Strut top thrust bearings

[Rich K]

Hi, stripped and started the refurb of the front suspension struts on the gold convertible. As they are apart it seems like a good idea to fit proper thrust bearings in order to optimise steering effort. I know that this topic has been discussed a number of times on the forum and there appears to be two bearing options available from the TR suppliers, namely the Ford Sierra thrust bearing and a thin needle roller thrust bearing. Both are not cheap at current prices.
It seems to me that the Sierra option has two drawbacks: It dispenses with the nylon thrust collar (UKC329) and hence you effectively lose the presence of a location bush that centres the damper rod in the upper spring pan (UKC5042) and hence it seems there is a possibility for the strut to oscillate. Secondly the thickness of the bearing (and the supplied washer that installs above it) results in an increase in suspension height of circa 7mm.
I know that some have turned the Sierra bearing upside down and machined a recess in the base of the alloy cone (UKC7495) to house the bearing and avoid any height increase. The problem I see with this approach is that this arrangement does not provide any bearing function between the cone and the upper spring pan. In the standard factory setup the cone (UKC7495) and steel thrust washer (UKC9395) sit on the machined shoulder on the damper rod and remain static. The rest of the strut assembly below this point turns with steering input and relies on the “bearing function” of the greased steel washer (UKC9395) and nylon thrust collar (UKC329) to minimise friction.
I’m currently trawling through bearing catalogues looking for a more suitable (and cheaper) alternative. Any thoughts or advice would be much appreciated.
Cheers,
Rich.

[busheytrader]

Hi Rich,

Admittedly I didn’t take your technical approach and just fitted the Robsport supplied bearing kit (Sealed Sierra bearings as opposed to open needle roller bearings?) when the gaiters covering the dampers started to perish. The previously greased standard washers / bearings were almost dry. I never really noticed an increase in ride height at the time since my ageing Triumptune Sprint front springs continued to slowly sag on to the bump stops. These were changed to 1” lowered & uprated later on.

The bearings make a smoother steering difference except when parallel parking, 195 wide tyres don’t help much at low speeds.

[Rich K]

Hi Bushytrader, thanks for your reply. The grease between the washer and nylon thrust collar was also dried up on my car. It’s not surprising that a lot of folks comment on heavy steering when the design relies on this grease to moderate the friction in the strut top when turning the steering and in most cases will have dried up long ago unless re greased during a rebuild. It’s a pretty poor design anyway in my opinion. Why not have a proper bearing in there like most other cars with MacPherson struts? Can’t have saved the bean counters much.
I also have 195 section tyres on the front wheels and it does make for heavier steering at low speeds, even using the old technique of getting the car moving before trying to turn the steering wheel.

[Hasbeen]

We fitted needle roller bearings to the 8 a few years back. At the same time we linished the the stock gear on the 7, & greased both with the same graphite grease. We dissembled, cleaned the hardened grease, re greased the racks & re shimmed the pinions. This made a considerable difference to the feel & effort involved in the steering of both.

My son said he could detect no difference in the steering effort or response between the 2. I "sort of" thought the 8 may be smoother, but that may be because I thought it aught to be.

Hasbeen

[dursleyman]

I have the needle rollers in one of my cars and the Sierra type in the other. Both give a really good result and improve the steering lightness a lot. The thicker Sierra ones can be fitted as a direct swap for the standard nylon washer and because of limited time I ran it like that for a while but it did give a slight increase in ride height - maybe 10mm?. I wanted to get that back down so had a mate with a lathe machine a recess in the aluminium cones so the bearing sits inside with its running surface just proud of the cone. The Sierra bearings are very chreap, lots for sale on Ebay for about £25 pair or less. Lots posted before about this but I will add some pictures as well.

[dursleyman]

Some pictures of the Sierra bearings:-
These are the bearings you need


These next two pictures originally posted by Beans so it would be worth looking at his Blog to see more



and another version, same idea

[Cobber]

I've got a set of these:


https://k-mac-camber-kits.com/product/triumph-tr7-tr8-front-camber-and-caster-kit-stage-2-streetrace-780616k2/

Yet to fit 'em

[stevie_a]

Been on my car for over 15 years and still good performance from them.

