Offside wheel too close to Chassis
Posted By : John Davies, 01-Sep-2006, 09:59pm
Andy,
Almost certainly a mis-set bonnet.
But a check of the chassis geometry would be reassuring too.
On a flat surface. choose three or four points that are the same on both sides,
Use a plumb line to mark their position on the floor.
Draw diagonals, which should all cross on the midline.
Here's the page from the Spitfire manual on how to do this.
The GT6 manual is identical.
The best way to draw the lines is with chalked string
John
Almost certainly a mis-set bonnet.
But a check of the chassis geometry would be reassuring too.
On a flat surface. choose three or four points that are the same on both sides,
Use a plumb line to mark their position on the floor.
Draw diagonals, which should all cross on the midline.
Here's the page from the Spitfire manual on how to do this.
The GT6 manual is identical.
The best way to draw the lines is with chalked string
John
Offside wheel too close to Chassis
Offside wheel too close to Chassis
Posted By : Chris Taylor, 02-Sep-2006, 09:06am
Is this a side to side matter, or a front to back issue?
If the problem is side to side, then a combination of oversize tyres/wheels and misaligned bonnet may be the answer. It's also worth checking that the wishbone bushes and upper ball joint (and lower trunnion) are all in good order. (SHOULD be or it should have failed the MOT!)
If the problem is front-to back, and the tyre is rubbing the bulkhead, then I'm afraid the problem is more likely to be accident damage or a slightly misaligned chassis and/or body during restoration. Again, worth making sure the wishbone bushes are correct, and that the lower wishbone is properly aligned. More shims under the front pivot bracket will tend to move the rear wheel backwards. A larger than standard tyre will exacerbate any slight misalignment problems here.
IF the problem is that the tyre is just rubbing on the chassis or wishbone edge only on maximum lock, then this is not a real problem! Not many people expect a a wheel to turn as tightly as the Herald. If this is more pronounced on one side than the other, then this may be a poorly set up rack. As long as you take an ACCURATE measurement across the car (eg locknut to locknut), and you maintain this distance, you can adjust the two trackrods to be equal length without changing the tracking.
If the problem is side to side, then a combination of oversize tyres/wheels and misaligned bonnet may be the answer. It's also worth checking that the wishbone bushes and upper ball joint (and lower trunnion) are all in good order. (SHOULD be or it should have failed the MOT!)
If the problem is front-to back, and the tyre is rubbing the bulkhead, then I'm afraid the problem is more likely to be accident damage or a slightly misaligned chassis and/or body during restoration. Again, worth making sure the wishbone bushes are correct, and that the lower wishbone is properly aligned. More shims under the front pivot bracket will tend to move the rear wheel backwards. A larger than standard tyre will exacerbate any slight misalignment problems here.
IF the problem is that the tyre is just rubbing on the chassis or wishbone edge only on maximum lock, then this is not a real problem! Not many people expect a a wheel to turn as tightly as the Herald. If this is more pronounced on one side than the other, then this may be a poorly set up rack. As long as you take an ACCURATE measurement across the car (eg locknut to locknut), and you maintain this distance, you can adjust the two trackrods to be equal length without changing the tracking.
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Offside wheel too close to Chassis
Posted By : Andrew Szczecinski, 02-Sep-2006, 03:43pm
Sorry Gents - should have been a bit more specific.
The problem is at the rear only. The rear offside wheel is running closer the chassis than the rear near side.
Any thoguhts?
Andy-
Offside wheel too close to Chassis
Posted By : John Davies, 02-Sep-2006, 04:28pm
REAR! So, Watson, this is only a one pipe problem.
If this is not a Rotaflex, then with certainty you have one half shaft longer than the other.
They came in two lengths, short early, long late. Difference, 1/2"
The gurus will supply details.
I've tried both on the Silverback.
With a lowering block on the diff, long shafts give you too much negative camber.
Looks very sporty, but only 4/5th of tread on road.
Without said block - GoK!
If you have Rotoflex - is one donut asembled wrongly?
Both the yokes should be inboard of the donut.
It's very tempting, a LOT easier, but wrong, to put one on each side!
John-
Offside wheel too close to Chassis
Posted By : Andrew Szczecinski, 02-Sep-2006, 07:01pm
It is a 1972 rotoflex, the previous owner couldnt have possibly fitted two differet length half shafts could he?
