Gunst Throwout Bearing Install ?

[TR250Tom]

Hello,

I'm installing the external spring for the Gunst throw-out bearing in my TR6, and I'm a little concerned about the amount of tension specified in the most recent instructions.

The original German instructions, available at the Buckeye Triumphs web site, specify stretching the spring 15mm to supply pretension. My written instructions from TRF called for 25mm, but I talked with Dave Swauger yesterday about a related issue, and he told me TRF now recommends 30mm, and using the bottom lever arm hole instead of the top, as originally specified.

I'm worried about frying my thrust bearings in short order with that much preload. 30mm of stretch produces a lot of preload, and using the bottom lever hole increases the effect at the TOB further. Is it really necessary?

Has anyone out there got some first-hand experience at a lower preload level? Was the TOB chirping or causing other problems?

TIA, Tom

[brosky]

I probably shouldn't post this since yours is now installed, but I'm hoping that you've installed a LUK pressure plate and not Borg & Beck as I did. And as you can see, I'm no fan of Mr. Gunst and his bearing(s). But I wish you luck with yours. If you have the LUK, I'm sure you'll be fine as others have.

http://www.74tr6.com/clutchreplacement.htm

[TR250Tom]

Paul,

Thanks for the reply.

I'm using a Sachs pressure plate. The B&B is incompatible with most 'alternative' TOB's, (including the Land Cruiser one you went with in clutch 2.0) because of the 'stepped' fingers on the diaphragm.

I'm curious about your Gunst install; there's no mention on your linked site of how much force you used on the external spring that's required on all Gunst installations? (The spring is what keeps the TOB engaged against the face of the pressure plate and prevents all the nasty damage in your photos.) You did run a spring from the transmission cover mounting bolts to the clutch fork lever arm, didn't you?

Cheers, Tom

[TR250Tom]

More information about Koyo/Land Cruiser TOB's :
http://www.buckeyetriumphs.org/technical/clutch/ReliableClutch/ReliableClutch.htm
http://www.buckeyetriumphs.org/technical/clutch/ReleaseBearing/ReleaseBearingWoes.htm

[brosky]

Tom,

I did a text book installation, not once but three times. The pressure was set all over the board and measured correctly. This is BEFORE Gunst admitted that the B&B would not work with the bearing, but after that experience, I was soured on his product. Especially when he wouldn't stand behind anything. TRF did replace the bearings, but I was out for everything else.

So to answer you, yes, I did have the spring installed from day one. Yes, I did try several different tensions as mentioned above. Yes, I tried all locations on the lever, middle, then bottom, then top. I have an email trail a mile long on this back and forth to Germany and TRF with every possible configuration that could be tried.

And that result was the same on all three bearings, two with less than 500 miles on each.

[TR250Tom]

Paul,

Wow! Thanks for sharing your experience, you're a whole lot further down this road than I.

As you said, I've got the Gunst/Sachs installed now, so I'll hope for the best. Can you confirm that Herr Gunst's latest recommendation is in fact 30mm preload and the lower hole?

Good Luck to us both.

Tom

[brosky]

Tom,

My last contact with him was nearly two years ago. At that time, it was middle hole on the lever and 25mm. Again at that time, the problems were just starting to surface and my Sachs/Luk style PP has been fine with the Koyo, as many have with the same and the Gunst.

You'll probably be fine, but keep that load down on the thrust washers. They have enough issues on their own without adding too much pressure from the rear, which will now be under a constant load.

[TR250Tom]

FWIW, Mr Gunst was kind enough to reply, and I'll give you the benefit of what he told me.

Dear Tom,

yes, the 30 mm are correct. May be less will do it. But the producer of the
rollerbearing obliges a preassure of 8 to 10 kp to the bearing. To me this
also seems high and I don't know the real reason. You might measure your
spring and calculate how much will get to the bearing.
You need not to worry about your thrust bearings. We never found an
increased wear. Anyway you should check the endfloat from time to time!

Best regards, Joachim

[brosky]

But the producer of the roller bearing obliges a preassure of 8 to 10 kp to the bearing. To me this also seems high and I don't know the real reason.

'To me this also seems high and I don't know the real reason???'

Uhhhh, excuse me, but isn't this his design and shouldn't he know exactly why and what he is recommending that customers do to their cars?

You need not to worry about your thrust bearings. We never found an
increased wear.

I would love to see the qualification lot of cars that they sampled that information from, along with the mileage driven with before and after end float tolerance readings.

I hate to say it, but I'm even more skeptical now than before. JMHO

[GlennD]

This is why I love this web site. I have a light noise coming from my throw out bearing and was looking around for options and came across the gunst bearing setup. Then I look on our website forum and find this thread.

Glenn

[airborne]

I'll second that - every time I get ready to take a step forward in my frame off re-assembly, I check this forum and get a migrane. Alot of lessons learned that are valuable to those of us entering the abyss.

[CA1971TR6]

Paul (Brosky),

I know this thread is old, but as I am reading it, I wondered what brands and product you eventually settled for on your clutch job. It sound like you had a B&B clutch and used the Gunst bearing. What bearing did yyou settle for after discovering that it was incompatible with your clutch? I purchased a B&B clutch some time ago in preparation for the eventual clutch job in my restoration. I am now researching the remaining parts of the system that I need to order (ie, bearing, sleeve, etc...)

I have read the Buckeye site and am evern more confused and undecided about the best combination of parts.


Thanks,

Mark

[brosky]

Mark,

What you see pictured in my tutorial is a TRF Magic Kit, which consists of the Sachs (Luk) style pressure plate and clutch and the Koyo bearing pressed on to a bronze sleeve. TRF NOW offers a New polished bronze sleeve that has a few polished in chamfers to insure there is no hang up on the main shaft or fingers in the fork.

I would recommend that you get that Magic setup and stay away from the B&B, but that's just my personal opinion.

Good luck!

[CA1971TR6]

Paul,

I have taken your experience and trials into account and decided to order the same setup as your clutch. I already have a new LUK clutch and pressure plate, and ordered the Magic Kit setup with the KOYO bearing and polished sleeve. Not to beat a dead horse (I apologize because I know everyone is sick of this topic), but given your setup, what was your final determination for the correct hole and spring stretch?

Thanks,

Mark

[brosky]

Middle hole and 25 works was what was best for the Gunst if that's what you mean. And if best is the yield shown in my pictures.....

But the middle hole is for every TR6 and a slight spring pull back on the lever is fine as well, even for the Koyo. I didn't measure the small spring that I have for the Koyo, but it's probably 1/2 of what was with the Gunst kit.