Page last updated 17 October, 2011
Questions - Suspension
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11th October 2011
By Francis G
I am in the process of restoring a 1974 TVR 2500M, I am looking for advice on coilover shock selection valving and spring rates. The car will be used for track days and vintage racing along with street driving. Any suggestions are greatly appreciated. I am located in Southern California. Thanks to all.
have no specific data - in fact there was a link on my site in the technical
questions area that pointed to the TVRCC USA which did have some data.
However the link has since gone dead so it may be worth contacting the
above to see if they have an archived webpage with such info.
4th September 2011
By John Keivit
from the rear
Follow up by John
is also wondering about the angle in the prop shaft. He is wondering if
the engine is not supposed to sit at a slight angle due to the offset
of the differential. He thinks that having an angle in the prop shaft
is very unusual. I think the engine mounting brackets can only be fit
one way which forces a central alignment of the engine. Can you confirm
For your info, it's a vibration that comes in around 50 mph or can be felt slightly under enthusiastic acceleration.
propshaft length is something that could occur if the prop was modified
(i.e. shortened at the front) to fit to a 5 speed gearbox, then fitted
to a4 speed car. Apart from this, have you checked the run-out of the
rear hub flanges. I have a new hub to fit to the 3000M due to an out of
true flange. This happens when the wrong method of flange removal is used
(I'm working on a new tool for this as it's almost impossible to remove
these without it). Hope that helps - if it's the hub see my homepage as
they are available as a unit now with bearings/hub complete.
Follow up by M-Fix on 4th Sept 2011
Not related to your problem but I have found steering column u/j problems before with binding of the u/j when using an incorrect complete universal coupling (on TVR Chimaera models). However as the u/j on the axles usually only requires the spider part, the two flanges that hold the spider should be fine unless there is wear inside on the bearing bores (common problem on the 3000M). This can of course be seen if stripped down. My car has the Salisbury diff so these are extremely rare & expensive to replace the flanges, but it needs two as they are slightly loose allowing the u/j bearing case to spin. I have used a product called Frenbloc which is like a glue that hardens like threadlock to stop this. However this problem almost certainly doesn't cause any noticeable vibration - I was unlucky enough to have one break back in the early 1990s just after buying the car - no vibration was felt before failure, then the half shaft broke loose with a loud bang! So in answer to your question I've never felt a vibration from the u/j angle yet.
Have you checked the diff bearings & diff for wear? Splines could be worn and slipping on the output shafts within the diff casing, or more commonly on the input shaft on the front of the diff where the propshaft flange bolts on to (happened to me on an old BMW 2002 once). Doubt the vibration would be too noticeable though and very soon you would have lost drive, but on a certain older model of Renault I have experienced a vibration on acceleration that ended up being a spline slipping.
The slight angle of the engine shouldn't matter as the prop u/j's should allow for this as far as I can see, the engine mount brackets are not handed I think according to the M Series Parts Catalogue. How about the gearbox rear mount & bracket - a common cause of vibration/noise? The mount can collapse & the 'box sits onto the aluminium bracket sometimes & slowly wears it away? Adrian Venn stocks new ones from Exactly TVR Ltd here in the UK.
helps a little - only other things would have already been looked at I
guess e.g. wheel balancing/wheel trueness/brake drum warping/tyres out
of round (common on modern Renaults!)/bent half shafts/worn diff mounts....
7th July 2009
By James Collier
I've just replaced all the rear upper and lower wishbone bushes on the 3000M with the TR6 front lower inboard bushes. As mentioned on your site the studs which hold the lower outer bushes were ceased into the upright. However I did mange to replace the bushes without the hassle of removing the studs. I removed the nut and washer and then carefully drilled out the rubber, which in turn enabled me to remove the bush sleeve. Now with a liberal amount of bush grease I was able to push the new bushes into the wishbone housing over the stud using a pair of large adjustable pliers.
I thought that your readers would like to know that this can be done, without the hassle of drilling, machining and crack checking the uprights.
I also have Koni part number for the shocker absorbers: 80-2365.
