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MG Midget and Sprite Technical - New dampers, and fun with pinch bolts

During a recent tech session with John Twist, he noticed that my front shocks were in bad shape. I was a bit embarrassed, because I like to stay on top of things like that. So I finally got around to ordering a set from Peter Caldwell, and dove into the installation yesterday.

Fun stuff... all went well, if slowly, until I attempted to refit the pinch bolt in the lever arm end. Even though the little notch in the upper trunnion pin was perfectly aligned, the pinch bolt was having a very hard time getting past it. I ruined two bolts by flattening out their threads as they ran over the detent. Apparently the new shock was a bit different tolerance-wise at the lever arm end.

So after driving across town to the hardware store for 68 cents worth of new bolts, I removed the trunnion pin and very slightly enlarged the notch with my Dremel. That time it all went back together fine. So I've now finished the LH installation, and hope to get to the other one shortly.

I played with the old damper on the workbench, and found that it offered no resistance whatever when I worked its lever up and down. Yikes. I try to top up my damper oil at least annually, but this one feels like all the oil has fallen out. Plus, the arm rattles in its bushing, so it was truly perished. I'm looking forward to seeing if the RH one is as bad. I could tell that the handling was a little off, but I didn't expect this.

Just on a whim, I got my front-end lowering kit out of the boot and am installing it to drop the nose an inch. This is the type with the spacers and longer spring-pan bolts, and I'm using it mainly because the current bolts look like crud and I didn't want to re-use them. Plus, I'm just curious to see what lowering will do, handling-wise.

Cheers,

-:G:-
Gryf Ketcherside

Gryf

Give us an update when you get through...I've been considering doing the exact same thing with the dampers & lowering.

My dampers have seen better days too, I even took them all (4) off, drained, cleaned & re-filled, but not much improvement on the fronts, the rears seem fine.
Dave Rhine ('78 1500)

See what happens when you get a new driveway?? : )
Richard Reeves

>>> See what happens when you get a new driveway?? : ) <<<

Heck, it was probably our old driveway that did in my old shocks. ;-)

And Dave, I'll update this thread as news happens. Never fails, I start a project on the midget and all my spare time goes away - last night was unavailable (theater), as is tomorrow night (school board meeting). I just want to finish the thing and go for a blat.

Stay tuned,

-:G:-
Gryf Ketcherside

Gryf,

I had the same embarrassing experience two years ago on my MGB. The RH front damper had no resistance at all. I knew it was leaking, but was very surprised it was THAT bad. How did John Twist find out?

Tore
Tore

>>> How did John Twist find out? <<<

I was at a Tech Session he led here in the St. Louis area recently, and he'd just talked about shocks. We headed out to the lot where our MGs were parked, and he bounced each of our cars to check the condition of our shocks. Mine was the only Midget there (most of the others were MGBs), and I was surprised (and a bit embarrassed) to see that it was as mushy as it was.

-:G:-
Gryf Ketcherside

"Plus, the arm rattles in its bushing,"

years ago i took my midget to spridgebits in Birmingham to have a rattle diagnosed (turned out to be piston slap resulting in a rebore) and it was only then that the mechanic noticed that one of my front dampers was about to fall apart. Whatever held the pin in place internally had let go and the pin had slid out about an inch. it was probably only the tightness of the kingpin on the fulcrum pin that was stopping the whole thing sliding out. Needless to say I didn't drive the car any further until I had a new set of (reconned) dampers and I spent the next few years checking them regularly.
When I get to the right part of my rebuild, I'll be replacing them with frontline's kit.

graeme
graeme jackson

Gryf,

How long have you had your uprated apples, im guessing a good 10 years, so its probably about time, I know my drivers side is mussy agian just sitting there

If your buying the standard shocks from peter cardwell you may want to take the valve out of your apples and put in the new shocks... at the vary least ask peters opinion. that way you get a stiffer ride for 45 sec. of wrench turning...
Prop

Actually I DID ask Peter about uprated shocks. (or heavy duty, call them what you will.) He made it pretty clear that while he can re-valve any of their units for a nominal fee, he doesn't recommend it. So I figured that was good enough for me.

Hopefully I can get back out the garage tonight. I need to reinstall the alternator and air pump and related bracketry before I can move to the other shock, which is quite a bit easier to get to.

By the way, if any of you don't know, Peter uses actual bearings in his damper rebuilds, vs the original bushes that are so adept at wearing out. He also installs an oil seal in each, preventing any leaking. Basically, his work involves a lot more than just repainting shocks... he fully disassembles and rebuilds them with new features they should have had originally. I'm really looking forward to trying them out.

-:G:-
Gryf Ketcherside

Peter C is THE MAN! One book even acknowledges him as the world expert!


