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Thursday, September 22, 2016

Triumph Spitfire Chassis Restoration Addendum - The Trouble with Trunnions

After several garage trips battling what I would consider sub-standard parts, I finally got the rear trunnions re-bushed and torqued down along with the front upper ball joints. Now, these wouldn't seem like terribly difficult jobs, but...Come with me, friend, on a little adventure.

First, as a lead in, I purchased a total of three kits, one of which was ultimately successful. The original kits were from The Roadster Factory, part no. BK9/U. The next kits were from SpitBits, part no. QSK151. The final, and working, kits were from Moss Motors, part no. 674-935.

2 of the 3 kits I ordered. R to L: What came off the trunnion originally, the SpitBits kit and the TRF kit.

The 3rd (and final) kit from Moss.

The trunnion kits are all very similar with some notable differences. First, they all stack up the same.

Trunnion stack up, with all parts outlined in the "A" boxes.

I assembled them by first covering everything in a liberal amount of bearing grease both to provide stickiness to keep everything together and lubrication. I then stacked the kit up as shown. One trick here is that the rubber o-rings, in all kits, go around the plastic bushing to provide a dust seal.

Example of o-ring placement. This is the SpitBit's kit.

One notable difference between the SpitBit's kit is that the inner washer, that mates with the trunnion face itself, is flat. The other kits, and the old one I pulled out of the trunnion have a cupped washer on the inside. In my opinion, the cupped washer is the better design because it will tend to retain the o-ring.

Measuring the thickness of the inner washer. You can clearly see the lip, however.

Now that you hopefully understand the design differences, I'll go back to the beginning. The TRF kit was first. Unfortunately, when I attempted to install it, I ran into serious fitment problems. First, the plastic bushings were very tight going into the trunnion, even after using quite a bit of grease.

The TRF bushing. You can see the extra little plastic burr on the right. Read on...

Then, the steel bolt sleeve required a mallet to push all the way through, even taking a small sliver of plastic bushing with it. Ultimately, the stack-up of the kit resulted in it sticking out from the trunnion too far on either side, making installation of the vertical link very difficult.

About 53mm. That's too wide.

The space for the vertical link was about 51.5mm. ~2mm may not seem a lot, but when you are dealing with 1/8" or so steel, it is.

Space between vertical link where trunnion fits.

When the vertical link was torqued down, it took a lot of effort (too much, in my opinion) to rotate the vertical link about the trunnion as it would need to do for wheel travel over the road. So, I took it apart.

Using a 2x4 as a spreader to allow the vertical link to fit over the trunnion.

Since SpitBits has always been (and will continue to be, I must stress) good to me, I went to Nigel for the next round of kits. Similar situation here with the kit running just shy of 54mm. Again, too wide, but I tried anyway.

The SpitBits kit fitted, with the resulting measurements.

I had to use the 2x4 spreader to get the vertical link to fit over the trunnion. Once I started to tighten it down, almost immediately the rubber o-ring started to extrude. By about 20 ft-lbs of torque, it was well on it's way out. Busted again.

O-ring extrusion. That's not going to work.

My next domestic resort was Moss. Now, I've only placed one other order from Moss, and that was for those caliper o-rings that I mentioned in my last post. While they obviously fit the bill for some stuff, I find that their part prices are generally higher than most so I've always gone the cheaper route. In this case, however, they were the cheapest of the bunch with their trunnion kits only $4.99 each, as compared to $7.99 each for SpitBits and about $20 for a pair from TRF.

Immediately upon receipt I thought I may be lucky. First, the bag said "Made in UK" on it.

Made in U.K. A good sign? Hope so!

Second, I could also tell that the washers, especially the inner one, were visibly thinner that the other kits. The plastic bushings seemed close, but maybe a bit thinner, too. I commenced installing this kit in the same method as all of the others.

Inner washers, plastic bushings and steel bolt sleeve installed.

Rubber o-ring around outside of plastic bushing.

Outer dust caps installed.

Proof is in the pudding. Just over 52mm; about 1.5mm less than the others and less than 1mm larger than the vertical link spacing.

Vertical link partially installed. This did not require the 2x4 spacer, just the rubber mallet for positioning.

I was very happy, needless to say, with these results. I bolted it down to the spec of about 40 ft-lbs and got good movement on the vertical link. I would call the movement as I expect. Tight, but not overly so and indicative of new parts.

Finally, with the battle finally won, I moved on to trying new front upper ball joints. The original set was from TRF, part no. 104552. These ball joints are specifically manufactured for TRF and also have grease fittings. However, I couldn't get the things to seat inside the front vertical link to save my life. I tried hammering with a 3lb sledge and wood, an impact wrench...nothing. The threaded rod would always turn and the taper would never gtab into the vertical link.

So, I ordered Lucas ones from SpitBits, part no. GSJ155. These worked like a champ and torqued right up to the spec with no rotation of the tapered rod. Really, these were very anti-climatic as I expected to have to do some beating on them, but I only tightened them down.

And done.

Let me say that between the rear trunnions and the upper ball joints, I was a defeated man. I wasn't sure that it was the parts and not me. Very frustrating to go to your rented garage that cost you a lot of money for one of the two days out of the week that you have arranged with the family to go to it and accomplish nothing, fighting the whole time to get the car back together and getting no where.

On the flip side, however, I felt vindicated after all was said and done that it was not me and it was the parts and I was going to get through this restoration with a quality job done on the other side. Only time will tell, I guess.

Hopefully if you've read this you aren't nodding your head saying to yourself that you feel my pain because you've gone through it. Hopefully you can learn these lessons from me instead of through your own trials.

Also, in the interest of transparency, I did contact Nigel at SpitBits. He attempted to recreate my issues and was not able to do so. I'm sure his years of experience helped, but there you go. He did also provide a credit to my account, which I'm sure I will use quickly. For the record, most of my orders have been with SpitBits and it will continue to be that way. Cheers!


  1. Wow, what a crappy experience you had. I'm surprised there were such sizing differences between the three kits (and price differences!) I'll keep it in imnd.

    1. Yes, I was surprised, too. It was not fun...but I did learn a lot.

  2. 11-30-2020 still a problem today, I bought 2 QSK151 kits 24 Sept, 2020 just now getting around to explaining to SB the problem with them, but the contact there is having nothing to do with it. Says nothing wrong with the kits. I used the i...t word, he told me to get a better mechanic.

  3. Nov 2020, SB told me They have "sold these kits for 15 years", I explained this same problem, next email "been selling these kits for 10 years, no complaints, just install them"...Hmmm. readdressed the problem, (you don't need calipers to install these, bur don't grease the O-rings to keep them in the shields"....The distance tube 1.9685" is too short, and vert link binds up!.. they replied "You need a better mechanic"...... I finally got the message, don't care...

    1. Yeah, Cal, I read your stuff on the forum. SpitBits is usually pretty good. Surprised that he seems to be blowing you off. There's lots of pieces, but it's not like its that complicated. You need a better mechanic is crap. The age of these cars, there really aren't better mechanics out there.