I want to put some new springs on my Mantula. When i first got my car my first thoughts were "frightening lightning". First thing i did was
overhauled the steering rack, didn't do much to help, next thing was the front bushes, this made me realise that there was a lot of play on the back. So
this was also rebushed. Still seemed to be pretty wobbly. Next on the list was the shocks the old shocks were Konis these were also knackered. These were
replaced with Gaz shocks at first this was also terrible until i spent some time setting them up. Still not satisfied i decided to make some new wishbones up
because the Triumph stuff is a little too flexible in my opinion. After Talking to DP i decided to modify the original wishbones to get the correct wheel
alignment. I also Shortened the steering rack by 70 mm. After doing all this the car is now starting to behave itself (i believe most effect was had from
cutting up the steering rod). I know want to put new springs under the car. I am thinking about progressive springs has any body done this or do you have
normal standard springs for Mantulas? who Knows any good spring manufacturers, i will be doing research into the subject and i thought i would start with the
people with the experience!!
Springs; Whos got what?
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 Tobyjugs |
Springs; Whos got what? |
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Posts: 4 Tue, 10-Mar-2009 10:32 |
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sandyv8 |
shocks | #1 | ||
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Posts: 73 Tue, 10-Mar-2009 11:08 |
Hi Tobyjugs,
Did you not have the springs with the Gaz shocks? Has your car got the Bump-steer mod ? If you refer to an earlier post on page 3 date 15 Feb 2008 , it should help sandyv8 |
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OldNoccer |
#2 | |||
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Posts: 534 Tue, 10-Mar-2009 20:07 |
Like Mr Sandy says, lots of previous on this. The search engine is pretty handy (except it ignores anything less that 4 letters).
Bump steer mods CRITICAL - all else falls into insignificance IMHO. After that there is still plenty to talk about over a pint ! For example the size of the rear tyres (205/60s ?) and if its an IRS model, then loads more to worry over ! Mine came with 400 and 450 pound/inch springs - not wobbly - but a bit bouncy ! Steve
There's a lot of talk these days about green transport. Well, I am ahead of the game, I already have green transport ... British racing green.
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Tobyjugs |
#3 | |||
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Posts: 5 Wed, 11-Mar-2009 09:56 |
I have read everything on this forum and have seen the before and after pictures from the bump steer mods. From the pictures i would guess that my lower
wishbones are in the correct place. It would be much better to see it in the flesh with my car as a comparison. I also found that the tyre size was also
important after changing the large tyres which the car came with for the reccomended size. I changed back to the original size which allows the body to drop
lower in comparison to the center of the wheel. It really is give and take small tyres lower ground clearance lift car up as not to leave sump or cats behind
on road or bigger tyres drop chassis down until rear wheels bottom out on arches. I did forget to mention that the the car is a live axel version and i do
think that with the larger tyers you can lower the chassis to get the trailing arms in a better position. and when i was adjusting the front geometry the
hieght also played its part in getting the correct settings.
My springs at the front are still ok in relation to each other but the back ones are sitting at two different heights with the same amout of pressure on them. I want to get new springs but i want to find out as much info as possible before i buy some. Cheers |
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dparslow |
#4 | |||
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Posts: 644 Wed, 11-Mar-2009 15:15 Chief mechanic |
I believe the original front springs were rated at 250lbs/inch and the rears 170lbs/inch and are both 12" in length on live axle Mantulas.
It`s not more power you need, it`s less weight and a few subtle mods!
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OldNoccer |
#5 | |||
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Posts: 538 Wed, 11-Mar-2009 23:28 |
You have cats ? Not needed on my 1995 car.
As regards the tyres, mine came with 195/60x14 on the back, and I tried 205/60x14 and 205/70x14, and the effect on the handling was quite marked. I have gone back to the 205/60x14s as they were the 'correct' size and the handling felt best - also the ground clearance and wheel arch appearance was best. However, in that size I couldn't get anything over H rating - which is fine for the road, but might be a bit stressed on a track day ! I asked my insurer and they said OK - for the road. I may buy a second set of wheels at some stage but I like the look of the original 14" Revolutions. Steve
There's a lot of talk these days about green transport. Well, I am ahead of the game, I already have green transport ... British racing green.
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dparslow |
#6 | |||
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Posts: 645 Thu, 12-Mar-2009 13:13 Chief mechanic |
Live axle cars originally had 195/60x14 front and 205/60x14 rear, IRS cars had 195/50x15 and 205/50x15.
It`s not more power you need, it`s less weight and a few subtle mods!
