Refurbishing rear struts

[chrishewett]

I am fitting new bearings to a pair of rear struts that I thought were in good condition. Now I have got the bearings out I discover that they had been fitted with a good amount of loctite or similar. The bearings are a tight fit on the driveshafts and the inner bearing is a fairly tight fit in the housing but the outer bearings drop easily into the housing. Will fitting them with copious amounts of loctite be enough to hold them in or am I wasting my time? Is there any other way to repair them to ensure a better fit.
chris

[type26owner]

My aluminum strut housings had worn oversize by .020" from first fretting and then creep to open up the bore like that. Just buy the bearing adhesive made to fill a large radial gap. Best to call Henkel/Loctite for advice. Can't remember the stuff they told me to use but it worked. Have replaced the bearings twice now in 130k miles with no more of the fretting wear of the housing.

A couple of infared heatlamps is all that is needed to melt the adhesive when the time comes to disassemble it again.

Here's a link that describes bearing creep.
http://www.ntn.ca/shaft_housing_fits.htm

[stuartgb100]

Chris/Keith,

I'm in the same position rebuilding rear struts and found out last night that the outer n/s bearing easily tapped into the housing.

TTR's info sheet clearly states that you must apply heat to the struts before inserting the bearings ..... I didn't have to.

On the other hand, Keith's link says:

"Typically, an inner ring rotating application will use a tight or interference fit on the shaft, and the housing will use a loose or clearance fit. Likewise, with an outer ring rotating application, the opposite is true."

So now I don't know what to think.

Regards,

Stuart.

[type26owner]

Stuart,
In this case the outer bearing race is stationary and as long as the Loctite is strong enough to keep it that way you're good to go. It will, no problem. Read and obey the instructions for the adhesive. BTW, IIRC the special catalyst they require and none of the suppliers stock it so you assume you're screwed. Not so, it turns out to just be methyl alcohol. Any kind will do but I keep a bottle of reagent grade stuff around to activate the surfaces in preparation.

To really get the porous casting clean the best way I found is to heat it up with the heatlamps to around 200F and rinse it with laquer thinner every couple of hours. The heat will draw the soaked-in oil to the surface and after a day of rinsing it about 6 times it will be clean enough to weld. If it's clean enough to weld then it's clean enough for the Loctite to adhere really well also.

[miked]

Yep, I agree. I had loose fit bearings. I had a long chat with Loctite boffin and used Loctite "Quick metal". It was about ?35, but top stuff. I also got the cleaner and stuff to make it go off quicker. Only thing is it sets quite quickly when the accelerator is used. I had a faulty bearing and had to pull it apart again. Was amazed at how it adhered the the outer surface of the bearings.

Mike.

[chrishewett]

Great! Thanks for all that. I will be on the phone tomorrow to source the required loctite and I will report on progress.
Many thanks once again for help on this great forum.
Chris

[rgh0]

There are a range of Loctite grades for improving bearing fits. Those designed for compensating for a loose clearance fit where a tighter press fit is required (such as quick metal) should be considered as a temporary repair only until you can sleeve or weld repair the bearing housing back to the original fit tolerances.

The Loctite literature generally emphasises the temporary nature of these products. I have used quick metal in both front and rear hubs in my Elan as an emergency repair. In the front hub brake temperaures lead to very short life. In the rear life was a few race meetings until I had enough time to have a weld repair done on the hub.

Rohan

[type26owner]

Rohan,
However that's those folks being very conservative. In the strut it's not being attacked chemically or exposed to UV or ozone or heat cycled very much. It is getting exposure to water. There isn't anything really degrading the stuff over time. My experience is that it works okay as a permanent solution.

However, I don't live where roadsalt is used in the winter and that might attack this stuff.

[chrishewett]

I spoke to the loctite tech man today and he tells me to use 641 if the gap is below 4 thou and 660 if it is over and up to 20 thou. He claims this is a near permanent solution. I don't intend to race the car ( maybe just the odd trackday) so I will try it until I decide on a more permanent solution at the end of the summer. The only real worry I have is that the car is reliable for Hockenheim in april and classic Le Mans in june. After that I will look at new struts.
So, new question- What are the options?
Chris

[type26owner]

Chris,
I originally intended to go back and have both strut bodies welded and remachine the pockets for the bearings also. That notion has passed because it's been ten years now and the Loctite has not let me down. Why fix something which is no longer a problem? I have no misgivings about taking out on the racetrack and flogging it either.

[chrishewett]

The struts finally went back on yesterday. The only problem I had was that the resilient mountings had a round hole instead of a D shaped hole as described in the manual. This meant holding the insert with mole grips to tighten the nut. Both the original inserts were shot so I was looking forward to seeing if the handling had improved. WOW! The inserts were definately the problem and now the car drives like a dream. I can't wait to get it out again today.
I just hope that the loctite repair lasts.
Chris