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 MGF Technical - Can you release Hydrogas fluid?

Hi all

Quick question im going to get my suspension pumped up a bit. I'm going to get it pumped a little over spec, but I want to let some of the fluid out myself.

Question 1:
Can fluid be let out DIY style without pump.

Question 2:
Does low suspension height increase ride harshness/skuttle shake?

Cheers

Russ (with new polybushes fitted to shockers)
Russ Fitz

The hydragas valves are quite similar to tyre valves, so yes, its pretty simple to let some out.

Just make sure the car has stood for a good couple of hours, then roll it back and forwards a couple of feet and bounce each corner before and between making adjustments so as to let the fluid "even out".

Low pressure / low suspension ought to make for a slightly SOFTER ride and less harsh, I would have thought...

If you let too much out, Stokenchurch Service station (I think you're "local") have a pump and let me "play" to get mine set to the level I wanted (I think it was even on a Saturday morning!). I think £10 was the charge... You're probably looking for about 400-425psi pressure in the system (which the pumps do show, though the gauge isn't the "accurate" way of setting it up...

Good luck,

Neil.
Neil

Neil

Cheers

Re: Local
Yes High Wycombe, been waving like a nutter at everyone in F's so you had better been waving back :-)

Re: Stokenchurch Service station
Just where about is that? (yeah I know its in Stokenchurch).

Re: Ride Quality
Yeah I'm guessing that with less pressure/lower ride height would mean softer ride, however I seem to be enjoying more skuttle shake and a slightly harsh ride at the front.

Thanks for your help Neil

Cheers

Russ
Russ Fitz

My car was running on low hydrogas pressure for a while - the car was visibly low, it actualy makes bumps harsher as the car moves about more freely to you get a low of bobing about over speed bumps, also remember when you change the ride height you should also get you alignment re-done as the ride heigt effects this, changing height without doing this would result in exessive tyre wear. a much better way is to use lowering nukles to have the car lower with the correct hydrogas pressure.
Kingsley

<<Yeah I'm guessing that with less pressure/lower ride height would mean softer ride>>

This certainly wasn't the case with mine.

depressurized hydragas, lead to harsh bumpy ride, that felt and handled really badly.

Techspeed, dampeners and lowering knuckles, hydragas at standard 400 PSI, on 17" rims...

...and the car is very low, but also very comfortable.
Nice ride, excellent handling.

I would suggest if you do deflate the hydragas, don't go too far. Stay within the recommended guidlines or do it properly and get the knuckles.

Think Rob Bell had a comprehensive guide to depressurizing the hydragas..a method of thirds..

paul weatherill

Everyone

Thanks guys.

Your responses encourage me into thinking that I may have found the reason for the change in ride quality. I'm running at 340mm ie 28mm below mid range spec.

Thanks again

Russ
Russ Fitz

<<Yeah I'm guessing that with less pressure/lower ride height would mean softer ride>>

Just the opposite. Les fluid is less spring length, is lower spring rate, means harder spring.

If you release fluid then keep in your mind that the front tracking will tend to more toe Out at the front, by getting the suspension lower.

For example, if the car got adjusted at the current ride hight to lets say Toe Out (-5 minutes) at each side, resulting in total toe angle -10 minutes, then another adding of -5 minutes by lowering the car for 10mm will result already in inner tyre wear.

This is no problem if the front suspension is for example at Toe Zero or Toe In.

Hope this makes sense.

Dieter
Dieter Koennecke

Dieter

Many thanks. Also many thanks for all the information you have on your web site. I has been very usefull as I do all my own maintainance including HGF.

I'm getting the suspension pumped up tomorrow for £20 and will let it down to 368mm myself. Will get the tracking done early next week.

What is the current thinking for the best tracking settings for a car with standard bush setup?

Cheers

Russ
Russ Fitz

>What is the current thinking for the best tracking settings for a car with standard bush setup?

Roooob !?!?! :)

IMO !! not approved and my opinion only !
:
Toe In (+5 minutes) all around for each wheel. Is also enough secure space if the suspension drops.
Dieter Koennecke

Stokenchurch Service station: Go from Wycombe to Stokenchurch on the A40. Just after New Road turns off to the left its on your left (actually on the A40).

