Anything and everything GT6.

Suspension and steering.

The rear lower wishbones have been lined bored to accept ball bearing races to improve handling!!!!
This was cut and pasted from an ebay add 120054699546
I am interested to find out who has done this, and well it works.
Any one have any ideas

I have found out that this mod was covered in the yellow cover GT Transmissions Triumph tuning book.
only thing is I have never seen such a book.
Any one owning such a book care to post a copy of this page here for everyone to see!!!!
Prity Plz

Ball bearing races! Never heard that one before. Rod end bearings yes but ball races? I can't see how that would work. As the wishbone moves up and down through bump and rebound, the tie rod/trailing arm link will describe an arc therefore creating a certain amount of toe variation. This is accommodated by the inner wishbone bush as it is flexible or by a rod end bearing but a ball race surely would only move in one plane ie around the fulcrum point which is the mounting point on the chassis allowing the suspension to move up and down. How would this cope with toe variation?

The Quote "The rear lower wishbones have been lined bored to accept ball bearing races to improve handling" were not my words, they were cut and pasted from the egay add that I gave.
I contacted the guy selling this car, and he told me to look in the said book.
Any one got a copy and are willing to scan the page for this topic?
many thanks
Piero

Piero, The modification to the rear rotoflex wishbone is mentioned in the December 1994 Courier No 174. I attach a page from the article you may find of interest. The whole article, by Steve Phillips, on GT6 suspension is well worth a read. I imagine you can still get copies from the club shop.

Aah, the trunnion end - it all makes sense now!

Thanks for your time and effort to post a copy of the courrier Lindsay,
Does any one have a copy of this tunning manual, and would they care to post the page??

I've got the GT Tuning Manual in my hand if someone can tell me how to post the page. Page 38 for those that have it.
Basically the mod is to ensure no drag on the wishbone during suspension travel. The inboard end gets a rod end for articulation as stated and the outboard end gets four of the bearings with appropriate spacers between the inner races
The bearings should be KLNJ 1/2 or R8. The dimensions are 1.125x.500x.250. He says this allows the use of the BL bush kit with O-rings.

Steve

Hi steve.
Thanks for the reply,
as to posting the page, you will need either a scanner, or a dig-camera, them simply up-load in on to pc, and in the post follow up page, use the browse butten to look for the image, depending on where you have stored it on your PC (e.g in your pictuers/or your documents etc)
Thanks

I have this mod on my Vitesse, and I also have the GT tuning manual.

I will try and find time to scan in and post the relevant page tonight when I get home from work.

Remember that we are 8 hours ahead of UK time here!

Regards

L&195;&169;on

Thanks Leon. I was going to do a digi-photo and attempt to post that. I trust GT won't be offended by our efforts? I thought our pics had to be on a website to link to?
Anyway, doing it right seems like a lot of elaborate machining to me. Line boring alone over that expanse is awkward and then doing shoulders and snap rings to locate everything is one hell of a machining bill. Is your's done more simply? I can envision a single thru bore and then everything else done with spacers.
Tonight is a big holiday eve in the US. Could that be why my keyboard is so awkward? Regards all, Steve

I was hopeing to use the info gained from the GT book, and do a more modern simpler route.
Dont forget, that book must have been writen a while ago.
With out trying to sound like a big head, I have always taken to doing mods, And I always find I can inprove in what I see.
If I get the time (as I am heavery into moding my engine at the mo) when I get round to doing this mod, I will happyly post it on the TSSC, for every one else.
Thats if it goes right!!!!!!!!!!
Piero

OK, it's 5am, I can't sleep, but my scanner is noisy and would wake everyone in the house, so I will copy the few words on this subject from Gareth Thomas's 1986 Tuning Manual: (there are no photos or drawings).

<page 37>

Re: GT6 & Vitesse MK.II Suspension:

When released in late 1968, the magazines called it a 'great improvement' over the swing axle, which wasn't difficult!
This rear suspension design deserves a little more appreciation than that. Despite its weird geometry, changes of track and camber, when it works well, it works very well. It was very expensive to produce, is still very expensive to maintain properly and is a pig to change UJs on. Something you have to get used to with a high powered engine!

The other biggest headaches are, changing the bulky CV joints (or Rotoflexes), and the wheel bearings, with the odd seized trunnion thrown in. Rear springs wear quickly because it takes part of the lateral cornering forces with the wishbone.

On Mk.IIs these forces are transferred by the wheel bearings through the hub direct from the vertical link to the wheel. (Swing axles, by contrast take nearly all cornering forces down the shaft to the stub axle bearings)

Consequently, MK.IIs wear wheel bearings out usually for three reasons:

Allowing the car to stand for a long time permits moisture to damage the sensitive tapered roller bearings.

<page 38>

(ii) Incorrect assembly with the wrong pre-loads.

(iii) Driving very hard with high cornering forces and inadequately rated grease.

Unlike swing axles, the bearings can 'growl' for quite some time before causing serious trouble.

To make this suspension work properly, 5 improvements are needed:

A method of making the rear trunnions move freely.

(ii) A stiffer rear spring with an option of changing the ride height.

(iii) Telescopic shock absorbers of adjustable rate.

(iv) Reinforcement of their mountings on GT6s

(v) Modification to the wishbone mounting bracket to allow camber adjustment.

BL Rotoflexes are very reliable, although bolts occasionally shear in the mounting forks.