[Rich K]

Hi guys, thanks for all your interesting and informative comments.
Hasbeen, that’s interesting that you found little difference between the re greased standard set up and the bearings. I always place value on your huge experience. I guess that shows the standard design is fit for purpose as long as there is sufficient fresh grease present.
Dursleyman, thanks for the info on the Sierra roller bearings. I just found a set of these in my parts stash which I now recall buying some years ago. I may well go down this route as I already have them to hand. I still think there are minor drawbacks to this route as previously stated. Also, correct me if I’m wrong, but Installing those bearings upside down with the smaller aperture (circa 12.1mm) face downwards means that the bearing seats on top of the shoulder of the damper rod. This results in the bearing being sandwiched between the (machined) cone and the damper rod shoulder and therefore it cannot act as a bearing with the upper spring pan i.e. the net result would give little or no bearing function. The bearing needs to act between the cone and the upper spring pan as it is everything from the spring pan downwards that turns with steering input, everything above stays static. Please see my diagram. Apologies for the poor quality drawing! Just my view.
Cobber, those look like the dogs nuts. Narrowly missed a set on eBay recently.
Stevie A. Hi, sorry but same comments apply to your set up as per Dursleyman’s diagram but if it works then that’s great.
Cheers all, Rich.

[dursleyman]

Rich, your diagram is pretty much spot on how I have my setup apart from the fact that the bearing is recessed up into the aluminium cone so it only just sits proud enough to give a working surface.
Couple of friends with TR7s have been surprised how light my steering is.

[Beans]

I've got a set of these ...

Looks like a nice piece of kit!

... Yet to fit 'em

That sounds vaguely familiar

[Rich K]

Hi, just did an interesting comparison. I assembled the strut on the bench with three different bearing configurations:

1) Standard factory specification with large steel washer and nylon thrust collar cleaned and re greased
2) Ford Sierra thrust bearing installed the correct way up per Robsport’s instructions I.e. smaller aperture upper most.
3) Ford Sierra thrust bearing installed upside down I.e. smaller aperture at the bottom

Interestingly none of the above worked properly off the car without partially compressing the spring using spring compressors. Only the factory setup showed any willingness to rotate without partial compression. Once the spring was partially compressed there was little noticeable difference in effort to rotate the strut between the factory set up and the Sierra thrust bearing installed as per 2). Option 3) with the upside down Sierra bearing did not work at all. I could barely rotate the strut and there was a graunching noise with the top nut fighting the D shape dished top locating washer. I guess the conclusion reached is that a properly greased factory set up works, and the Sierra thrust bearing works but only if installed the right way up. I would not recommend anyone installing the Sierra thrust bearing upside down as it appears not to function as a bearing in that orientation and could cause some damage.

Cheers, Rich.

[Beans]

... I would not recommend anyone installing the Sierra thrust bearing upside down ...

It is 15 years since I installed my set up (incorrectly according to you ). And so far it works as it should without doing any damage

[Hasbeen]

For what it is worth, I have always found that the heavy steering of all the 7s I have owned has been down to rack lubrication.

I recently thought that I was starting to show my 82 years, when I found the 7s steering a bit heavy. Yes the problem was my 82 years, but only because they had made me a bit slack, it was 3,400 kilometres since I had greased the rack. My system is 3 strokes of the grease gun, one in the centre & one each at 2/3 lock every 2500 kilometres. This keeps the thing easy & free of wear.

Every 7 I have owned has come with almost rock hard remains of grease in the rack, & heavy steering. The 8 is a prime example. Despite coming with a near A$40,000 receipt file from a top Melbourne shop specialising in performance classics the steering was heavy particularly at near full lock. On inspection the grease was really rock hard, & it had been shimmed to reduce the play at the centre caused by wear, thus near binding at full lock.

After a thorough clean it was obvious it was not good enough. I had a spare good rack & used that. My system is to coat the rack & pinion with a little EP90 & STP mixture brushed on, & shim the pinion with no added grease. I then grease as above, using a graphite grease I have been using for 58 years now. People who know 7s have remarked on how light my steering is, some asking if it is a power system, which does my vanity no harm at all.

This I believe is more important than the strut top area, but of course that must be up to scratch for the car to be nice to drive.

Hasbeen

[Rich K]

Hi Beans, I respect your view and I’m glad that works for you on your car. However, having conducted a physical comparison test, I have to go with the evidence and if I use the Sierra thrust bearing it will be installed with the small aperture upper most. This way it will act between the bottom of the alloy cone (UKC7495) and the upper spring pan (UKC5042) as intended and will mirror the way the factory setup works with the greased large steel thrust washer (UKC9395) and the nylon thrust collar (UKC329).
Hi Hasbeen, thanks for your advice regarding the steering rack. This will be next on my list and I have several spare racks in my stash so will be able to choose the best one and follow your maintenance regime.
Cheers, Rich.