help please, with twin rear springs/shocks on S3 Vixen
Discussion
I have a replacement chassis on my Vixen S3 rebuild (from DG), and I bought the S2 longer pins and twin shocks/springs for the rear end. Managed to refurb rear castings and get the old bent pins out after a lot of trouble....
On reassembly however the top brackets on the chassis are further apart than the bottom shock positions (on the rod). So the shocks aren't parallel, and this causes the rear to be VERY stiff. Anyone had this problem ?
Brackets seem to be in same place as original chassis. Did S2 have its chassis brackets in a slightly different place ? Anyone know ??
Thanks.
On reassembly however the top brackets on the chassis are further apart than the bottom shock positions (on the rod). So the shocks aren't parallel, and this causes the rear to be VERY stiff. Anyone had this problem ?
Brackets seem to be in same place as original chassis. Did S2 have its chassis brackets in a slightly different place ? Anyone know ??
Thanks.
Hi,
I experienced exactly the same when i converted my S3 to twin spring rear. I solved it by making spacers for the pivot bar which orientate the coilover units parallel to one another. If i remember rightly, it was the front unit which needed spacing away from the upright to bring it into alignment with the rear unit.
Tom
I experienced exactly the same when i converted my S3 to twin spring rear. I solved it by making spacers for the pivot bar which orientate the coilover units parallel to one another. If i remember rightly, it was the front unit which needed spacing away from the upright to bring it into alignment with the rear unit.
Tom
Astacus said:
Same for me too.
But having spent many pennys on the brand new Avos, it would gall rather to have to go out an buy rose jointed shocks!
Have you fitted one or two when my S2 was done Alan converted to one Avo instead of two which he was advised improves the ride for road use and he says he notice a great improvement I cant confirm this but the ride is rather nice.But having spent many pennys on the brand new Avos, it would gall rather to have to go out an buy rose jointed shocks!
Andrew
Thanks Guys,
I did space the shockers with extra washers, and had another look since posting. I added another couple of washers so that shockers are as far apart as possible whilst still getting the nuts on... There is now a small difference (11 inches between shockers at top, 10 5/8 at bottom). Still not quite parallel, but close.
What I DID find though, was that the holes in the chassis were drilled horizontal, but of course pivot bar sits at an angle, and therefore so do the shocks - the rubber bushes allow some flex, but I reckon filing one of the holes will make a difference ?
Good to know I'm not the only one, so I wasn't doing it wrong !!
I did space the shockers with extra washers, and had another look since posting. I added another couple of washers so that shockers are as far apart as possible whilst still getting the nuts on... There is now a small difference (11 inches between shockers at top, 10 5/8 at bottom). Still not quite parallel, but close.
What I DID find though, was that the holes in the chassis were drilled horizontal, but of course pivot bar sits at an angle, and therefore so do the shocks - the rubber bushes allow some flex, but I reckon filing one of the holes will make a difference ?
Good to know I'm not the only one, so I wasn't doing it wrong !!
Astacus said:
Should be a two shock one spring set up, but I was advised that 2 shock two spring was better. Unfortunately never drive the car yet and wont for another two years at least at the present rate
That setup matches original Vixen 2500 publicity shot, but I've always though the idea of all the weight running on the end of a stud or bolt is a BAD idea. Twin springs at least will halve the force (more or less) on the ends, so reducing the bending forces, which is why I did it.My original (short) pins were both noticeably bent, and whilst trying to get the old ones out, one sheared just at the edge of the casting, which would be point of bending force/fatigue....
a bit scary to think about.
I couldn't help but notice TVR sorted this in M series by attaching spring/shock direct to rear casting.
I'm not a mettalurgist but i suspect that to get a steel rod in that diameter that can can carry the loads imposed by the Vixen is probably not that difficult. I also suspect that TVR didn't actually engineer this particular piece of the Vixen but instead just went for some mild steel that was "right size, right shape". Hence the bendiness.
I walked round the TVR factory c 1999 and i swear there was a man in a brown coat with a wing mirror in his hand walking up and down the line of nearly finished vehicles, trying to figure put which one it belonged to. Rewind 30 years and you can make a reasonable assumption of the standards employed at the time.
Tom
I walked round the TVR factory c 1999 and i swear there was a man in a brown coat with a wing mirror in his hand walking up and down the line of nearly finished vehicles, trying to figure put which one it belonged to. Rewind 30 years and you can make a reasonable assumption of the standards employed at the time.
