Rotoflexes

[jcocking]

Randall Fehr, Tim Mullen, P-O Hakansson, and et-al:

Please review and provide comments on this tech write-up concerning Rotoflex
replacements. This write-up was created by combining your comments from a
previous thread. I have not had the pleasure of replacing mine yet, but
have four of them in a box waiting. thanks jeff

The overall installation of the Rotoflex Donuts are:
1. Install the donuts to the half-shafts
2. Mount to the inboard side/differential
3. Mount outboard side

Installation tips:
1. Keep the half-shafts in a parallel position.
2. Use hose clamps to expand and contract the diameter as necessary (I find
it's actually easier than with the fixed diameter band.) Initially tighten
the hose clamp as tight as can be done by hand. Check for size by fitting
the shafts to the donuts with the correct fastener. (2 two inch hose clamps
strung together work fine.)
3. Use at least grade 6 bolts or better.
4. The use of a pilot bolt, to protect the threads on the long term bolts,
is recommended.
5. Placing items in the trunk to assist loading down the car will help.
(Comments of 200kg of fertilizer)
6. Remember to be safe. You will be under a vehicle with the suspension
system in a load condition. This is potentially dangerous.

Instructions:
1. Mount the donuts on the halfshafts and tighten.
2. Install the half-shaft/donut to the differential/inboard.
3. Now the fun part, the outboard side with the brake disc and hub fork.
Put the body high on stands. With the rear suspension fully assembled except
driveshaft & rotoflexes, place a trolley (rolling) jack under the strut
housing from the side (not the rear) and jack up to near ride height (so
driveshaft will be nearly level with ground). Hang brake disc over stub axle
fingers, don't bolt up yet (but now is good time to check rotor runout with
temporary short bolts).
4. Some levering with a big screwdriver or pry bar may be required. Be sure
you get rotoflexes and bolts in correct orientation (see manual).
5. Install a bolt such that it passes thru the "lowest" hole in the Rotoflex
and the "highest" hole on the outboard stub axle. Now it gets harder...
Rotate the shaft and axle so that next two holes line up and install another
bolt. You will notice that the Rotoflex doesn't really want to "flex" - this
makes it difficult to install the bolt - you just have to work at it. Then
repeat for the last bolt. The hose clamp comes in handy during the last
stages, since you can use the clamp to "adjust" the diameter of the
Rotoflex. It takes a lot of effort, but it will just fall into place...By
allowing the wheel to have movement, it will be easier to rotate the
outboard mounting locations.

And the last parting comments:

I'd rather change U-joints on a drive shaft any day. The Rotoflexes are a
huge pain in the a**!!!

[jcocking]

I have a few comments on this.

1) I never use a "hydraulic" jack like a roller jack to lift the
wheel, use a screw jack, it will not leak down. I use the factory
supplied tire changing jack. With the car up on four jack stands lift
the rear wheel until the frame just leaves the surface of the jack
stand (maybe 2 or Hmm), this puts the wheel at almost exactly the
right height (YMMV) for the final assembly. As you raise the axle you
need to "rotate" the drive shafts and the wheel to get the half shaft
into a mating position (interleaved between the other bolts).No
fertilizer required.

2) I found it was easier to assemble the donut to the outer drive
shaft/brake first, then to connect the half shaft to the outer donut
last. You can do the outer donut/brake while the stuff is still on the
bench, much easier than while laying on your back (one of the lotus
positions

3) you need 18" of band clamps. I used a 4" and a 2", try to get the
longest one you can to reduce the number of joints since the band
clamp joint may not rotate past some of the obstructions (rear
calliper).

P.S I would rather pull the engine out than change the donuts. Donuts
are possibly one of the most horrible jobs I have ever done (actually
changing the power steering belt in my NX2000 was worse). But to be
perfectly honest it was MUCH easier the second time after I knew what
I was doing.

--
Lawrence King Ottawa Ontario Canada

[jimfixit]

Had mine converted to CV joints 13 years ago. Haven't had any problems what
so ever. When I bought my elan 16 years ago, The PO blew up a rotoflex and
took out the ebrake and punched a hole in the body as well as bent the rear
tower. I replaced roto's once and that was enough. Back then the
conversion cost $850.00 and it was every cent worth it.
jimbo

[abstamaria]

A suggestion on installing those pesky Rotoflexes.

What about disengaging the strut from the lower A arm and the upper mount
(Lotocone?), installing the Rotoflexes on the now straight shaft, and then
reinstalling the A arms and the strut to the upper damper mount?

Regards,

Andres
Manila

[Citromike]

Ditto to Jimfixit.

My Elan's PO paid for nice looking CV joints in boots that have given no
trouble at all, even when I foolishly dropped the clutch and did a 200 foot
burnout the other day. I didn't mean to, honest, it just got away from me ...

