CV Driveshaft upgrade for the GT6

 I recently had an advisory at an MOT test that the Rubber Rotoflex couplings (Donuts) were starting to deteriorate. 

The genuine Rotoflex couplings (made by metalastic) are now very expensive (over £200 each) and the pattern ones like most  rubber components on our cars don't last very long. However, there is now and alternative, an upgraded driveshaft set up which replaces the rotoflex coupling and UJ for  more modern CV joints. This is the set up used in modern rear wheel drive cars like BMWs. I know from covering 125,000 miles in my recently sold BMW 3 series that I'd owned from new that a CV joint solution is very durable as I'd never had to replace them. The CV upgrade to GT6 and Vitesse Rotoflex drive shafts is made by Classic Driving developments. It is quite expensive but will work out cheaper in the long run. It also changes the drive shaft nut on the end of the shaft to a meatier 20mm x 1.5mm from the puny 5/8 unf  (c16mm) diameter on the original which is a weak point and prone to stripped threads.

I therefore decided to take the plunge and buy a CV driveshaft kit, unusually Rimemrs was the cheapest place to buy them as they had a sale on and the kit cost me £714 vs the normal price of £780

The new CV driveshafts

The old driveshafts were removed from the car and the bub/vertical link assembly pulled off the shafts with a hub puller.

Using a puller to remove the hub/upright assembly from the old shaft

My bearings were in good condition so I didn't change them but did clean them and re-pack with grease.

 The bearings on GT6/Vitesse rotoflex suspension are adjusted with shims and if I had changed the bearings then I'd have had to measure the end float and reshim them which is a tricky operation. So with the existing bearings I just had to remove the shims and distance pices from the old shafts and reuse on the new shafts.

Distance Piece on new shaft, this side had no shims

I fitted the new shafts to the car without the uprights and hubs, one small issue I found is that the standard spring lifting tool got in the way and prevented the shafts from being pushed into place due to the inner CV joint being larger than the old UJ set up. So I had to jack up the end of the spring without the spring lifter just to get it into place.

Getting the bolts that hold the CV joint to the diff flanges into place was a little bit fiddly but once in place all was good. The bolts are 3/8 unf x 3/4 and they use a special lockwasher called a schnor washer.

Attaching the inner CV joint to the diff flange

I then added the upright/hub assembly (after fitting the shims/distance piece) and tightened the axle nut on the end. On one side of my car the adjustment of the bearing was correct with just a distance piece which is the one shown in the picture.

Once I had reassembled everything and connected/adjusted the handbrake I put the hand brake on and torqued the axle nut up fully to 105 ft/lb with a torque wrench. The nut is a special flange nut and once tightened the flange is distorted into a groove in the shaft to lock it into place. 

Axle Nut locked into place

The nut is a 20mm x 1.5mm pitch thread, 30mm across flats and 20mm high. I found that several Ford and VW cars use a similar nut so I bought a couple for my spares stash as they will need to be replaced for any jobs where the hub nut is removed in the future.

Suzuki off the road for a while but now fixed

So back at the beginning of May the Suzuki started misfiring on the left hand cylinder.

I went through checking the spark, changed the plugs, checked the points and points gap, checked and reset the timing and still no change. 

Then by mistake I happened to leave the fuel tap on overnight, there was a pool of fuel under the bike but when I started it the misfire went away and the bike rode OK for about 10 miles then it returned and there was fuel overflowing from the left hand carb

I therefore thought it must be an issue with the left hand carb. I replaced the float needle valve assembly and set up the float height to 27.3mm as specified in the workshop manual and Suzuki tuning data. However the misfire was still there and fuel was still overflowing. I experimented with increasing the float height bit by bit until it would stop overflowing, but then when running it it would hold back due to fuel starvation. I experimented with different float heights but the misfire was still there and I either had a carb overflow or fuel starvation. 

Then disaster struck! Where fuel had leaked on to the top of the crankcase it somehow ignited and I had a fire! I put it out very quickly by smothering it with a rag. Sadly the fire had damaged one of the oil injection lines which was now leaking and letting in bubbles of air. 