I also replaced the anti roll bar bushes. The inboard ones are from a Triumph Herald anti roll bar and the outer ones are a Triumph Herald front lower wishbone bush which has to be shortened.
I hope this helps others out when doing similar jobs.
|Many thanks for the info - very useful as many people write to me regarding these areas - shock absorber & anti roll bar especially!|
28th August 2008
By Alan Nicholls
What is the standard and preferred ride height of a 3000m measured at the front and rear outriggers? The question relates to a 1976 3000m.
Follow up by Alan:
have replaced the original slots with 15" compomotives with 205 *
65 tyres. This will give a rolling diameter very similar to the 185's
which were fitted.
have no data on this I'm afraid - guessing that you have the standard
T-Slot wheels? I think Wolfrace slot were the other option on this year,
but not sure if the same diameter & tyre size.
20th September 2007
Hello, I am trying to replace the front bushings in my 1979 Taimar with Prothane bushings. I have the new bushes in the wishbone, but cannot seem to get them squeezed into their place on the chassis. Is there a tool to compress them for install? Does anyone now the prothane part# for me to double check my bushings?
Follow up by Don
The manufacturer is Prothane ( www.prothane.com/ ). I am in the USA, and they were sold as lower-inner TR6 bushings part#27-45096. They will fit nicely into the Chassis, when they are not installed in the wishbone. I just cannot get them in the chassis once installed into the wishbone.
up by Don
Follow up by Don
I thought I would send you some pics of my upper wishbone bushing tool. It is rediculously overbuilt, but I just used steel and bits and pieces of things I had around the house. As you will see, the tool is based on a wedge shape which compresses the bushing to 1/16" smaller than the opening the bushings fit into. The entire tool bolts to the chassis and a feed screw pushes the bushing into place while compressing it at the same time. I lubricated the inside of the wedge to protect the bushing while sliding. The mechanical advantage is so great, I didn't have to use a wrench to turn the feed screw, and it didn't even scratch the paint on the wishbone.
No tool is available for this. They can be tight - is the anti squash tube the correct length? Do you know what make are the bushes you have or where you bought them from?
Follow up by M-Fix
Glad you sorted it. I was looking to see if TR6 are the same as M series bushes - which of course they are. This problem is similar to that on Mini engine mounts - I think they are a tighter fit to make sure there's no problem with loose bushes.
23rd March 2007
I have a 1971 2500 and I have just replaced the front shocks and springs. I would like to replace the 4 rear springs. Any idea what weight they should be?
Follow up by Ed
the help. Here is some info on the fronts that I can share. I replaced
the old Konis with QA1 Proma Star www.QA1.net
coil overs. I used the 17 inch fully extended ones with 12 way valving
and adjustable ride height which I set at 13.5 inches (34cm). My pre-M
frame shocks mount at 32 degrees from verticle. The 200 pound springs
end up as 140 pounds actual after using www.proshocks.com
rate calculator. The stock springs were rated at 135 pounds but I believe
that was the verticle rate. I'm also running a small block Chevrolet so
the front end is about 100 pounds heavier than stock. I'll have the car
on the road in a couple of weeks. I'll let you know how it worked out.
Follow up by Chris Gale on 5th April 2007
|Difficult one this as I have very little information on spring poundages. Will put your request on the homepage to see if anyone can help.|
24th July 2006
by ?? no name given
|could you give me info/spec on the front springs for a 3000m, i've been offered some new ones with an internal diameter of 2 inches which is fine but not sure about the poundage of the springs? cheers.||As
far as I can see the springs come in 2.25", 2.5" and 2.75"
internal diameters see this page for shock
absorbers (SPAX) to suit the various spring sizes that are found on classic TVRs:
I am not sure on poundages but from the above webpage it looks like 2" diameter springs would
be too small?
7th February 2006
|hi, just come across your website, i have 1974 3000m, i need new front shocks for mot. where can i source some? adjustable or standard? cost?||Try
here for some pretty good prices (covers the types of springs fitted but
there are various damper part numbers so you'll need to email or call them
Standard dampers were Monroe and I'm pretty sure David Gerald Sportscars Ltd had the last batch and have now run out, may be worth contacting them if you get stuck - see my links page).