I've been happiest with the tracking stetting that Mel of Meltech did to my car (OK, I'm running on the BBS setting of 5' in at both ends, and have polybushes fitted....). He did it "in the racing way" with string and a ruler (from what he said!) in about an hour of his time (=£30 something - no VAT). I'd had it done by Rover garages and tyre places a couple of times before, and still wasn't happy...

You pass Mel's on your left just before the turning to Radnage before Stokenchurch (if you do it, you'll see what I mean!). I trust him with my car - he used to look after a MGF cup car, so knows them quite well, and is a "real racing mechanic". You could pop in and talk as you went past quite easily, he's usually about (unless off at a circuit!)

You could even pop in for a coffee while they work, if you like (I can just about see both Mels and the service station from where I'm sitting!)

Cheers,

Neil.
Neil

Neil

Cheers for the info.

I actually shot out to Stokenchurch at lunchtime and found Stokenchurch Service Station. I'm thinking of taking the car to Merit Tyres in hazelmere for the setting of the tracking.

Cheers

Russ
Russ Fitz

Just to agree what everybody else has said above regarding the ride quality. I noticed a very marked increase in ride quality when I lowered my car properly with lowering knuckles which allow you to use the correct hydragas prssure. Previously the car was riding quite low and I didn't notice how much the ride had deteriorated as the drop was gradual over a long period of time.

If you intend to let fluid out yourself bear in mind that you have to take it easy. It takes a while for the height to settle after removing some fluid. ie don't expect to release some fluid and see the true effect immediately. Rather, let out a bit of fluid, drive around for about ten miles and let the car rest for a while. Better wait for a day and if you are still not happy with the height release some more fluid and so on. Being patient will save you having to go to the garage for another pump up if you release too much fluid at once.

Spyros
Spyros Papageorghiou

Be careful the fluid is at 400psi!
Ian Walker

The guys all make good points regarding hydragas pressure and ride: the spring and damper rates reduce. Result, along with the shorter 'spring length' as Dieter eloquently describes it, means that the car frequently bottoms out on the bump stops = harsh ride. I went for the Tech-speed option - knuckles + dampers, although even lowering knuckles alone (100 quid, Brown and Gammons et al) will be a far better option than a low hydragas pressure alone.

As Paul mentioned, there's some directions on how to lower the car yourself. Reasonably straightforward. 340 mm is as low as I'd personally take it (believe me, I've tried it to 320 mm, and I wasn't too happy with the result :o( )

http://www.mgf.ultimatemg.com/howto_lower.htm

As Dieter says, always get the tracking re-checked after lowering the suspension. The rear of the car needs some degree of stabilising toe-in. Use either the standard 0 deg 10 min toe-in or for a more progressive rear end (more prone to step out, but tells you about it) 0 deg 5 min toe-in. Front, go for parallel or even some toe-in as this result in the steering having a much more eager to turn in. It also makes the front end more stable and improves steering feel.

What I always go for (and never suffer from inner edge tyre wear!) is the setting Dieter mentioned: 0 deg 5 min toe - IN all round.

Hope that helps! :o)
Rob Bell

>Roooob !?!?!
that's it, thank you !
Dieter Koennecke

Thanks All!

Rob:
Will those tracking settings be OK for a 97mpi with standard suspension bushes etc?

All:

Just the info I needed. Some a little too late though...... Pumped the suspension up to freelander mode and then let some out back at home. Yeap! you guessed it ........ settled down even further over the following two days. Oh well back to get it pumped up again ....... you live and learn.

Cheers all

Russ
Russ Fitz

Hi Russ,

Learning the vageries of Hydragas suspension are certainly an 'experience' thing. I reckon that anyone who has attempted this themselves will have had problems with the first attempt! LOL I found the method I finally arrived at worked well for me :o)

Regarding the tracking settings, yes, they'll work for your car. Although, without the rear tie-control arm bush spacer (http://www.mgf.ultimatemg.com/upgrading_bushes.htm), I'd advise the STANDARD track settings at the rear - namely 0 deg 10 minutes toe- IN because of the standard set-up's bump-steer characteristics.
Rob Bell

This thread was discussed between 12/04/2002 and 15/04/2002

MG MGF Technical index

This thread is from the archives. Join the live MG MGF Technical BBS now