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OldNoccer |
#7 | |||
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Posts: 540 Fri, 13-Mar-2009 00:19 |
I am not sure you are right about the 15" wheel on IRS models. Mine is IRS and has 14" wheels and has had them for at least 10 years as I have
receipts for tyres. Also I have the 30th anniversary price list from when mine was bought (Bought 1990, Registered 1995), and that says it is independent
suspension only, but still states the tyres are 14". I think they must have gone up a size when they went to the Mantara, and changed to silver wheels.
Steve
There's a lot of talk these days about green transport. Well, I am ahead of the game, I already have green transport ... British racing green.
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dparslow |
#8 | |||
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Posts: 647 Fri, 13-Mar-2009 12:13 Chief mechanic |
Steve, you may be correct, maybe the split rim 15" wheels were are option on the very last of the Mantula Spyders as I have not seen them on coupes.
It`s not more power you need, it`s less weight and a few subtle mods!
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Tobyjugs |
#9 | |||
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Posts: 6 Sun, 29-Mar-2009 20:14 |
Thanks for the replys i have spoke to a few spring manufactures and will try some progressive springs for a more comfortable ride but first i need to fit the
engine back in to measure the weight front and back, the ride height and the length of the shocks compressed plus ride height.
I also phoned Rory at MHS about the bump steer kit but the answer i got was not too clear so i have made a photo. As you can see the back of the bottom wishbone is lowered and the front side is still in the center of the bottom chassis rail. Is this the same as the modified chassis or is this standard?Hmm Can't get it on here i don't get on with computers. |
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Tobyjugs |
#10 | |||
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Posts: 7 Sun, 29-Mar-2009 20:40 |
It looks like i have put them in my images
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TayMant |
#11 | |||
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Posts: 10 Thu, 2-Apr-2009 15:46 |
Can anyone answer Tobyjugs question. Do his pictures show the anti bump steer mod or is this a case for suitable treatment. Were the chassis ever modified
before production stopped?
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Tobyjugs |
#12 | |||
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Posts: 8 Fri, 3-Apr-2009 08:20 |
Just looked at martin123 photo's of his chassis and the bottom wishbone pick up points look like they are in the same position as mine. I don't know if
this is any help but my chassis is from 1989.
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MarcosMantula |
#13 | |||
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Posts: 29 Fri, 3-Apr-2009 13:55 |
I'm not aware of the chassis ever being modified but a few of the later Mantulas (mine being one) were fitted with a different steering rack. The racks
were manufactured by Jack Knight and was essentially a Morgan steering rack. This was mounted higher up with the steering arms mounted below the rack so the
loads aren't transmitted in the same way.
I've never driven a Marcos with a standard setup so don't know what it's like but mine has virtually no bump steer. |
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Tobyjugs |
#14 | |||
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Posts: 10 Sat, 4-Apr-2009 08:33 |
I used to have contact now and again with CF Mantula and he did ask a few questions on this forum for me about the jack knight rack. That was the reason why i
modified the original steering rack. This has made a lot of difference to the car. If you google bump steer there is lots of information to read on the
subject. I want to design the front suspension from new, but just do not have the time. It took me two years just to solve an intermitant over heating problem!
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dparslow |
#15 | |||
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Posts: 649 Mon, 6-Apr-2009 16:37 Chief mechanic |
The MHS front anti-bump steer modification I have seen have additional lower wishbone brackets welded below the existing ones to lower the pivot point on the
chassis rail, the original Triumph rack is also modified. The images shown are that of an original chassis with the lower wishbone brackets as it left the
factory. The very last Mantulas had the Jack Knight rack with really long inner tie rods which cured the problem without having to move the wishbone pivots.
It`s not more power you need, it`s less weight and a few subtle mods!
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Tobyjugs |
#16 | |||
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Posts: 11 Mon, 6-Apr-2009 17:12 |
Thanks DP. I will have to finnish the car and try to get back to Britain to have a good look at all the different mods made to the Mantula's, after all
this is a special year for The Marcos clan!!!
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jomeo69 |
#17 | |||
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Posts: 27 Wed, 8-Apr-2009 19:44 |
Hmm interesting. DP how would a Jack knight rack be identified??? Apparently ours was one of the last to leave the factory and would be interesting to know for
historical reasons and also for handling reasons.
Would it have the name stamped on it somewhere??? |
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MarcosMantula |
#18 | |||
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Posts: 31 Wed, 8-Apr-2009 20:19 |
If you want to PM me your email address and I will take a picture of mine and send it to you.
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which is what a Marcos is for.
