Ride Height

[cact1972]

What is the difference in ride height between standard and GTE?

[monkeynuts]

i believe the gt/e is about 50mm lower and alot stiffer

[Mantaray80]

I think it's more like 30mm. Stiffer springs and Bilstein gas shocks.

[andyc]

Also different stub axels to the non GTE cars

Andy

[eldoradoCoupe]

Whats the difference in the stub axles, are they interchangeable ok ?

[eldoradoCoupe]

Bump, interested to hear the difference in stub axles as I have spare set of unknown ones which were destined for my GTE. Anyone know ?

Cheers

[andyc]

I beleive the stub is at a slightly different angle to allow ffor a different camber as the suspension is lower on the GTE

GTE stubs are very hard to find new as well

Cheers

Andy

[opel2000]

I beleive the stub is at a slightly different angle to allow ffor a different camber as the suspension is lower on the GTE

Yes definate difference between the stub axles, seen this in person when giving a 1.8 stub axle to go onto a gte. 2 totally different items.

Edited November 11, 2010 by opel2000

[Christ]

Yes definate difference between the stub axles, seen this in person when giving a 1.8 stub axle to go onto a gte. 2 totally different items.

[cact1972]

Christ

Which ones which in your pic?

[Kevin Abbott]

Good info mate

Top ball joint hole in a different place altering camber and track rod end looks different too altering steering angle?

Bloody hell i need to start matching pairs up now

[MANTAMAN]

I have a bit of knowledge of suspension geometery and this has opened a real can of worms.

The top view of the two uprights show the stearings arms are different lengths, this i dont understand, the stearing arms where the trackrod ends attach have thier length governed by the need to maintain the 'Ackerman angles' during turns, thier length and position can be arrived at by drawing a line from the 'stearing angle inclination' (pivot axis of front uprigths) and the center of the rear axle,the trackrod end pivot falling on this line,or in the case of the Manta where the stearing rack is infront of the of the front suspension the imaginary line is projected forward at the same angle as it projects rearwards.

This means that as all Manta 'B's' have the same length wheelbase then the stearing arm lengths have to be the same, infact if there was a need for the stearing arms to be differnt lengths then the stearing rack castings and stearing column links would have to be differnt to match the differnt distances forward either respective arms are.

DO NOT CONFUSE STEARING ANGLE INCLINATION (king pin angle as was) WITH CAMBER ANGLE

The stearing angle inclincation is governed by the wheel and tire which in turn is govenerd by the stub axle bearings, the bearings have got to have the correct force exerted on the them,not too much on either the inner or outer bearing, this is why you have offset of the hub face/wheel face which on a Manta B is 30mm outboard of the wheel center line. (the ET30 bit of wheel measurements)

The stearing angle inclination is an imaginary line drawn through the top and bottom pivots on the stub axle, this line extended downwards should fall right in the middle of the tire contact patch so as the wheel is steared it pivots on a single point,if the line does not fall through the center of the tire contact patch the when the wheel is steared it will swing through an arc, this means that during stearing one wheel will be infront of the axle line and the other behind,this 'stagger' in wheelbase lengths side to side on a car can cause other problems such as pulling to one side.

There is a need to have different stearing angle inclination if there are different wheel and tire diameters fitted to a vehicle,the larger the overall wheel and tire diameter the shallower the angle the stearing angle inclination has to be so as the imaginary line meets the road in the middle of the contact patch, so if a Manta 1800 and Manta GTE have different overall wheel and tire diameters than the uprights will have to have different stearing angle inclination, though i suspect that if they do then such a variation would be hard to judge by sight as it would not be many degrees.

WHEEL CAMBER

This is how much a wheel leans in or out,top leaning out = positive camber,top leaning in = negative camber, the wheels vertical center line and the stearing angle inclination are fixed relative to each other so camber is altered by lengthening or shortening either the top or bottom suspension arms,shorten the top arm and the wheel has more nagative camber,which can benifit handling in performance driving.

So if there are different wheel and tire sizes between Manta's needing different stearing angle inclinations then at the least the top suspension arms will also have to be different lengths to maintain the correct camber angles.

CASTOR ANGLE

This is exactly the same thing as the wheels on a shopping trolly,back to the imaginary line that is the stearing angle inclination,if the top pivot is ahead of the lower pivot then there is castor on that wheel,it is this that pulls the wheels back to straight ahead when you let go of the stearing wheel.Apparently Manta's handle well with alot of castor but this makes the stearing very heavy,thank goodness for Corsa power stearing conversions!

Now having said all of the above the photo clearly shows a large difference between stearing arm lengths (where the trackrod ends attach) so what on earth is going on? is one from an A series, one from a B series? this is a subject that needs investigation, it'll effect all of us who 'tinker' with our Manta's.

[xecoupe]

That's what I love about this club, there are so many people here who have a wealth of knowledge. Shame I am a Carpenter not a mechanic

[cam.in.head]

sorry to add more confusion ! many years back i obtained an axle from a nearly new accident damaged manta.. this showed no signs of ever been taken apart & was from a 1.8 model.. i fitted this to my cam in head engined cav mk1 forgetting about it being from a 1.8.hence the front end was much too low.springs were changed for the correct ones to bring height back correct but it never seemed to corner quite right.it had been perfect with its original axle.i swapped over the parts until steering was back to normal this was after changing the stub axles. the stub axles from the 1.8 car were like the ones in the right picture with regard to track rod end holes. my original cav ones & my stock cav ones were all like the left hand picture. !!!!!

