Rear suspension setup/mods

[jaguar68]

Hi chaps,

I'm in the process of converting my '69 4 door over to a 5 speed 1275cc Ital engine (when the new throttle cable finally arrives ). The engine is "mildly" tuned, running a big valve 12G940 head, HIF44 with a K&N air filter, although running the standard Ital cam, but this may be changed at a later date for a Kent 276 cam at a later date.

My question is this:- the car will be driving the 'box through the standard 4.22 ratio diff and Minor rear axle. From other posts of mine regading the conversion, I'm aware that axle tramp may be a problem with the "additional" power from the 1275. I have an axle tramp bar kit, again in the garage, from an aborted hot rod project, which I intend to fit. Would it be worth fitting a rear telescopic damper kit at the same time? Once again, I have the kit languishing around gathering dust.

Any advice/suggestions will be gratefully recieved.

Regards

John

[bmcecosse]

If you can ADD the tele dampers on while retaining the lever arm dampers (filled with SAE 40 oil) then yes, since you have the kit. If it's the kit where the dampers sit across the car at 45 degrees - then it's pretty hopeless..... Dampers need to operate vertically to give of their best. Best way to control the tramp (and the power) would be 7 leaf Trav springs - but again since you have the anti-tramp kit, may as well fit it! A 4.22 final drive will be a bit low for a good 1275 - better to search out a 3.7!! Note that to change the cam 'later' is not so easy on a 1275 without taking the engine out - although it can be done.....

[jaguar68]

Thanks Roy, the damper kit is the one sold by ESM, which has a variety of holes in which to mount the dampers. I'm not sure if it's possible to mount both the original lever arms and the new dampers. On your advice in a previous post, I was going to fit the anti tramp bars, although my main focus is to get the car back on the road, I haven't been able to drive her since well before Christmas due to the 4 speed box jumping out of 4th gear. I have discovered that changing into 4th at around 25 mph, and being "cautious" with the throttle, I can get the car into 4th and keep it in gear.

I have a 3.9 ratio diff, again, kicking around in the garage, although I intent to run the car round, for the time being, on the 4.22, just to see how it all goes.

The suspension at the moment is awful, the rear seems to be incredibly harsh, although this could be down to the springs binding due to rust between the leaves. I have some new 5 leaf springs, again in the garage. Wouldn't fitting traveller springs result in the rear suspension being even stiffer? Luckily, noone goes in the rear seats, as moving the Metro seats back on the furthest seat mounting holes means that clearance is minimal, that combined with the lack of rear seatbelts.

I'm aware that changing the cam in the Ital A+ engine is a pig of a job which needs the engine to be out of the car. Had to buy the Haynes manual for the Ital to discover that. My friend has an A+ powered Mini which still has the tappet chest covers, although there are pics on the 'net of earliy '70's Spridget engines without the covers

Regards

John

[IslipMinor]

Lots of options with the rear suspension.

Do you want to lower it? If so the easiest way on a 7-leaf early car is to remove the bottom, smallest leaf, turn it upside down and put it back on to the top of the spring. Lowers and slightly softens the spring, and no need for lowering blocks. Ours has been like that since 1970!

I didn't have anti-tarmp bars with the original modified 948 engine, and it was not very good, but probably better than standard 5-leaf springs? With the 1380 I have always had anti-tramp bars and they do exactly what they are supposed to!

Rear dampers - yes vertical telescopics are 'correct' and the right way to go, but with wider wheels there is not enough room between the tyre and the inner arch, which is one option, and I did not want turrets inside the boot, as that severely compromises boot and particularly spare wheel space. So I fitted adjustable Koni's at the 'incorrect' angle up to a cross-mounted channel. On their 'full soft' setting they work very well, despite serious concerns during the restoration when they were fitted that they would not, and with no opportunity to experiment. They control 'bounce' very well, and are not harsh.

I have tried tweaking them up to about 'half hard', but that just creates harshness, so they stay at full soft.

I don't understand why you would keep the original lever arms + telescopics?

Obviously polyurethene bushes and pads throughout, plus an Ital rear anti-roll bar fitted as well on to the Minor axle casing. Had to make the brackets for the axle and the floor mounts, but other than that is it a complete Ital unit.

[jaguar68]

Richard,
I hadn’t intended in lowering the car unless there would be a genuine beneficial effect on the handling. The car is tuned mostly because I had the parts available or managed to come by them at a reasonable rate. Mostly the car will be used as a daily runner, which was the original intention when I bought the car all those many moons ago.

Although the first priority is to get the car back to a running condition, scoping out the suspension mods at the same time as changing the engine and gearbox seems like a good idea whilst the car is on axle stands etc. There’s no problem with wider wheels either, as the car is running standard saloon wheels with 145/14 tyres.