The method I used for the trunnions was to line bore the wishbones and fit small replaceable ball races and spacers.
Bearing No. KLNJ 1 I/8.

This allows you to fit the BL bush kit with O rings. Grease points were also tapped into the wishbone arms.

The ride height can also be changed by adding plate(s) under the rear transverse leaf spring. This will also give more negative camber.

The only telescopic shock absorbers to use on the rear of the Vitesse is a Koni Pt No. 80/1717.
Forget anything else. This is the one to give correct suspension travel. Anything else gives a

<page 39>

dreadful ride because they bottom out before the bump stops and knock out your UJs on humpbacks. Set them soft or it will oversteer dreadfully!

The wishbone brackets will usually have to be lengthened by approx &189;" to increase negative camber.

Trying to lower the diff' in the chassis is a lot of work, and frankly a waste of time, because it also disturbs the ptop-box-diff datum line for minimum UJ wear.

Once the rear suspension has been set-up you will almost inevitably find all the problems come from the front especially on GT^s while the rear feels immovable. To aid the understeer situation I suggest you fit a firmly mounted rear anti-roll bar of modest dimension &189;" - 5/8".

Whatever you do, don't go fitting stiffer front roll bars. The limit is the 1500 3/4" bar, in certain cases only, otherwise you will get a feeling of less roll, more stability certainly, but go sailing straight on at every corner! One firm had the gall to call this an 'ideal competition modification'!

GT6s fit softer springs than the Vitesse with shorter travel and the fronts particularly need stiffening from the standard 230 lb to about 400 lb. Fitting adjustable height and rate Spax will then allow you to get the front off the deck especially if the Spitfire front suspension recommendations are followed on camber. The final road behaviour will depend very much on choice of tyres.

175/70 are really ideal, permitting some roll. 60 series tyres are much more fussy. The only ones at present which work really well are Pirelli 185/60 and Uniroyal 185/60. Most of the others demonstrate very nervous performance in the wet. Use them on a 5&189;" or 6" wheel.

Like the Spitfire, most poor handling is caused by worm/seized bits. In addition, the Vitesse,

<page 40>

particularly the convertible suffers severe chassis flex and eventual fatigue. High mileage examples can only be partially cured by complete reconstruction and reinforcement.

The GT6 has the strongest structure of all, supported by the sills and roof, and the only thing to watch for is the dreaded tin worm.

<end of subject>

Hope that helps some.

L&195;&169;on

Oooh, I LIKE the end cap/spacer and O-ring. Very clever! Maybe I'll take another look at that over the winter. Thanks Leon, Steve
Friends, Today is the Thanksgiving holiday in the US and I believe Leon is enjoying it with pouring rain or snow. Much like your own weather I imagine...Steve

Hi Guys
And thanks for the grate responce

Dont know about you, but I think the polybush kits used with stainless steel (no more rusted bushes) are ok, ish.
My main concern is more in the up-right.
All the rotoflexes I have stripped, have been siezed hear (up-right to long bolt), I would have thought a poly bush set up, with stainless steel bolt etc (and probably what I will do) fit a grease nipeal to the upright, and small groves cut along the stainless bold (only at up-right contact area) solve most of the issues.

There has been previous discussion on this site about stainless steel bolts (and bushes) in rear suspension.
As for the bolt, unless you can be absolutely sure it is the right grade of stainless steel, DON'T. The rear trunnion bolt is an absolutley key component, but many grades of stainless are not suitable for this sort of use. (Too brittle?)
Stainless bushes are better (and I think Canley do, or did, such for the Rotoflex rear suspension) but apparently will NOT prevent corrosion. Disimilar metals (bolt and bush primarily, but perhaps also any contact with wishbone, or upright) can cause corrosion. This may not cause the bush to seize to the bolt in the way we all know and curse, but it does show that perhaps the most important thing is GREASE, and lots of it. The idea of grease nipples to get grease where it is needed and being able to replace it seems an excellent idea.

Steve, happy thanksgiving to you and your family. By the way, it's not raining or snowing here today. It has been raining a lot lately but today the sun is shining, albeit weakly. If you like, I will try and send you some higher resolution pictures of the conversion.

Best regards

Check my ebay item out - 230053871910

Not many of these books around - good reading if you can't sleep!!!

very important information: stainless steel hardware is only grade 2, you can not get stainless steel hardend or its no longer stainless steel best alternative for bolts sp they dont rust is zinc coated.

thats a great mod, where can you get that book

could you do this mod to instead of every trunnion

i am gonna look into this

incase somebody knows it would save me some time

Section : Suspension

Lower wishbone mod!!

Followups :

Lower wishbone mod!!

Lower wishbone mod!!

Lower wishbone mod!!

Lower wishbone mod!!

Lower wishbone mod!!

Lower wishbone mod!!

Lower wishbone mod!!

Lower wishbone mod!!

Lower wishbone mod!!

Lower wishbone mod!!

Lower wishbone mod!!

Lower wishbone mod!!

Lower wishbone mod!!

Lower wishbone mod!!

Lower wishbone mod!!

Lower wishbone mod!!

Lower wishbone mod!!

Lower wishbone mod!!

Lower wishbone mod!!

Lower wishbone mod & GT Transmissions Triumph tuning book

Lower wishbone mod & GT Transmissions Triumph tuning book

Lower wishbone mod & GT Transmissions Triumph tuning book