[Christ]

Christ

Which ones which in your pic?

no idea

....stuff....

...this is a subject that needs investigation, it'll effect all of us who 'tinker' with our Manta's.

yes, or perhaps just check your stub axles match when replacing them

[opel2000]

Cor Blimey, just woke up on the computer desk, Yaaawn! Ah now I remember, I was half way through Mantaman's post last night only fkking with you Ian

Anyway I have a complete 1.8 Manta coupe crossmember on my B can't see any reason why this should be any issue for me whatsoever........... Except I'm now thinking that it may actually have been the one that supplied Christ's Stub axle, only hope I fitted a matching stub axle back in place

Edited November 13, 2010 by opel2000

[Retro Power]

Mmm. Interesting - never had the two side-by-side like that before. The GTE would be the ne on the right I's say. They've given it a touch more caster and quicker steering. I don't recall the rack position changing on the GTE, so presumably they've just not worried about the very slight change in akerman angle.

[upk]

they are both b series as the a series steering arm was a seperate bolt on to stub axle component.

looks to me like all this is doing is changing steering respone, the gte if the nearer to the stub will react slightly quicker and feel slightly heavier!!

if you had these mixed on a car i doubt you would realise the differance !

kev

[Christ]

if you had these mixed on a car i doubt you would realise the differance !

kev

I could, never felt right but couldn't figure out what it was. much better with a matching pair

[MANTAMAN]

Cam-in-head may have the answer, one stub axel is from a MK 1 Cav and the other from a Manta( B, 1800, GTE etc) after all the MK 1 Cav's were the only models of this group that in part were built at Luton so may have aquired curious variations.

Looking at the Manta suspension the other night, in particular the possibilities for altering the geometery, Manta's have built into the front suspension means of adjusting the Castor angle and possibly the Camber angle.

The Castor angle can be altered by changing the washer spacing on the inner end pivot's of the top suspension arm.

Camber angle, the top pivot that goes into the stub axle is held onto the top suspension arm by two bolts which are NOT on the same center line as pivot, Did Opels ever make top pivots with the bolts offset at different distances from the pivot center line so as the camber angle could be changed?

Many people go to alot of expense buying performance springs and dampers to improve the handling of thier Manta's, there also may be gains to be had by fine tuning the front suspension angles.

[cact1972]

Wow! From a simple question we have had a full geometry lesson!!!

Great work guys !!!! ;-)

[cam.in.head]

Cam-in-head may have the answer, one stub axel is from a MK 1 Cav and the other from a Manta( B, 1800, GTE etc) after all the MK 1 Cav's were the only models of this group that in part were built at Luton so may have aquired curious variations.

Looking at the Manta suspension the other night, in particular the possibilities for altering the geometery, Manta's have built into the front suspension means of adjusting the Castor angle and possibly the Camber angle.

The Castor angle can be altered by changing the washer spacing on the inner end pivot's of the top suspension arm.

Camber angle, the top pivot that goes into the stub axle is held onto the top suspension arm by two bolts which are NOT on the same center line as pivot, Did Opels ever make top pivots with the bolts offset at different distances from the pivot center line so as the camber angle could be changed?

Many people go to alot of expense buying performance springs and dampers to improve the handling of thier Manta's, there also may be gains to be had by fine tuning the front suspension angles.

yeah its a subject that i beleive i have seen mentioned on here a couple of years back. someone was questioning the correct stub axle to use as they had noticed the differing track rod end positions. all i can say for 100% definate is that i have a 76 cav which had only 1 owner before me & said the car was untouched.i also have a 78 sportshatch.all the ones on my cars ,my brothers 2 cavs & a friends 2 asconas were all identical in the track rod end positioning.the only other front axle i have had was from a manta 1.8 & the stubs were different. not sure about top ball joint hole being different thou. very early cars had a different top arm in which the balljoint was in a different position. this altered the camber a minmal amount which gm must have thought was necesary as all later cars inc manta c had this. (see haynes book,id by punched raised pip behind joint)

[Christ]

Camber angle, the top pivot that goes into the stub axle is held onto the top suspension arm by two bolts which are NOT on the same center line as pivot, Did Opels ever make top pivots with the bolts offset at different distances from the pivot center line so as the camber angle could be changed?

camber angle can be changed by mounting the top ball joint the other way round (or elongating the mounting holes )

[MANTAMAN]

camber angle can be changed by mounting the top ball joint the other way round (or elongating the mounting holes )

The top ball joint offset is inboard of it's two attachment bolts, so if it was turned round it would give positive camber (wheel leaning out) it can be desirable to add a little negative camber to aid cornering, it would be possible to 'slot' the bolt holes but i'm concerned that they may move under cornering loads, this is something that i have sat and stared at for sometime without coming up with the perfect modification.

[Christ]

still not sure the amount of difference between the studs would put it into +ve camber, just less -ve

If you're adding -ve camber by slotting the holes the bolts will be to the back (chassis side) of the slots, surely any cornering forces would be pushing in that direction also so the bolts wouldn't move.

unless the slots were too long, in which case weld a nut upright behind the ball joint and wind a bolt, and lock nut, through so it's touching the ball joint - shouldn't move