Rear wheel bearings and hubs
If you've been following my blog you'll know back in November 2017 I made significant progress on the 7 building the rear of the car including the DeDion tube and various associated or connected components. I was making excellent progress which eventually stalled when I came to install the rear hubs. In this blog post, I'll cover what went wrong and how the situation was resolved by Caterham Cars.
The root cause of the issue was that my kit components were supplied with the rear wheel bearings not pre-pressed into the rear hubs. The assembly guide does not clarify the situation, and at the time I merely assumed I had to press the bearings home. I recall feeling the expectation was a little unrealistic and not in keeping with the expectations set by Caterham over the tools and skill needed to build the car. There is certainly no mention of a bearing press in the official Caterham Draper toolkit. It was only after things went badly and I spoke to Derek at Caterham Cars that I became aware of the error, that being the bearings should have been pressed into the supplied rear hubs.
In the image below, the hub and bearing combination on the left illustrates how the hubs should have been supplied, while on the right, a separate hub and bearing is shown, this is how I initially received the parts.
I didn't and still don't have a bearing press, so needed to imprevise, it didn't go well. It was suggested to me through support from the Lotus 7 club forum to heat the hub so that it expanded and then push the bearing home. It might even help to warm the hub in an oven, whilst freezing the bearing in the freezer. I didn't go that far, opting to heat the hub with a heat gun, sadly it didn't work.
I heated the hub until it was too hot to handle by hand, then placed the bearing on top, used a flat piece of wood (kitchen worktop offcut) large enough to cover the entire bearing and wellied it with a lump hammer. I managed to gain about 10 to 15mm of movement before the bearing became stuck, and eventually, through perseverance, I ended up damaging one of the seals.
At this point, it became clear I wasn't going to seat the bearing with the tools I had. I was probably going to need the support of a local garage to press the bearing home. Although my immediate concern was replacing the now damaged bearing, so I contacted Derek at Caterham Cars to seek clarification on which part I needed to order. It was then through this conversation that I became aware the bearings should have been supplied pre-pressed in the hub. Derek graciously acknowledged the issue and sent me through some replacements ready to go.
I was now ready to install the rear hub onto the car.
Installing the rear hub with the pressed bearing requires bolting the pair to each of the ears (see earlier post), whilst passing the end of the driveshaft through the bearing. The ends of the driveshaft are also a very tight fit with respect to the hub and bearing, not so tight as to require pressing, but tight enough to prevent sliding on with ease.
To allow me to gradually pull the hub into situ I decided to use the large cable ties I'd purchased for use on the exhaust spring. I passed one cable tie through each of the 4 bolt holes and the gradually closed the cable tie one click and a time. Doing so gradually pulled the hub and bearing onto the driveshaft evenly and without risk to the threads of the bolts holes.
Once home it was a case of cutting each cable tie off and immediately replacing with the required bolt and washer as per the assembly guide.
and from the front;
Next up rear brake disc, and calliper, followed by ARB bracket.