Tom
k all. Just ram it in.
Yeah - I got 4 springs at 80lbs as I understand the originals were 150.
Astacus, I reckon that's about the same as I had, the rubbers will allow the shocks to be pushed in by hand, but then I noticed the bolts don't go through without a big fight (not on my chassis anyway), then I noticed the slight, but definite angle difference in the shocker eyelets...
Click on smileys to find out, or type 'biglaugh' between colons (no spaces)
Pins - according to a coversation I had with DG a long while ago, originals were standard high tensile automotive (whatever 'standard' means , I guess 'T' in imperial, about 8.8 metric) and DG supply higher grade than that and are 'EN something' ?.
I know metric are 8.8, 10.8 and 12.8, 2.8 Cologne head bolts are 12.8, and I seem to remember imperial head bolts were marked 'X' ? not sure, it's hazy memory by now...
Astacus, I reckon that's about the same as I had, the rubbers will allow the shocks to be pushed in by hand, but then I noticed the bolts don't go through without a big fight (not on my chassis anyway), then I noticed the slight, but definite angle difference in the shocker eyelets...
Click on smileys to find out, or type 'biglaugh' between colons (no spaces)
Pins - according to a coversation I had with DG a long while ago, originals were standard high tensile automotive (whatever 'standard' means , I guess 'T' in imperial, about 8.8 metric) and DG supply higher grade than that and are 'EN something' ?.
I know metric are 8.8, 10.8 and 12.8, 2.8 Cologne head bolts are 12.8, and I seem to remember imperial head bolts were marked 'X' ? not sure, it's hazy memory by now...
Edited by RCK974X on Sunday 2nd June 23:20
Explain something TVR Vixen peeps ...do the shocks get mounted to the chassis top lugs and then 'finding' their natural position on the pivot bar below before then spacing and packing this accordingly adding what ever length pivot pin required to allow that to happen then add the rear tracking bar into the equation ...OR.
Adrian@
Adrian@
Adrian@ said:
Explain something TVR Vixen peeps ...do the shocks get mounted to the chassis top lugs and then 'finding' their natural position on the pivot bar below before then spacing and packing this accordingly adding what ever length pivot pin required to allow that to happen then add the rear tracking bar into the equation ...OR.
Adrian@
Yes they do, but, you can't photograph how far out they are if you do that! Adrian@
The issue seemed to me to be that, done this way, the lower wishbone sets the back to front position of the upright. On mine, if you hang the shock from the top lugs, the shock's bottom bush then fouls the rear track bar bush housing, even with the thinnest washers, as if, either the bottom wishbones are mounted too far back, or the top, too far forward.
I have yet to find a solution to this
Must be me being dumb, but I don't quite get what Astacus said there...
On my S3 , the pivot bar is NOT horizontal when shocks are disconnected. The upper and lower suspension arms set the rear casting at an angle, about 10 degrees would be my guess, possibly a bit less. (Is that right ?)
Adding washers/spacers to separate the shockers to the maximum distance apart gets them pretty close to the chassis brackets, but they still sit at that slight angle. The chassis mounts appear to be at same height as each other, and have horizontal holes, so there is a small inbuilt stress already, and shockers aren't compressed by the same amount after assembly.
That's why I was wondering if I did something wrong, but rebuild matches my photos of original (with single shock) as far as I can see...
With shockers at ends of long pivot bar, nothing fouls, but you can't move the [new] front
shocker backwards (towards casting) much before it does ....
DOes that make sense ?
On my S3 , the pivot bar is NOT horizontal when shocks are disconnected. The upper and lower suspension arms set the rear casting at an angle, about 10 degrees would be my guess, possibly a bit less. (Is that right ?)
Adding washers/spacers to separate the shockers to the maximum distance apart gets them pretty close to the chassis brackets, but they still sit at that slight angle. The chassis mounts appear to be at same height as each other, and have horizontal holes, so there is a small inbuilt stress already, and shockers aren't compressed by the same amount after assembly.
That's why I was wondering if I did something wrong, but rebuild matches my photos of original (with single shock) as far as I can see...
With shockers at ends of long pivot bar, nothing fouls, but you can't move the [new] front
shocker backwards (towards casting) much before it does ....
DOes that make sense ?
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