Rear Strut Rebuild & ride height Mod
With the Brakes rebuilt, it was time to start on the rear uprights. The car had the stock struts and was pretty raunchy from sitting all those years. Surprisingly, the bearings turned smoothly, but since I was taking the strut completely apart, it was good insurance to go with brand new ones. And "while I was in there", I wanted to rebuild the suspension better than stock. First thing was changing over to ride adjustable coil overs, coupled with TTR's adjustable Koni inserts with droop limiters, and matching TTR front height adjustable coil overs and adjustable shocks. I wanted the height adjustment in order to corner weight the car, after all, it was a Formula Ford for the street.
I read that getting the rear hub off could be a bear, so I bought RD Enterprises hub removal tool. It is double sided and will thread on both right and left hand threads. Once threaded on the KO threads, the bolt in the center is tightened and the hub just pops off.
As mentioned, the strut was rusty and dirty after 40 years of sitting. Disassembly was pretty straight forward until the bearing removal. There are two bearings in the upright. the outer bearing is pressed in with a Circlip holding it in place. the inner bearing has two circlips, one holding the bearing in the upright and another one on the inside of the upright holding the axle shaft. You must take the inner outside circlip off first and clean around the bearing for any hope of getting the bearing out. Lots of WD40 wouldn't hurt either. The circlip is behind the 3 spoke axle shaft and did not come out easily. But once off, I thought I was home free.....not. The factory manual says the axle shaft should tap out along with the inner bearing, it didn't. So I soaked the bearing some more with no joy. Had it on the 12 ton press and carefully applied pressure and it wouldn't budge. Finally I applied a bit of heat to both bearings, the inside race for the outer and the outside race for the inner. Tapped some more and it finally broke free. Don't forget to protect the threads on the shaft with a nut while you tap away. Propane is your friend. The rear axle will come out with the inner bearing leaving the outer bearing in the housing. Using a drift, there are two half moon cut outs in the casting, just tap out the bearing from the race going side to side until it fall out.
With the upright completely stripped, it was now time to start on the height adjustable mod. Using a angle grinder and cut off disc, carefully cut off the spring perch. Leave enough material so you can grind it down with a bench grinder to level it out and to get it even on both uprights (Left and Right). Be careful not to cut into the tube itself. Once you grounded the perch collar level and at the correct height via test fitting the threaded tube, it was time to sand blast, wire brush, and paint up the strut. I used POR15 on all the steel parts and Alumi-blast on the Aluminum.
There are many coil over systems from the usual suspects, but they tend to be over priced, often costing several hundreds of dollars. Plus they are all made from steel which will be prone to rust. Bud English discovered that the inexpensive coil over kit for the Honda CRX 88-97 found on ebay for $59 or so was a perfect fit. Plus it was from aluminum construction. The kit contains 4 threaded tubes, perches and lock nuts, coils and a perch wrench. Toss the coils as they are crap anyway and you will have enough parts for two cars. But as I found out, there are several variations for these kits so ask the seller for the dimensions of the tube. What you need to get is a tube that is slightly bigger than 2" I.D. and 5" in overall length. These tubes most likely are made in metric dimensions, so the I.D. should be around 52mm. As you can see from the third picture, what you want to do is to grind the perch so that the top of the threaded tube is just below the top of the strut tube when fully seated.
The tubes, once installed has about 0.040" of play. I made some shims from 24 ga. aluminum which snugged up the tubes nicely. Test fit with one shim on top and one on the bottom. Once you are happy with the fit, remove the tube and use JB Weld to glue down the top shim. Spread some more epoxy on the shim and slide the tube down trying not to drag the shim down along with it. Add more epoxy as you go, giving the tube a twist here and there to spread the glue. Place the bottom shim in place and continue with the epoxy until the tube is driven home to the top of the perch. Note the holes in the shims which I made with a hole punch. This will allow the epoxy to flow through the shim locking it and giving the tube added bonding directly to the strut tube. Maybe over kill, but easy to do. These tubes should never break free.
After the epoxy sets, you can start on the new bearings. Installation is reverse of removal. First place the circlip on the stab axle, then the deflector (washer), press the bearing on, and then secure with the circlip on to the axle. Install the outer bearing into the upright and circlip, then press the stub axle assembly in place and finally secure the inner bearing circlip from the back.
The new CRX coil over kit uses the US standard 2.5" ID coil springs and not the popular 2.25" in the UK. The stock spring was about a 4" ID and 14" free length with 80 lbs/in spring rate. I bought a 2.5" ID QA1 spring from Summit racing, but reduced the length to 12" so I had room for adjustment. The new coil over tubes will give me 3" of adjustment, so at stock ride height, I should be 2/3 up the tube which gives me the ability to keep the stock height or to lower it while having a good range for corner weight adjustments. But now I had to address the top spring plate. The Lotus had a special domed plate with a "D" shaped hole that was hard to replicate from scratch. So I found some 14 ga 1" bar at Home Depot and rolled it to the correct diameter and welded it in the stock spring plate.
After tack welding the ring on to the top spring plate, I chucked it up in my lathe and cut off the excess and laid a bead of weld around the outside rim. I used POR 15 again with a coat of chassis black. The parts fitted perfectly, but the 12" spring required compression to install it on the strut.
Received my new TTR Koni struts with droop limiters and dropped them into the strut tube. Noticed that the strut sat about 0.175" above the top of the strut tube. This caused the flange nut to sit up by the same height when fully tightened. I called TTR and spoke to Stuart, and he assured me that this is the normal. I guess I'll use Teflon tape on the treads so the oil doesn't leak out. But since I will not be installing these for some time, I'll leave them dry for now.
Another anomaly I found with the shocks was that the retaining nut just barely fitted on the top of the strut. This was strange as the kit included a thick lock washer, along with the TTR top hat that inserted into the Lotocone as the shock shaft was smaller in diameter than the original Lotus shaft. Stuart also indicated that this was fine and just to use the nut without the lock washer. I'll use some loctite green just in case. I also was looking into U Joint and CV axles as an alternative to the Donuts. Found this guy on ebay who was selling a CV diff output shaft for the Lotus. I contacted him and it appears that he makes all the domestically available CV conversion kits. But the ones he was selling was his old design using the VW Type 1 Beetle shaft. While he claims that the new design was to accommodate the new axles currently available, the old design required you to source out an original set of Beetle axles with circlips on both ends. Once again ebay came through with a used set of axles for $60. I was also able to get a set of outboard adapter plates that he makes for a package price of $388. When I recieved them, I fitted them right away. I was surprised that the holes aligned perfectly with the yoke. Not that the plate was at issue, rather the Lotus made part. But I will have another section discussing this project.
The hubs were the last part of the this build. I soaked the hubs in Muratic acid and the rust just melted away, leaving all the good metal and what ever good paint was on the hub. I sand blasted the hub and painted it with POR15. The hub was originally bare metal, red oxide primer, and the red and green marker designating whether it was left hand or right hand thread. The back looked like it was painted black. But I didn't want to leave the bare metal areas bare as original and covered everything in POR15. But since I covered the entire hub with the POR15, I painted the bare metal areas with Eastwood's Cast steel silver and the rest with the appropriate colors. Looked like a 1965 World's Fair pavilion when I was done, but no one see this anyway.