Daniel Thirteen-Twelve

Gryf,

IIRC Peter fits acetal bushes made to his requirements into the bored out original parent metal bores. Basically the original lever arm pin ran directly in the, IIRC pressure diecast, body of the damper. No bushes involved in the original just the damper body material, potentially a good engineering decision at the time as they lasted and the MOT requirements weren't that strict. Changing times and the lack of quality rebuilds shows up the issues involved.
David Billington

Gryf,

Can I ask where you got your spring lowering kit, the ones I've seen say 1/2" and since I've removed the bumpers and don't plan to replace them an inch sounds good.

Thanks,
Bud
Bud K

Gryf,

Did you have to give your old shocks to peter.

if you find your car on a downward slope when you fit the front lowering kit.

Let me Know, Ive got a 1 inch lowering kit that came with my rear tube shocks ...your welcome to it for the asking if you need it. Im not sure If it came with longer U-bolts, I think it did...anyway, if you need it, give me a hooler.


Prop

BTW did you get new shocks for the rear also.
Prop

Gryf,

Oh ye lover of heat and humidity!
I'm doing the exact same thing today!

I've been experiencing a clunk from the front end and uneven tire wear so I decided today was the day I would find out what was up.

I got the left side disassembled and found that the lever arm of the shock was the source of the clunk. You can move it fore and aft in addition to up and down. I will be contacting Peter C. tomorrow.

I also found that my fulcrum pin was way loose.
Does that mean a worn king pin or fulcrum pin? the king pin in the swivel axle is nice and tight.

Will tackle the right side tomorrow.

Lee
Lee Fox

AUGH.... Lee,

My bet is on a wishbone pan, the F. pin is case hardened, and the Kign pin is high speed steel, where as the Wish pan is just mild pot metal.

Might be worth a call to barry kign if it is the Pan,

I feel for ya, I really do.

Prop
Prop

Prop,

Well the fulcrum pin is a loose fit in the bottom of the king pin. Is this normal?
If not, which is likely to be worn?
The fulcrum pin seems to be a snug fit in the A arm, but it's hard to tell if there is any slop.

Lee
Lee Fox

>>>>>>>Well the fulcrum pin is a loose fit in the bottom of the king pin. Is this normal?<<<<<<

Its been along time scence Ive been in that area and Im certianly no expert, But Id think any kind of slop between the kign pin and the F. pin would not be a good thing

you said (the lever on the shock was flopping both up and down as well as for and aft),

I think that has to have some type of wear effect on that whole joint that makes up the F. pin, kign pin, the A-Arm

Id certianly raise the issue when you talk to peter cardwell tomarrow he would certianly have some insight.

I think its one of those things you will have to tear down to have a better understanding...but to me personally that play is odd and got the ol brain noddle fired up.

Im curious ... was there any wear in the rubber bushungs in the turrion link

Prop
Prop

Something else you might consider talking to peter about (esp. being you got all that play in the lever arm), is that (shock bar... for lack of a better word) It triangulates the lever arm and makes it stronger and helps keep the lever arm in place under hard turning ...makes the shock look like a MGB lever shock.

Prop
Prop

Prop,

What on earth makes you think the kingpin is high speed steel?.
David Billington

Dont forget to check your toe in after lowering the front
neil munn

>>> Dont forget to check your toe in after lowering the front <<<

Right, Neil - that's part of the plan, thanks.

I got the project finished last night. Giving the Midget the ol' bumper bounce shows that rebound is now very nicely checked.

So I took it out for a little run, and came right home. Seems that the aft lower bracket securing the air pump is -almost- contacting the steering column at rest, and does indeed touch it on the overrun and when reversing, when the engine is torqued toward the left side of the car. Sigh. I won't be able to get to that tonight, but will try to brain out a fix shortly. Other than that, the car felt great.

Lee - as for the fore-aft rattle of the lever arms, I ran into that years ago with the shocks that were on my car when I bought it. That's when I fitted the Apple rebuilds I used until last night. I also have some motion in my lower trunnions. I'd address that, but it ain't a cheap fix. :-(

Bud - I think I got the lowering kit from Moss, but that was years ago. It may have been Victoria British. Whatever, I remember that I ordered it mainly to bump my total bill up a bit and get discounted shipping or something. It was some sort of deal they had at the time.

-:G:-
Gryf Ketcherside

Hey david,

What kind of steel is it? Seriously I dont know... its not mild, but it definatly has a lot of hardness to it like a crankshaft.