Mike Roeder
[email protected]

[jcocking]

Jeff,
I saw your draft tech sheet, and wondered if I could add a few
details. My notes concern the Elan +2, but I think they also apply to the
baby Elan.
As prelim information, remember that:-

i)The metal bosses are offset in the rubber, three each way, and it is the
HIGH bosses on each face that contact the drive shaft flanges.
ii)When fitting bolts, their heads must be contact with the LOW bosses in
the couplings. The exception to this is the bolts which secure the brake
disc and coupling to both the outboard and intermediate drive shafts, when
all bolt heads are towards the wheel.
iii)The three bolts through the brake disc are 3.25inches by 7/16 UNF, and
are longer than the other bolts.

[rodbean]

"A. Sta. Maria" wrote:

A suggestion on installing those pesky Rotoflexes.

What about disengaging the strut from the lower A arm and the upper mount
(Lotocone?), installing the Rotoflexes on the now straight shaft, and then
reinstalling the A arms and the strut to the upper damper mount?

Andres,

If you ever try this, you won't stop cursing for a week! What happens is,
you find that the strut top and bottom connections were instrumental
(essential) in locating everything. The combination of the spring
wanting to
be fully extended and four donuts wanting to be in their free state (instead
of preloaded as they will be once installed) requires some solid things to
lever that energy against. Imagine the strut disconnected as this
battle is
fought.

I'm sure Randall will explain it better. I can only tell you it doesn't feel
good.

Rod

[types26/36]

My comments inserted between asterisks ***. -Randall

The overall installation of the Rotoflex Donuts are:
1. Install the donuts to the half-shafts
2. Mount to the inboard side/differential
3. Mount outboard side

Installation tips:

***
Wait! While rotoflexes are out, take the opportunity to check condition of
differential output bearings and hub bearings. Rotate by hand and listen
for dry rubbing sound or roughness. If in doubt, replace the bearings.
***

1. Keep the half-shafts in a parallel position.
2. Use hose clamps to expand and contract the diameter as necessary (I find
it's actually easier than with the fixed diameter band.) Initially tighten
the hose clamp as tight as can be done by hand. Check for size by fitting
the shafts to the donuts with the correct fastener. (2 two inch hose clamps
strung together work fine.)
3. Use at least grade 6 bolts or better.

***
Not sure there is a grade 6. If this means bolts with six marks on head,
that indicates grade 8. Original Lotus bolts appear to be grade 5 or
equivalent. Best alternative when new bolts are needed is military/aircraft
AN spec, mainly because they have longer unthreaded portion than grade 5 or
8. Original Lotus bolts were 3.25 inch for the six passing through brake
rotor, and 2.75 inch for the 18 remaining bolts (with 2.12 inch
non-threaded length as shown in the shop manual). Nuts are torqued to 35-40
ft lbs.
***

4. The use of a pilot bolt, to protect the threads on the long term bolts,
is recommended.
5. Placing items in the trunk to assist loading down the car will help.
(Comments of 200kg of fertilizer)
6. Remember to be safe. You will be under a vehicle with the suspension
system in a load condition. This is potentially dangerous.

Instructions:
1. Mount the donuts on the halfshafts and tighten.
2. Install the half-shaft/donut to the differential/inboard.
3. Now the fun part, the outboard side with the brake disc and hub fork.
Put the body high on stands. With the rear suspension fully assembled except
driveshaft & rotoflexes, place a trolley (rolling) jack under the strut
housing from the side (not the rear) and jack up to near ride height (so
driveshaft will be nearly level with ground). Hang brake disc over stub axle
fingers, don't bolt up yet (but now is good time to check rotor runout with
temporary short bolts).
4. Some levering with a big screwdriver or pry bar may be required. Be sure
you get rotoflexes and bolts in correct orientation (see manual).
5. Install a bolt such that it passes thru the "lowest" hole in the Rotoflex
and the "highest" hole on the outboard stub axle. Now it gets harder...
Rotate the shaft and axle so that next two holes line up and install another
bolt.

***
This bolt is installed head outboard, so one must orient the rotor/stub
axle finger so that the bolt can be slipped between the brake caliper
mounting boss and the strut tube - the valley at the top of the hub
carrier. Clearance is tight - rotate bolt head to pass.
***

You will notice that the Rotoflex doesn't really want to "flex" - this
makes it difficult to install the bolt - you just have to work at it. Then
repeat for the last bolt. The hose clamp comes in handy during the last
stages, since you can use the clamp to "adjust" the diameter of the
Rotoflex. It takes a lot of effort, but it will just fall into place...By
allowing the wheel to have movement, it will be easier to rotate the
outboard mounting locations.