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MG MGB Technical - rear shock oem or convert to tube?

I have a 67 B and have always replaced the orginal shocks when they were worn; usually every 5 years or so. Well its time again and was curious if others had tried the conversion kits available thru Moss or others to a standard tube style shock.I bought a set on ebay (quite cheap I may add) and I suspect the design of the bracket mount is not very robust. Has anyone had any experience with the Monroe setup from Moss? It call for the ubolt brackets shock mounts to be switched..doesnt look like a lot of travel either.
chuck

If you're looking at replacing your lever shocks, and still have the old ones, I'd get a set of rebuilts from Worldwide. I think they run around $60 each with exchange of your old ones. I've got them on the front of my car, and they are great. I've had the tubes on the rear, but I don't think you gain anything with them. Plus when it comes time to replace them, new tube shocks (Munroe Sensitracs) may actually cost more than the rebuilt levers. Having spent the money, if I was to do it all over again, I'd just replace the existing levers with a properly rebuilt pair from Worldwide. You can get the stiffer valved ones if you so desire. The Moss kit is notorious for being overly stiff, since the shocks that came with the kit are for a full sized van.
SteveO

Chuck-
I have to agree with Steve. Unless you're going racing on a track there's no advantage to converting from the OE Armstrong lever arm dampers to a set of tubular shock absorbers. If you're only getting five years service out of your rebuilds, then they're very poorly done. Like Steve I use the rebuilds from World Wide Auto Parts and I'm convinced that they're actually better than the new ones presently being offered.
Steve S.

Hmm. I am tempted to try the DIY conversions described at the MGB Experience and elsewhere, but using a non-gas pressurized shock of the under-$15-variety, as a cheap (say, under $40 total) experiment. Anyone else go this route?
Andrew Blackley

I have some VW rear shocks with a tube conversion kit that seems to work well
Pat
patrick bailey

Chuck,
I've done the conversion on my 69 MK11. Robust system sold through the local MG (Rover) firm.
Inverting the plates required re-positioning the line of the exhaust as the pipe was rubbing on the lower shock mounting bolt.
Frankly I'm thinking of changing back. There was an improvement when done as the lever arm units were pretty tired. Not sure that properly rebuilt original units may not give a better ride over the range of travel of the rear end. Thats the main motivation for changing back - I want to see the result.
Regards
Roger
Roger

I would have to agree with the general consenus here that the OE lever shocks are probably the best choice for the street. Steve S. has modified his suspension perhaps more than most as I understand it, and if he is still using his Lever shocks in conjuction with his mods, then I would say that is a good recommendation for keeping a good set on your car.

I like to experiment with options and alternatives, and did try a tube shock conversion some years ago, going to a set of Monroe SensaTrak shocks in the more or less usual rear configuration. Although they seem to work very well, in driving friends cars with good lever shocks, I cannot discern any real or significant difference or benefit for ordinary street use. When this set of SensaTraks wear out, I will be replacing them with World Wide's rebuilts!

World Wide can be contacted at:
http://www.mailbag.com/users/nosimport/ Ask for their explanation of the differences in their rebuilding processes from others practices.

Bob Muenchausen

BTW, just for everyone's interest, here is an excerpt from an email sent a couple years ago to me by the fellow who runs World Wide about how they go about rebuilding their shocks.

"below is some info I sent to the Blue Grass Healey Club on

"How World Wide Approaches Rebuilding Lever Shocks...

"First. What fails in a lever shock? Almost all of the (non-traumatic) failures result from lack of oil in the shock. The manuals always recommend Checking or topping-up your shox in various intervals 3000 miles or so. Why? Because they leak!.. what a surprise! They don't leak just because they are British, they leak by design (now there's a bumper sticker).

"Speaking here of the rear shox... the shaft that protrudes from the body of the shock is rotating in the body without a bearing. To ensure sufficient lubrication there is often a channel or groove in the shaft bore. At the outside there is a rubber packing retained by a thin metal washer. A packing needs some lubrication to work at all and the weeping of oil acts as a deterrent to dirt getting in. Dirt getting in will score the shaft at the seal area hastening the demise of the packing and wearing the bearing surface in the body.
The solution that all of us rebuilders use is to machine the body and install a bearing. We use Delrin, others use bronze. Bronze requires oil, Delrin doesn't. We also machine the body for a rotary oil seal (others don't) (in fact we use a double lip seal with dust excluder). One guy does use a rotary single lip seal and the others use several rubber washers held in place with a steel washer or two.

