some damage and one was totally destroyed with the result that my car spent several days up on stands while our friends at UPS got the new knuckles (and their customs charge) to me. Of course the nylon part isn't available separately so you have to buy the complete knuckle for 50-odd quid each. I now have 7 spare stock length pins which I hope to never use. I was able to do some minor repairs on the less badly damaged housings using super glue.

This one wasn't repairable!

A few other points to consider...The scrivets holding the wheel arch liners in place are likely to, ahem, fail, when being removed. The bolts and nuts holding the Hydragas brackets in place have the same "chocolate" heads as the other fasteners on the car. As long as you have things apart you will probably want to replace the shocks (I put in Gaz Adjustables)along with their mounting bolts. As long as you are removing the shocks you may want to install braided brake lines as they mount along with the shocks at the front. Don't forget...You WILL need a way to pump up your Hydragas suspension when you are finished, so if you don't have your own pump you will want to check with your local British car repair shop to see if they have one you can rent/borrow. A good fluid mix is 50% Glycol Antifreeze/ 50% methyl alcohol.(which is commonly used in marine stoves).
I found that my grease gun type hydro pump (from E-Bay.uk) worked very well, if slowly.
So there...If you decide to do this job take the time to do a recce first and see if you have rusty nuts, suspension arms and try to lay on the parts that you may need. With some of the inexpensive bits like bolts and scrivets it's worthwhile getting replacements anyway. With pricier bits like knuckles have a plan to get them to you quickly, like I did with Rimmers/UPS (3 days).
Like most jobs if it goes well it's easy.

I get to do mine again somtime this summer as I just bought a set of(much nicer than my rusty ones) spheres from a friend in the UK, and was able to find a set of NOS Hydro brackets on e-bay.uk. That will give me an excuse to do some subframe painting as well.

If your suspension has this sort of corrosion expect challenges!
(Surprisingly the threaded portion of the bolts was luckily not badly corroded.

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Modern MGs aren't just Transportation, They're a Hobby!



Edited 3 time(s). Last edit at 04/16/2012 07:06PM by Rich in Vancouver.

Great write up Rich!!

If I lowered my car it would get lost in a pothole!!

I won't send you a picture of MY rusty displacer!!!

Cheers!!



Edited 1 time(s). Last edit at 04/16/2012 08:45PM by terreneuve.

The glare off your perfectly preserved displacers would probably blind me!
The nice thing about using the lowering pins is they just lower your car by 30mm
which is enough to make it look right without making it too low.
I'll try to get a couple of pics of my car tomorrow.

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Modern MGs aren't just Transportation, They're a Hobby!

Very interesting Rich, thanks for the writeup.

So, can you give a bit more details around draining and pumping up the suspension? How did you do and control the draining of the system? I understand that you don't want to let air in or else you need(?) to get the air out. How well did your pump work aside from the speed?

Interesting that you mention about renting/borrowing a pump from "your local LBC shop". I emailed a half dozen people/shops in SW Ontario area and not one positive response yet to the question where to get a pump-up, or who has a pump. The only one that I personally know of is one owned by Steve, who works for Christian Hollum Imports. I guess an eight hour drive to Montreal for a pump-up might be a good idea

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Canadian Modern MG Rover Car Club - www.cmmgrcc.org

Geez Rich, after looking at the rust on those displacers I don't think I will ever complain about working on our MGF's again!

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1967 MGB Roadster
1969 MGC GT

Mark,

If you can get to me I have a pump and I won't charge you for it either!!!

John

Eric, I made a mistake buying a UK car rather than waiting for the right Japanese car to come along.
On the other hand I have got my car to the point where it runs great, handles great and is a reliable daily driver.
I can take my time cleaning up the rusty suspension, and eventually get the body licked into shape.
(mostly minor dings with some damage to the jacking points.)

The only problem with having to drive your car 4 hours to get to a Hydrolastic pump is that it really shouldn't be driven
at all when it is depressurised. My little pump cost me around 50 quid plus postage. It doesn't have a vacuum function and
this bothered me particularly this time as I had the displacers off the car. This didn't seem to cause any problems when
pumping up the car. It took the proper amount of fluid and hasn't settled at all since the pump-up. I don't know if the air is still in there, just compressed or if it was able to escape through the pump when the valve was open.
When I first got my car it was very low and I pumped it up the same way. I didn't have any settling for a year.

Mark, Draining and filling the system is surprisingly straightforward. The valves are behind the plastic cover in the front compartment. As the fluid is under 400psi pressure you have to catch it when you open the valve. You just take a plastic container and punch 2 opposing holes into it. Push one hole over the valve, and stich a screwdriver through the opposite hole to depress the valve and release the fluid. It only takes a few seconds and the suspension drops dramatically. (Make sure the car is up on stands before you do this or you will never get a jack under it!) Once the system is depressurised the fitting on the displacers can simply be unscrewed to remove them. Pumping it back up is also very simple, you just screw the fitting on the pump onto the valve and pump until the suspension reaches the correct height and pressure. The guage on the cheap pumps isn't accurate but it does give an indication of the psi. The main thing is the suspension height. I was able to get my car so the suspenion is within 5mm side to side with only a couple of adjustments (bleeding fluid if too high, more pumping if too low) It's really quite easy.

Mark, if you or any of the Canadian forum members want to borrow my pump there's no problem. The Post Office is just down the street.

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Modern MGs aren't just Transportation, They're a Hobby!

Here's a good thread on .org about changimg didplacers and fitting lowering pins.
Lowering the MGF

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Modern MGs aren't just Transportation, They're a Hobby!