PDA

View Full Version : TR4/4A Steering bushing: replacing rubber with poly, do I snug to 1/8" gap or...?



Popeye
01-11-2017, 09:48 AM
Hi all,

I am looking for advice on installing a steering rack on my 1966 TR4A: I have received my freshly rebuilt steering rack from CAR/TRF, and plan to install it using polyurethane bushings. The technical manual states to compress the bushings until 1/8" of gap is present between the two flanges. (I do not have the book in front of me; I hope what I am saying makes sense - sorry if that is not the case!)

Poly is stiffer than rubber. Should I still compress until I get 1/8"? Or just make it "firm", using good judgement?

Secondly, I assume these poly bushings should not be greased - as the purpose is to keep the rack in place. Am I correct? (No worries about squeaking?)

Also, I have the proverbial "cart before the horse": I am ready to install the rack on a freshly painted frame and rebuilt front suspension, but the engine is at the rebuild shop, and the body is at the body shop. Is there a good way to align the rack, i.e. make sure the steering nub points in the right direction, without the steering wheel attached? Should I wait on installing the rack until everything else is in place?

(I need to build a tool to compress the bushings; thanks to a few of you on the forum who have posted photos and suggestions!)

TR4nut
01-12-2017, 12:37 PM
Mike-

I would just use judgement and make it snug, those factory instructions didn't contemplate poly bushings so the measurement may not be useful at all. I wouldn't hesitate to install the rack now while everything is accessible, you can work alignment and steering wheel hookup later.

TBU_Triumph
01-12-2017, 12:40 PM
Hi Mike,

I'm not in a positon in offer any advice about the need to compress the poly bushings. Perhaps a call to TRF will offer some guidance.

My recommendation is to wait and do the final install of the rack after the engine is in place. Then you can install the steering shaft and time the wheel with the center of travel of the rack.

My experience with a 1966 TR4A is that the steering rack cannot be in-place when you remove and install the engine. When we removed the engine we removed the U-bolts for the rack mounting. We then moved the rack forward and down so we could move the engine forward and then lift it. When we installed the engine we had not yet mounted the new rack so there were no issues.

I expect that there might be a combination of engine lift height and tilt angle that would allow you to install the engine with the rack in place. My estimate is that it would be a fairly steep angle. That would require the car to sit fairly high so the end of the transmission does not hit the ground before you start leveling the engine.

I would encourage you to trial fit the rack now to minimize problems later. Compare it closely to the configuration and details before you took things apart. We got caught with longer than stock U-bolts for the aluminum bushings the owner wanted to use. The rear leg of the left U-bolt stuck down so far it interfered with the lower radiator hose.

Rusty

Popeye
01-17-2017, 10:55 AM
Thank you Randy and Rusty!

I installed the rack last night with the new bushings, pressing out the u-bolts as far as common sense told me to do. A few comments:

1. The nylon "button" on top of the rack, opposite the steering shaft. The rubber bushings were soft enough to allow this button to "compress" inside the bushing. However, there was no (reasonable) way I could install the poly bushing with the nylon button sitting proud of the tube. Using an exacto knife I cut an opening in the bushing, allowing installation. After thinking about this a little last night, I plan to fill the void with some silicon caulking, to keep dirt out and the plug in. (I have not yet - I'm not sure I can get in there.)

2. I fabricated a spreader per the below photos. Comments and suggestions welcome! Crude, but seemed to be effective. I welded the nuts too far back - that is why there are three nuts to act as locknuts on one side. The rubber ducky serves as my helper (I was working with my youngest :)) Other versions of this spreader can be found in the BCF, thanks to Opa, Randall and KVH: https://www.britishcarforum.com/bcf/showthread.php?86259-TR6-Steering-Rack-Mounts/page2, https://www.britishcarforum.com/bcf/showthread.php?88174-Compressing-steering-rack-bushes-TR4A.

467034670546704