I'll check the yokes!
Andy-
Offside wheel too close to Chassis
Posted By : Andrew Szczecinski, 02-Sep-2006, 08:28pm
John
Sorry for my ignorance but when you say yoke do you mean the drive coupling?
Thanks - Andy-
Offside wheel too close to Chassis
Posted By : Colin Wake, 02-Sep-2006, 08:35pm
Make sure you haven't got an odd pair of wheels, there are GT6, spitfire, Marina and Dolomite wheels that look the same, but are differnt.
Cheers
Colin -
Offside wheel too close to Chassis
Posted By : John Davies, 02-Sep-2006, 10:03pm
Andrew,
At the outer end of the inner drive shaft is a three fingered spider, that bolts to the donut.
The outer drive shaft has a similar spider, that bolts onto the other three holes in the donut.
They are called 'coupling flanges' in the workshop manual diagrams.
Both spiders should be on the in-board side of the donut.
See Canley page: http://www.canleyclassics.com/catalogue.asp?id=vit...
BUT, to replace the donut the hub must be removed from the outer end of the outer drive shaft.
This is a nightmare, that needs powerful presses, accurate measurement of preload etc. etc!
Why Triumph did it , I don't know, as I've seen donuts on other cars with the spiders on either side.
It would be a simple mistake to re-assemble it the wrong way, so that the whole drive shaft is longer by the thickness of a donut. A bit more than 15mm, but anyway.
Hope I'm wrong!
John-
Offside wheel too close to Chassis
Posted By : Kevin Rochfort, 02-Sep-2006, 10:10pm
John,
If the spider was on the side of the doughnut, then the driveshaft would be the thickness of the doughnut PLUS the thickness of the spider flanges longer than it should be. Without having some bits to hand to measure, I believe it will be about 2" longer than it should be.
Kevin
Some pictures
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Offside wheel too close to Chassis
Posted By : John Davies, 03-Sep-2006, 00:44am
Ever since I wrote that, Kevin, I've been thinking that too.
I just didn't have a scale in my mind to the image of the donut thickness.
You pics show that it would be that much longer.
It's something else, Andrew!
John
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Offside wheel too close to Chassis
Posted By : Mark Palmer, 02-Sep-2006, 08:50pm
Andy,
Minor details, but have you checked that the wheels and tyres the same on both sides, and that the tyre pressures are the same? If so, is the camber the same on both sides, under equal load? Does the car have upper or lower wishbone mounting brackets fitted, that can affect camber? If so, are they set the same on both sides? Do you have a split donut (doubt it, if the MoT man hasn't failed the car on this?) Are all bolts securely tightened down between leaf spring and diff housing? Loose ones on one side will affect camber.
Mark-
Offside wheel too close to Chassis
Posted By : Andrew Szczecinski, 02-Sep-2006, 09:01pm
Gents
The wheels and tyres are the same, wheels are Minilites
As yet i haven't been underneath but have looked closely at the stance and the cambers look OK.
However, not sure if this is linked but i do get quite a bit of noise when dropping down off the drive onto the road from what i thought was the leaf spring. As sort of squeaking sound?
I really need to get underneath and have a good look around. Might try and have a look tomorrow if the heavens don't open again!
Andy-
Offside wheel too close to Chassis
Posted By : Van Hamlin, 02-Sep-2006, 11:24pm
Previous wing replacement would account for wheel being nearer to wheel arch one side than the other. On my car, the same wheel is nearer both the inner and outer arches, so the space for the wheel must be less on this side.
Leaf spring can account for one side being higher than the other. They never seem to be quite symmetrical.
Not sure what the squeaking noise is, but my car has always done it when I drive off if I've had it jacked up. After new spring, shocks, bushes, diff, UJs, bearings, rotoflexes (twice), tyres (4 times) and anything else I haven't thought of it still does it.
I don't expect this to solve your problems but at least you know you're not alone.
Van
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Offside wheel too close to Chassis
Posted By : Andrew Szczecinski, 03-Sep-2006, 06:53am
Thanks Van
You're right, the squeaking may well be completely unrelated but the replacement wing explanation might be worth considering. I do know there has been some work done on the offside rear wing. Theres certainly been some welding done inside the car so i'll have a closer look.
Thanks for help!