"To solve the pitted and scored shaft problem, others sand or grind the shaft down.(you don't need to be precise with rubber washers) We have manufactured for us, to our specs, stainless steel sleeves that allows us to have a 3 micron finish and consistent diameter and concentricity of the shaft. After many years, we have found this to be very reliable. Our shox don't leak.

"The process... step by step. Receive grimy old shock, tumble clean in a deburring/tumble cleaner. Glass bead blast entire shock. Disassemble.
Tumble and hot wash internals. Bead blast the rest of the arm. Machine for
the bearing and for the seal. Wash again. Press in bearing and seal. Press
on sleeve. Inspect and repair/replace as necessary the pistons and the
valving. Reassemble components using all new hardware of proper thread and
style. Fill with oil and bleed. Compare valving with NOS shock, adjust if necessary. Wash AGAIN. Paint 2 coats primer and 3 coats high heat black enamel. Date code and ship.

"There you have it.
Peter Caldwell president."
Bob Muenchausen

I got bored yesterday at work and decided to be a test monkey and on the way home stopped and got everything necessary to put tube shocks on the car. Nothing difficult about the job at all, just remember to release the tension from the rear leaf springs BEFORE unbolting the bottom spring bracket! (OUCH!) Other then that, no problems, nothing to worry about. After 1 test drive the car was DEFINITELY more stiff in the rear end then it had been. It wasn't stiff to the point of wheels letting go on curves, or the rear end jumping around, but it was certainly more firm then it had been.

When I got home I looked at my old levers and did a test: I held the shock with one hand, and moved the lever with the other, when I moved the lever, it didn't "spring" back to it's original position, it just stayed wherever I moved it. That can't be good!

My conclusion: I spent $45.00 and got rear shocks that feel what I suspect lever shocks in great condition should feel like. Lever shocks are about 70 bucks each....

Anyone have suggestions for the $95.00 I just saved?

Justin
Justin

Justin-
Regardless of design, be they tubular or lever arm, there's no reason for a damper to return to its original position as its sole function is to control the rate of displacement of the fluid inside. I hate to tell you this after you've spent all that money, but if you wanted stiffer damping, you could've gone down to your friendly local machine shop and bought some shims for a few dollars and simply shimmed the valve springs in your dampers. Live and learn.
Steve S.

Justin: What shocks did you buy?
Andrew Blackley

I am not going to profess to be a suspension guru. Frankly, I don't do suspension work unless something breaks or is making a god awful noise that I KNOW can't be right. What I do know is when I go over rail road tracks, potholes, or ruts in the pavement, I not only feel the initial jolt, but I feel atleast 2 after shocks from the car bouncing around afterwards. That I know isn't a good thing. In areas of multiple pot holes, the suspension bottoms out and the ride is absolutely horrific. For my $45 dollar investment, I no longer have the 2 after shocks from each bump I hit. Yes I still feel the bumps, no the car isn't riding on air, and my life hasn't been forever changed, *but* the suspension feels considerably better. There was virtually no resistance when I moved the lever with one hand.

I dunno, maybe I'm a complete idiot, I have no taste in suspension, and I should sell the car I spent 3 years building, but feeling a single bump the one time you hit it as opposed to having it reverberate through your car 3 times HAS to be an improvement. So you're right, live and learn. And I learned how to improve a worn out suspension system for considerably less then one would normally pay.

The shocks were Gabriel model 81108 which cross referenced to gabriel model c8091. I paid $15.00 each from car quest. (Car quest part number was 47334)

Justin
Justin

Might as well be happy with it. Sounds like your old shocks had no fluid in them. Maybe they were worn out, maybe not. It's surprising what topping them off can do. Stiffness is easily varied by using different weights of oil or by changing the valving. I've run everything from 50 wt shock oil to ATF. I've also run tube shocks on the rear and they work but are a lot less versatile. Plus they commonly stick down too far. What I finally settled on is ATF and competition valves. This is on a highly tuned street warrior. YMMV.
Jim Blackwood

Justin,

if you are used to dealing with gas charged shocks, such as the SensaTraks I mentioned, then indeed, they will try to return to their "static" state, which is to extend the rod in a tube shock. You could easily then think that the Armstrong lever shocks should do the same. But as Steve says, they won't. Not even if properly filled with fluid. They simply are not pressurized with gas as the more common (today) gas shocks are and so, have no tendency to expand against the initial impact direction.

