Lotus Elan

Bill's 26S

PostPost by: CBUEB1771 » Wed Mar 07, 2018 11:59 pm

Bill,
There is another engine mount supplier I just remembered, Milton Race, who specialize in Anglia 105E competition parts.
http://www.miltonrace.co.uk
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PostPost by: bill308 » Fri Jun 01, 2018 9:51 pm

Hi Russ, thanks for the additional motor mount info.

I resolved the bonnet height to cam cover clearance issue since my last post. The engine needs to be lowered about 5/16 inch to allow 1/8 inch clearance with the underside of the bonnet. The start position was based upon the OEM style HD mount (Stromberg style-lower on carb side than the Weber setup).

dsc01979d.jpg and
The cam cover contacts the bonnet with the OEM style motor mounts.


I managed to get my hands on a set of Kelvedon street (big bushing) motor mounts from Russ, thank you Russ, and tried to install them on the exhaust side of the engine, but with links to accommodate a bushing height, 1/4 inch lower than OEM Stromberg HD mounts, to rectify bonnet clearance issues. The bushing carrier easily bolted to the block. The chassis is flexible enough in the motor mount plane that it is possible to force fit the Kelsport mounts by spreading the pre stressing the chassis about 1/4 inch, not a good thing. This motor mount kit does not work for me as is. It didn’t fit on my chassis/engine combination where OEM spec mounts fit fine. Dimensions are different. The Kelvedon stack of 2 pieces was longer than the TTR HD mounts they replaced. The best solution for me was to fabricate replacement chassis to bushing links that could work in the confined space. Further, the carb side Kelsport links had two right angle bends each and the rear one needed to pass between the carb side chassis motor mount bracket and the Kelsport motor mounted bushing carrier.

dsc02055d.jpg and
This is my first attempt to fabricate the carb side motor mount links. Only the front link is shown. A similar rear Z-link, from the front face of the chassis mount to the bushing carrier will not fit due to clearance issues.


This design would not work for the back side link as there was a maximum of only 0.050 inches clearance between the chassis motor mount bracket and the engine mounted bushing carrier. The other issue was the engine still needed to go down, about 1/4 inch at this location.
So, I decided to change the design of the carb side links and replace them with non-bent parallel links, anchored by large, stiff standoffs. I need to get the geometry right and my first attempt with this design works pretty good, but a bit heavy. The back side spacer/standoff can be slimmed down about 1/8 inch to thickness of 3/8 inch. I plan to make the final link pieces out of 416 (marine grade) stainless. This mount is much stiffer without the bends, so 0.075 thick should be fine. The Kelsport bent links appear to be 2 mm (0.080 inches) mild steel with a passivation coating.

dsc02056d.jpg and
This is my second attempt to fabricate the carb side motor mount links. Instead of a Z-shaped section, they are just flat plates with appropriately space holes.


dsc02064d.jpg and
This is my second attempt to fabricate the exhaust side motor mount links. The location of one of the bends needs to be adjusted to better fit the bushing carrier.


The interesting question is whether it makes sense to lower the engine even more for a lower CG and what effect this will have on the exhaust system height and rocking clearance between the tranny and the chassis bulkhead, near the speedometer sender.

The good news now is that the body is at the original fitted height, the bonnet clears the cam cover, and the bonnet perimeter fits the surrounding bodywork with the air box in its installed position. I may wait, until I next take the body off, to fabricate the final motor mount pieces. There may yet be some clearance issues that need to be discovered and refined.

dsc02070d.jpg and
The result of the new motor mount is the back of the engine is lowered about 1/8 inch. The front of the engine, where it previously contacted the bonnet, is lowered about 1/4 inch, so there is now about 1/8 clearance.


Bill
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PostPost by: CBUEB1771 » Sat Jun 02, 2018 1:55 am

Bill,

Good to see you are making progress. I am pleased to hear that at least the Metalastic bush holders bolted to your block easily. They weren't that way when I first received them. I spent a bit of time to determine the minimum amount to open the bolt holes with the right reamer to get them to fit easily without excessive clearance. As you and I discussed the likely problem was in punching the bolt holes in flat stock before the individual component parts were formed and then welded together. I don't recall if we ever talked about possible problems with the width of your block across the engine mount bolting planes. I am sure that Kelvedon designed the pieces around a standard Twin Cam block. The later castings, 711, AX and others are wider in this dimension.

I am now 30 days from going onto part time status at work and I am looking forward to spending some real time to get the +2 and Elite back together. Perhaps later in the year we can find a time for me to drive down to Connecticut and take a look at your project. I have been spending some time on making the Voight T9 conversion work a bit better.

Russ
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PostPost by: TomR » Tue Jun 05, 2018 1:40 pm

Perhaps my car will be running by then and we can all get together :D

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PostPost by: bill308 » Wed Jun 06, 2018 4:09 pm

Hi Russ,

It's about time to decided to wind down on work. :D

You're more then welcome to stop by anytime. Do you sail by chance?

