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MG MGB Technical - Alternatie Shocks

At the risk of opening a can or worms, here goes. I have a 67B that I going to install new rear springs. I am also considering converting to tube shocks. The standard conversion by Moss uses Monroe shocks and is very stiff. The MGB Experience page has a link to using the rear shocks from a Dodge Colt. Ok, similar weight vehicle but still something does not look quite right. British Automotive has a tech article on shocks and they say that the rear suspension travel is 5 1/2 to 6 inches. KYB has a neat download program that lists all of their shocks and you can search by car or by length of shock. The Dodge Colt shock is 16.18 extended, 10.79 compressed with a stroke of 5.39 inches. That is more than the maximum travel of the suspension with rebound straps. Using the KYB program I found that the VW type 3 shock was 16.46 extended, 10.35 compressed with a stroke of 6.10 inches. The mounts on the VW shock are the same as the Dodge Colt and the weight of the car is similar to the MGB. My question is has anyone tried the VW shock as a replacement for the rear lever shock?
Jim Lema

Jim,
I haven't tried KYBs on my GT, but I have used them on two VW Type 1 sedans over the years, and I loved them. In the right combination they gave a firm, controlled ride, but were not harsh. I used GR-2(low-pressure) in front and Gas-A-Just (high pressure) in the rear. I tried the high-pressure version on the front of one of the VWs, and they were so hard, it was like having no suspension movement at all over bumps. If you go for the KYBs for your B, I would strongly recommend the low-pressure version.

~Jerry
Jerry Causey

There's an awful lot about this in the archives, have a look.

I had Spax all round on my roadster, much too hard and choppy at the rear even on the softest setting. I have just newly reverted to lever arms (uprated) on the rear and left the Spax teles on the front. The car is now more comfortable, still hard(ish) at the rear but handling very satisfactorily. In addition it's a heck of a lot cheaper than telescopics.
Iain MacKintosh

Unless you are going for wholesale suspension improvements simply fitting tubulars at the rear is a waste of time and money. A rear ARB and an uprated front one is a different kettle of fish.
Paul Hunt

What started this whole thing for me was the PO had put new springs on the rear four years ago. Finding that they were two inches higher than the front he put longer rebound straps on the rear. Thus lever shocks were allowed to travel near or past the limit of their travel and now both are shot along with the bolt on the top of the down links. If I stay with lever shocks I will need two new shocks, two down links, and new rebound straps. The rebound straps are being replaced when I replace the rear springs with the correct springs. None of this would have happen if he had sent the springs back instead of trying to make them work. From center of wheel to chrome strip is 13 1/4 inches on the front and 15 1/4 on the rear. Thats what started me thinking of a change.
Jim Lema

Jim,

Tubes are a better type of damper for heat dissipation, the downside is the engineering compromise being not at 90deg, but not much is perfect, and gas filled being too hard. If changing to parabolic then tubes are part of package. Koni's are soft enough but are off car adjustable, but then how often on a road car do you adjust dampers.

Paul
Paul

To thoroughly confuse the issue more, I have used Monroe tube shocks on the rear of my GT, installed in the Moss manner, but of a different specification. The ones I used were Monroe Sensamatic Gas shocks, # 5893 ST. They worked just fine without being too stiff, but frankly, were really no significant improvement over the stock levers.

But if tubes are what you want, I would check the archives on this topic, and possibly consider the shocks I used ~ they are the right lengths, extended and contracted, so as to not hit the stops in either direction and tear up the shocks internally, and are at the least no stiffer or worse than OE lever shocks. Most folks have discovered that tube shocks' place is for competition use rather than mixed or street-only usage. FWIW.
Bob Muenchausen

Found this in the archives.
These shocks are still listed by Monroe, has anyone else used them to replace the original Spax in the Moss kit. The nearside Spax on my car has failed and the car just bounces that side when you push it down. I know they went on in 1987, but the car has only run about 25K miles since then so as well as being a poor choice for the damping they offered they havent given much service on a mileage basis,
Fitting the Monroes seems a reasonable quick fix, I'm going back the the banjo axle when I can so I want a quick fix for now. These look like the just bolt on.
Stan Best

http://catalog.monroe.com/catalogPart/displayPartDetails.do?partKey=216556&catalogKey=313&partNumber=5893&catalogCode=monroe&loadStatus=ACTIVE&locale=en&methodName=displayPartDetails
This link should take you to the spec.
Stan Best

