246
Rear
shock absorbers for MGBV8s Gordon Hesketh-Jones
(Harvest Gold 1904) from Cornwall has just clocked 200,000 miles in his MGBGTV8
so clearly uses his V8 a great deal. This note sets out his research into rear
shockers on his V8 and his findings which will prove interesting for V8 enthusiasts.
(Feb 02) The lever arm shock absorbers fitted
to the rear of the MGBGTV8 were never incredibly efficient even when new and did
not have a particularly long life. I feel they were a poor design from the beginning.
You can buy replacements from places like MGB Hive for around £11.50 on
an exchange basis plus the cost of return carriage, but you have to remember that
these are not "remanufactured or new" units, but are simply old units,
possibly 25 years old, which have been given new seals, topped up with oil and
given a lick of paint. A dealer told me that he used to buy in these "repaired"
units for £4.50 plus VAT, so with a typical labour charge-out rate of around
£16.00 an hour, you can see how much time on average was devoted to "servicing
and repairing" the shock absorbers! It seems quite rare for an MGBV8 on standard
rear shock absorbers, doing an average annual mileage, to go through two consecutive
MOTs without at least one shock absorber failure. So I feel considering replacement
with telescopic units makes economic sense and gives a better ride as well.
In the early 1990s I was covering 20,000 miles or more a year in my V8 so
had more than one failure of the old lever arm units every year. I quickly changed
to Spax oil filled telescopic units which suited the five-leaf springs and lasted
150,000 miles without a problem, but one snag with these older Spax designs was
that they were a bit long for the V8 so their mounting brackets extended down
well below the springs which reduced ground clearance. Nowadays Spax,
Koni and Bilstein all make gas-filled telescopic units which are even more efficient.
All three are basically of the same length and fitting involves taking off the
existing lower mounting plates, swapping them from side to side and inverting
them so that the mounting flange points down rather than up to allow for the longer
length of the telescopic units. The Koni and Spax units are priced at around £100
for the pair including the fitting kit but the Bilstein units cost around £156
as they are a more complex design. Both the Koni and Spax units are adjustable,
but the Spax are far easier to adjust as there is a 28 position adjustment screw
at the base of the unit which can be easily reached, whereas I find adjusting
the Koni involves removing the unit from the car. The Bilstein is not adjustable,
basically because its design is said to have been pre-set to match each individual
type of car. In all cases you have to specify when ordering that you require the
shock absorbers for use on an MGBV8, due to the different length caused by the
depth of our five-leaf rear springs. Having covered some 200,000 miles
in my MGBGTV8 over the last 15 years, here are my comments on the ride comfort
provided by the different makes of rear shock absorbers when fitted to my V8,
bearing in mind I have fitted the full Ron Hopkinson handling kit and front coil-over-Bilstein
suspension. Standard
lever arm - I would give them full marks for comfort, but only 2 out of 10
for overall performance due to their relatively poor reliability and need for
early replacement. Konis
- I find they are totally unsuited to the characteristics of our five-leaf rear
springs even when set on their softest setting and they gave a teeth-chattering
ride even on smooth motorways. I discarded them after less than 1,000 miles of
use. Marks out of 10 - nil! Bilstein
- In theory these should give a good ride as they match the Bilsteins on the front
of my V8, but the ride is choppy and harsh. Marks out of 10 I feel would |
be 4.
Spax - As
I had such excellent results from an earlier set of oil-filled Spax telescopics,
I now plan to fit the gas-filled variety and will report further when I have had
them in service for a while. We await Gordon's report on his gas-filled
Spax units and the comments of other members on their experiences with shock absorbers
on the MGBV8. (Editor: Gordon subsequently reported his in service experience
with the Spax units - see the second footnote below). Footnote
from Roger Parker. Gordon's experience is long and extremely useful. However
where he is about to tread I have already trodden so my comments may be useful.
My own experience followed a similar path to that of Gordon with the performance
of the lever arms not being dissimilar. I went to a Spax oil-filled conversion
a couple of decades ago and found these gave superb service and performance. These
only became subject to a change when corrosion on the upper sleeve cover then
exposed the piston to the weather. I naturally changed these for another pair
of Spax, but these were the new gas-filled Spax which had replaced the previous
spec. Expecting
similar performance, I was a little surprised to find that immediately after fitting
these I believed I had replaced the dampers with a solid steel bar, such was the
solidity of the rear! Even winding to the minimum setting I found the ride at
best poor and the handling only very good on smooth roads. Bumps in bends would
see the rear bouncing out of line without the need for power inputs. The disappointment
did not improve with time and miles covered and by 10,000 miles use I replaced
them with Konis which have shown a much improved standard of control and ride.
I would therefore
want to confirm that the gas-filled Spax of the late 1980s have been consistently
softened in their ride compared with the product offered in 2002, otherwise I
fear that Gordon's experience with previous Konis will be the same as with the
gas-filled Spax. Editor:
The question of telescopic shock absorbers as suitable replacements for the original
lever arms was raised at the first Don Hayter Talk put on by the V8 Register
at Sandford-on-Thames on Saturday 23rd February 2002. The talk on the concept,
development and production of the MGBGTV8 by Don Hayter was a magical afternoon
with many insights into the issues and concerns that faced the team designing
and developing the V8 powered MGBGT. Geoff Allen, the V8 Historian from the start
of the V8 Register in 1978 and a member of the Rectifications Department at the
MG Factory for over 27 years, provided his recollections of the V8 during Don's
talk. The question and answer session that followed was fascinating.
A twenty three page transcript
of Don's talk, Geoff's recollections and the question and answer session that
followed, with photos, has been produced by Victor Smith. Copies of the transcript
in Word and PDF formats are available on a CD for £7.50 (reduced price of
£5.00 to members of the V8 Register). All cheques payable to "V8 Register
- MG Car Club" please, mailed with your order to Victor Smith - click the
"contacts" button for details of the mailing address. Follow
up report from Gordon Hesketh-Jones (May 02) Having now completed a 2,000
mile trip to John o' Groats for the le Jog event and also a 6,000 mile trip to
Sicily for another rally, I can report that the Spax gas filled shock absorbers,
set to the softest setting (28) give excellent results in terms of ride and handling.
Assuming that they will last as long as the oil-filled versions, I would mark
them 10 out of 10. Does anyone want a slightly used set of Bilsteins!
Copyright reserved
by the V8 Register of the MG Car Club, PO Box 251, Abingdon-on-Thames, Oxfordshire
OX14 1FF |