3rd September 2005
By Paul Bennett
|Do you know what torque setting the front / rear wishbones to chassis brackets should be.||This
is not very easy to find. I have asked David Gerald before now and they
have told me that there is no torque, it is simply done by feel and should
not be overtightened! Don't quote me on that but it's honestly what they
told me a couple of years ago.
Looking at the TR6 data I have, the lower wishbone fixing to the fulcrum bracket is 45 to 50 lb ft, but it is a different bush fitted the the TVR own make arms.
31st August 2004
by John Kievit
to start replacing the chassis bushes and I've hauled the rear
on the subject of bushes, are the ones used in the TVR 3000M
option is possible although i would strongly recommend removing the
studs from the carriers just from the point of view of "knowing what you've
got". For example, if there is a problem with the carrier i.e. play in the
stud or corrosion (remember steel against alloy is a good way to make
corrosion worse) would be worth sorting out at the same time. The wishbone
weld is possible to remove of course but the problem here is
re-alignment...and even if done correctly maybe the re-welding could weaken
What I did
was remove the rubber part of the bush from each side, then you
If the worst
comes to the worst, you'll have to cut off one end of the stud,
good luck - but with patience you will be surprised at what can
Yes the bushes are off a TR6 - from the front lower wishbones
18th August 2004
Since I rebuilt the rear suspension on my 2500M (TR6 Diff.) I have had a constant constant clonking during suspension movement. It isn't that noticeable when you take up drive. The suspension was rebuilt with new dampers, bushes and UJ's etc.
6th August 2004
Updated 7th Aug 04
have a 1972 2500m which I rebuilt a number of years ago. I have a problem
with the front suspension when viewed from the front the front wheels
lean in at the top I am not sure whether this is camber or castor angle
but it is wearing both tyres out on the inside. I know that the top wishbone
has slots in it for the top joint but there is not enough adjustment to
get the wheels upright I am using spax dampers I have a new pair of original
Monroe's to fit would this make any difference. Any suggestions welcome.
I used the tvr for about 5 years before Irestored the car and never noticed any uneven tyre wear. during the rebuild the only parts I changed on the front suspension were the wishbone bushes and the dampers. I have checked to make sure that all the parts are assembled correctly and I have had one of the mechanics from David Gerald check it over. The only thing we can think of is as you suggest ! the spax dampers. I think I will change them to the original spec monroes.
sounds like you have the wrong parts fitted, or perhaps something isn't
7th August 2003
-- I'm in the States, currently re-building my 2500M. The suspension bushes
are all worn out, and I'd like to replace them, but the bolts
holding the rear suspension's A-Arms to the aluminium hub carrier are seized in. Do you have any tips on getting these bolts out of the hub carriers?
|You will find that the "bolts" are in fact two long studs which pass right through the hub carrier. They seize up due to the bi-metallic reaction between the steel stud and the alloy hub carrier, and can be extremely stubborn to remove. The only way to remove the wishbones successfully is to hacksaw off each end of the stud (nearest the hub carrier). This then leaves the stud flush with the carrier and once both have been done you can get the carrier onto a sturdy bench and drift them (or better still press) them out. Be careful as you could damage the carrier - it's always best to get them crack detected after if you use this method. Of course you will need a pair of new studs, and sometimes a tailor made bush insert to repair an elongated hub carrier stud hole. If you do this it will improve stud removal in the future as there will only be steel against steel, so no bi-metallic reaction can occur.|
by Stewart Weston
|Could you please forward any info and more importantly your views on - shortened anti roll bar?||I
take it this is to stiffen up the anti roll (less leverage on the bar hence
stiffer bar)? I suppose it all depends on the type of driving you do, for
track days the bar would be great to stop the car tipping so much round
tight fast corners. I have not personally heard of this mod. but can guess
why it's been done.
While on the subject of these bars, I have seen a rear anti-roll bar on an M series car, but most will say this is not necessary (it was used on a track day car so was probably necessary due to it's high state of tune).