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Author: Subject: Front rocker tubes
peter030371

posted on 24/7/23 at 01:34 PM Reply With Quote
Front rocker tubes

I had my car geo and corner weights checked and tweaked last week and they found a slight issue. On the front suspension, with the shock disconnected' and the front jacked up, the suspension wouldn't drop back down under its own weight. It was very stiff and need a little push to settle back down. I have rose joints so with it jacked up and the shock not connected it should just drop back down.

They slackened off the nut/bolt by half a turn and as if by magic it all drops back down again with zero stiction.

When I built the car 6-7 years ago there was no stiction. I have just popped out one of the steel tubes and it is corroded up. I have only done just over 1k miles and most in the dry.

I have cleaned the tube up with emery paper in the lath and its nice and smooth again but how 'slack' should the tube be in the top hats and any tips on cleaning them out? Is it worth putting anything on the tubes before refitting to help stop corrosion?

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ReMan

posted on 24/7/23 at 01:55 PM Reply With Quote
presume the rose joint body must be being pinched then as the centre of the joint should be be held tight
perhaps a shim washer is needed either side?

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peter030371

posted on 24/7/23 at 02:10 PM Reply With Quote
quote:
Originally posted by ReMan
presume the rose joint body must be being pinched then as the centre of the joint should be be held tight
perhaps a shim washer is needed either side?


The top rocker is not on a rose joint, the rest of the pickups are. Its difficult to describe. Just looked for a picture and found this on a Fury which is the same thing. http://www.robcollingridge.com/400kg/design/suspension/Front_Suspension.jpg interesting that this one has a grease nipple.....sort of answer my question as I can grease them up and then add a nipple over the winter

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obfripper

posted on 24/7/23 at 03:54 PM Reply With Quote
For the top hat bushes, 0.5mm end float and a bit less for radial play has been fine for me, I sprayed the centre part of the tube with zinc primer and greased the top hat and sleeve before reassembling.

When i first had the car, the top hat bushes were not reamed sufficiently, and the tube was stiff to turn within the bushes (even when clean and greased), reaming them removed the stiction. The sylva kits were supplied with the bushes unreamed, I don't know if the later raw kits were the same.
The length of the tube was also not adjusted to fit as supplied by sylva, when I reamed the bushes I found I had to shorten the tube to get the endfloat correct.

I've not had to readjust or regrease for quite a few years, but do spanner check them from time to time as they can work loose.

Has the end of the tube worn into the powder coat? This would cause the end float to decrease by the powder coat thickness and might be enough to make the top hat ends bind.

Dave

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peter030371

posted on 24/7/23 at 04:02 PM Reply With Quote
quote:
Originally posted by obfripper
For the top hat bushes, 0.5mm end float and a bit less for radial play has been fine for me, I sprayed the centre part of the tube with zinc primer and greased the top hat and sleeve before reassembling.

When i first had the car, the top hat bushes were not reamed sufficiently, and the tube was stiff to turn within the bushes (even when clean and greased), reaming them removed the stiction. The sylva kits were supplied with the bushes unreamed, I don't know if the later raw kits were the same.
The length of the tube was also not adjusted to fit as supplied by sylva, when I reamed the bushes I found I had to shorten the tube to get the endfloat correct.

I've not had to readjust or regrease for quite a few years, but do spanner check them from time to time as they can work loose.

Has the end of the tube worn into the powder coat? This would cause the end float to decrease by the powder coat thickness and might be enough to make the top hat ends bind.

Dave


End float is still 0.5mm. I have just cleaned up both tubes and ordered a reamer to clean out the top hats. I think that is the issue as the tubes really were not that bad.

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adithorp

posted on 24/7/23 at 05:18 PM Reply With Quote
It doesn't take much corrosion on the tube to sieve them up. I reamed my Fury bushes to the point the rocker when not attached to shock or upright will just hold in any position but move with the slightest pressure.
Then after mine had rusted/siezed (2or3 years), I also put a spiral groove the bushes and fitted a grease nipple to the center of the rocker arm. I now grease that once a year and the old grease gets pushed out via the grooves. Been fine ever since (12/13yrs). I know pthers have done the same with grease nipples.

I did think of getting stainless crush tubes but never bothered to follow that up as I had no more problems.

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peter030371

posted on 24/7/23 at 05:36 PM Reply With Quote
quote:
Originally posted by adithorp
It doesn't take much corrosion on the tube to sieve them up. I reamed my Fury bushes to the point the rocker when not attached to shock or upright will just hold in any position but move with the slightest pressure.
Then after mine had rusted/siezed (2or3 years), I also put a spiral groove the bushes and fitted a grease nipple to the center of the rocker arm. I now grease that once a year and the old grease gets pushed out via the grooves. Been fine ever since (12/13yrs). I know pthers have done the same with grease nipples.

I did think of getting stainless crush tubes but never bothered to follow that up as I had no more problems.

Thanks Adi. Some used to say grease was a bad thing as it trapped dirt. I don't do the miles to worry about that. I have a bag of grease nipples so will follow that route

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pigeondave

posted on 25/7/23 at 01:01 PM Reply With Quote
Yep another vote for nipples
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peter030371

posted on 25/7/23 at 01:03 PM Reply With Quote
quote:
Originally posted by pigeondave
Yep another vote for nipples


spits coffee out over keyboard....

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peter030371

posted on 31/7/23 at 09:01 AM Reply With Quote
Just to update in case someone finds this in a search one day this is what I did.

Once removed (with a drift, and took some hitting to get them out) the metal tubes had some signs of corrosion. Popped them in the lath and cleaned them up like new with some emery paper Checked size after with a micrometre and all came in between 19.05mm and 19.10mm so still round enough for me

Tried them for size and it was very 'snug', would of had to be pressed in so no use like that.

Got a 19mm reamer which with a simple adapter turned up in the lath was mounted in an electric drill...a quick blast with the reamer in each nylon top hat and the tube fitting was snug but not tight, easy to slid in and out. May not be the way a 'proper' engineer would do it but worked a treat although it was a proper engineer that told me to try this way first

19mm reamer
19mm reamer


I did find that the top hats were not perfectly in line so the reamer was used to go through one into the other and out the other side if that makes sense. This really helped free it up.

Refitted the tubes with a smear of grease and re-assembled the front end. Now when I lift the suspension up it just drops straight back down with no stiction to speak of. The metal tubes a clamped solid and the nylon top hats move as they should.

I will look at adding grease nipples over the winter. My other suspension joints have them so no issue to add a couple more as long as I can find a place to fit them that can be reached with a grease gun and doesn't foul the chassis over the full range of travel.

The car is now fighting fit ready for Three Sisters sprints at the weekend, still won't make up for my mediocre driving skills so will need to find another excuse

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