One of the biggest problems with assessing shock performance is that most of us don't have good OEM shocks to compare our new alternative shocks to, so anything that actually functions properly will definitely seem like an improvement. Why shouldn't it? However, as I stated above, in comparing my SensaTraks to "known good" OEM lever shocks on a similar MGB in good repair, the actual difference becomes more apparent, and at least in my case, not terribly significant in any aspect of handling to recommend them over the OE levers.

If you are like me, now that you have made the switch and invested your money, you perhaps can live with your choice until you either decide to revert to lever shocks or go on to other pursuits with your B for which the Tube shocks do have some real advantages. We all pays our money and takes our pick and learn in the meantime. ;-) Have fun with your B, that is the main thing.



Bob Muenchausen

I definitely think 25 years of service have gotten the best of my armstrong levers. I did the conversion for 2 reasons: 1) I was bored at work 2) It only cost $45.00

The vast majority of people have concluded that tube shocks are about equal to lever shocks in great working order. I'd say that's true but I've never had lever shocks in great working order, so I can't comment. But man, $45.00 for a feel that supposedly is equivalent to $140.00? How can you go wrong?

Justin.

p.s. I hadn't noticed the shocks sticking down abnormally far (half an inch further then stock?)
Justin

Justin,
That spare $95.00 in your pocket should almost be enough to pay for the gas to get you down to Texas for MG2002. I sure love spending other people's money....
SteveO

Justin-
Don't throw those worn lever arm dampers away. Some owners will gladly buy them from you so that they can keep driving while the ones that they got from you are sent to a rebuilder. They can also avoid paying the core charges that they would otherwise be faced with. On the other hand, by the time that your Gabriel tube shocks wear out you'll be a fairly proficient MG mechanic and might want to have them rebuilt so that you can experiment with shimming to acheive different damping rates.
Steve S.

Could someone explain how to shim the OEM shocks for different dampening.
Thanks,
Doug
Doug Brooke

Doug-
The valve mechanism has a small spring on it that has its preload increased by adjusting its preload with a nut. This small spring will control the damping rate on rebound. The greater the preloading of the spring, the higher the damping rate on rebound will be. To increase damping on the compression stroke, the larger spring must be compressed by inserting springs between the body of the damper and the spring. This will increase the preload of the larger spring and thus result in an increase of the damping rate. Some dampers already have shims in them but more can be added. Remember to write down the original specifications of the damper valve mechanism (size and number of shims and how many turns on the nut) prior to altering it so that you can reset it to an established baseline should your adjustments produce unsatisfactory results. Most drivers find that increasing the damping rate of the front dampers by 25% gives an impressive improvement in handling. Be aware that petroleum-based fluids are not compatible with the natural rubber seals. Armstrong still makes its own specially formulated fluid available. It can be obtained through Brit Tek at their website http://www.brittek.com/ If necessary, 20W mineral oil may be substituted for this fluid during warm-weather use.
Steve S.

Justin:
Now that you've joined the fallen, and will probably rot in Hell anyway, let that $95 be the down payment on a set of Doug Jackson's plastic, single-leaf, rear springs and a Panhard rod. The faster response time of the tube shocks will be a definite asset.

And THEN, there's poly bushings, bigger sway bars, Kevlar V-8 brake pads, slotted brake rotors, taller, wider alloy wheels, 60 series tires, and, of course, you'll need MORE POWER...

Regards,
Jerry
Jerry Causey

Jerry-
Amen.
Steve S.

The Armstrong shock absorbers are the best because they act directly above the axle at an angle of 90 degrees. The Monroe, Spax etc work at an angle of 45 degrees and are not as efficeient. The problem is that the reconditioned Armstrong shock absorbers have been reconditioned that many times there is too much play in them. The best alternative is to buy brand new Armstrongs from MOSS.
peter bramble

This thread was discussed between 08/05/2002 and 11/05/2002

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