I think my block width is closely comparable with the standard twincam. The TTR heavy duty mounts fit well side to side, they just held the engine too high for my valve cover to clear the underside of the bonnet.

What refinements are you considering for your Voights setup?

Hi Tom,

Let me know if you need any help getting your car up and running. I'd love for all of us to get together sometime this summer.

Bill
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PostPost by: CBUEB1771 » Wed Jun 06, 2018 5:22 pm

Hello Bill,

I will start by completely stripping the Voight box for inspection. I spent a lot of time taking casting flash off of the outside of the tail housing. Therefore I expect to find plenty of the same on the inside where nobody thinks the buyer will ever look. I will rebuild with a Quaife aluminum main case and top cover and adapt a Quaife short-throw gear lever. I think I can modify the Quaife lever to look exactly like the lever that Lotus installed on the +2 and therefore use the same boot. I will also make a more tidy mount to the chassis using the isolation mount from VibraTechnics (image below). This mount will give me more clearance to the frame (meaning less to trim from the frame). I will also be taking a hard look at the shift lever detent/travel limiting device that Voight installs in the top cover (now relocated to the tail housing). His parts are a bit agricultural in execution.

As for sailing, it has been a long time. I went through a youth sailing program when I was a kid and my father was pretty good at it. I still know to put my head down and how to work the jib sheets after I hear "ready about". I used to sail with a friend who had a very fine wooden hulled boat from the 1930s which he kept between Mystic and Groton, Connecticut. That was work, he insisted on winding the jib sheets into Flemish coils after tacking, even if we were going to tack again in 60 seconds. He also owned a DB4.
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PostPost by: bill308 » Wed Jun 06, 2018 6:14 pm

Hi Russ,

I do like the VibraTecnics mount. It looks like a more compact mount height wise. If this is the case, I am interested too. A little lower mount would give a little more wiggle room for the speedo angle drive.

The Mystic and Groton area is a great place to sail. I do Lightning class one design racing, but used to crew on an Ensign that sailed the Mystic to Groton area. Several fleets there and very picturesque. Some of the races went around Fishers Island. My friend Eric, an ex Elan racer (S1 with Brian Hart motor) has a really nice Brit Chance 41 that he sails out of Westport, CT. If interested, maybe we can do a Lotus group day sail?

Bill
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PostPost by: bill308 » Tue Jun 19, 2018 3:07 am

The engine crankshaft is now centered and the engine is at an acceptable height, so it’s back to the pedal box.

dsc02134d.jpg and
A center line was stretched over the body and a plumb bob dropped. The crank is centered.


Initial fitment of the pedal box proved to be a little too high at the front panel and not quite horizontal side to side. Holes that were previously drilled for the master cylinders and pedal box through studs, needed to be slotted to get a better fit. Once everything was the way I wanted it, I added material to the foot well panel to clean things up. The first step was to glass in crescents at the tops of master cylinder through holes.

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You can see the material added to the master cylinder holes in this photo. The through stud holes have not yet been addressed. Note the pedal box assembly was not level side to side initially, thus the more material was added to the hole closest to the steering column.


The next step was to reduce the slot sizes for the through studs to ensure positive placement of the pedal box. Reasonably tight holes assure the pedal box will go back into the proper position after paint. The last step was to trim the master cylinder holes so that there was clearance between the master cylinder boot and the sandwiched fiberglass panel. This was accomplished using sticky back paper over a length of aluminum tube I had lying around. Master cylinder boot fit into the steel bracket holes, either side of the foot well panel, is very tight on the clutch master cylinder. This end cylinder is supported by little more than half a crescent of the forward side steel doubbler plate. When the retaining nuts are tightened, this master cylinder cocks a few degrees, which I’d like to eliminate. I will try to build up the bed for the minimally supported side.

dsc02130d.jpg and
A minimum outline hole was cut in the left (port) front wheel well to accommodate the clutch master cylinder. The hole will be enlarged and trimmed to facilitate a closing blister on the wheel side. Note the base of the master cylinder is not seated at this time. A metal plate extends from the engine side to just past the retaining studs. I want to fill the gap at the mounting base.


I’m not sure now if I need to notch the carbon fiber beam running under the bottom of the pedal box. I’m now thinking that it may be ok. Full depression of the accelerator pedal bottoms out on the beam face, about 3.75 inches from the face of the wheel well panel. The pedals on my S2 will depress more. Still, this may be acceptable as the pedals travel through a vertical plane before stopping. The push rod on the slave cylinder actually seems a little long, but without a clevis and pin on hand, I can’t tell for sure. It may need to be shortened. I’m also not sure what the full stroke measures on the master cylinders. I haven’t tried to fit the balance beam assemble yet and I’m not sure what the relationship should be between the brake pedal and the accelerator pedal heights, assuming heal/toeing is desirable.

dsc02124d.jpg and
All three pedals are positioned as far forward as possible in this picture. The accelerator pedal is about 3.75 inches from the front panel of the foot well. The other pedals are not yet attached to their respective master cylinders but a clevis and pint for the clutch, and a balance beam for the brake pedal.