There IS a tubular rear shock absorber available specifically calibrated for application in an MGB. I've fitted these to my car a few years ago and have been absolutely delighted with the improvement. The rear suspension is palpably more supple, skips about on bumps less, and paradoxically rolls less at the rear too. The only downsides in your situation would be the cost of overseas postage and the current high value of the Australian dollar.
These shocks are hydraulic, not gas shocks, as it was found during development that gas shocks gave too stiff a ride in a car as light in the rear as an MGB
http://www.nepeanclassic.com.au/pages/rear_telescopic.php
T Aczel

Jim,

I have Gabriel Classic Shocks fitted - catalog number 82001 (rear only). Car is a 69 roadster. These are for the Colt and VW (beetle, fastback, squareback and super)as you mentioned.

They work very well, good control and response to the road surface. My driving is day use and spirited touring on B roads - no sport driving. The Gabriel website has a wealth of information on their shocks. Fitting info, how to measure ext/coll lengths, tube diameter, eye ring verses bush fitting with measurement specs et al. Worth a look.

I emphasise that I took careful measurements of my car prior to selecting these shocks. My fitting brackets came from a local supplier. I know the system Terry Aczel referenced but the mounting brackets are different, so too are the Moss type I have seen. All of which means that the bracket mounting point may differ somewhat from kit to kit.

I'd recommend checking measurements of travel on your own car as a basis for selecting. Also watch out for the clearance of shock diameter, it gets crowded up in there.

One last point, make sure your bottom mounting plate holes are at a true vertical to the axle when mounted. Any angle stress put on the shock tube there will distort the travel of the shock itself.

Regards
Roger
Roger T

I have ordered a pair of Monroes, I'm not looking for a development program now I just want 4 working corners for the Kop Hill Climb in Sept.
If they work well I might try moving the top mounting so they are vertical and maybe in a bit at the top to approximate the curve described by the axle when one side hitsa bump, or hollow. That can wait until the banjo axle goes back on. If these Monroes are still too bumpy then these units mentioned above may be useful. From other posts on here it seems the parabolic rear springs have problems, and the fibreglass ones are history.
Stan Best

Had similar problems with Spax, having replaced them once already at great expense compared to exchange lever-arm, which is why I have gone back to lever-arm.
PaulH Solihull

Maybe I was unkind to the Spax above, they dont have much chance at an angle. Regardless I'm too old now to put up with that ride.
When I found the old lever arms they were in a bad way so no wonder the car handled better with the tubular shock conversion, I was comparing new with worn out. If the Monroes fit and work OK they are well priced so I may stick with them.
Stan Best

Before ordering I downloaded the data sheet for the Monroe 5893. They may be usable but dont bolt onto the early spax "Van Shock" mounting points.
I took one of the Spax off and measured eye centre to eye centre open and closed and overall open. I also measured the dia of the mounting pins and their length.All in inches as I think they were designed in imperial

Closed 11.3 open 17.5 (18.5 O/A). So I make that over 6" stroke

Dia 5/8 length 1 3/8

The monroe is much shorter shorter stroke and the top sleeve is 1/2" id.
Stan Best

There you go, its a split bush Spax.


Stan Best

After having KYB's for a long time, I am so much happier with my stock dampers back on the car. World Wide does a great job rebuilding them.
Matt
M. H. Dabney

Lever arms back on and I wonder why I bothered with the Spax. As Paul H has observed, its dangerous to compare the old worn lever arms with new telescopic. Thanks to all for your inputs. The car is still on GT springs all round plus 10% uprated front shocks and a 3/4" ARB. It rides and handles pretty well.
Stan Best

This thread was discussed between 15/04/2004 and 16/09/2011

MG MGB Technical index

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