Andy-
Offside wheel too close to Chassis
Posted By : John Davies, 03-Sep-2006, 10:55am
Andy,
In my own defence, you did say that,"The rear offside wheel is running closer to the CHASSIS than the rear near side." (My capitals)
That would indicate a suspension problem and make any bodywork abnormality out of the question.
How are the flange couplings/spiders?
John
(Failed guru - desperate to dig himself out of pit)
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Offside wheel too close to Chassis
Posted By : Chris Taylor, 03-Sep-2006, 12:14pm
It would be impossible to fit a driveshaft with a rotoflex coupling assembled the wrong way. It is the lower wishbone and leaf spring that dictate where the rear upright is located, and that dictates where the rear wheel hub sits laterally across the car. (Different of course with swing axles).
It would be worth checking the distance from lower wishbone to the chassis, and spring eye to the diff on both sides of the car. If they are different, it shows where to start looking for the problem. If they are the same, the problem must be with the rear hub or the wheel itself (different width or offset).
To check on the rear wing issue, try measuring from the wheel arch lip to the chassis on both sides.-
Offside wheel too close to Chassis
Posted By : Kevin Rochfort, 03-Sep-2006, 12:47pm
I was wondering if all the wheels were really the same.
Apparently they are all minilites, but as with most aftermarket wheels, they come with different offsets.
Is it possible that the set of wheels is not actually a matched set ?
Try swapping the rear wheels side for side and see if the problem moves to the other side.-
Offside wheel too close to Chassis
Posted By : Andrew Szczecinski, 03-Sep-2006, 09:13pm
Gents
Firstly thanks for all the responses, much appreciated when youÂ’re new to the GT6
Anyhow - i had the wheels off the rear and have a bit more detail.
It seems that the original comments by the MOT guy aren't quite correct. The inner rim of the minilite on the offside is just touching the top plastic gaiter of the Spax shocker and when the car boot is loaded theres also signs of the rim touching the rubber bump stop. Its no where near the chassis.
On the near side the problem isn't as bad but its still damn close, maybe only 4 to 6mm to spare. However, there are signs that this has also touched the shocker top gaiter but not the bump stop.
I have the original wheels and tried one and the gap was nearer to 10mm of clearance so the minilites are obviously a factor but it doesnÂ’t explain everything.
I made a few measurements and it looks like the car is sitting about 10mm lower to the ground on the offside compared to the near side which might be part of the problem.
I also dropped another plumb line off the wing and measured to the outer rim and theres a difference of about 10mm. However, im not sure this is a good guide as the wing isn't really a safe datum to use. Am i right in saying that with reference to a safe datum the lower wishbone is fixed so that means that the lower part of the hub isn't going anywhere? However, im not sure how the upper end of the suspension is controlled? Is it the positioning of the leaf spring which dictates the final position of the upper end and thus the camber? Is the camber adjustable and if so how?
I might also add that i have Spax adjustables fitted. Not ride height just ride. I didnÂ’t fit them and know nothing about them but i assume the ride tension/firmness couldn't affect the ride height?
I was also wondering what affect the body position or more precisely the wing position might have on the set up. Is it possible the body tub could be slightly out of position on the chassis and thus the upper fixing points of the shockers are also out??
Getting more confused.
Andy
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Offside wheel too close to Chassis
Posted By : Andrew Szczecinski, 03-Sep-2006, 09:41pm
Gents
Sorry but brain is working overtime at the moment
Looking at the way the rear axle/suspension is arranged if the rear leaf spring was slightly off centre would this alter the camber, possibly pulling in the top edge of one hub and pushing out the other or am I way off the mark?
Andy
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Offside wheel too close to Chassis
Posted By : Chris Povey, 07-Sep-2006, 12:47pm
Having just bolted the body back onto my GT6 MK2 rotoflex I can confirm that it is easy to move the whole shell a good few mm which could easily cause the difference in clearance that you have found. The spring has a central spigot that engages in a recess the top of the differential case and its the spring that controls the position of the top of the vertical link.
The only way that the vertical link position could be changed in relation to the chassis is if the bottom wishbone or mounting is damaged, the spring is poorly made or damaged or the diff mounts are damaged / incorrect. All of this is highly unlikely and I would say that the difference in clearances between the wheel rim and shock / bump stop are almost certainly due to the body position. (Shock absorbers / bump stops attached to body not the chassis).
Regards
Chris
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