The other reason for addressing the pedal box and outer master cylinder at this time is to check clearance with the wheels and tires. To this end, I took delivery of a pair of Toyo RA1’s in a 205/60R13 size. I had 2 tires mounted on 26R Kelsport sourced, center lock wheels. These wheels are made of cast aluminum in classic 26R style. I don’t think they are particularly light or strong, but should be fine for a street car. I have open center, matching knock off spinners, also made of aluminum, somewhere in my inventory, but for now, the US style octagon nuts work for fitting purposes.

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The left front KO wheel is shown in natural cast aluminum with an RA1 tire fitted. You can just see the clutch master cylinder at the 2 o'clock wheel position. I expect the tire will contact the anti roll bar a full lock before it contacts the master cylinder blister. S3-S4 rack stops plus 0.120 inches will be fitted to my new rack, then trimmed in situ to just prevent contact with the anti roll bar which has not yet been fitted.


Initially, I set the ride height with the longest leg of the 26R lower front wishbones horizontal. This setting didn’t work with my wheel and tire combination. I then set the inner and outer lower wishbone pivots on a level line. That is the setting used for these pictures and I now believe it is correct. The previous setting left almost no room for bump travel. Even with this setting, wheel travel will have to be checked. All suspension geometry will have to be reset. The 26R lower wishbones are fixed in length, but the uppers are adjustable. The other thing is I’m having a replacement rack assembly rebuilt with new components. The special rack is ½ inch shorter, which moves the inboard tie rod pivots ¼ inch more inboard per side, but minimizes bump steer effects over a much larger range of suspension travel.

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This photo shows the relative position of the lower 26R wishbone in the static position. While not readily apparent, the inner an outer pivots are at the same elevation. The suspension is supported by a threaded rod for convenience.


You still have to set the rack height as usual, but toe change will be less or even eliminated altogether over a much larger range of travel than with the standard length rack. I expect the new rack to be shipped by DBE at the end of June.
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PostPost by: nmauduit » Tue Jun 19, 2018 12:56 pm

bill308 wrote:Initially, I set the ride height with the longest leg of the 26R lower front wishbones horizontal. This setting didn’t work with my wheel and tire combination.


Than you for your post. Would you elaborate on the rationale for your front wishbone setting? I believe the bent ones are for lowering the body, while keeping the neutral position (longest arm horizontal) symetrical up and down. If you want to keep the setting as pictured (higher body, i.e. outer holes aligned horizontally), would you not be better off with straight arms?
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PostPost by: Davidb » Tue Jun 19, 2018 5:20 pm

I second nmaudit on this. With the two mounting points -chassis and lower pivot-at the same heights there is no point in having 'cranked' arms. Especially concerned since I am considering fitting 26R lower A arms to my car to lower the front. However, I have height adjustable spring perches so do I need them? Anybody checked the geometry and can comment?
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PostPost by: bill308 » Wed Jun 20, 2018 4:29 pm

Hi nmauduit and Davidb.

Thanks for your input. My rationale for the current setting is to allow room for tire bump travel. Both my front and rear spring purchases are adjustable for height so I have some latitude as to where I set them.
I think as long as the distance between the inboard and outboard pivot centers remains fixed, the shape of the in between member has does not affect wheel/tire geometry, only the travel range. For my case, there may not be an advantage with the cranked lowers. What the cranked lowers offer is a workaround for a front shock assembly that that may not compress enough at full bump. If the ride height is reduced at the front, a corresponding amount of shock travel is used up. The cranked design restores this “used up” travel with a lower shock attachment point, nothing more IMHO.

How much suspension travel does one need? If one is racing on relatively smooth surfaces, probably not much travel is necessary or even desirable. I suspect suspension travel is very limited for this case? If one is driving on rough secondary roads, especially with pot holes and speed bumps, a lot more suspension travel and a higher ride height is likely desirable. It is my understanding, Colin et al, appreciated this and provided the Elan with generous suspension travel, modest spring rates, and firm damping. My plan is to strike a balance between the road/race applications, or at least provide a reasonably painless means of adjustment between them. To this end, I will fit TTR’s fast road setup, which is adjustable for height and damping. I’ve had a car set on the shelf for a number of years now, so it’s not likely the latest and greatest, but it should be an acceptable compromise and a good place to start and evaluate.

The question remains, how much bump and droop do I need? This will dictate the ride height to a large degree and the resulting geometry. Your further thoughts are appreciated.

