Date asked

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.

I 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.

For spring diameters that were used there were 2.0", 2.25", 2.5" & 2.75" - please see here: http://www.needforspeed.co.uk/pages/sbv_pl.asp?Vehicle=TVTUS02&PartType=SUS04

From this list you should at least be able to see which spax shock absorber can be used, also see: http://www.spax.co.uk/downloads/RSX%20Kits%20pdf/kits.pdf

If you email spax i'm sure they can reply with some guidance on the best setup for your car.

4th September 2011

By John Keivit

Vibration from the rear

I've had a recurring problem with vibration from the rear of the car. It
kicks in around 50 mph. I greased the u-joint in the prop shaft which
helped a bit but didn't solve the problem. I asked a mechanic to have a
look and he suggested that if the prop shaft were about an inch longer it
would straighten the shaft and reduce the possibility of whipping. I have
to admit that when I was reassembling the car and reinstalled the prop
shaft I was a bit surprised that the gearbox end of the shaft didn't slide onto the pinion very far. It makes me wonder if I have the right prop shaft.
Is this a TVR part and do you know what the length of the shaft is supposed to be?

Follow up by John

One of the flanges was slightly bent and replaced but it hasn't remedied the vibration.
One of things that the mechanic seems concerned about is the angle in the various u-joints.
He seems to think that I should lower the differential so that the rear axles are approximately level with the rear wheels. But the angle in the axle u-joints is a "feature" of the design. Have you ever encountered a TVR that has had vibration caused by the angle in the axle u-joints?

The mechanic 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 this?

For your info, it's a vibration that comes in around 50 mph or can be felt slightly under enthusiastic acceleration.

The 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.

Hope that 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.

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:

I 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.

Any suggestions will be welcome - don't worry about sag, apparently it comes to us all after 32 years. Had some success through Pistonheads - it would appear that 6" front an 7" rear might be the answer. Any thoughts

I 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.

I can measure the 3000M later this week if that helps? It is the standard setup but may have sagged a few mm over the years!

Follow up by M-Fix:

Finally had some spare time to measure the 3000M, results are as follows unladen:

Front = 159mm to the base of the front outrigger square tube (behind front wheel)
(About 6¼")

Rear = 184mm to the base of the rear outrigger square tube (in front of rear wheel)
(About 7¼")

Sounds your findings were about right ;oD

20th September 2007

By Don

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.

Follow up by Don

Thanks again for your attempt to help with my bushings.  I got frustrated today and set about making a tool to squeeze them in.  It worked better than expected and allowed a quick easy install, very easy on the bushings too.

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

By Ed

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

I appreciate 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.
I have two friends with TVRs who both have M frames. One is Chevrolet and one is Ford. They also bought QA1 Proma Stars with an extended length of 15 inches. The M frame springs are much more verticle than pre M. They are still experimenting with spring rates. I'll let you know what they end up with once they decide on what works the best.

Follow up by Chris Gale on 5th April 2007

Saw your front page question ...

http://www.tvrna.com/tech-m02.html

has the data ..

24th July 2006

by ?? no name given

7th February 2006

by Steve

3rd September 2005

By Paul Bennett

31st August 2004

by John Kievit

I'm ready to start replacing the chassis bushes and I've hauled the rear
assembly around to a couple of shops to get
some idea of the cost involved and how they intend to get the job done. For
the most part they've echoed your
approach but one shop suggested something else which I'd like to get your
opinion on. They suggested separating
the lower A-arm by breaking the welds on one side, replacing the bushes and
rewelding. If this is indeed feasible
it sounds much more straightforward and doesn't risk damage to the hub
carrier.

Since we're on the subject of bushes, are the ones used in the TVR 3000M
standard TR6?

What I did was remove the rubber part of the bush from each side, then you
have a bit of movement. Next, try to remove the inner metal sleeve of the
bush. This then frees up the stud and means if loosened in the hub carrier,
it can be drifted out, or twisted out using two nuts as lock nuts on one
end - I have successfully done that before. Use plent of penetrating oil
inside the alloy carrier as well as outside.

If the worst comes to the worst, you'll have to cut off one end of the stud,
take off the wishbone, then use a big pipe wrench to twist it out, possibly
with some hammer "taps"! Re-bushing will almost certainly be required after
this type of removal, and make sure the end that travels through the carrier
is smooth (i.e. cut off any burrs made by the pipe wrenchbeforehand).

Wishing you good luck - but with patience you will be surprised at what can
be achieved.

Yes the bushes are off a TR6 - from the front lower wishbones

18th August 2004

by Craig

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.

Any ideas?

6th August 2004

by Craig

Updated 7th Aug 04

I 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.

Craig's reply

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.

This problem sounds like you have the wrong parts fitted, or perhaps something isn't fitted correctly.
Firstly, since when did you notice this problem and wheels with such a negative camber? Maybe it was always like that? Or perhaps only since maintenance was carried out or the Spax dampers fitted. Camber is pretty minimal (see the suspension Data page) on the front wheels and of course can be moved to any position, but you should be able to get an upright (eg 0º) camber.
I would have to look at the suspension to remember how the wheel attitude changes according to suspension loads, but it should remain constant to a point. Your mention of the spax shock absorbers does however make me wonder - I know if the wrong type are fitted the could cause a problem with not allowing the suspension to fully relax, or similarly under load. Take off a damper and check the travel comparing it to the Monroe standard item.

Once you find out what's wrong, please let me know.

7th August 2003

by Jeff