Hhmmm "High speed" ... perhaps Im thinking drill bits...LOL


Prop
Prop

Prop,

I don't know specifically what type of steel it is but HSS is unlikely due to cost and the complexities of heat treating it. I would hazard a guess that the kingpin material would be a plain carbon steel, likely a medium carbon content, or a similar low alloy steel. Steel metallurgy is a big subject but generally the potential hardness of steel is governed by its carbon content with about 0.9% IIRC giving the maximum hardness potential, mild steel having very little carbon down around 0.1% and not being hardenable by heat treatment. Other elements added to the steel add other beneficial properties such as fatigue resistance, wear resistance, all sort of things depending on what's required and what is cost effective.

The kingpins I've had appear to have been induction hardened so that indicates a carbon content sufficient to allow hardening, maybe up around 0.3% - 0.4%.

Plain carbon steels will lose their hardness when the temperature is raised above certain limits, normally in the range 200C to 300C, but that should not be an issue in a kingpin.

The thing about HSS, and hence the name High Speed Steel, is that the alloying elements allow it to operate at much higher temperatures with out loss of hardness. This is why HSS is used for cutting tools such as used on lathes , milling machines, etc. The tools can operate at a higher temperature without loss of the cutting edge and therefore be more productive.
David Billington

Yes... Got the air pump bracketry straightened out, and went for a nice drive this morning. Felt great! I'm really happy with the results.

-:G:-
Gryf Ketcherside

Gryf

Did Peter Caldwell's shocks meet you expectations & would you recommend them?
Dave Rhine ('78 1500)

>>> Did Peter Caldwell's shocks meet you expectations & would you recommend them? <<<

Yes and yes.

;-)

-:G:-
Gryf Ketcherside

when I had a loose fulcrum pin I bought a new pan from Peter Caldwell and not only did it come with the pin fitted (a pain of a job to do, if you have to do it yourself), it also came with a second grease fitting on the other side for improved greasing. I forget who made them, but he carries them and says that they are the best A-pans available. I believe him after working with this one.


Norm
Norm Kerr

Bud,
The spacers themselves are 1/2 inch in height. Since they are located roughly halfway between the inner pivot and the outer pivot, that will result in an inch of lowering.

Dave Rhine,
Just wait until you check out Peter's warranty. THEN you can be impressed all over again.

Lee,
Unlike the MGB, the Midget fulcrum pin is not supposed to move in relation to the kingpin. There is a tapered cotter bolt through the kingpin against the flat on the center of the fulcrum pin intended to hold it steady. The fulcrum pin rotates in the "threads" in the a-arm in normal operation. Given the extreme hardness of the fulcrum pin, I rather doubt that it is worn to any degree. Sorry, but if the cotter does not eliminate the slop, you will likely have to replace the kingpins, although I would certainly try a new fulcrum pin first, as it is so much easier to do. Always seems that any time you take a good look at the front suspension of a Spridget, you wind up changing most everything in sight.

David "ignorance is bliss?" Lieb
David Lieb

Success!

I ordered rebuilt shocks from Peter Caldwell at Worldwide on Friday and he told me they were hit with a big order and it may be a few days before he had any to ship, but a big box arrived on Tuesday! They were nicely packed and made returning the cores simple.

I found the left side A-arm to be toast, but luckily I had a good spare and fulcrum pin to use. Peter strongly recommends against poly bushings, but that is what I have, so I'll keep them for now.

My concern about the fulcrum pin being loose in the king pin was erroneous. I forget to install the wedge pin which locks the two together when I was checking. This has to be the stupidest design of a front suspension anywhere. No wonder the drivers handbook says to grease the front end every 500 miles!

Installing the coil springs with the jack method just did not work for me and using the long bolt method was always a pain. I took, I think, Bill Young's advice and bought some 1-1/2 x 5/16 spacer nuts and threaded rod, welded one nut on the end of the rod and that gave me plenty of purchase on both ends for a wrench. Worked brilliantly.

I took it for a spin and am very much pleased. Will check the front alignment when it cools off a bit.

Thanks to all for your advice and encouragement.

Lee

Here's a picture of the "tool" to install the springs. I painted the ends red (and also the springs) so I could find them again.




Lee Fox

I own an air ratchet but almost never use it. Unless I have Midget front springs to remove!

Those tools came out really nicely. Great idea for additional wrench space/access!



Norm
Norm Kerr

Like Norm, I use an air ratchet on the spring pan bolts. I didn't have a socket quite deep enough to fit over the threaded rods, so I made a special deep socket from an old 1/2" socket and some steel tubing, just ground the socket in half and welded in the spacer. Now it's a one time operation with the air ratchet, just place the socket on and give the wrench a chance to do the work. Lee, glad the tool worked out for you.
Bill Young

This thread was discussed between 06/07/2010 and 15/07/2010

MG Midget and Sprite Technical index

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