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PostPost by: Davidb » Wed Jun 20, 2018 5:15 pm

Bill, thanks for the response. Do you think that part of the problem may be using 205/60 tires? That is very wide for a street Elan. I use 175/70x13 on 6" rims and I find they are plenty wide enough and the diameter is the same as the original tires. (And they look fine). As regards suspension movement I would think 3" of bump should be more than enough...

Could I ask you to weigh one of the Kelsport 26R wheels you have? I would like to compare weights with the 6x13 Revolutions that I use. (9.25lbs).

Looking at the workshop manual illustration of the front suspension it is easy to see why Lotus chose the 'cranked' lower arms to lower the suspension. Are there any geometry geniuses out there who can tell if that is preferable to lowering the spring seat?
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PostPost by: rgh0 » Thu Jun 21, 2018 11:04 am

bill308 wrote:Hi nmauduit and Davidb.

......

The question remains, how much bump and droop do I need? This will dictate the ride height to a large degree and the resulting geometry. Your further thoughts are appreciated.

Bill


A suspension expert I know who worked for Koni and who I used to race against told me that you need around 50 mm minimum bump and droop travel for a road going sports car to handle well on vary degrees of road smoothness and have an acceptable ride.

On a car designed for smooth racing tracks with a stiff suspension you could have less.

The Elan and Plus 2 in standard form had about 75mm

The standard Elan had

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PostPost by: bill308 » Fri Jun 22, 2018 2:01 am

Hi Davidb.
I just weighed one of my unmounted wheels on an old bathroom scale. This scale read 5 lbs with nothing on it and 17 lbs with the wheel weight, so 12 lbs +/- 1lb I’m guessing.

Yes, I think the tire size is an issue. My friend Eric runs this size on his ex-racer without issue. I do not know if he uses 26R lower wishbones as I do and I note his suspension is about as stiff as I would accept for street car.
Hi Rohan
Thanks for your input. Do you run 26R lowers?
dsc02149d.jpg and
This photo shows what the wheel/tire looks like with the lower wishbone pivots at the same height. The bottom edge of the rim has a height of about 27-1/4 inches.

dsc02151d.jpg and
The long leg of the lower wishbone is horizontal in this photo.

dsc02152d.jpg and
This is what the wheel/tire looks like when the long leg of the lower wishbone is horizontal. The bottom edge of the rim is at the 28-3/8 inch height.

dsc02154d.jpg and
This photo shows the wishbone at full bump, limited by light contact with the underside of the wheel flair. Contact just allows movement of a piece of paper feeler gauge with the wheel/tire aligned dead ahead.

dsc02153d.jpg and
This photo shows the wheel with first contact with the underside of the flair, at the notch. The paper feeler gauge shows the area of first contact. The bottom edge of the rim is now at a height of 30-¼ inches. This reflects a difference of 1-7/8 inches from the horizontal leg case and a difference of 3 inches from the level inboard/outboard pivot case. These travel dimensions are consistent with Rohan’s 50mm track and 75mm road requirements. Thanks for that input Rohan.

dsc02160d.jpg and
This photo shows the approximate area of first contact with the tires in the straight ahead position. If the tire could be moved inboard, additional bump space may be available. I need to inspect this area a little more closely but it appears the edge of the tread pattern is the limiting feature.

What to do? Maybe I can set the suspension height to the level wishbone setting and live with the 1-7/8 bump travel. I guess I need to check first contact with the wheels/tires throughout the lock range and see what that looks like. I also need to look at both sides closely. I do prefer the look at the lower (level wishbone) ride height, but bump travel seems insufficient.
I could go with TTR recommended Avon tire in a 185/70R13 size or a smaller RA1 in a 185/60/R13 size? Other work arounds might be to look at moving the wheel/tire inboard ¼ inch per side by some means. Maybe adjustable lowers would allow me to bring the wheel/tire inboard to increase room for bump? I could set the front ride height to the horizontal pivot height which would give me 3 inches of travel before contact for road use. This setting is equivalent to the stock Elan ride height. A setting for occasional track use would be to set the long leg horizontal and dial up the damping, or maybe something in between?
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PostPost by: rgh0 » Fri Jun 22, 2018 10:24 am

Hi Bill

I use the straight lower arms. But most of my lowering comes from running 175 / 60 x 13 tyres so i have sufficient travel of around 50mm with the TTR front shocks and 200 lb front springs. My Elan is drive-able on the road but really to hard for routine road use.

With higher profile tyres you need to have the cranked arms to lower the car and still have sufficient travel to bump in the shocks but you run up against to wheel clearance issues to the top inside of the of the wheel well. You will find that the wheel hits the body at full opposite lock with bump compression of the suspension with body roll. I find that even with my smaller tyres and have the cracks to prove it !

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