One thing that does worry me is the talk on the forum of splitting the boot floor.

Regards

John

[IslipMinor]

talk on the forum of splitting the boot floor

Been there, done that!

In its original 948 days I fitted a set of non-adjustable telescopic dampers and used the lower angled mounting brackets from an A40 Farina, then drilled a hole in the boot floor, with a reinforcing ring clamped both sides as the top mount. It seemed to survive very well for ~10 years, but when I stripped everything off before the restoration, the floor had split out slightly from each of the top mount holes. The floor was reshaped back to original and all sorted out during the subsequent restoration.

The current crossmember is a 10G (3mm or 1/8") 'U' section running the full width between the chassis rails and is fixed with 4 bolts to the floor above. Above the floor there are large washers to spread the load, and in the last 14 years and 40,000+ miles there have been no signs of cracking at all.

[jaguar68]

The "crossmember" supplied in the kit is pretty chunky, and, as you say has large diameter load spreading washers. As the car is a road car I'm hoping that the floor cracking issues won't come up.

Regards

John

[bmcecosse]

Most Minors are 'harsh' at the rear because they are effectively sitting on the bump stops! My Trav is very definitely softly sprung at the rear - until it hits the bump stops when it quickly becomes harsh in the extreme. That's with a good 1.5" cut off the top of the bump stops - and newish 7 leaf springs. The answer is to get suspension movement - so don't lower, and do cut the bump stops. Actually - AEON rear stops would be much better but I don't know if anyone makes them for a Minor - Mini ones would be too small. Colin Chapman's theory always was - long travel soft suspension with excellent damping. I suspect the ESM rear damper kit does not contain excellent Koni dampers......which is why I would keep the levers. Unfortunately there is little/no strength in the back of a Trav to add tele dampers - without going to turrets and cross bracing, which at the moment I am not prepared to do. I have some larger uprated MGB lever dampers which I intend to fit when I get a few minutes.....but meantime it's the standard dampers with heavier 40 oil - works well enough, but won't exactly give Lewis Hamilton any challenge on the corners...

[jaguar68]

Sitting at the side of the road there's a little over an inch of free space between the top of the bump stop and the plate welded to the floor (measured using the Mark 1 eyeball). There's quite a bit of evidence that the car has hit the bump stops (probably after tackling the numerous speed bumps there are around here) as the drivers side plate is nice and shiny. As suspected, the springs are probably contributing to the harshness, as they are red with rust.

[jaguar68]

Roy, you are correct, the ESM kit uses Spax Krypton gas adjustable dampers.

[bmcecosse]

Krypton gas ??? Geeeeeeeeeezzz. Well -1" of free travel explains your harsh suspension! It will be constantly on the stops. You need to raise it - and cut away the bump stops. Then the suspension will get some movement - and then you can judge if the dampers are doing the job.

[jaguar68]

I take it then that the springs are shot? It's raining here now, othrewise I'd go out and measure the free space accurately.

[bmcecosse]

Well - no, not if you are happy with 2.5" suspension travel after cutting 1.5" off the stops.

[jaguar68]

What is the standard amount of free space from the top of the bump stop to the chassis? How do you cut down and reshape the bump stop? With a hacksaw?

Regards

John

[bmcecosse]

Sorry - no idea what was 'standard' -and yes - hacksaw....wet the blade as you go.

[bmcecosse]

I gather that the JLH vertical damper conversion is specifically designed to fit without fouling the wheel.
" Our turreted damper kit is specifically designed to be fitted below the boot floor boards in all of the Minor variants.
You can also still fit a standard road wheel and tyre in the original position. " JLH can supply photos if anyone is interested. The conversion is featured on their website http://www.jlhmorrisminors.co.uk/store/ ... roductId=6

[jaguar68]

Thing is, I already have the ESM kit and really can't justify the cost of the JLH kit at this point in time, even if I could sell the kit I have. Unfortunately I can't do the welding required myself.

I started to ntotal up the cost of fitting the 1275 engine and 5 speed 'box. I stopped counting when I got to nearly £1700.

[bmcecosse]

Good grief......hope it's all worth the cost..........

[jaguar68]

Thats for absolutely everything, the 5 speed 'box and fitting kit come to about £1000 on their own, factor in £350 (ish) for a decent 1275 engine, £300 ish for a LCB exhaust and carb..........

[chrisryder]

I admit to trimming the bump stops myself, but surely they're that length for a reason?

Someone must have arrived at their height with some logic... not just 'that'll do'?

The bump stops are quite critical with my wide wheels to keep the tyres from catching the wings. But in standard trim, the wheels don't get close to anything really.

How come the rears were made too tall originally?! Could it have been to stop the rear dampers reaching their limits?