New injection lines are not available anymore and they are a rare part secondhand. I've only seen two sets of oils lines for sale in the UK since owning the bike and couldn't find any for sale at all in the UK now I need the part. I did however find a set on ebay in the US from an American motorcycle shop. Priced at $99 USD (about £80) it was about the same price as they sell for in the UK, the carriage was $16 but I decided to buy. Then I was hit with VAP applied by the UK government when I checked out on ebay so an £80 part cost me £115 with carriage and tax, ouch! The parts took a couple of weeks to arrive.

Used set of oil lines from the US

In the meantime out of desperation and replaced the condensor, I had fitted a new one last year but thought it was worth a try. The condensors are a little awkward to fit as they have a soldered but joint with a heatshrink cover on one of the wires. I'm getting a little shaky in my old age and soldering is not easy so I recruited my son to solder it for me. I tried the bike and the misfire was cured, I still had a leaky carb and the oil line was still leaking so I didn't go far but at least it was now running.

I stripped down the carb yet again and tried resetting the float height. The float unit has two floats joined together with a bar/pivot tube. I happened to check both floats this time and found that one was nearly 3 mm lower than the other, it was slightly bent out of shape, so setting to the correct float height on one side wasn't actually correct. I got hold of another float and fitted it. 

Float assembly with pivot shaft

The oil lines then arrived from the US and I fitted them, cleaning them out first with petrol injected from a syringe which also checked the function of the non return valves which they have built in. I also primed the lines with fresh two stroke oil using the syringe. I also followed the Suzuki recommended method of purging the oil lines which is to start the bike but open up the oil pump cable lever to the full throttle position, obviously this had to wait until I had refitted the carbs.

The bike now runs properly without and oil injection leak or overflowing carb. It's great to get out on it again, a shame I've missed a couple of months of motorcycle events but I took it out this morning to the Blackbushe daytime meet.

At the Blackbushe meet today

Grab Rail Added to my T500

 My 1975 T500M is painted and restored to look like a 1973 T500K. One detail that was fitted to the T500K but was omitted by Suzuki on the T500M was a rear grab rail. Although I'm not that likely to carry pillion passengers I wanted the bike to look as much like a T500K as possible so I decided to fit the missing grab rail.

They are no longer available as a new Suzuki part and I've been looking for a used one for about a year now, however they are available as a new aftermarket part made of polished stainless steel rather than chrome plated steel. So I bit the bullet and ordered one last week from classicbikeracks.co,uk. It arrived today and I fitted it this evening. It's a quality bit of kit and really looks the part.

Rear Grab rail prior to fitting

Grab Rail fitted left hand view

Grab Rail fitted right hand view

A bit of a detail job on the Suzuki

 It's the little details that make a difference to a restored vehicle if you are going for an originality look. OK so my '75 T500M has been restored to look like the earlier '73 T500K but that is a better looking colour scheme IMHO.

However, one small item that is missing that would have been present on both a T500M or T500K are reflectors on the front forks. The reflectors themselves are readily available as a pattern part, but the bracket that holds them is not. I did see one single reflector for sale on ebay last week and it had the bracket in place in the photos. This meant I could design and make a couple of brackets.

I bought a pair of reflectors, made up the brackets and mounted them on the bike. The brackets are not at all load bearing so I made them out of 1.6mm aluminium and gave them a polish with a wire brush so they look fairly similar to the originals which would have been chromed.

Bracket in place on a reflector prior to fitting

Bracket in place on a reflector prior to fitting

Fitted on the bike

Fitted on the bike

 

Another little job on the Suzuki

Just swapped out the handlebars for ones that are correct for the later model T500. Mine had early bars with a cross brace fitted by the previous owner. The new ones are the same profile and rise but without the brace. 

New Handlebars and Mirrors Fitted

Handlebars and Mirrors fitted by the previous owner

I also fitted a new pair of mirrors as the previous ones didn't match.

The bike is a '75 T500M but has been restored with the '73 T500K paintwork, both models had the bars without the brace like I've fitted. I'm trying to make the bike look as much like a T500K as I can having already previously changed the rear lamp unit for the classic Suzuki "Dogbone" rear lamp as it had been fitted with the earlier smaller round one by the former owner. It's now looking very close to a proper T500K, I just need a rear grab rail now which was fitted to the T500K but not the T500M, thats a job for the future.