"Uncle Jack's" Front Axles - 2016
Or - why Being Flexible may not always be good for you!
A technical article from the "Professor" aka Rob Bradford

The euphoria of resurrecting a TR and racking up 40,000 miles remains strong even after having to develop the habit of constantly pumping the brakes when involved with and spirited mountain driving. This is a necessity when one lives in mountain regions where going for a fang means lots of "OOOH bother" moments when going for the brake to find they only work properly on the third pump.

Old salt TR men know this of course and just sigh with a comment like “Well talk to Uncle Jack”. So who is “Uncle Jack?” and what does he know that we do not? Well he was Jack .W. Drews who was a Vintage racer in TR’s in the USA under the banner of “Uncle Jack Racing” he ran a TR performance business until he was killed in 2008 so the business is now under Tony Drews.

Being keen to understand the issue, I thought it might be a good idea to try and quantify what was happening before seeing what Uncle Jack had to offer.

The first piece of evidence came to light when taking the hub off and seeing how the steel housing for the rear felt seal behind the inboard bearing was worn on one side. Curiosity prompted a similar check on the other hub only to find a similar wear pattern. The left hand side was worse by 10%. There was 0.050” worn off the RH side and 0.055” worn off the LH side. This is consistent enough to conclude that axles are flexing upward by a multiple of that.

Based on the 2” dia of the seal housing and the .055” wear I calculated an angle of 2.3 Deg which by my bush geometry equates to a deflection of 0.219” or 0.220” at the OD of the disc. The brake pads are about 0.2 to thick on my car at the moment so I estimate that there is a full pad thickness to be pumped up before the brakes become effective. This is enough to produce many an “OOHH Golly Gosh” moment when least expected. Lady navigators restrict the use of more appropriate expressions!

The evidence was sufficient to check out “Uncle Jack(prices shown here for Tony Drews kit).

He manufactures a kit to reduce the flexing of the front axles with higher strength axles combined with spacers between the bearings to stiffen up the whole assembly.

I thought I might purchase one of these kits and see what it was all about. The Kit is also available from the Roadster Factory under Part number HP661. The price is about US$300.

The kit come with 4x .001”, 2x .002”, 4x .005”, 2x .007”, 2x .010” and 2x .015” shims and everything is BIG Note: the following instructions are included in the kit The objective of the kit is to install the spacer and shims so that the outer nut can be tightened very tight, there will be no play in the hub bearings, and the hub will still spin freely. Ideally you should end up with zero clearance in the bearings.

Compare the much beefier
supplied axle on the lower right >

Remove the old spindle.

This is usually (but not always) pretty easy and can be done on the car. Remove the bolts that hold the upper ball joint in place, swing the upright down and onto a wood block, for example, screw the inner nut to the end of the threads, and hit the end of the stub axle HARD.

The old stub axle usually falls out.

Well, YES and NO. A few big hits with a copper mallet and bingo, the RHS was free. Not so the LHS

The other side, which had a new axle used during the resurrection, was not easy to remove. Basically I had to unscrew the whole assembly about 17 turns and take it to a machine shop to be pressed out.

Belting thinks with big hammers is not something I feel comfortable with so unscrewing the assemblies and taking them to a press has more appeal.

It is all quite basic, like hanging up the brake caliper but then one really has to remove all the backing plates and other hanging bits before the assembly can be pivoted down or removed if required.

I digress - continue with the instructions. [ check HERE for additional photos of the assembly - albeit on a TR6)

* Remove the felt seal and the inner bearing from the hub.

* Wipe the grease off of the faces of the inner and outer bearing so that you get an accurate reading of the tightness in the shimming step.

* Install the inner cone bearing, spacer, and hub in that order.

* Then install a .015 shim and the outer bearing, D washer, and castellated nut.

* Torque the nut to 50 ft lb. Spin the hub. It should spin freely. Grab the brake rotor and wiggle it side-to-side and top-to-bottom. Start decreasing the thickness of the shims until there is no play but the rotor and hub spin freely even with the nut tightened to 50 ft lb. Most customers report needing about .007 shim thickness to achieve that. (yes that was spot on for the first hub but not so for the second one. DO NOT ASSUME ANYTHING. Measure carefully as there will be variations)

* Remove hub and spacers, re-install the felt 'seal, and reinstall the hub, spacer, and shims. Install the washer and castellated nut. Torque to 40-50 lbs. It might be necessary to use a shim under the washer to get the right pre-load on the nut with the cotter pin fitted, or sometimes it might be easier to take a smidge off the nut.

* Finally install the dust cap.

All the old salts have nothing but praise for Uncle Jack and his upgrade for the TR. By all accounts it has been the best thing they ever did to their cars and works a treat. After testing the car quite vigorously in Tasmania I can confirm that Uncle Jack was indeed on the right track. Multiple high speed hairpin bends and brutal steering wheel action sometimes on full lock diminished the availability of a full brake pedal by about half but it was always there when needed. Under normal non brutal but vigorous driving the brakes are a pleasure and my co-pilot assures me that decorum has returned

Cheers Rob Bradford